Human Anatomy & Physiology: Chapter 16 The Endocrine System Flashcards


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1

Hormones are

chemical messengers secreted by cells into the extracellular fluids

2

The major process that hormones control and integrate include

  • Reproduction
  • Growth and development
  • Maintenance of electrolyte, water, and nutrient balance of the blood
  • Regulation of cellular metabolism and energy balance
  • Mobilization of bode defenses
3

The scientific study of hormones and the endocrine organs is called

Endocrinology

4

Endocrine Glands

produce hormones and lack ducts

5

Endocrine glands include the

  • Pituitary
  • Thyroid
  • Parathyroid
  • Adrenal
  • Pineal
  • Pancreas
  • Gonads (Ovaries and testes)
  • Placenta
  • Hypothalamus
6

Autocrines are

chemicals that exert their effects on the same cells that secret them

7

Paracrines

affect cell types other than those releasing the paracrine chemicals

8

Nearly all hormones can be classified chemically as

either amino acid based or steroids

9

A hormone influences

the activity of only those tissue cells that have receptors for it

10

Target cells

are tissues with receptors for specific hormone

11

A hormone typically produces one or more of the following changes

  • alters plasma membrane permeability or membrane potential, or both, by opening or closing ion channels
  • stimulates synthesis of enzymes and other proteins withing the cell
  • activates or deactivates enzymes
  • induces secretory activity
  • stimulates mitosis
12

Water-soluble hormones

act on receptors in the plasma membrane

13

Lipid-soluble hormones

act on receptors inside the cell

14

Amino acid-based hormones

exert their signaling effects through intracellular second messenger generated when a hormone binds to a receptor in the plasma membrane

15

The cyclic AMP (cthe sAMP) signaling mechanism involves interaction of three plasma membrane component

  • a hormone receptor
  • a G protein
  • and an effector enzyme (adenylate cylase)
16

Target cell activation depends equally on three other factors

  • blood levels of the hormone
  • relative numbers of receptors for that hormone on or in the target cells
  • strength of the binding between the hormone and the receptor
17

Up-regulation

are target cells that form more receptors in response to low hormone levels

18

Down-regulation

are target cells that lose receptors in response to high hormone levels

19

Three types of stimuli trigger endocrine glands to manufacture and release their hormones.

  • Humoral
  • Neural
  • Hormonal Stimuli
20

Humoral stimuli

secrete their hormones in direct response to changing blood levels of certain critical ions and nutrients

21

Neural stimuli

happens when nerve fibers stimulate hormone release

22

Hormonal Stimuli

release their hormones in response to hormones produced by other endocrine organs

23

Hormones circulate in the blood in two forms

  • Free
  • Bound to a protein carrier
24

The concentration of a circulating hormone in blood at any time reflects

  • its rate of release
  • the speed at which it is inactivated and removed from the body
25

Permissiveness

is the situation in which one hormone cannot exert its full effects without another hormone being present

26

Synergism

occurs when more than one hormone produces the same effects at the target cell and their combined effects are amplified

27

Antagonism

occurs when one hormone opposes the action of another hormone

28

Pituitary Gland

also called the hypophysis, secretes at least eight hormones

29

Posterior pituitary

is composed largely of neural tissue.

30

Posterior pituitary

is a hormone storage area and not a true endocrine gland that manufactures hormones

31

Posterior pituitary

is commonly called neurohypophysis

32

Anterior Pituitary

is commonly called adenohypophysis

33

Anterior Pituitary

is composed of glandular tissue

34

The neurons in the posterior pituitary synthesize one of two neurohormones in their cell bodies

  • Oxytocin
  • Antidiuretic Hormone (ADH)
35

Oxytocin

is released in significantly higher amounts during childbirth and in nursing women

36

Antidiuretic Hormone (ADH)

prevents wide swings in water balance, helping the body avoid dehydration and water overload

37

There are six anterior pituitary hormones, all of them proteins

  • Growth hormone (GH)
  • Thyroid-stimulating hormone (TSH)
  • Adrenocorticotropic hormone (ACTH)
  • Follicle-stimulating hormone (FSH)
  • Luteinizing hormone (LH)
  • Prolactin (PRL)
38

Tropic hormones

regulate the secretory action of other endocrine glands

39

Four of the six anterior pituitary hormones are tropic hormones

  • Thyroid-stimulating hormone (TSH)
  • Adrenocorticotropic hormone (ACTH)
  • Follicle-stimulating hormone (FSH)
  • Luteinizing hormone (LH)
40

Thyroid gland is

located in the anterior neck, on the trachea just inferior to the larynx

41

Isthmus

is a median tissue mass that connects its two lateral lobes

42

Often referred to as the body's major hormone

Thyroid hormone (TH)

43

Thyroid hormone (TH)

is two iodine-containing amine hormones, thyroxine, or T4, and triiodothyronine, or T3

44

Effects of thyroid hormone include

  • Increasing basal metabolic rate and body heat production, by turning on transcription of genes concerned with glucose oxidation
  • Regulating tissue growth and development
  • Maintaining blood pressure by increasing the number of adrenergic receptors in blood vessels
45

The thyroid gland is

composed of hollow, spherical follicles

46

The walls of each follicle

produce the glycoprotein thyroglobulin

47

The central cavity, or lumen, of the follicle

stores colloid

48

Most released T4 and T3 immediately bind to

thyroxine - binding globulins (TBGs)

49

Calcitonin

a polypeptide hormone released by the parafollicular, or C, cells of the thyroid gland in response to a rise in blood Ca2+ levels

50

Parathyroid glands

are tiny, yellow-brown glands nearly hidden from view in the posterior aspect of the thyroid gland

51

Parathyroid hormone (PTH), or parathormone,

is the single most important hormone controlling calcium balance in the blood

52

Adrenal glands

are pyramid-shaped organs perched atop the kidneys, where they are enclosed in a fibrous capsule and a cushion of fat

53

Adrenal glands

Suprarenal glands

54

Adrenal medulla

is part of the sympathetic nervous system

55

Adrenal cortex

is glandular tissue derived from embryonic mesoderm

56

Adrenal cortex has three layers of glandular tissue

  • Zona glomerulosa
  • Zona fasciculata
  • Zona reticularis
57

Zona Glomerulosa

produces mineralocorticoids, hormones that help control the balance of minerals and water in the blood

58

Zona Fasciculata

mainly produce the metabolic hormones called glucocorticoids

59

Zona Reticularis

mainly produce small amounts of adrenal sex hormones, or gonadocorticoids

60

Somatotropic Cells

produce growth hormone (GH)

61

Growth hormone

increases blood levels of fatty acids, encourages use of fatty acids for fuel, and protein synthesis

62

Growth Hormone

medieates most of its growth- enhancing effects indirectly vie a family of growth-promoting proteins called insulin-like growth factors (IGFs)

63

Growth hormone–releasing hormone (GHRH)

stimulates GH release

64

Growth hormone-inhibiting hormone (GHIH)

inhibits GH release

65

Growth hormone-inhibiting hormone (GHIH)

somatostatin

66

Thyroid - Stimulating Hormone (TSH)

is a tropic hormone that stimulates normal development and secretory activty of the thyroid gland

67

Adrenocorticotropic Hormone (ACTH)

is secreted by the corticotropic cells of the anterior pituitary

68

Thyroid - Stimulating Hormone (TSH)

Thyrotropin

69

Adrenocorticotropic Hormone (ACTH)

Corticotropin

70

Gonadotropins

Follicle-stimulating hormone (FSH) and Luteinizing hormone (LH)

71

Gonadotropins

regulate the function of the gonads (ovaries and testes)

72

Prolactin (PRL)

is a protein hormone structurally similar to GH

73

Prolactin (PRL)

stimulate milk production by the breasts

74

Mineralocorticoids

essential function is to regulate the electrolyte (mineral salts) concentrations in extracellular fluids, particularly of Na+ and K+

75

Changes in Na+ concentration lead to

changes in blood volume and blood pressure

76

Aldosterone

reduces excretion of Na+ from the body, thereby lowering blood volume and blood pressure

77

The renin-angiotensin-aldosterone mechanism

influences both blood volume and blood pressure by regulating the release of aldosterone and therefore Na+ and water reabsorption by the kidneys

78

Glucocorticoids

influence the energy metabolism of most body cells and help is resist stressors

79

Glucocorticoids hormones include

  • Cortisol (hydrocortisone)
  • Cortisone
  • Corticosterone
80

Excessive levels of glucocorticoids

  • Depress cartilage and bone formation
  • Inhibit inflammation by decreasing the release of inflammatory chemicals
  • Depress the immune system
  • Disrupt normal cardiovascular, neural, and gastrointestinal function
81

Gonadocorticoids (Adrenal Sex Hormones)

secreted by the adrenal cortex are weak, androgens, or male sex hormones.

82

Adrenal Medullary Hormones

catecholoamines (epinephrine and norepinephrine)

83

Pineal Gland

hangs from the roof of the third ventricle in the diencephalon

84

The pineal gland secreted cells called

pinealocytes

85

The pineal gland's only major secretory product is

melatonin

86

Melatonin

an amine hormone derived from serotonin

87

The pancreas

is a mixed gland composed of both endocrine and exocrine gland cells

88

Acinar cells

produce an enzyme-rich juice that is carried by ducts to the small intestine during digestion

89

Pancreatic Islets

tiny cell clusters that produce pancreatic hormones

90

The islets contain two major populations of hormone-producing cells

  • the glucagon-synthesizing Alpha cells
  • insulin-synthesizing Beta cells
91

Glucagon

is a hyperglycemic hormones

92

Insulin

is a hypoglycemic hormone

93

Glucagon

is a 29-amino-acid polypeptide

94

Glucagon promotes

  • Breakdown of glycogen to glucose
  • Synthesis of glucose from lactic acid and from noncarbohydrate molecules
  • Release of glucose to the blood by liver cells, causing blood glucose levels to rise
95

Insulin

is a small protein consisting of two amino acid chains linked by disulfide bonds

96

Proinsulin

is a large polypeptide chain that synthesizes insulin

97

Insulin lowers blood glucose levels in 3 ways

  • Enhances membrane transport of glucose into most body cells
  • Inhibits the breakdown of glycogen to glucose
  • Inhibits the conversion of amino acids or fats to glucose
98

Insulin stimulates glycogen formation

Glucagon stimulates glycogen breakdown

99

The female and male gonads

produce steriod sex hormones

100

Ovaries are

located in the female's abdominopelvic cavity

101

Ovaries produce

ova, or eggs, and estrogens ad progesterone

102

Male testes

located in an extra-abdominal skin pouch called the scrotum

103

Males testes

produce sperm and male sex hormones, primarily testosterone

104

The placenta is a

temporary endocrine organ

105

Placenta hormones include

estrogen and progesterone and human chorionic gonadotropin (hCG)

106

Leptin is

released by Adipose cells, tells your body how much stored energy you have

107

Resistin is an insulin antagonist while

Adiponectin enhances sensitivity to insulin

108

Enteroendocrin cells are

hormone-secreting cells sprinkled in the mucosa of the gastrointestinal (GI) tract

109

Atrial Natriuretic Peptide (ANP) is

secreted by specialized cardiac (heart) muscle cells

110

ANP

decreases the amount of sodium in the extracellular fluid

111

Erythropoietin is

a glycoprotein hormone that signals the bone marrow to increase production of Red Blood Cells (RBCs)

112

Osteoblast (bone creating cells) in bone secrete osteocalcin

a hormone that prods pancreatic beta cells to divide and secrete more insulin

113

The skin produces cholecalciferol

an inactive form of vitamin D3

114

Calcitriol

the active form of vitamin D3

115

Other hormone-producing cells occur in various organs include

  • Heart
  • Gastrointestinal Tract
  • Kidneys
  • Skin
  • Adipose Tissue
  • Skeleton
  • Thymus
116

The thymus secretes several different families of peptide hormones including

  • Thymulin
  • Thymopoietins
  • Thymosins