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electron transport chain (ETC) : ATP production pathway in which electrons are passed through a series of oxidation-reduction reactions that forms water and produces a proton gradient
https://openstax.org/books/anatomy-and-physiology-2e/pages/24-key-terms
energy-consuming phase : first phase of glycolysis, in which two molecules of ATP are necessary to start the reaction
https://openstax.org/books/anatomy-and-physiology-2e/pages/24-key-terms
energy-yielding phase : second phase of glycolysis, during which energy is produced
https://openstax.org/books/anatomy-and-physiology-2e/pages/24-key-terms
enterokinase : enzyme located in the wall of the small intestine that activates trypsin
https://openstax.org/books/anatomy-and-physiology-2e/pages/24-key-terms
evaporation : transfer of heat that occurs when water changes from a liquid to a gas
https://openstax.org/books/anatomy-and-physiology-2e/pages/24-key-terms
FADH2 : high-energy molecule needed for glycolysis
https://openstax.org/books/anatomy-and-physiology-2e/pages/24-key-terms
fatty acid oxidation : breakdown of fatty acids into smaller chain fatty acids and acetyl CoA
https://openstax.org/books/anatomy-and-physiology-2e/pages/24-key-terms
flavin adenine dinucleotide (FAD) : coenzyme used to produce FADH2
https://openstax.org/books/anatomy-and-physiology-2e/pages/24-key-terms
glucokinase : cellular enzyme, found in the liver, which converts glucose into glucose-6-phosphate upon uptake into the cell
https://openstax.org/books/anatomy-and-physiology-2e/pages/24-key-terms
gluconeogenesis : process of glucose synthesis from pyruvate or other molecules
https://openstax.org/books/anatomy-and-physiology-2e/pages/24-key-terms
glucose-6-phosphate : phosphorylated glucose produced in the first step of glycolysis
https://openstax.org/books/anatomy-and-physiology-2e/pages/24-key-terms
glycogen : form that glucose assumes when it is stored
https://openstax.org/books/anatomy-and-physiology-2e/pages/24-key-terms
glycolysis : series of metabolic reactions that breaks down glucose into pyruvate and produces ATP
https://openstax.org/books/anatomy-and-physiology-2e/pages/24-key-terms
hexokinase : cellular enzyme, found in most tissues, that converts glucose into glucose-6-phosphate upon uptake into the cell
https://openstax.org/books/anatomy-and-physiology-2e/pages/24-key-terms
hydroxymethylglutaryl CoA (HMG CoA) : molecule created in the first step of the creation of ketone bodies from acetyl CoA
https://openstax.org/books/anatomy-and-physiology-2e/pages/24-key-terms
inactive proenzymes : forms in which proteases are stored and released to prevent the inappropriate digestion of the native proteins of the stomach, pancreas, and small intestine
https://openstax.org/books/anatomy-and-physiology-2e/pages/24-key-terms
insulin : hormone secreted by the pancreas that stimulates the uptake of glucose into the cells
https://openstax.org/books/anatomy-and-physiology-2e/pages/24-key-terms
ketone bodies : alternative source of energy when glucose is limited, created when too much acetyl CoA is created during fatty acid oxidation
https://openstax.org/books/anatomy-and-physiology-2e/pages/24-key-terms
Krebs cycle : also called the citric acid cycle or the tricarboxylic acid cycle, converts pyruvate into CO2and high-energy FADH2, NADH, and ATP molecules
https://openstax.org/books/anatomy-and-physiology-2e/pages/24-key-terms
lipogenesis : synthesis of lipids that occurs in the liver or adipose tissues
https://openstax.org/books/anatomy-and-physiology-2e/pages/24-key-terms
lipolysis : breakdown of triglycerides into glycerol and fatty acids
https://openstax.org/books/anatomy-and-physiology-2e/pages/24-key-terms
metabolic rate : amount of energy consumed minus the amount of energy expended by the body
https://openstax.org/books/anatomy-and-physiology-2e/pages/24-key-terms
metabolism : sum of all catabolic and anabolic reactions that take place in the body
https://openstax.org/books/anatomy-and-physiology-2e/pages/24-key-terms
minerals : inorganic compounds required by the body to ensure proper function of the body
https://openstax.org/books/anatomy-and-physiology-2e/pages/24-key-terms
monoglyceride molecules : lipid consisting of a single fatty acid chain attached to a glycerol backbone
https://openstax.org/books/anatomy-and-physiology-2e/pages/24-key-terms
monosaccharide : smallest, monomeric sugar molecule
https://openstax.org/books/anatomy-and-physiology-2e/pages/24-key-terms
NADH : high-energy molecule needed for glycolysis
https://openstax.org/books/anatomy-and-physiology-2e/pages/24-key-terms
nicotinamide adenine dinucleotide (NAD) : coenzyme used to produce NADH
https://openstax.org/books/anatomy-and-physiology-2e/pages/24-key-terms
oxidation : loss of an electron
https://openstax.org/books/anatomy-and-physiology-2e/pages/24-key-terms
oxidation-reduction reaction : (also, redox reaction) pair of reactions in which an electron is passed from one molecule to another, oxidizing one and reducing the other
https://openstax.org/books/anatomy-and-physiology-2e/pages/24-key-terms
oxidative phosphorylation : process that converts high-energy NADH and FADH2into ATP
https://openstax.org/books/anatomy-and-physiology-2e/pages/24-key-terms
pancreatic lipases : enzymes released from the pancreas that digest lipids in the diet
https://openstax.org/books/anatomy-and-physiology-2e/pages/24-key-terms
pepsin : enzyme that begins to break down proteins in the stomach
https://openstax.org/books/anatomy-and-physiology-2e/pages/24-key-terms
polysaccharides : complex carbohydrates made up of many monosaccharides
https://openstax.org/books/anatomy-and-physiology-2e/pages/24-key-terms
postabsorptive state : also called the fasting state; the metabolic state occurring after digestion when food is no longer the body’s source of energy and it must rely on stored glycogen
https://openstax.org/books/anatomy-and-physiology-2e/pages/24-key-terms
proteolysis : process of breaking proteins into smaller peptides
https://openstax.org/books/anatomy-and-physiology-2e/pages/24-key-terms
pyruvate : three-carbon end product of glycolysis and starting material that is converted into acetyl CoA that enters the Krebs cycle
https://openstax.org/books/anatomy-and-physiology-2e/pages/24-key-terms
radiation : transfer of heat via infrared waves
https://openstax.org/books/anatomy-and-physiology-2e/pages/24-key-terms
reduction : gaining of an electron
https://openstax.org/books/anatomy-and-physiology-2e/pages/24-key-terms
salivary amylase : digestive enzyme that is found in the saliva and begins the digestion of carbohydrates in the mouth
https://openstax.org/books/anatomy-and-physiology-2e/pages/24-key-terms
secretin : hormone released in the small intestine to aid in digestion
https://openstax.org/books/anatomy-and-physiology-2e/pages/24-key-terms
sodium bicarbonate : anion released into the small intestine to neutralize the pH of the food from the stomach
https://openstax.org/books/anatomy-and-physiology-2e/pages/24-key-terms
terminal electron acceptor : oxygen, the recipient of the free hydrogen at the end of the electron transport chain
https://openstax.org/books/anatomy-and-physiology-2e/pages/24-key-terms
thermoneutral : external temperature at which the body does not expend any energy for thermoregulation, about 84 °F
https://openstax.org/books/anatomy-and-physiology-2e/pages/24-key-terms
thermoregulation : process of regulating the temperature of the body
https://openstax.org/books/anatomy-and-physiology-2e/pages/24-key-terms
transamination : transfer of an amine group from one molecule to another as a way to turn nitrogen waste into ammonia so that it can enter the urea cycle
https://openstax.org/books/anatomy-and-physiology-2e/pages/24-key-terms
tricarboxylic acid cycle (TCA) : also called the Krebs cycle or the citric acid cycle; converts pyruvate into CO2and high-energy FADH2, NADH, and ATP molecules
https://openstax.org/books/anatomy-and-physiology-2e/pages/24-key-terms
triglycerides : lipids, or fats, consisting of three fatty acid chains attached to a glycerol backbone
https://openstax.org/books/anatomy-and-physiology-2e/pages/24-key-terms
trypsin : pancreatic enzyme that activates chymotrypsin and digests protein
https://openstax.org/books/anatomy-and-physiology-2e/pages/24-key-terms
trypsinogen : proenzyme form of trypsin
https://openstax.org/books/anatomy-and-physiology-2e/pages/24-key-terms
urea cycle : process that converts potentially toxic nitrogen waste into urea that can be eliminated through the kidneys
https://openstax.org/books/anatomy-and-physiology-2e/pages/24-key-terms
vitamins : organic compounds required by the body to perform biochemical reactions like metabolism and bone, cell, and tissue growth
https://openstax.org/books/anatomy-and-physiology-2e/pages/24-key-terms
The kidney glomerulus filters blood mainly based on particle size to produce a filtrate lacking cells or large proteins. Most of the ions and molecules in the filtrate are needed by the body and must be reabsorbed farther down the nephron tubules, resulting in the formation of urine. Urine characteristics change depend...
https://openstax.org/books/anatomy-and-physiology-2e/pages/25-chapter-review
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...
https://openstax.org/books/anatomy-and-physiology-2e/pages/25-chapter-review
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 ve...
https://openstax.org/books/anatomy-and-physiology-2e/pages/25-chapter-review
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...
https://openstax.org/books/anatomy-and-physiology-2e/pages/25-chapter-review
The entire volume of the blood is filtered through the kidneys about 300 times per day, and 99 percent of the water filtered is recovered. The GFR is influenced by hydrostatic pressure and colloid osmotic pressure. Under normal circumstances, hydrostatic pressure is significantly greater and filtration occurs. The hydr...
https://openstax.org/books/anatomy-and-physiology-2e/pages/25-chapter-review
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...
https://openstax.org/books/anatomy-and-physiology-2e/pages/25-chapter-review
Mechanisms of solute recovery include active transport, simple diffusion, and facilitated diffusion. Most filtered substances are reabsorbed. Urea, NH3, creatinine, and some drugs are filtered or secreted as wastes. H+and HCO3–are secreted or reabsorbed as needed to maintain acid–base balance. Movement of water fro...
https://openstax.org/books/anatomy-and-physiology-2e/pages/25-chapter-review
The kidneys are innervated by sympathetic nerves of the autonomic nervous system. Sympathetic nervous activity decreases blood flow to the kidney, making more blood available to other areas of the body during times of stress. The arteriolar myogenic mechanism maintains a steady blood flow by causing arteriolar smooth m...
https://openstax.org/books/anatomy-and-physiology-2e/pages/25-chapter-review
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...
https://openstax.org/books/anatomy-and-physiology-2e/pages/25-chapter-review
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...
https://openstax.org/books/anatomy-and-physiology-2e/pages/25-chapter-review
The effects of failure of parts of the urinary system may range from inconvenient (incontinence) to fatal (loss of filtration and many others). The kidneys catalyze the final reaction in the synthesis of active vitamin D that in turn helps regulate Ca++. The kidney hormone EPO stimulates erythrocyte development and pro...
https://openstax.org/books/anatomy-and-physiology-2e/pages/25-chapter-review
anatomical sphincter : smooth or skeletal muscle surrounding the lumen of a vessel or hollow organ that can restrict flow when contracted
https://openstax.org/books/anatomy-and-physiology-2e/pages/25-key-terms
angiotensin I : protein produced by the enzymatic action of renin on angiotensinogen; inactive precursor of angiotensin II
https://openstax.org/books/anatomy-and-physiology-2e/pages/25-key-terms
angiotensin II : protein produced by the enzymatic action of ACE on inactive angiotensin I; actively causes vasoconstriction and stimulates aldosterone release by the adrenal cortex
https://openstax.org/books/anatomy-and-physiology-2e/pages/25-key-terms
angiotensin-converting enzyme (ACE) : enzyme produced by the lungs that catalyzes the reaction of inactive angiotensin I into active angiotensin II
https://openstax.org/books/anatomy-and-physiology-2e/pages/25-key-terms
angiotensinogen : inactive protein in the circulation produced by the liver; precursor of angiotensin I; must be modified by the enzymes renin and ACE to be activated
https://openstax.org/books/anatomy-and-physiology-2e/pages/25-key-terms
anuria : absence of urine produced; production of 50 mL or less per day
https://openstax.org/books/anatomy-and-physiology-2e/pages/25-key-terms
aquaporin : protein-forming water channels through the lipid bilayer of the cell; allows water to cross; activation in the collecting ducts is under the control of ADH
https://openstax.org/books/anatomy-and-physiology-2e/pages/25-key-terms
Bowman’s capsule : cup-shaped sack lined by a simple squamous epithelium (parietal surface) and specialized cells called podocytes (visceral surface) that participate in the filtration process; receives the filtrate which then passes on to the PCTs
https://openstax.org/books/anatomy-and-physiology-2e/pages/25-key-terms
brush border : formed by microvilli on the surface of certain cuboidal cells; in the kidney it is found in the PCT; increases surface area for absorption in the kidney
https://openstax.org/books/anatomy-and-physiology-2e/pages/25-key-terms
calyces : cup-like structures receiving urine from the collecting ducts where it passes on to the renal pelvis and ureter
https://openstax.org/books/anatomy-and-physiology-2e/pages/25-key-terms
cortical nephrons : nephrons with loops of Henle that do not extend into the renal medulla
https://openstax.org/books/anatomy-and-physiology-2e/pages/25-key-terms
countercurrent multiplier system : involves the descending and ascending loops of Henle directing forming urine in opposing directions to create a concentration gradient when combined with variable permeability and sodium pumping
https://openstax.org/books/anatomy-and-physiology-2e/pages/25-key-terms
detrusor muscle : smooth muscle in the bladder wall; fibers run in all directions to reduce the size of the organ when emptying it of urine
https://openstax.org/books/anatomy-and-physiology-2e/pages/25-key-terms
distal convoluted tubules : portions of the nephron distal to the loop of Henle that receive hyposmotic filtrate from the loop of Henle and empty into collecting ducts
https://openstax.org/books/anatomy-and-physiology-2e/pages/25-key-terms
diuretic : compound that increases urine output, leading to decreased water conservation
https://openstax.org/books/anatomy-and-physiology-2e/pages/25-key-terms
efferent arteriole : arteriole carrying blood from the glomerulus to the capillary beds around the convoluted tubules and loop of Henle; portion of the portal system
https://openstax.org/books/anatomy-and-physiology-2e/pages/25-key-terms
endothelins : group of vasoconstrictive, 21-amino acid peptides; produced by endothelial cells of the renal blood vessels, mesangial cells, and cells of the DCT
https://openstax.org/books/anatomy-and-physiology-2e/pages/25-key-terms
external urinary sphincter : skeletal muscle; must be relaxed consciously to void urine
https://openstax.org/books/anatomy-and-physiology-2e/pages/25-key-terms
fenestrations : small windows through a cell, allowing rapid filtration based on size; formed in such a way as to allow substances to cross through a cell without mixing with cell contents
https://openstax.org/books/anatomy-and-physiology-2e/pages/25-key-terms
filtration slits : formed by pedicels of podocytes; substances filter between the pedicels based on size
https://openstax.org/books/anatomy-and-physiology-2e/pages/25-key-terms
forming urine : filtrate undergoing modifications through secretion and reabsorption before true urine is produced
https://openstax.org/books/anatomy-and-physiology-2e/pages/25-key-terms
glomerular filtration rate (GFR) : rate of renal filtration
https://openstax.org/books/anatomy-and-physiology-2e/pages/25-key-terms
glomerulus : tuft of capillaries surrounded by Bowman’s capsule; filters the blood based on size
https://openstax.org/books/anatomy-and-physiology-2e/pages/25-key-terms
glycosuria : presence of glucose in the urine; caused by high blood glucose levels that exceed the ability of the kidneys to reabsorb the glucose; usually the result of untreated or poorly controlled diabetes mellitus
https://openstax.org/books/anatomy-and-physiology-2e/pages/25-key-terms
incontinence : loss of ability to control micturition
https://openstax.org/books/anatomy-and-physiology-2e/pages/25-key-terms
intercalated cell : specialized cell of the collecting ducts that secrete or absorb acid or bicarbonate; important in acid–base balance
https://openstax.org/books/anatomy-and-physiology-2e/pages/25-key-terms
internal urinary sphincter : smooth muscle at the juncture of the bladder and urethra; relaxes as the bladder fills to allow urine into the urethra
https://openstax.org/books/anatomy-and-physiology-2e/pages/25-key-terms
inulin : plant polysaccharide injected to determine GFR; is neither secreted nor absorbed by the kidney, so its appearance in the urine is directly proportional to its filtration rate
https://openstax.org/books/anatomy-and-physiology-2e/pages/25-key-terms
juxtaglomerular apparatus (JGA) : located at the juncture of the DCT and the afferent and efferent arterioles of the glomerulus; plays a role in the regulation of renal blood flow and GFR
https://openstax.org/books/anatomy-and-physiology-2e/pages/25-key-terms
juxtaglomerular cell : modified smooth muscle cells of the afferent arteriole; secretes renin in response to a drop in blood pressure
https://openstax.org/books/anatomy-and-physiology-2e/pages/25-key-terms
juxtamedullary nephrons : nephrons adjacent to the border of the cortex and medulla with loops of Henle that extend into the renal medulla
https://openstax.org/books/anatomy-and-physiology-2e/pages/25-key-terms
leaky tight junctions : tight junctions in which the sealing strands of proteins between the membranes of adjacent cells are fewer in number and incomplete; allows limited intercellular movement of solvent and solutes
https://openstax.org/books/anatomy-and-physiology-2e/pages/25-key-terms
leukocyte esterase : enzyme produced by leukocytes that can be detected in the urine and that serves as an indirect indicator of urinary tract infection
https://openstax.org/books/anatomy-and-physiology-2e/pages/25-key-terms
loop of Henle : descending and ascending portions between the proximal and distal convoluted tubules; those of cortical nephrons do not extend into the medulla, whereas those of juxtamedullary nephrons do extend into the medulla
https://openstax.org/books/anatomy-and-physiology-2e/pages/25-key-terms
macula densa : cells found in the part of the DCT forming the JGA; sense Na+concentration in the forming urine
https://openstax.org/books/anatomy-and-physiology-2e/pages/25-key-terms
medulla : inner region of kidney containing the renal pyramids
https://openstax.org/books/anatomy-and-physiology-2e/pages/25-key-terms
mesangial : contractile cells found in the glomerulus; can contract or relax to regulate filtration rate
https://openstax.org/books/anatomy-and-physiology-2e/pages/25-key-terms