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The cells in the zone between the pituitary lobes secrete a hormone known as melanocyte-stimulating hormone (MSH) that is formed by cleavage of the pro-opiomelanocortin (POMC) precursor protein. Local production of MSH in the skin is responsible for melanin production in response to UV light exposure. The role of MSH m... | {
"Header 1": "**17.3 | The Pituitary Gland and Hypothalamus**",
"Header 3": "**Intermediate Pituitary: Melanocyte-Stimulating Hormone**",
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By the end of this section, you will be able to:
- Describe the location and anatomy of the thyroid gland
- Discuss the synthesis of triiodothyronine and thyroxine
- Explain the role of thyroid hormones in the regulation of basal metabolism
- Identify the hormone produced by the parafollicular cells of the thyroid
... | {
"Header 1": "**17.4 | The Thyroid Gland**",
"token_count": 364,
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Hormones are produced in the colloid when atoms of the mineral iodine attach to a glycoprotein, called thyroglobulin, that is secreted into the colloid by the follicle cells. The following steps outline the hormones' assembly:
1. Binding of TSH to its receptors in the follicle cells of the thyroid gland causes the ce... | {
"Header 1": "**17.4 | The Thyroid Gland**",
"Header 3": "**Synthesis and Release of Thyroid Hormones**",
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The release of T3 and T4 from the thyroid gland is regulated by thyroid-stimulating hormone (TSH). As shown in **[Figure](#page-721-0) [17.13](#page-721-0)**, low blood levels of T3 and T4 stimulate the release of thyrotropin-releasing hormone (TRH) from the hypothalamus, which triggers secretion of TSH from the anteri... | {
"Header 1": "**17.4 | The Thyroid Gland**",
"Header 3": "**Regulation of TH Synthesis**",
"token_count": 201,
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The thyroid hormones, T3 and T4, are often referred to as metabolic hormones because their levels influence the body's basal metabolic rate, the amount of energy used by the body at rest. When T3 and T4 bind to intracellular receptors located on the mitochondria, they cause an increase in nutrient breakdown and the use... | {
"Header 1": "**17.4 | The Thyroid Gland**",
"Header 3": "**Functions of Thyroid Hormones**",
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As discussed above, dietary iodine is required for the synthesis of T3 and T4. But for much of the world's population, foods do not provide adequate levels of this mineral, because the amount varies according to the level in the soil in which the food was grown, as well as the irrigation and fertilizers used. Marine fi... | {
"Header 1": "**17.4 | The Thyroid Gland**",
"Header 2": "**Endocrine System: Iodine Deficiency, Hypothyroidism, and Hyperthyroidism**",
"token_count": 606,
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The thyroid gland also secretes a hormone called **calcitonin** that is produced by the parafollicular cells (also called C cells) that stud the tissue between distinct follicles. Calcitonin is released in response to a rise in blood calcium levels. It appears to have a function in decreasing blood calcium concentratio... | {
"Header 1": "**17.4 | The Thyroid Gland**",
"Header 2": "**Endocrine System: Iodine Deficiency, Hypothyroidism, and Hyperthyroidism**",
"Header 3": "**Calcitonin**",
"token_count": 212,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
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By the end of this section, you will be able to:
- Describe the location and structure of the parathyroid glands
- Describe the hormonal control of blood calcium levels
- Discuss the physiological response of parathyroid dysfunction
The **parathyroid glands** are tiny, round structures usually found embedded in the... | {
"Header 1": "**17.5 | The Parathyroid Glands**",
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By the end of this section, you will be able to:
- Describe the location and structure of the adrenal glands
- Identify the hormones produced by the adrenal cortex and adrenal medulla, and summarize their target cells and effects
The **adrenal glands** are wedges of glandular and neuroendocrine tissue adhering to t... | {
"Header 1": "**17.6 | The Adrenal Glands**",
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The most superficial region of the adrenal cortex is the zona glomerulosa, which produces a group of hormones collectively referred to as **mineralocorticoids** because of their effect on body minerals, especially sodium and potassium. These hormones are essential for fluid and electrolyte balance.
**Aldosterone** is... | {
"Header 1": "**17.6 | The Adrenal Glands**",
"Header 3": "**Hormones of the Zona Glomerulosa**",
"token_count": 449,
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The intermediate region of the adrenal cortex is the zona fasciculata, named as such because the cells form small fascicles (bundles) separated by tiny blood vessels. The cells of the zona fasciculata produce hormones called **glucocorticoids** because of their role in glucose metabolism. The most important of these is... | {
"Header 1": "**17.6 | The Adrenal Glands**",
"Header 3": "**Hormones of the Zona Fasciculata**",
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As noted earlier, the adrenal cortex releases glucocorticoids in response to long-term stress such as severe illness. In contrast, the adrenal medulla releases its hormones in response to acute, short-term stress mediated by the sympathetic nervous system (SNS).
The medullary tissue is composed of unique postganglion... | {
"Header 1": "**17.6 | The Adrenal Glands**",
"Header 3": "**Adrenal Medulla**",
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Several disorders are caused by the dysregulation of the hormones produced by the adrenal glands. For example, Cushing's disease is a disorder characterized by high blood glucose levels and the accumulation of lipid deposits on the face and neck. It is caused by hypersecretion of cortisol. The most common source of Cus... | {
"Header 1": "**17.6 | The Adrenal Glands**",
"Header 3": "**Disorders Involving the Adrenal Glands**",
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"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
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By the end of this section, you will be able to:
- Describe the location and structure of the pineal gland
- Discuss the function of melatonin
Recall that the hypothalamus, part of the diencephalon of the brain, sits inferior and somewhat anterior to the thalamus. Inferior but somewhat posterior to the thalamus is ... | {
"Header 1": "**17.7 | The Pineal Gland**",
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By the end of this section, you will be able to:
- Identify the most important hormones produced by the testes and ovaries
- Name the hormones produced by the placenta and state their functions
This section briefly discusses the hormonal role of the gonads—the male testes and female ovaries—which produce the sex ce... | {
"Header 1": "**17.8 Gonadal and Placental Hormones**",
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The endocrine system can be exploited for illegal or unethical purposes. A prominent example of this is the use of steroid drugs by professional athletes.
Commonly used for performance enhancement, anabolic steroids are synthetic versions of the male sex hormone, testosterone. By boosting natural levels of this hormo... | {
"Header 1": "**17.8 Gonadal and Placental Hormones**",
"Header 3": "**Anabolic Steroids**",
"token_count": 270,
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By the end of this section, you will be able to:
- Describe the location and structure of the pancreas, and the morphology and function of the pancreatic islets
- Compare and contrast the functions of insulin and glucagon
The **pancreas** is a long, slender organ, most of which is located posterior to the bottom ha... | {
"Header 1": "**17.9 | The Endocrine Pancreas**",
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The pancreatic islets each contain four varieties of cells:
- The **alpha cell** produces the hormone glucagon and makes up approximately 20 percent of each islet. Glucagon plays an important role in blood glucose regulation; low blood glucose levels stimulate its release.
- • The **beta cell** produces the hormone i... | {
"Header 1": "**17.9 | The Endocrine Pancreas**",
"Header 3": "**Cells and Secretions of the Pancreatic Islets**",
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Receptors in the pancreas can sense the decline in blood glucose levels, such as during periods of fasting or during prolonged labor or exercise (**[Figure 17.19](#page-733-0)**). In response, the alpha cells of the pancreas secrete the hormone **glucagon**, which has several effects:
- It stimulates the liver to con... | {
"Header 1": "**17.9 | The Endocrine Pancreas**",
"Header 3": "**Glucagon**",
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The primary function of **insulin** is to facilitate the uptake of glucose into body cells. Red blood cells, as well as cells of the brain, liver, kidneys, and the lining of the small intestine, do not have insulin receptors on their cell membranes and do not require insulin for glucose uptake. Although all other body ... | {
"Header 1": "**17.9 | The Endocrine Pancreas**",
"Header 3": "**Insulin**",
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Dysfunction of insulin production and secretion, as well as the target cells' responsiveness to insulin, can lead to a condition called **diabetes mellitus**. An increasingly common disease, diabetes mellitus has been diagnosed in more than 18 million adults in the United States, and more than 200,000 children. It is e... | {
"Header 1": "**17.9 | The Endocrine Pancreas**",
"Header 3": "**Endocrine System: Diabetes Mellitus**",
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The endocrine cells of the GI tract are located in the mucosa of the stomach and small intestine. Some of these hormones are secreted in response to eating a meal and aid in digestion. An example of a hormone secreted by the stomach cells is gastrin, a peptide hormone secreted in response to stomach distention that sti... | {
"Header 1": "**17.10 | Organs with Secondary Endocrine Functions**",
"Header 3": "**Gastrointestinal Tract**",
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The liver is responsible for secreting at least four important hormones or hormone precursors: insulin-like growth factor (somatomedin), angiotensinogen, thrombopoetin, and hepcidin. Insulin-like growth factor-1 is the immediate stimulus for growth in the body, especially of the bones. Angiotensinogen is the precursor ... | {
"Header 1": "**17.10 | Organs with Secondary Endocrine Functions**",
"Header 3": "Liver",
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By the end of this section, you will be able to:
- Describe the embryonic origins of the endocrine system
- Discuss the effects of aging on the endocrine system
The endocrine system arises from all three embryonic germ layers. The endocrine glands that produce the steroid hormones, such as the gonads and adrenal co... | {
"Header 1": "**17.11** Development and Aging of the Endocrine System",
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- **acromegaly** disorder in adults caused when abnormally high levels of GH trigger growth of bones in the face, hands, and feet - **adenylyl cyclase** membrane-bound enzyme that converts ATP to cyclic AMP, creating cAMP, as a result of G-protein activation - **adrenal cortex** outer region of the adrenal glands consi... | {
"Header 1": "**17.11** Development and Aging of the Endocrine System",
"Header 3": "**KEY TERMS**",
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to women who were iodine-deficient during pregnancy - **norepinephrine** secondary catecholamine hormone secreted by the adrenal medulla in response to short-term stress; also called noradrenaline - **osmoreceptor** hypothalamic sensory receptor that is stimulated by changes in solute concentration (osmotic pressure) i... | {
"Header 1": "**17.11** Development and Aging of the Endocrine System",
"Header 3": "**KEY TERMS**",
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Hormones are derived from amino acids or lipids. Amine hormones originate from the amino acids tryptophan or tyrosine. Larger amino acid hormones include peptides and protein hormones. Steroid hormones are derived from cholesterol.
Steroid hormones and thyroid hormone are lipid soluble. All other amino acid–derived h... | {
"Header 1": "**17.11** Development and Aging of the Endocrine System",
"Header 3": "**[17.2 Hormones](#page-702-0)**",
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The hypothalamus–pituitary complex is located in the diencephalon of the brain. The hypothalamus and the pituitary gland are connected by a structure called the infundibulum, which contains vasculature and nerve axons. The pituitary gland is divided into two distinct structures with different embryonic origins. The pos... | {
"Header 1": "**17.11** Development and Aging of the Endocrine System",
"Header 3": "**[17.3 The Pituitary Gland and Hypothalamus](#page-710-0)**",
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After studying this chapter, you will be able to:
- Identify the primary functions of blood, its fluid and cellular components, and its physical characteristics
- Identify the most important proteins and other solutes present in blood plasma
- Describe the formation of the formed element components of blood
- Discuss... | {
"Header 1": "**Introduction**",
"Header 2": "**Chapter Objectives**",
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By the end of this section, you will be able to:
- Identify the primary functions of blood in transportation, defense, and maintenance of homeostasis
- Name the fluid component of blood and the three major types of formed elements, and identify their relative proportions in a blood sample
- Discuss the unique physica... | {
"Header 1": "**18.1 | An Overview of Blood**",
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You have probably had blood drawn from a superficial vein in your arm, which was then sent to a lab for analysis. Some of the most common blood tests—for instance, those measuring lipid or glucose levels in plasma—determine which substances are present within blood and in what quantities. Other blood tests check for th... | {
"Header 1": "**18.1 | An Overview of Blood**",
"Header 3": "**Composition of Blood**",
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When you think about blood, the first characteristic that probably comes to mind is its color. Blood that has just taken up oxygen in the lungs is bright red, and blood that has released oxygen in the tissues is a more dusky red. This is because hemoglobin is a pigment that changes color, depending upon the degree of o... | {
"Header 1": "**18.1 | An Overview of Blood**",
"Header 3": "**Characteristics of Blood**",
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About 7 percent of the volume of plasma—nearly all that is not water—is made of proteins. These include several plasma proteins (proteins that are unique to the plasma), plus a much smaller number of regulatory proteins, including enzymes and some hormones. The major components of plasma are summarized in **[Figure 18.... | {
"Header 1": "**18.1 | An Overview of Blood**",
"Header 3": "**Plasma Proteins**",
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Phlebotomists are professionals trained to draw blood (phleb- = "a blood vessel"; -tomy = "to cut"). When more than a few drops of blood are required, phlebotomists perform a venipuncture, typically of a surface vein in the arm. They perform a capillary stick on a finger, an earlobe, or the heel of an infant when only ... | {
"Header 1": "**18.1 | An Overview of Blood**",
"Header 3": "**Phlebotomy and Medical Lab Technology**",
"token_count": 334,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
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By the end of this section, you will be able to:
- Trace the generation of the formed elements of blood from bone marrow stem cells
- Discuss the role of hemopoietic growth factors in promoting the production of the formed elements
The lifespan of the formed elements is very brief. Although one type of leukocyte ca... | {
"Header 1": "**18.2 | Production of the Formed Elements**",
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Prior to birth, hemopoiesis occurs in a number of tissues, beginning with the yolk sac of the developing embryo, and continuing in the fetal liver, spleen, lymphatic tissue, and eventually the red bone marrow. Following birth, most hemopoiesis occurs in the red marrow, a connective tissue within the spaces of spongy (c... | {
"Header 1": "**18.2 | Production of the Formed Elements**",
"Header 3": "**Sites of Hemopoiesis**",
"token_count": 219,
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All formed elements arise from stem cells of the red bone marrow. Recall that stem cells undergo mitosis plus cytokinesis (cellular division) to give rise to new daughter cells: One of these remains a stem cell and the other differentiates into one of any number of diverse cell types. Stem cells may be viewed as occupy... | {
"Header 1": "**18.2 | Production of the Formed Elements**",
"Header 3": "**Differentiation of Formed Elements from Stem Cells**",
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Development from stem cells to precursor cells to mature cells is again initiated by hemopoietic growth factors. These include the following:
- • **Erythropoietin (EPO)** is a glycoprotein hormone secreted by the interstitial fibroblast cells of the kidneys in response to low oxygen levels. It prompts the production ... | {
"Header 1": "**18.2 | Production of the Formed Elements**",
"Header 3": "**Hemopoietic Growth Factors**",
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In its original intent, the term blood doping was used to describe the practice of injecting by transfusion supplemental RBCs into an individual, typically to enhance performance in a sport. Additional RBCs would deliver more oxygen to the tissues, providing extra aerobic capacity, clinically referred to as VO2 max. Th... | {
"Header 1": "**18.2 | Production of the Formed Elements**",
"Header 3": "**Blood Doping**",
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Sometimes, a healthcare provider will order a **bone marrow biopsy**, a diagnostic test of a sample of red bone marrow, or a **bone marrow transplant**, a treatment in which a donor's healthy bone marrow—and its stem cells—replaces the faulty bone marrow of a patient. These tests and procedures are often used to assist... | {
"Header 1": "**18.2 | Production of the Formed Elements**",
"Header 3": "**Bone Marrow Sampling and Transplants**",
"token_count": 332,
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By the end of this section, you will be able to:
- Describe the anatomy of erythrocytes
- Discuss the various steps in the lifecycle of an erythrocyte
- Explain the composition and function of hemoglobin
The **erythrocyte**, commonly known as a red blood cell (or RBC), is by far the most common formed element: A si... | {
"Header 1": "**18.3 | Erythrocytes**",
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As an erythrocyte matures in the red bone marrow, it extrudes its nucleus and most of its other organelles. During the first day or two that it is in the circulation, an immature erythrocyte, known as a **reticulocyte**, will still typically contain remnants of organelles. Reticulocytes should comprise approximately 1–... | {
"Header 1": "**18.3 | Erythrocytes**",
"Header 3": "**Shape and Structure of Erythrocytes**",
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"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
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**Hemoglobin** is a large molecule made up of proteins and iron. It consists of four folded chains of a protein called **globin**, designated alpha 1 and 2, and beta 1 and 2 (**[Figure 18.7a](#page-761-0)**). Each of these globin molecules is bound to a red pigment molecule called **heme**, which contains an ion of iro... | {
"Header 1": "**18.3 | Erythrocytes**",
"Header 3": "**Hemoglobin**",
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Production of erythrocytes in the marrow occurs at the staggering rate of more than 2 million cells per second. For this production to occur, a number of raw materials must be present in adequate amounts. These include the same nutrients that are essential to the production and maintenance of any cell, such as glucose,... | {
"Header 1": "**18.3 | Erythrocytes**",
"Header 3": "**Lifecycle of Erythrocytes**",
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The size, shape, and number of erythrocytes, and the number of hemoglobin molecules can have a major impact on a person's health. When the number of RBCs or hemoglobin is deficient, the general condition is called **anemia**. There are more than 400 types of anemia and more than 3.5 million Americans suffer from this c... | {
"Header 1": "**18.3 | Erythrocytes**",
"Header 3": "**Disorders of Erythrocytes**",
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Although leukocytes and erythrocytes both originate from hematopoietic stem cells in the bone marrow, they are very different from each other in many significant ways. For instance, leukocytes are far less numerous than erythrocytes: Typically there are only 5000 to 10,000 per *µ*L. They are also larger than erythrocyt... | {
"Header 1": "**18.4 | Leukocytes and Platelets**",
"Header 3": "**Characteristics of Leukocytes**",
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We will consider the granular leukocytes in order from most common to least common. All of these are produced in the red bone marrow and have a short lifespan of hours to days. They typically have a lobed nucleus and are classified according to which type of stain best highlights their granules (**[Figure 18.11](#page-... | {
"Header 1": "**18.4 | Leukocytes and Platelets**",
"Header 3": "**Granular Leukocytes**",
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Agranular leukocytes contain smaller, less-visible granules in their cytoplasm than do granular leukocytes. The nucleus is simple in shape, sometimes with an indentation but without distinct lobes. There are two major types of agranulocytes: lymphocytes and monocytes (see **[Figure 18.4](#page-756-0)**).
**Lymphocyte... | {
"Header 1": "**18.4 | Leukocytes and Platelets**",
"Header 3": "**Agranular Leukocytes**",
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**Leukopenia** is a condition in which too few leukocytes are produced. If this condition is pronounced, the individual may be unable to ward off disease. Excessive leukocyte proliferation is known as **leukocytosis**. Although leukocyte counts are high, the cells themselves are often nonfunctional, leaving the individ... | {
"Header 1": "**18.4 | Leukocytes and Platelets**",
"Header 3": "**Disorders of Leukocytes**",
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You may occasionally see platelets referred to as **thrombocytes**, but because this name suggests they are a type of cell, it is not accurate. A platelet is not a cell but rather a fragment of the cytoplasm of a cell called a **megakaryocyte** that is surrounded by a plasma membrane. Megakaryocytes are descended from ... | {
"Header 1": "**18.4 | Leukocytes and Platelets**",
"Header 3": "**Platelets**",
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**Thrombocytosis** is a condition in which there are too many platelets. This may trigger formation of unwanted blood clots (thrombosis), a potentially fatal disorder. If there is an insufficient number of platelets, called **thrombocytopenia**, blood may not clot properly, and excessive bleeding may result.
![](_pag... | {
"Header 1": "**18.4 | Leukocytes and Platelets**",
"Header 3": "**Disorders of Platelets**",
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In the second step, platelets, which normally float free in the plasma, encounter the area of vessel rupture with the exposed underlying connective tissue and collagenous fibers. The platelets begin to clump together, become spiked and sticky, and bind to the exposed collagen and endothelial lining. This process is ass... | {
"Header 1": "**18.5 | Hemostasis**",
"Header 3": "**Formation of the Platelet Plug**",
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Those more sophisticated and more durable repairs are collectively called **coagulation**, the formation of a blood clot. The process is sometimes characterized as a cascade, because one event prompts the next as in a multi-level waterfall. The result is the production of a gelatinous but robust clot made up of a mesh ... | {
"Header 1": "**18.5 | Hemostasis**",
"Header 3": "**Coagulation**",
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"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
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In the coagulation cascade, chemicals called **clotting factors** (or coagulation factors) prompt reactions that activate still more coagulation factors. The process is complex, but is initiated along two basic pathways:
- The extrinsic pathway, which normally is triggered by trauma.
- The intrinsic pathway, which be... | {
"Header 1": "**18.5 | Hemostasis**",
"Header 3": "**Clotting Factors Involved in Coagulation**",
"token_count": 826,
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The **intrinsic pathway** (also known as the contact activation pathway) is longer and more complex. In this case, the factors involved are intrinsic to (present within) the bloodstream. The pathway can be prompted by damage to the tissues, resulting from internal factors such as arterial disease; however, it is most o... | {
"Header 1": "**18.5 | Hemostasis**",
"Header 3": "**Intrinsic Pathway**",
"token_count": 282,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
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The stabilized clot is acted upon by contractile proteins within the platelets. As these proteins contract, they pull on the fibrin threads, bringing the edges of the clot more tightly together, somewhat as we do when tightening loose shoelaces (see **[Figure 18.14a](#page-772-0)**). This process also wrings out of the... | {
"Header 1": "**18.5 | Hemostasis**",
"Header 3": "**Fibrinolysis**",
"token_count": 239,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
An **anticoagulant** is any substance that opposes coagulation. Several circulating plasma anticoagulants play a role in limiting the coagulation process to the region of injury and restoring a normal, clot-free condition of blood. For instance, a cluster of proteins collectively referred to as the protein C system ina... | {
"Header 1": "**18.5 | Hemostasis**",
"Header 3": "**Plasma Anticoagulants**",
"token_count": 343,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
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Either an insufficient or an excessive production of platelets can lead to severe disease or death. As discussed earlier, an insufficient number of platelets, called thrombocytopenia, typically results in the inability of blood to form clots. This can lead to excessive bleeding, even from minor wounds.
Another reason... | {
"Header 1": "**18.5 | Hemostasis**",
"Header 3": "**Disorders of Clotting**",
"token_count": 1118,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
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Antigens are substances that the body does not recognize as belonging to the "self" and that therefore trigger a defensive response from the leukocytes of the immune system. (Seek more content for additional information on immunity.) Here, we will focus on the role of immunity in blood transfusion reactions. With RBCs ... | {
"Header 1": "**18.6 | Blood Typing**",
"Header 3": "**Antigens, Antibodies, and Transfusion Reactions**",
"token_count": 420,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
Although the **ABO blood group** name consists of three letters, ABO blood typing designates the presence or absence of just two antigens, A and B. Both are glycoproteins. People whose erythrocytes have A antigens on their erythrocyte membrane surfaces are designated blood type A, and those whose erythrocytes have B an... | {
"Header 1": "**18.6 | Blood Typing**",
"Header 3": "**The ABO Blood Group**",
"token_count": 291,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
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In contrast to the ABO group antibodies, which are preformed, antibodies to the Rh antigen are produced only in Rh<sup>−</sup> individuals after exposure to the antigen. This process, called sensitization, occurs following a transfusion with Rhincompatible blood or, more commonly, with the birth of an Rh<sup>+</sup> ba... | {
"Header 1": "**18.6 | Blood Typing**",
"Header 3": "**Table 18.2**",
"token_count": 647,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
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Clinicians are able to determine a patient's blood type quickly and easily using commercially prepared antibodies. An unknown blood sample is allocated into separate wells. Into one well a small amount of anti-A antibody is added, and to another a small amount of anti-B antibody. If the antigen is present, the antibodi... | {
"Header 1": "**18.6 | Blood Typing**",
"Header 3": "**Determining ABO Blood Types**",
"token_count": 287,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
To avoid transfusion reactions, it is best to transfuse only matching blood types; that is, a type B<sup>+</sup> recipient should ideally receive blood only from a type B<sup>+</sup> donor and so on. That said, in emergency situations, when acute hemorrhage threatens the patient's life, there may not be time for cross ... | {
"Header 1": "**18.6 | Blood Typing**",
"Header 3": "**ABO Transfusion Protocols**",
"token_count": 901,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
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- **ABO blood group** blood-type classification based on the presence or absence of A and B glycoproteins on the erythrocyte membrane surface - **agglutination** clustering of cells into masses linked by antibodies - **agranular leukocytes** leukocytes with few granules in their cytoplasm; specifically, monocytes, lymp... | {
"Header 1": "**18.6 | Blood Typing**",
"Header 3": "**KEY TERMS**",
"token_count": 1766,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
lymphocyte that forms after exposure to a pathogen - **monocytes** agranular leukocytes of the myeloid stem cell line that circulate in the bloodstream; tissue monocytes are macrophages - **myeloid stem cells** type of hemopoietic stem cell that gives rise to some formed elements, including erythrocytes, megakaryocytes... | {
"Header 1": "**18.6 | Blood Typing**",
"Header 3": "**KEY TERMS**",
"token_count": 967,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
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The most abundant formed elements in blood, erythrocytes are red, biconcave disks packed with an oxygen-carrying compound called hemoglobin. The hemoglobin molecule contains four globin proteins bound to a pigment molecule called heme, which contains an ion of iron. In the bloodstream, iron picks up oxygen in the lungs... | {
"Header 1": "**18.6 | Blood Typing**",
"Header 3": "**[18.3 Erythrocytes](#page-758-0)**",
"token_count": 253,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
Leukocytes function in body defenses. They squeeze out of the walls of blood vessels through emigration or diapedesis, then may move through tissue fluid or become attached to various organs where they fight against pathogenic organisms, diseased cells, or other threats to health. Granular leukocytes, which include neu... | {
"Header 1": "**18.6 | Blood Typing**",
"Header 3": "**[18.4 Leukocytes and Platelets](#page-765-0)**",
"token_count": 237,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
Hemostasis is the physiological process by which bleeding ceases. Hemostasis involves three basic steps: vascular spasm, the formation of a platelet plug, and coagulation, in which clotting factors promote the formation of a fibrin clot. Fibrinolysis is the process in which a clot is degraded in a healing vessel. Antic... | {
"Header 1": "**18.6 | Blood Typing**",
"Header 3": "**[18.5 Hemostasis](#page-770-0)**",
"token_count": 202,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
Antigens are nonself molecules, usually large proteins, which provoke an immune response. In transfusion reactions, antibodies attach to antigens on the surfaces of erythrocytes and cause agglutination and hemolysis. ABO blood group antigens are designated A and B. People with type A blood have A antigens on their eryt... | {
"Header 1": "**18.6 | Blood Typing**",
"Header 3": "**[18.6 Blood Typing](#page-775-0)**",
"token_count": 357,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
After studying this chapter, you will be able to:
- Identify and describe the interior and exterior parts of the human heart
- Describe the path of blood through the cardiac circuits
- Describe the size, shape, and location of the heart
- Compare cardiac muscle to skeletal and smooth muscle
- Explain the cardiac cond... | {
"Header 1": "**Chapter Objectives**",
"token_count": 315,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
By the end of this section, you will be able to:
- Describe the location and position of the heart within the body cavity
- Describe the internal and external anatomy of the heart
- Identify the tissue layers of the heart
- Relate the structure of the heart to its function as a pump
- Compare systemic circulation to ... | {
"Header 1": "**19.1 | Heart Anatomy**",
"token_count": 288,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
The human heart is located within the thoracic cavity, medially between the lungs in the space known as the mediastinum. **[Figure 19.2](#page-792-0)** shows the position of the heart within the thoracic cavity. Within the mediastinum, the heart is separated from the other mediastinal structures by a tough membrane kno... | {
"Header 1": "**19.1 | Heart Anatomy**",
"Header 3": "**Location of the Heart**",
"token_count": 442,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
The position of the heart in the torso between the vertebrae and sternum (see **[Figure 19.2](#page-792-0)** for the position of the heart within the thorax) allows for individuals to apply an emergency technique known as cardiopulmonary resuscitation (CPR) if the heart of a patient should stop. By applying pressure wi... | {
"Header 1": "**19.1 | Heart Anatomy**",
"Header 3": "**CPR**",
"token_count": 630,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
The shape of the heart is similar to a pinecone, rather broad at the superior surface and tapering to the apex (see **[Figure](#page-792-0) [19.2](#page-792-0)**). A typical heart is approximately the size of your fist: 12 cm (5 in) in length, 8 cm (3.5 in) wide, and 6 cm (2.5 in) in thickness. Given the size differenc... | {
"Header 1": "**19.1 | Heart Anatomy**",
"Header 3": "**Shape and Size of the Heart**",
"token_count": 315,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
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The human heart consists of four chambers: The left side and the right side each have one **atrium** and one **ventricle**. Each of the upper chambers, the right atrium (plural = atria) and the left atrium, acts as a receiving chamber and contracts to push blood into the lower chambers, the right ventricle and the left... | {
"Header 1": "**19.1 | Heart Anatomy**",
"Header 3": "**Chambers and Circulation through the Heart**",
"token_count": 800,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
The membrane that directly surrounds the heart and defines the pericardial cavity is called the **pericardium** or **pericardial sac**. It also surrounds the "roots" of the major vessels, or the areas of closest proximity to the heart. The pericardium, which literally translates as "around the heart," consists of two d... | {
"Header 1": "**19.1 | Heart Anatomy**",
"Header 3": "**Membranes**",
"token_count": 444,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
If excess fluid builds within the pericardial space, it can lead to a condition called cardiac tamponade, or pericardial tamponade. With each contraction of the heart, more fluid—in most instances, blood—accumulates within the pericardial cavity. In order to fill with blood for the next contraction, the heart must rela... | {
"Header 1": "**19.1 | Heart Anatomy**",
"Header 3": "**Heart: Cardiac Tamponade**",
"token_count": 277,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
Inside the pericardium, the surface features of the heart are visible, including the four chambers. There is a superficial leaflike extension of the atria near the superior surface of the heart, one on each side, called an **auricle**—a name that means "ear like"—because its shape resembles the external ear of a human ... | {
"Header 1": "**19.1 | Heart Anatomy**",
"Header 3": "**Surface Features of the Heart**",
"token_count": 337,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
The wall of the heart is composed of three layers of unequal thickness. From superficial to deep, these are the epicardium, the myocardium, and the endocardium (see **[Figure 19.5](#page-796-0)**). The outermost layer of the wall of the heart is also the innermost layer of the pericardium, the epicardium, or the viscer... | {
"Header 1": "**19.1 | Heart Anatomy**",
"Header 3": "**Layers**",
"token_count": 813,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
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The word septum is derived from the Latin for "something that encloses;" in this case, a **septum** (plural = septa) refers to a wall or partition that divides the heart into chambers. The septa are physical extensions of the myocardium lined with endocardium. Located between the two atria is the **interatrial septum**... | {
"Header 1": "**19.1 | Heart Anatomy**",
"Header 3": "**Septa of the Heart**",
"token_count": 690,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
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One very common form of interatrial septum pathology is patent foramen ovale, which occurs when the septum primum does not close at birth, and the fossa ovalis is unable to fuse. The word patent is from the Latin root patens for "open." It may be benign or asymptomatic, perhaps never being diagnosed, or in extreme case... | {
"Header 1": "**19.1 | Heart Anatomy**",
"Header 3": "**Heart: Heart Defects**",
"token_count": 1275,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
The right atrium serves as the receiving chamber for blood returning to the heart from the systemic circulation. The two major systemic veins, the superior and inferior venae cavae, and the large coronary vein called the **coronary sinus** that drains the heart myocardium empty into the right atrium. The superior vena ... | {
"Header 1": "**19.1 | Heart Anatomy**",
"Header 3": "**Right Atrium**",
"token_count": 418,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
The right ventricle receives blood from the right atrium through the tricuspid valve. Each flap of the valve is attached to strong strands of connective tissue, the **chordae tendineae**, literally "tendinous cords," or sometimes more poetically referred to as "heart strings." There are several chordae tendineae associ... | {
"Header 1": "**19.1 | Heart Anatomy**",
"Header 3": "**Right Ventricle**",
"token_count": 601,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
A transverse section through the heart slightly above the level of the atrioventricular septum reveals all four heart valves along the same plane (**[Figure 19.12](#page-803-0)**). The valves ensure unidirectional blood flow through the heart. Between the right atrium and the right ventricle is the **right atrioventric... | {
"Header 1": "**19.1 | Heart Anatomy**",
"Header 3": "**Heart Valve Structure and Function**",
"token_count": 1495,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
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When heart valves do not function properly, they are often described as incompetent and result in valvular heart disease, which can range from benign to lethal. Some of these conditions are congenital, that is, the individual was born with the defect, whereas others may be attributed to disease processes or trauma. Som... | {
"Header 1": "**19.1 | Heart Anatomy**",
"Header 3": "**Heart Valves**",
"token_count": 771,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
Cardiologists are medical doctors that specialize in the diagnosis and treatment of diseases of the heart. After completing 4 years of medical school, cardiologists complete a three-year residency in internal medicine followed by an additional three or more years in cardiology. Following this 10-year period of medical ... | {
"Header 1": "**19.1 | Heart Anatomy**",
"Header 3": "**Cardiologist**",
"token_count": 229,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
Cardiovascular technologists/technicians are trained professionals who perform a variety of imaging techniques, such as sonograms or echocardiograms, used by physicians to diagnose and treat diseases of the heart. Nearly all of these positions require an associate degree, and these technicians earn a median salary of \... | {
"Header 1": "**19.1 | Heart Anatomy**",
"Header 3": "**Cardiovascular Technologist/Technician**",
"token_count": 302,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
**Coronary arteries** supply blood to the myocardium and other components of the heart. The first portion of the aorta after it arises from the left ventricle gives rise to the coronary arteries. There are three dilations in the wall of the aorta just superior to the aortic semilunar valve. Two of these, the left poste... | {
"Header 1": "**19.1 | Heart Anatomy**",
"Header 3": "**Coronary Arteries**",
"token_count": 626,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
Myocardial infarction (MI) is the formal term for what is commonly referred to as a heart attack. It normally results from a lack of blood flow (ischemia) and oxygen (hypoxia) to a region of the heart, resulting in death of the cardiac muscle cells. An MI often occurs when a coronary artery is blocked by the buildup of... | {
"Header 1": "**19.1 | Heart Anatomy**",
"Header 3": "**Heart: Myocardial Infarction**",
"token_count": 839,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
**Coronary veins** drain the heart and generally parallel the large surface arteries (see **[Figure 19.15](#page-809-0)**). The **great cardiac vein** can be seen initially on the surface of the heart following the interventricular sulcus, but it eventually flows along the coronary sulcus into the coronary sinus on the... | {
"Header 1": "**19.1 | Heart Anatomy**",
"Header 3": "**Coronary Veins**",
"token_count": 294,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
Coronary artery disease is the leading cause of death worldwide. It occurs when the buildup of plaque—a fatty material including cholesterol, connective tissue, white blood cells, and some smooth muscle cells—within the walls of the arteries obstructs the flow of blood and decreases the flexibility or compliance of the... | {
"Header 1": "**19.1 | Heart Anatomy**",
"Header 3": "**Heart: Coronary Artery Disease**",
"token_count": 651,
"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 of cardiac muscle
- Identify and describe the components of the conducting system that distributes electrical impulses through the heart
- Compare the effect of ion movement on membrane potential of cardiac conductive and contractile cells
- Re... | {
"Header 1": "**19.2 | Cardiac Muscle and Electrical Activity**",
"token_count": 365,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
Compared to the giant cylinders of skeletal muscle, cardiac muscle cells, or cardiomyocytes, are considerably shorter with much smaller diameters. Cardiac muscle also demonstrates striations, the alternating pattern of dark A bands and light I bands attributed to the precise arrangement of the myofilaments and fibrils ... | {
"Header 1": "**19.2 | Cardiac Muscle and Electrical Activity**",
"Header 3": "**Structure of Cardiac Muscle**",
"token_count": 724,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
If embryonic heart cells are separated into a Petri dish and kept alive, each is capable of generating its own electrical impulse followed by contraction. When two independently beating embryonic cardiac muscle cells are placed together, the cell with the higher inherent rate sets the pace, and the impulse spreads from... | {
"Header 1": "**19.2 | Cardiac Muscle and Electrical Activity**",
"Header 3": "**Conduction System of the Heart**",
"token_count": 258,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
Normal cardiac rhythm is established by the **sinoatrial (SA) node**, a specialized clump of myocardial conducting cells located in the superior and posterior walls of the right atrium in close proximity to the orifice of the superior vena cava. The SA node has the highest inherent rate of depolarization and is known a... | {
"Header 1": "**19.2 | Cardiac Muscle and Electrical Activity**",
"Header 3": "**Sinoatrial (SA) Node**",
"token_count": 655,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
The **atrioventricular (AV) node** is a second clump of specialized myocardial conductive cells, located in the inferior portion of the right atrium within the atrioventricular septum. The septum prevents the impulse from spreading directly to the ventricles without passing through the AV node. There is a critical paus... | {
"Header 1": "**19.2 | Cardiac Muscle and Electrical Activity**",
"Header 3": "**Atrioventricular (AV) Node**",
"token_count": 282,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
Arising from the AV node, the **atrioventricular bundle**, or **bundle of His**, proceeds through the interventricular septum before dividing into two **atrioventricular bundle branches**, commonly called the left and right bundle branches. The left bundle branch has two fascicles. The left bundle branch supplies the l... | {
"Header 1": "**19.2 | Cardiac Muscle and Electrical Activity**",
"Header 3": "**Atrioventricular Bundle (Bundle of His), Bundle Branches, and Purkinje Fibers**",
"token_count": 462,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
Action potentials are considerably different between cardiac conductive cells and cardiac contractive cells. While Na<sup>+</sup> and K + play essential roles, Ca2+ is also critical for both types of cells. Unlike skeletal muscles and neurons, cardiac conductive cells do not have a stable resting potential. Conductive ... | {
"Header 1": "**19.2 | Cardiac Muscle and Electrical Activity**",
"Header 3": "**Membrane Potentials and Ion Movement in Cardiac Conductive Cells**",
"token_count": 368,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
There is a distinctly different electrical pattern involving the contractile cells. In this case, there is a rapid depolarization, followed by a plateau phase and then repolarization. This phenomenon accounts for the long refractory periods required for the cardiac muscle cells to pump blood effectively before they are... | {
"Header 1": "**19.2 | Cardiac Muscle and Electrical Activity**",
"Header 3": "**Membrane Potentials and Ion Movement in Cardiac Contractile Cells**",
"token_count": 528,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
The pattern of prepotential or spontaneous depolarization, followed by rapid depolarization and repolarization just described, are seen in the SA node and a few other conductive cells in the heart. Since the SA node is the pacemaker, it reaches threshold faster than any other component of the conduction system. It will... | {
"Header 1": "**19.2 | Cardiac Muscle and Electrical Activity**",
"Header 3": "**Comparative Rates of Conduction System Firing**",
"token_count": 346,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
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