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- **absorptive state** also called the fed state; the metabolic state occurring during the first few hours after ingesting food in which the body is digesting food and absorbing the nutrients
- **acetyl coenzyme A (acetyl CoA)** starting molecule of the Krebs cycle
- **anabolic hormones** hormones that stimulate the sy... | {
"Header 1": "**24.7 | Nutrition and Diet**",
"Header 2": "**Major Minerals**",
"Header 3": "**KEY TERMS**",
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Metabolism is the sum of all catabolic (break down) and anabolic (synthesis) reactions in the body. The metabolic rate measures the amount of energy used to maintain life. An organism must ingest a sufficient amount of food to maintain its metabolic rate if the organism is to stay alive for very long.
Catabolic react... | {
"Header 1": "**24.7 | Nutrition and Diet**",
"Header 2": "**Major Minerals**",
"Header 3": "**[24.1 Overview of](#page-1098-1) [Metabolic Reactions](#page-1099-0)**",
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Metabolic enzymes catalyze catabolic reactions that break down carbohydrates contained in food. The energy released is used to power the cells and systems that make up your body. Excess or unutilized energy is stored as fat or glycogen for later use. Carbohydrate metabolism begins in the mouth, where the enzyme salivar... | {
"Header 1": "**24.7 | Nutrition and Diet**",
"Header 2": "**Major Minerals**",
"Header 3": "**[24.2 Carbohydrate Metabolism](#page-1104-0)**",
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Lipids are available to the body from three sources. They can be ingested in the diet, stored in the adipose tissue of the body, or synthesized in the liver. Fats ingested in the diet are digested in the small intestine. The triglycerides are broken down into monoglycerides and free fatty acids, then imported across th... | {
"Header 1": "**24.7 | Nutrition and Diet**",
"Header 2": "**Major Minerals**",
"Header 3": "**[24.3 Lipid Metabolism](#page-1116-0)**",
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Digestion of proteins begins in the stomach, where HCl and pepsin begin the process of breaking down proteins into their constituent amino acids. As the chyme enters the small intestine, it mixes with bicarbonate and digestive enzymes. The bicarbonate neutralizes the acidic HCl, and the digestive enzymes break down the... | {
"Header 1": "**24.7 | Nutrition and Diet**",
"Header 2": "**Major Minerals**",
"Header 3": "**[24.4 Protein Metabolism](#page-1122-0)**",
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There are three main metabolic states of the body: absorptive (fed), postabsorptive (fasting), and starvation. During any given day, your metabolism switches between absorptive and postabsorptive states. Starvation states happen very rarely in generally well-nourished individuals. When the body is fed, glucose, fats, a... | {
"Header 1": "**24.7 | Nutrition and Diet**",
"Header 2": "**Major Minerals**",
"Header 3": "**[24.5 Metabolic States of the Body](#page-1127-0)**",
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Nutrition and diet affect your metabolism. More energy is required to break down fats and proteins than carbohydrates; however, all excess calories that are ingested will be stored as fat in the body. On average, a person requires 1500 to 2000 calories for normal daily activity, although routine exercise will increase ... | {
"Header 1": "**24.7 | Nutrition and Diet**",
"Header 2": "**Major Minerals**",
"Header 3": "**[24.7 Nutrition and Diet](#page-1133-0)**",
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After studying this chapter, you will be able to:
- Describe the composition of urine
- Label structures of the urinary system
- Characterize the roles of each of the parts of the urinary system
- Illustrate the macroscopic and microscopic structures of the kidney
- Trace the flow of blood through the kidney
- Outlin... | {
"Header 1": "**Chapter Objectives**",
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"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
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**Table 25.1**
**Urinalysis** (urine analysis) often provides clues to renal disease. Normally, only traces of protein are found in urine, and when higher amounts are found, damage to the glomeruli is the likely basis. Unusually large quantities of urine may point to diseases like diabetes mellitus or hypothalamic tu... | {
"Header 1": "**25.1 | Physical Characteristics of Urine**",
"Header 3": "**Normal Urine Characteristics**",
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Urine volume varies considerably. The normal range is one to two liters per day (**[Table 25.2](#page-1151-1)**). The kidneys must produce a minimum urine volume of about 500 mL/day to rid the body of wastes. Output below this level may be caused by severe dehydration or renal disease and is termed **oliguria**. The vi... | {
"Header 1": "**25.1 | Physical Characteristics of Urine**",
"Header 3": "**Figure 25.2 Urine Color**",
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The pH (hydrogen ion concentration) of the urine can vary more than 1000-fold, from a normal low of 4.5 to a maximum of 8.0. Diet can influence pH; meats lower the pH, whereas citrus fruits, vegetables, and dairy products raise the pH. Chronically high or low pH can lead to disorders, such as the development of kidney ... | {
"Header 1": "**25.1 | Physical Characteristics of Urine**",
"Header 3": "**Table 25.2**",
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By the end of this section, you will be able to:
- Identify the ureters, urinary bladder, and urethra, as well as their location, structure, histology, and function
- Compare and contrast male and female urethras
- Describe the micturition reflex
- Describe voluntary and involuntary neural control of micturition
Ra... | {
"Header 1": "**25.2 | Gross Anatomy of Urine Transport**",
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The **urethra** transports urine from the bladder to the outside of the body for disposal. The urethra is the only urologic organ that shows any significant anatomic difference between males and females; all other urine transport structures are identical (**[Figure 25.3](#page-1153-0)**).
![](_page_1153_Figure_1.jpeg... | {
"Header 1": "**25.2 | Gross Anatomy of Urine Transport**",
"Header 3": "**Urethra**",
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The male urethra passes through the prostate gland immediately inferior to the bladder before passing below the pubic symphysis (see **[Figure 25.3b](#page-1153-0)**). The length of the male urethra varies between men but averages 20 cm in length. It is divided into four regions: the preprostatic urethra, the prostatic... | {
"Header 1": "**25.2 | Gross Anatomy of Urine Transport**",
"Header 3": "**Male Urethra**",
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The urinary bladder collects urine from both ureters (**[Figure 25.4](#page-1154-0)**). The bladder lies anterior to the uterus in females, posterior to the pubic bone and anterior to the rectum. During late pregnancy, its capacity is reduced due to compression by the enlarging uterus, resulting in increased frequency ... | {
"Header 1": "**25.2 | Gross Anatomy of Urine Transport**",
"Header 3": "**Bladder**",
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**Micturition** is a less-often used, but proper term for urination or voiding. It results from an interplay of involuntary and voluntary actions by the internal and external urethral sphincters. When bladder volume reaches about 150 mL, an urge to void is sensed but is easily overridden. Voluntary control of urination... | {
"Header 1": "**25.2 | Gross Anatomy of Urine Transport**",
"Header 3": "**Micturition Reflex**",
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The kidneys and ureters are completely retroperitoneal, and the bladder has a peritoneal covering only over the dome. As urine is formed, it drains into the calyces of the kidney, which merge to form the funnel-shaped renal pelvis in the hilum of each kidney. The hilum narrows to become the ureter of each kidney. As ur... | {
"Header 1": "**25.2 | Gross Anatomy of Urine Transport**",
"Header 3": "**Ureters**",
"token_count": 439,
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By the end of this section, you will be able to:
- Describe the external structure of the kidney, including its location, support structures, and covering
- Identify the major internal divisions and structures of the kidney
- Identify the major blood vessels associated with the kidney and trace the path of blood thro... | {
"Header 1": "**25.3 | Gross Anatomy of the Kidney**",
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The left kidney is located at about the T12 to L3 vertebrae, whereas the right is lower due to slight displacement by the liver. Upper portions of the kidneys are somewhat protected by the eleventh and twelfth ribs (**[Figure 25.7](#page-1157-0)**). Each kidney weighs about 125–175 g in males and 115–155 g in females. ... | {
"Header 1": "**25.3 | Gross Anatomy of the Kidney**",
"Header 3": "**External Anatomy**",
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**Nephrons** are the "functional units" of the kidney; they cleanse the blood and balance the constituents of the circulation. The afferent arterioles form a tuft of high-pressure capillaries about 200 µm in diameter, the **glomerulus**. The rest of the nephron consists of a continuous sophisticated tubule whose proxim... | {
"Header 1": "**25.3 | Gross Anatomy of the Kidney**",
"Header 3": "**Figure 25.9 Blood Flow in the Kidney**",
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As discussed earlier, the renal corpuscle consists of a tuft of capillaries called the glomerulus that is largely surrounded by Bowman's (glomerular) capsule. The glomerulus is a high-pressure capillary bed between afferent and efferent arterioles. Bowman's capsule surrounds the glomerulus to form a lumen, and captures... | {
"Header 1": "**25.4 | Microscopic Anatomy of the Kidney**",
"Header 3": "**Renal Corpuscle**",
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The collecting ducts are continuous with the nephron but not technically part of it. In fact, each duct collects filtrate from several nephrons for final modification. Collecting ducts merge as they descend deeper in the medulla to form about 30 terminal ducts, which empty at a papilla. They are lined with simple squam... | {
"Header 1": "**25.4 | Microscopic Anatomy of the Kidney**",
"Header 3": "**Collecting Ducts**",
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The volume of filtrate formed by both kidneys per minute is termed the **glomerular filtration rate (GFR)**. The heart pumps about 5 L blood per min under resting conditions. Approximately 20 percent or one liter enters the kidneys to be filtered. On average, this liter results in the production of about 125 mL/min fil... | {
"Header 1": "**25.5 | Physiology of Urine Formation**",
"Header 3": "**Glomerular Filtration Rate (GFR)**",
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GFR is influenced by the hydrostatic pressure and colloid osmotic pressure on either side of the capillary membrane of the glomerulus. Recall that filtration occurs as pressure forces fluid and solutes through a semipermeable barrier with the solute movement constrained by particle size. Hydrostatic pressure is the pre... | {
"Header 1": "**25.5 | Physiology of Urine Formation**",
"Header 3": "**Table 25.4**",
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NFP determines filtration rates through the kidney. It is determined as follows:
NFP = Glomerular blood hydrostatic pressure (GBHP) – [capsular hydrostatic pressure (CHP) + blood colloid osmotic pressure (BCOP)] = 10 mm Hg
That is:
NFP = GBHP – [CHP + BCOP] = 10 mm Hg
Or:
NFP = 55 – [15 + 30] = 10 mm Hg
As ... | {
"Header 1": "**25.5 | Physiology of Urine Formation**",
"Header 3": "**Net Filtration Pressure (NFP)**",
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By the end of this section, you will be able to:
- List specific transport mechanisms occurring in different parts of the nephron, including active transport, osmosis, facilitated diffusion, and passive electrochemical gradients
- List the different membrane proteins of the nephron, including channels, transporters, ... | {
"Header 1": "**25.6 | Tubular Reabsorption**",
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"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
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Mechanisms by which substances move across membranes for reabsorption or secretion include active transport, diffusion, facilitated diffusion, secondary active transport, and osmosis. These were discussed in an earlier chapter, and you may wish to review them.
Active transport utilizes energy, usually the energy foun... | {
"Header 1": "**25.6 | Tubular Reabsorption**",
"Header 3": "**Mechanisms of Recovery**",
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The renal corpuscle filters the blood to create a filtrate that differs from blood mainly in the absence of cells and large proteins. From this point to the ends of the collecting ducts, the filtrate or forming urine is undergoing modification through secretion and reabsorption before true urine is produced. The first ... | {
"Header 1": "**25.6 | Tubular Reabsorption**",
"Header 3": "**Reabsorption and Secretion in the PCT**",
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More substances move across the membranes of the PCT than any other portion of the nephron. Many of these substances (amino acids and glucose) use symport mechanisms for transport along with Na<sup>+</sup> . Antiport, active transport, diffusion, and facilitated diffusion are additional mechanisms by which substances a... | {
"Header 1": "**25.6 | Tubular Reabsorption**",
"Header 3": "**Figure 25.18 Substances Reabsorbed and Secreted by the PCT**",
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**Table 25.7**
| Basal membrane | Apical membrane |
|----------------|---------------------------------|
| 3 −<br>PO4 | Amino acids |
| Amino acids | Glucose |
| Glucose | Fructose |
| Fructose | Galactose ... | {
"Header 1": "**25.6 | Tubular Reabsorption**",
"Header 3": "**Reabsorption of Major Solutes by the PCT**",
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The loop of Henle consists of two sections: thick and thin descending and thin and thick ascending sections. The loops of cortical nephrons do not extend into the renal medulla very far, if at all. Juxtamedullary nephrons have loops that extend variable distances, some very deep into the medulla. The descending and asc... | {
"Header 1": "**25.6 | Tubular Reabsorption**",
"Header 3": "**Reabsorption and Secretion in the Loop of Henle**",
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The ascending loop is made of very short thin and longer thick portions. Once again, to simplify the function, this section only considers the thick portion. The thick portion is lined with simple cuboidal epithelium without a brush border. It is completely impermeable to water due to the absence of aquaporin proteins,... | {
"Header 1": "**25.6 | Tubular Reabsorption**",
"Header 3": "**Ascending Loop**",
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As discussed above, the ascending loop has many Na<sup>+</sup> pumps that actively pump Na<sup>+</sup> out of the forming urine into the interstitial spaces. In addition, collecting ducts have urea pumps that actively pump urea into the interstitial spaces. This results in the recovery of Na<sup>+</sup> to the circulat... | {
"Header 1": "**25.6 | Tubular Reabsorption**",
"Header 3": "**Figure 25.20 Countercurrent Multiplier System**",
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Approximately 80 percent of filtered water has been recovered by the time the dilute forming urine enters the DCT. The DCT will recover another 10–15 percent before the forming urine enters the collecting ducts. Aldosterone increases the amount of Na<sup>+</sup> /K<sup>+</sup> ATPase in the basal membrane of the DCT an... | {
"Header 1": "**25.6 | Tubular Reabsorption**",
"Header 3": "**Reabsorption and Secretion in the Distal Convoluted Tubule**",
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Solutes move across the membranes of the collecting ducts, which contain two distinct cell types, principal cells and intercalated cells. A **principal cell** possesses channels for the recovery or loss of sodium and potassium. An **intercalated cell** secretes or absorbs acid or bicarbonate. As in other portions of th... | {
"Header 1": "**25.6 | Tubular Reabsorption**",
"Header 3": "**Collecting Ducts and Recovery of Water**",
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The kidneys are innervated by the sympathetic neurons of the autonomic nervous system via the celiac plexus and splanchnic nerves. Reduction of sympathetic stimulation results in vasodilation and increased blood flow through the kidneys during resting conditions. When the frequency of action potentials increases, the a... | {
"Header 1": "**25.7 | Regulation of Renal Blood Flow**",
"Header 3": "**Sympathetic Nerves**",
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The **tubuloglomerular feedback** mechanism involves the JGA and a paracrine signaling mechanism utilizing ATP, adenosine, and nitric oxide (NO). This mechanism stimulates either contraction or relaxation of afferent arteriolar smooth muscle cells (Table 25.8). Recall that the DCT is in intimate contact with the affere... | {
"Header 1": "**25.7 | Regulation of Renal Blood Flow**",
"Header 3": "**Tubuloglomerular Feedback**",
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Renin is an enzyme that is produced by the granular cells of the afferent arteriole at the JGA. It enzymatically converts angiotensinogen (made by the liver, freely circulating) into angiotensin I. Its release is stimulated by prostaglandins and NO from the JGA in response to decreased extracellular fluid volume.
ACE... | {
"Header 1": "**25.8** Endocrine Regulation of Kidney Function",
"Header 3": "Renin–Angiotensin–Aldosterone",
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Natriuretic hormones are peptides that stimulate the kidneys to excrete sodium—an effect opposite that of aldosterone. Natriuretic hormones act by inhibiting aldosterone release and therefore inhibiting Na<sup>+</sup> recovery in the collecting ducts. If Na<sup>+</sup> remains in the forming urine, its osmotic force wi... | {
"Header 1": "**25.8** Endocrine Regulation of Kidney Function",
"Header 3": "**Natriuretic Hormones**",
"token_count": 352,
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The body cannot directly measure blood volume, but blood pressure can be measured. Blood pressure often reflects blood volume and is measured by baroreceptors in the aorta and carotid sinuses. When blood pressure increases, baroreceptors send more frequent action potentials to the central nervous system, leading to wid... | {
"Header 1": "**25.9 | Regulation of Fluid Volume and Composition**",
"Header 3": "**Volume-sensing Mechanisms**",
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A **diuretic** is a compound that increases urine volume. Three familiar drinks contain diuretic compounds: coffee, tea, and alcohol. The caffeine in coffee and tea works by promoting vasodilation in the nephron, which increases GFR. Alcohol increases GFR by inhibiting ADH release from the posterior pituitary, resultin... | {
"Header 1": "**25.9 | Regulation of Fluid Volume and Composition**",
"Header 3": "**Diuretics and Fluid Volume**",
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Sodium has a very strong osmotic effect and attracts water. It plays a larger role in the osmolarity of the plasma than any other circulating component of the blood. If there is too much Na<sup>+</sup> present, either due to poor control or excess dietary consumption, a series of metabolic problems ensue. There is an i... | {
"Header 1": "**25.9 | Regulation of Fluid Volume and Composition**",
"Header 2": "**Regulation of Extracellular Na<sup>+</sup>**",
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The acid–base homeostasis of the body is a function of chemical buffers and physiologic buffering provided by the lungs and kidneys. Buffers, especially proteins, HCO<sup>3</sup> 2 − , and ammonia have a very large capacity to absorb or release H<sup>+</sup> as needed to resist a change in pH. They can act within fract... | {
"Header 1": "**Regulation of Ca++ and Phosphate**",
"Header 3": "**Regulation of H<sup>+</sup> , Bicarbonate, and pH**",
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In order for vitamin D to become active, it must undergo a hydroxylation reaction in the kidney, that is, an –OH group must be added to calcidiol to make calcitriol (1,25-dihydroxycholecalciferol). Activated vitamin D is important for absorption of Ca++ in the digestive tract, its reabsorption in the kidney, and the ma... | {
"Header 1": "**25.10 | The Urinary System and Homeostasis**",
"Header 3": "**Vitamin D Synthesis**",
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EPO is a 193-amino acid protein that stimulates the formation of red blood cells in the bone marrow. The kidney produces 85 percent of circulating EPO; the liver, the remainder. If you move to a higher altitude, the partial pressure of oxygen is lower, meaning there is less pressure to push oxygen across the alveolar m... | {
"Header 1": "**25.10 | The Urinary System and Homeostasis**",
"Header 3": "**Erythropoiesis**",
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Due to osmosis, water follows where Na<sup>+</sup> leads. Much of the water the kidneys recover from the forming urine follows the
reabsorption of Na<sup>+</sup> . ADH stimulation of aquaporin channels allows for regulation of water recovery in the collecting ducts. Normally, all of the glucose is recovered, but loss... | {
"Header 1": "**25.10 | The Urinary System and Homeostasis**",
"Header 3": "**Blood Pressure Regulation**",
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Stem cells are unspecialized cells that can reproduce themselves via cell division, sometimes after years of inactivity. Under certain conditions, they may differentiate into tissue-specific or organ-specific cells with special functions. In some cases, stem cells may continually divide to produce a mature cell and to ... | {
"Header 1": "**25.10 | The Urinary System and Homeostasis**",
"Header 2": "**Stem Cells and Repair of Kidney Damage**",
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- **anatomical sphincter** smooth or skeletal muscle surrounding the lumen of a vessel or hollow organ that can restrict flow when contracted
- **angiotensin I** protein produced by the enzymatic action of renin on angiotensinogen; inactive precursor of angiotensin II
- **angiotensin II** protein produced by the enzyma... | {
"Header 1": "**25.10 | The Urinary System and Homeostasis**",
"Header 2": "**Stem Cells and Repair of Kidney Damage**",
"Header 3": "**KEY TERMS**",
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between the parietal peritoneum and the abdominal wall
- **sacral micturition center** group of neurons in the sacral region of the spinal cord that controls urination; acts reflexively unless its action is modified by higher brain centers to allow voluntary urination
- **specific gravity** weight of a liquid compared ... | {
"Header 1": "**25.10 | The Urinary System and Homeostasis**",
"Header 2": "**Stem Cells and Repair of Kidney Damage**",
"Header 3": "**KEY TERMS**",
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The urethra is the only urinary structure that differs significantly between males and females. This is due to the dual role of the male urethra in transporting both urine and semen. The urethra arises from the trigone area at the base of the bladder. Urination is controlled by an involuntary internal sphincter of smoo... | {
"Header 1": "**25.10 | The Urinary System and Homeostasis**",
"Header 2": "**Stem Cells and Repair of Kidney Damage**",
"Header 3": "**[25.2 Gross Anatomy of Urine Transport](#page-1152-0)**",
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As noted previously, the structure of the kidney is divided into two principle regions—the peripheral rim of cortex and the central medulla. The two kidneys receive about 25 percent of cardiac output. They are protected in the retroperitoneal space by the renal fat pad and overlying ribs and muscle. Ureters, blood vess... | {
"Header 1": "**25.10 | The Urinary System and Homeostasis**",
"Header 2": "**Stem Cells and Repair of Kidney Damage**",
"Header 3": "**[25.3 Gross Anatomy of the Kidney](#page-1156-0)**",
"token_count": 250,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
The functional unit of the kidney, the nephron, consists of the renal corpuscle, PCT, loop of Henle, and DCT. Cortical nephrons have short loops of Henle, whereas juxtamedullary nephrons have long loops of Henle extending into the medulla. About 15 percent of nephrons are juxtamedullary. The glomerulus is a capillary b... | {
"Header 1": "**25.10 | The Urinary System and Homeostasis**",
"Header 2": "**Stem Cells and Repair of Kidney Damage**",
"Header 3": "**[25.4 Microscopic Anatomy of the Kidney](#page-1161-0)**",
"token_count": 293,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
The kidney regulates water recovery and blood pressure by producing the enzyme renin. It is renin that starts a series of reactions, leading to the production of the vasoconstrictor angiotensin II and the salt-retaining steroid aldosterone. Water recovery is also powerfully and directly influenced by the hormone ADH. E... | {
"Header 1": "**25.10 | The Urinary System and Homeostasis**",
"Header 2": "**Stem Cells and Repair of Kidney Damage**",
"Header 3": "**[25.6 Tubular Reabsorption](#page-1168-0)**",
"token_count": 619,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
Endocrine hormones act from a distance and paracrine hormones act locally. The renal enzyme renin converts angiotensinogen into angiotensin I. The lung enzyme, ACE, converts angiotensin I into active angiotensin II. Angiotensin II is an active vasoconstrictor that increases blood pressure. Angiotensin II also stimulate... | {
"Header 1": "**25.10 | The Urinary System and Homeostasis**",
"Header 2": "**Stem Cells and Repair of Kidney Damage**",
"Header 3": "**[25.8 Endocrine Regulation of Kidney Function](#page-1178-0)**",
"token_count": 234,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
The major hormones regulating body fluids are ADH, aldosterone and ANH. Progesterone is similar in structure to aldosterone and can bind to and weakly stimulate aldosterone receptors, providing a similar but diminished response. Blood pressure is a reflection of blood volume and is monitored by baroreceptors in the aor... | {
"Header 1": "**25.10 | The Urinary System and Homeostasis**",
"Header 2": "**Stem Cells and Repair of Kidney Damage**",
"Header 3": "**[25.9 Regulation of Fluid Volume and Composition](#page-1180-0)**",
"token_count": 350,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
After studying this chapter, you will be able to:
- Identify the body's main fluid compartments
- Define plasma osmolality and identify two ways in which plasma osmolality is maintained
- Identify the six ions most important to the function of the body
- Define buffer and discuss the role of buffers in the body
- Exp... | {
"Header 1": "**Chapter Objectives**",
"token_count": 257,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
By the end of this section, you will be able to:
- Explain the importance of water in the body
- Contrast the composition of the intracellular fluid with that of the extracellular fluid
- Explain the importance of protein channels in the movement of solutes
- Identify the causes and symptoms of edema
The chemical r... | {
"Header 1": "**26.1 | Body Fluids and Fluid Compartments**",
"token_count": 295,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
Human beings are mostly water, ranging from about 75 percent of body mass in infants to about 50–60 percent in adult men and women, to as low as 45 percent in old age. The percent of body water changes with development, because the proportions of the body given over to each organ and to muscles, fat, bone, and other ti... | {
"Header 1": "**26.1 | Body Fluids and Fluid Compartments**",
"Header 3": "**Body Water Content**",
"token_count": 213,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
Body fluids can be discussed in terms of their specific **fluid compartment**, a location that is largely separate from another compartment by some form of a physical barrier. The **intracellular fluid (ICF)** compartment is the system that includes all fluid enclosed in cells by their plasma membranes. **Extracellular... | {
"Header 1": "**26.1 | Body Fluids and Fluid Compartments**",
"Header 3": "**Fluid Compartments**",
"token_count": 222,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
The ICF lies within cells and is the principal component of the cytosol/cytoplasm. The ICF makes up about 60 percent of the total water in the human body, and in an average-size adult male, the ICF accounts for about 25 liters (seven gallons) of fluid (**[Figure 26.4](#page-1197-1)**). This fluid volume tends to be ver... | {
"Header 1": "**26.1 | Body Fluids and Fluid Compartments**",
"Header 3": "**Intracellular Fluid**",
"token_count": 232,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
The ECF accounts for the other one-third of the body's water content. Approximately 20 percent of the ECF is found in plasma. Plasma travels through the body in blood vessels and transports a range of materials, including blood cells, proteins (including clotting factors and antibodies), electrolytes, nutrients, gases,... | {
"Header 1": "**26.1 | Body Fluids and Fluid Compartments**",
"Header 3": "**Extracellular Fluid**",
"token_count": 217,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
The compositions of the two components of the ECF—plasma and IF—are more similar to each other than either is to the ICF (**[Figure 26.5](#page-1198-0)**). Blood plasma has high concentrations of sodium, chloride, bicarbonate, and protein. The IF has high concentrations of sodium, chloride, and bicarbonate, but a relat... | {
"Header 1": "**26.1 | Body Fluids and Fluid Compartments**",
"Header 3": "**Composition of Body Fluids**",
"token_count": 581,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
**Hydrostatic pressure**, the force exerted by a fluid against a wall, causes movement of fluid between compartments. The hydrostatic pressure of blood is the pressure exerted by blood against the walls of the blood vessels by the pumping action of the heart. In capillaries, hydrostatic pressure (also known as capillar... | {
"Header 1": "**26.1 | Body Fluids and Fluid Compartments**",
"Header 3": "**Fluid Movement between Compartments**",
"token_count": 858,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
The movement of some solutes between compartments is active, which consumes energy and is an active transport process, whereas the movement of other solutes is passive, which does not require energy. Active transport allows cells to move a specific substance against its concentration gradient through a membrane protein... | {
"Header 1": "**26.1 | Body Fluids and Fluid Compartments**",
"Header 3": "**Solute Movement between Compartments**",
"token_count": 344,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
Edema is the accumulation of excess water in the tissues. It is most common in the soft tissues of the extremities. The physiological causes of edema include water leakage from blood capillaries. Edema is almost always caused by an underlying medical condition, by the use of certain therapeutic drugs, by pregnancy, by ... | {
"Header 1": "**26.1 | Body Fluids and Fluid Compartments**",
"Header 3": "**Fluid Balance: Edema**",
"token_count": 788,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
By the end of this section, you will be able to:
- Explain how water levels in the body influence the thirst cycle
- Identify the main route by which water leaves the body
- Describe the role of ADH and its effect on body water levels
- Define dehydration and identify common causes of dehydration
On a typical day, ... | {
"Header 1": "**26.2 | Water Balance**",
"token_count": 265,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
Osmolality is the ratio of solutes in a solution to a volume of solvent in a solution. **Plasma osmolality** is thus the ratio of solutes to water in blood plasma. A person's plasma osmolality value reflects his or her state of hydration. A healthy body maintains plasma osmolality within a narrow range, by employing se... | {
"Header 1": "**26.2 | Water Balance**",
"Header 3": "**Regulation of Water Intake**",
"token_count": 714,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
Water loss from the body occurs predominantly through the renal system. A person produces an average of 1.5 liters (1.6 quarts) of urine per day. Although the volume of urine varies in response to hydration levels, there is a minimum volume of urine production required for proper bodily functions. The kidney excretes 1... | {
"Header 1": "**26.2 | Water Balance**",
"Header 3": "**Regulation of Water Output**",
"token_count": 248,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
**Antidiuretic hormone (ADH)**, also known as vasopressin, controls the amount of water reabsorbed from the collecting ducts and tubules in the kidney. This hormone is produced in the hypothalamus and is delivered to the posterior pituitary for storage and release (**[Figure 26.11](#page-1205-0)**). When the osmorecept... | {
"Header 1": "**26.2 | Water Balance**",
"Header 3": "**Role of ADH**",
"token_count": 559,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
By the end of this section, you will be able to:
- List the role of the six most important electrolytes in the body
- Name the disorders associated with abnormally high and low levels of the six electrolytes
- Identify the predominant extracellular anion
- Describe the role of aldosterone on the level of water in the... | {
"Header 1": "**26.3 | Electrolyte Balance**",
"token_count": 225,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
These six ions aid in nerve excitability, endocrine secretion, membrane permeability, buffering body fluids, and controlling the movement of fluids between compartments. These ions enter the body through the digestive tract. More than 90 percent of the calcium and phosphate that enters the body is incorporated into bon... | {
"Header 1": "**26.3 | Electrolyte Balance**",
"Header 3": "**Roles of Electrolytes**",
"token_count": 711,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
Sodium is the major cation of the extracellular fluid. It is responsible for one-half of the osmotic pressure gradient that exists between the interior of cells and their surrounding environment. People eating a typical Western diet, which is very high in NaCl, routinely take in 130 to 160 mmol/day of sodium, but human... | {
"Header 1": "**26.3 | Electrolyte Balance**",
"Header 3": "**Sodium**",
"token_count": 490,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
Potassium is the major intracellular cation. It helps establish the resting membrane potential in neurons and muscle fibers after membrane depolarization and action potentials. In contrast to sodium, potassium has very little effect on osmotic pressure. The low levels of potassium in blood and CSF are due to the sodium... | {
"Header 1": "**26.3 | Electrolyte Balance**",
"Header 3": "**Potassium**",
"token_count": 506,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
Chloride is the predominant extracellular anion. Chloride is a major contributor to the osmotic pressure gradient between the ICF and ECF, and plays an important role in maintaining proper hydration. Chloride functions to balance cations in the ECF, maintaining the electrical neutrality of this fluid. The paths of secr... | {
"Header 1": "**26.3 | Electrolyte Balance**",
"Header 3": "**Chloride**",
"token_count": 301,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
Bicarbonate is the second most abundant anion in the blood. Its principal function is to maintain your body's acid-base balance by being part of buffer systems. This role will be discussed in a different section.
Bicarbonate ions result from a chemical reaction that starts with carbon dioxide (CO2) and water, two mol... | {
"Header 1": "**26.3 | Electrolyte Balance**",
"Header 3": "**Bicarbonate**",
"token_count": 286,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
About two pounds of calcium in your body are bound up in bone, which provides hardness to the bone and serves as a mineral reserve for calcium and its salts for the rest of the tissues. Teeth also have a high concentration of calcium within them. A little more than one-half of blood calcium is bound to proteins, leavin... | {
"Header 1": "**26.3 | Electrolyte Balance**",
"Header 3": "**Calcium**",
"token_count": 275,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
Phosphate is present in the body in three ionic forms: $H_2PO_{4-}$ , $HPO_{4-}^2$ , and $PO_{4-}^3$ . The most common form is
$\mathrm{HPO}_4^{2-}$ . Bone and teeth bind up 85 percent of the body's phosphate as part of calcium-phosphate salts. Phosphate is found
in phospholipids, such as those that make up the... | {
"Header 1": "**26.3 | Electrolyte Balance**",
"Header 3": "**Phosphate**",
"token_count": 246,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
Angiotensin II causes vasoconstriction and an increase in systemic blood pressure. This action increases the glomerular filtration rate, resulting in more material filtered out of the glomerular capillaries and into Bowman's capsule. Angiotensin II also signals an increase in the release of aldosterone from the adrenal... | {
"Header 1": "**26.3 | Electrolyte Balance**",
"Header 3": "**Angiotensin II**",
"token_count": 262,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
Calcium and phosphate are both regulated through the actions of three hormones: parathyroid hormone (PTH), dihydroxyvitamin D (calcitriol), and calcitonin. All three are released or synthesized in response to the blood levels of calcium.
PTH is released from the parathyroid gland in response to a decrease in the conc... | {
"Header 1": "**26.3 | Electrolyte Balance**",
"Header 3": "**Regulation of Calcium and Phosphate**",
"token_count": 216,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
Phosphates are found in the blood in two forms: sodium dihydrogen phosphate ( $Na_2H_2PO_4^-$ ), which is a weak acid, and sodium monohydrogen phosphate ( $Na_2HPO_4^{2-}$ ), which is a weak base. When $Na_2HPO_4^{2-}$ comes into contact with a strong acid, such as HCl, the base picks up a second hydrogen ion to form... | {
"Header 1": "**26.4 | Acid-Base Balance**",
"Header 3": "Phosphate Buffer",
"token_count": 316,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
The bicarbonate-carbonic acid buffer works in a fashion similar to phosphate buffers. The bicarbonate is regulated in the blood by sodium, as are the phosphate ions. When sodium bicarbonate (NaHCO<sub>3</sub>), comes into contact with a strong acid, such as HCl, carbonic acid (H<sub>2</sub>CO<sub>3</sub>), which is a w... | {
"Header 1": "**26.4 | Acid-Base Balance**",
"Header 3": "**Bicarbonate-Carbonic Acid Buffer**",
"token_count": 539,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
The respiratory system contributes to the balance of acids and bases in the body by regulating the blood levels of carbonic acid (**Figure 26.16**). CO<sub>2</sub> in the blood readily reacts with water to form carbonic acid, and the levels of CO<sub>2</sub> and carbonic acid in the blood are in equilibrium. When the C... | {
"Header 1": "**26.4 | Acid-Base Balance**",
"Header 3": "**Respiratory Regulation of Acid-Base Balance**",
"token_count": 734,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
The renal regulation of the body's acid-base balance addresses the metabolic component of the buffering system. Whereas the respiratory system (together with breathing centers in the brain) controls the blood levels of carbonic acid by controlling the exhalation of CO2, the renal system controls the blood levels of bic... | {
"Header 1": "**26.4 | Acid-Base Balance**",
"Header 3": "**Renal Regulation of Acid-Base Balance**",
"token_count": 751,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
Diabetic acidosis, or ketoacidosis, occurs most frequently in people with poorly controlled diabetes mellitus. When certain tissues in the body cannot get adequate amounts of glucose, they depend on the breakdown of fatty acids for energy. When acetyl groups break off the fatty acid chains, the acetyl groups then non-e... | {
"Header 1": "**26.4 | Acid-Base Balance**",
"Header 3": "**Acid-Base Balance: Ketoacidosis**",
"token_count": 309,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
By the end of this section, you will be able to:
- Identify the three blood variables considered when making a diagnosis of acidosis or alkalosis
- Identify the source of compensation for blood pH problems of a respiratory origin
- Identify the source of compensation for blood pH problems of a metabolic/renal origin ... | {
"Header 1": "**26.5 | Disorders of Acid-Base Balance**",
"token_count": 435,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
| Cause | Metabolite |
|-----------------------|--------------------------------------------------|
| Diarrhea | Bicarbonate |
| Uremia | Phosphoric, sulfuric, and lactic acids |
| Diabetic k... | {
"Header 1": "**26.5 | Disorders of Acid-Base Balance**",
"Header 3": "**Common Causes of Metabolic Acidosis and Blood Metabolites**",
"token_count": 353,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
**Respiratory alkalosis** occurs when the blood is overly alkaline due to a deficiency in carbonic acid and CO2 levels in the blood. This condition usually occurs when too much CO2 is exhaled from the lungs, as occurs in hyperventilation, which is breathing that is deeper or more frequent than normal. An elevated respi... | {
"Header 1": "**26.5 | Disorders of Acid-Base Balance**",
"Header 2": "**Respiratory Acidosis: Primary Carbonic Acid/CO2 Excess**",
"Header 3": "**Respiratory Alkalosis: Primary Carbonic Acid/CO2 Deficiency**",
"token_count": 221,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR... |
Lab tests for pH, CO2 partial pressure (pCO2), and HCO3 – can identify acidosis and alkalosis, indicating whether the imbalance is respiratory or metabolic, and the extent to which compensatory mechanisms are working. The blood pH value, as shown in **[Table 26.3](#page-1219-0)**, indicates whether the blood is in acid... | {
"Header 1": "**26.5 | Disorders of Acid-Base Balance**",
"Header 2": "**Respiratory Acidosis: Primary Carbonic Acid/CO2 Excess**",
"Header 3": "**Diagnosing Acidosis and Alkalosis**",
"token_count": 286,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
**Table 26.3 Reference values (arterial): pH: 7.35–7.45; pCO2: male: 35–48 mm Hg, female: 32–45 mm Hg; total venous bicarbonate: 22–29 mM. N denotes normal; ↑ denotes a rising or increased value; and ↓ denotes a falling or decreased value.**
Metabolic acidosis is problematic, as lower-than-normal amounts of bicarbona... | {
"Header 1": "**26.5 | Disorders of Acid-Base Balance**",
"Header 2": "**Respiratory Acidosis: Primary Carbonic Acid/CO2 Excess**",
"Header 3": "**Types of Acidosis and Alkalosis**",
"token_count": 357,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
After studying this chapter, you will be able to:
- Describe the anatomy of the male and female reproductive systems, including their accessory structures
- Explain the role of hypothalamic and pituitary hormones in male and female reproductive function
- Trace the path of a sperm cell from its initial production thr... | {
"Header 1": "**Chapter Objectives**",
"token_count": 296,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
By the end of this section, you will be able to:
- Describe the structure and function of the organs of the male reproductive system
- Describe the structure and function of the sperm cell
- Explain the events during spermatogenesis that produce haploid sperm from diploid cells
- Identify the importance of testostero... | {
"Header 1": "**27.1 | Anatomy and Physiology of the Male Reproductive System**",
"token_count": 380,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
The testes are located in a skin-covered, highly pigmented, muscular sack called the **scrotum** that extends from the body behind the penis (see **[Figure 27.2](#page-1226-0)**). This location is important in sperm production, which occurs within the testes, and proceeds more efficiently when the testes are kept 2 to ... | {
"Header 1": "**27.1 | Anatomy and Physiology of the Male Reproductive System**",
"Header 3": "**Scrotum**",
"token_count": 324,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
The **testes** (singular = testis) are the male **gonads**—that is, the male reproductive organs. They produce both sperm and androgens, such as testosterone, and are active throughout the reproductive lifespan of the male.
Paired ovals, the testes are each approximately 4 to 5 cm in length and are housed within the ... | {
"Header 1": "**27.1 | Anatomy and Physiology of the Male Reproductive System**",
"Header 3": "**Testes**",
"token_count": 617,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
As just noted, spermatogenesis occurs in the seminiferous tubules that form the bulk of each testis (see **[Figure 27.4](#page-1228-0)**). The process begins at puberty, after which time sperm are produced constantly throughout a man's life. One production cycle, from spermatogonia through formed sperm, takes approxima... | {
"Header 1": "**27.1 | Anatomy and Physiology of the Male Reproductive System**",
"Header 3": "**Spermatogenesis**",
"token_count": 766,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
Sperm are smaller than most cells in the body; in fact, the volume of a sperm cell is 85,000 times less than that of the female gamete. Approximately 100 to 300 million sperm are produced each day, whereas women typically ovulate only one oocyte per month as is true for most cells in the body, the structure of sperm ce... | {
"Header 1": "**27.1 | Anatomy and Physiology of the Male Reproductive System**",
"Header 3": "**Structure of Formed Sperm**",
"token_count": 352,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
From the lumen of the seminiferous tubules, the immotile sperm are surrounded by testicular fluid and moved to the **epididymis** (plural = epididymides), a coiled tube attached to the testis where newly formed sperm continue to mature (see **[Figure 27.4](#page-1228-0)**). Though the epididymis does not take up much r... | {
"Header 1": "**27.1 | Anatomy and Physiology of the Male Reproductive System**",
"Header 3": "**Role of the Epididymis**",
"token_count": 258,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
During ejaculation, sperm exit the tail of the epididymis and are pushed by smooth muscle contraction to the **ductus deferens** (also called the vas deferens). The ductus deferens is a thick, muscular tube that is bundled together inside the scrotum with connective tissue, blood vessels, and nerves into a structure ca... | {
"Header 1": "**27.1 | Anatomy and Physiology of the Male Reproductive System**",
"Header 3": "**Duct System**",
"token_count": 506,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
As shown in **[Figure 27.2](#page-1226-0)**, the centrally located **prostate gland** sits anterior to the rectum at the base of the bladder surrounding the prostatic urethra (the portion of the urethra that runs within the prostate). About the size of a walnut, the prostate is formed of both muscular and glandular tis... | {
"Header 1": "**27.1 | Anatomy and Physiology of the Male Reproductive System**",
"Header 3": "**Prostate Gland**",
"token_count": 516,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
The final addition to semen is made by two **bulbourethral glands** (or Cowper's glands) that release a thick, salty fluid that lubricates the end of the urethra and the vagina, and helps to clean urine residues from the penile urethra. The fluid from these accessory glands is released after the male becomes sexually a... | {
"Header 1": "**27.1 | Anatomy and Physiology of the Male Reproductive System**",
"Header 3": "**Bulbourethral Glands**",
"token_count": 237,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
The **penis** is the male organ of copulation (sexual intercourse). It is flaccid for non-sexual actions, such as urination, and turgid and rod-like with sexual arousal. When erect, the stiffness of the organ allows it to penetrate into the vagina and deposit semen into the female reproductive tract.
![](_page_1232_F... | {
"Header 1": "**27.1 | Anatomy and Physiology of the Male Reproductive System**",
"Header 3": "**The Penis**",
"token_count": 623,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
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