Chapter 17 Outline Flashcards
(113 cards)
1
Q
What are the four principal avenues of communication from cell to cell in the body?
A
- Gap junctions
- Neurotransmitters
- Paracrines
- Hormones
2
Q
What is the definition of hormones?
A
Chemical messengers transported by the bloodstream that stimulate physiological responses of cells of another tissue or organ.
3
Q
What is endocrinology?
A
The study of the endocrine system and the diagnosis and treatment of its disorders.
4
Q
Name three familiar hormone sources.
A
- Pituitary gland
- Thyroid gland
- Adrenal glands
5
Q
What distinguishes endocrine glands from exocrine glands?
A
Endocrine glands are ductless and release their secretions into the bloodstream.
6
Q
What type of capillaries do endocrine glands have?
A
Fenestrated capillaries.
7
Q
True or False: Exocrine secretions have intracellular effects.
A
False.
8
Q
How do the nervous and endocrine systems differ in terms of communication speed?
A
The nervous system responds within milliseconds, while hormonal responses take seconds to days.
9
Q
What is the role of neuroendocrine cells?
A
They act like neurons but release their secretions into the bloodstream.
10
Q
What are the two main structures of the pituitary gland?
A
- Anterior pituitary (adenohypophysis)
- Posterior pituitary (neurohypophysis)
11
Q
What connects the pituitary gland to the hypothalamus?
A
The infundibulum.
12
Q
What hormones are produced in the hypothalamus?
A
- Releasing hormones
- Inhibiting hormones
- Oxytocin (OT)
- Antidiuretic hormone (ADH)
13
Q
What is the function of follicle-stimulating hormone (FSH)?
A
Stimulates secretion of ovarian sex hormones and development of follicles in ovaries; stimulates sperm production in testes.
14
Q
What is the role of luteinizing hormone (LH) in females?
A
Stimulates ovulation and secretion of progesterone from the corpus luteum.
15
Q
What does thyroid-stimulating hormone (TSH) stimulate?
A
Stimulates growth of the thyroid gland and secretion of thyroid hormone.
16
Q
What is the function of adrenocorticotropic hormone (ACTH)?
A
Stimulates the adrenal cortex to release glucocorticoids, especially cortisol.
17
Q
What is the primary function of prolactin (PRL)?
A
Stimulates mammary glands to synthesize milk after childbirth.
18
Q
What is unique about the secretion of growth hormone (GH)?
A
GH has widespread effects on the body and stimulates growth in various tissues.
19
Q
What are the two posterior lobe hormones?
A
- Antidiuretic hormone (ADH)
- Oxytocin (OT)
20
Q
What triggers the release of ADH?
A
Increased blood osmolarity detected by hypothalamic osmoreceptors.
21
Q
Fill in the blank: The hypothalamus controls the anterior pituitary by secreting _______.
A
[releasing hormones]
22
Q
What is the feedback mechanism most often used to regulate pituitary hormone secretion?
A
Negative feedback inhibition.
23
Q
What stimulates the secretion of growth hormone?
A
Trauma, hypoglycemia, vigorous exercise, and high-protein meals.
24
Q
How does growth hormone (GH) affect lipid metabolism?
A
Stimulates adipocytes to catabolize fat and release fatty acids and glycerol.
25
What effect does GH have on electrolyte balance?
Promotes Na+, K+, and Cl– retention by the kidneys; enhances Ca2+ absorption by the small intestine.
26
True or False: Growth hormone levels increase with age.
False.
27
What is the GH level in blood plasma during the first 2 hours of deep sleep?
20 nanograms per milliliter (ng/mL) or higher
28
What factors stimulate GH secretion?
Trauma, hypoglycemia, and high-protein meals
29
How do GH levels change as a person ages?
GH levels decline gradually with age
30
What is the average GH concentration in adolescence?
6 ng/mL
31
What is the average body composition at age 30?
10% bone, 30% muscle, 20% fat
32
What is the pineal gland's shape reminiscent of?
A pine cone
33
What happens to the pineal gland after age 7?
It undergoes involution
34
What hormone does the pineal gland synthesize during the night?
Melatonin
35
What effect does melatonin have on gonadotropin secretion?
It may suppress gonadotropin secretion
36
Where is the thymus located?
In the mediastinum, superior to the heart
37
What is the primary role of the thymus?
Maturation of T cells
38
What hormones does the thymus secrete?
Thymopoietin, thymosin, thymulin
39
What is the primary function of the thyroid gland?
Endocrine function
40
What are the two main hormones secreted by the thyroid gland?
Thyroxine (T4) and triiodothyronine (T3)
41
What is the primary effect of thyroid hormone (TH)?
Increase the body's metabolic rate
42
What do C (clear) cells in the thyroid secrete?
Calcitonin
43
What is the function of parathyroid hormone (PTH)?
Regulate blood calcium levels
44
What are the adrenal glands also known as?
Suprarenal glands
45
What two regions compose the adrenal gland?
Adrenal medulla and adrenal cortex
46
What do chromaffin cells in the adrenal medulla release?
Catecholamines (epinephrine, norepinephrine, dopamine)
47
What is the most significant mineralocorticoid secreted by the adrenal cortex?
Aldosterone
48
What is cortisol's primary role?
Stimulate fat and protein catabolism, gluconeogenesis
49
What are the primary adrenal sex steroids?
Androgens, specifically dehydroepiandrosterone (DHEA)
50
What is the main source of estrogen after menopause?
Estradiol from the adrenal glands
51
What is the pancreas primarily known for?
Secreting digestive enzymes
52
What are the pancreatic islets also known as?
Islets of Langerhans
53
What hormone do alpha cells in the pancreas secrete?
Glucagon
54
What is the primary function of insulin?
Lower blood glucose levels
55
What is somatostatin's role in the pancreas?
Inhibit secretion of stomach acid
56
What are the exocrine products of the gonads?
Whole cells (eggs and sperm)
57
What hormones do the ovaries primarily secrete?
Estradiol, progesterone, inhibin
58
What is the role of testosterone in males?
Stimulate development of the male reproductive system and sex drive
59
What do keratinocytes in the skin convert into cholecalciferol?
A cholesterol-like steroid
60
What regulates the rate of sperm production?
Inhibin regulates the rate of sperm production by limiting FSH secretion.
## Footnote
FSH stands for follicle-stimulating hormone.
61
What is the source of gonadal steroids in the male reproductive system?
Clusters of interstitial cells (cells of Leydig) are the source of gonadal steroids.
## Footnote
These cells are located between the seminiferous tubules in the testes.
62
What are the functions of testosterone?
* Stimulates development of the male reproductive system in the fetus
* Promotes development of the male physique in adolescence
* Enhances sex drive
63
Which organ converts cholecalciferol to calcitriol?
The liver and kidneys convert cholecalciferol to calcitriol.
## Footnote
Calcitriol is a calcium-regulating hormone.
64
What hormone does the liver secrete that stimulates red blood cell production?
Erythropoietin (EPO) stimulates the production of red blood cells by the red bone marrow.
65
What role does hepcidin play in the body?
Hepcidin promotes intestinal absorption of dietary iron and mobilization of iron for hemoglobin synthesis and other uses.
66
What hormones do the kidneys produce?
* Calcitriol
* Angiotensin II
* Erythropoietin
67
What effect do natriuretic peptides have on the body?
Natriuretic peptides increase sodium excretion and urine output, opposing the action of angiotensin II.
68
What hormone is secreted by adipose tissue and regulates appetite?
Leptin is secreted by adipose tissue and regulates appetite.
69
What is the function of osteocalcin?
Osteocalcin increases the number of pancreatic beta cells, pancreatic output of insulin, and insulin sensitivity of other body tissues.
70
What hormones are secreted by the placenta?
* Estrogen
* Progesterone
* Other hormones that regulate pregnancy and stimulate fetal development
71
What are the three chemical classes of hormones?
* Steroids
* Monoamines
* Peptides
72
What are steroid hormones derived from?
Steroid hormones are derived from cholesterol.
73
Which hormones are classified as monoamines?
* Dopamine
* Epinephrine
* Norepinephrine
* Melatonin
* Thyroid hormone
74
What is the structure of peptide hormones?
Peptide hormones are chains of 3 to 200 or more amino acids.
75
What is the role of cholesterol in hormone synthesis?
Cholesterol serves as the precursor for the synthesis of steroid hormones.
76
What happens during the synthesis of insulin?
Insulin begins as proinsulin, which is modified by removing the connecting peptide to form mature insulin.
77
What is the function of transport proteins in hormone transport?
Transport proteins bind hydrophobic hormones, allowing them to circulate in the blood.
78
What is the difference between bound and unbound hormones?
Bound hormones are attached to transport proteins, while unbound hormones are free to leave blood capillaries and act on target cells.
79
What is signal amplification in hormonal action?
Signal amplification is when one hormone molecule triggers the synthesis of a large number of enzyme molecules.
80
How can target cells modulate their sensitivity to hormones?
* Up-regulation: increases number of receptors
* Down-regulation: decreases number of receptors
81
What are the three types of interactive effects hormones can have on target cells?
* Synergistic effects
* Permissive effects
* Antagonistic effects
82
What is the role of the kidneys in hormone clearance?
The kidneys help in the uptake and degradation of hormones, which are then excreted in bile or urine.
83
What are synergistic effects in hormone action?
Two or more hormones act together to produce an effect greater than the sum of their separate effects.
84
Define permissive effects in hormone action.
One hormone enhances the target organ’s response to a second hormone secreted later.
85
What are antagonistic effects in hormone action?
One hormone opposes the action of another.
86
What occurs during hormone clearance?
Hormones are taken up and degraded by the liver and kidneys and then excreted in bile or urine.
87
What is the metabolic clearance rate (MCR)?
The rate of hormone removal from the bloodstream.
88
What is the half-life of a hormone?
The length of time required to clear 50% of the hormone from the blood.
89
What constitutes stress?
Any situation that upsets homeostasis and threatens an individual’s physical or emotional well-being.
90
What is the general adaptation syndrome (GAS)?
The body's response to stress, typically involving elevated levels of epinephrine and cortisol.
91
What are the three stages of GAS according to Hans Selye?
* Alarm reaction
* Stage of resistance
* Stage of exhaustion
92
What mediates the alarm reaction in response to stress?
Mainly norepinephrine from the sympathetic nervous system and epinephrine from the adrenal medulla.
93
What physiological changes occur during the alarm reaction?
* Consumption of stored glycogen
* Increase in angiotensin and aldosterone
* Rises in blood pressure and sodium/water conservation
94
What characterizes the stage of resistance in stress response?
Entered when glycogen reserves are depleted; cortisol dominates this stage.
95
What hormone is released by the hypothalamus during the stage of resistance?
Corticotropin-releasing hormone (CRH).
96
How does cortisol affect metabolism during stress?
* Promotes breakdown of fat and protein
* Inhibits glucose uptake and protein synthesis
97
What are the adverse effects of long-term cortisol elevation on the immune system?
* Inhibits synthesis of leukotrienes and prostaglandins
* Suppresses antibody production
* Kills immature T and B cells
98
What occurs during the stage of exhaustion in stress response?
The body’s fat reserves are depleted, leading to reliance on protein breakdown and potential rapid decline or death.
99
What can result from aldosterone secretion during the stage of exhaustion?
A state of hypertension.
100
What are paracrine messengers?
Chemical signals released by cells into tissue fluid that diffuse to nearby cells.
101
Give an example of a paracrine messenger.
* Histamine
* Nitric oxide
* Catecholamines
102
What are eicosanoids?
An important family of paracrine secretions derived from arachidonic acid.
103
What enzyme converts arachidonic acid to leukotrienes?
Lipoxygenase.
104
What is Cushing syndrome?
Excess cortisol secretion due to various causes.
105
What are the classic signs of diabetes mellitus?
* Polyuria
* Polydipsia
* Polyphagia
106
What are the two forms of diabetes mellitus?
* Type 1
* Type 2
107
What is the primary issue in type 2 diabetes mellitus?
Insulin resistance.
108
What is the consequence of hyperglycemia in diabetes mellitus?
Disruption of carbohydrate, fat, and protein metabolism.
109
What is the primary cause of diabetic neuropathy?
Nerve damage resulting from impoverished blood flow.
110
What is a goiter?
A pathological enlargement of the thyroid.
111
What causes endemic goiter?
Dietary deficiency of iodine.
112
What is the consequence of hypoparathyroidism?
Rapid decline in calcium levels, potentially leading to fatal larynx spasms.
113
What is the relationship between hyperparathyroidism and kidney stones?
It raises blood levels of calcium and phosphate, promoting renal calculi formation.
