Exam 3: Ch 11 Hormones Flashcards
1
Q
Endocrine glands =
A
ductless & secrete hormones
2
Q
hormones
A
- regulatory molecules secreted into the bloodstream by endocrine glands
- go to target cells that contain receptor proteins for it
3
Q
Main endocrine glands are
A
discrete organs whose primary function is to produce and secrete hormones
4
Q
The endocrine system includes
A
many other organ whose primary function is NOT to release hormones but do Neurohormones
5
Q
Neurohormones
A
are secreted into blood by specialized neurons (e.g. hypothalamus)
6
Q
Chemical Classification of Hormones:
Amino Acid Base
A
- Amine
- Polypeptide(<100 aa)/protein(>100 aa)
- Glycoproteins
7
Q
Chemical Classification of Hormones:
Steroid Base
A
Steroids
8
Q
Amine hormones are
A
derived from the amino acids tyrosine or tryptophan
9
Q
Amine hormones include
A
Include hormones secreted by adrenal medulla and pineal glands (NE, Epi,melatonin)
10
Q
Polypeptide(<100 aa)/protein(>100 aa)
A
hormones are chains of amino acids (Include AntiDiruetic Hormone, GH, insulin, oxytocin, glucagon, Adrenocorticotrophic hormone (ACTH), PTH)
11
Q
Glycoproteins =
A
long polypeptide chains connected to 1 or more carbohydrate (include LH, FSH, TSH)
12
Q
Steroids
A
are lipids derived (as are thyroid hormones) from cholesterol so they can diffuse into cells (include testosterone, estrogen, progesterone &; cortisol);
13
Q
Steroids made only by
A
adrenal cortex and gonads
14
Q
Prohormones
A
are precursors of hormones; E.g. proinsulin
15
Q
Prehormones
A
are precursors of prohormones; E.g. preproinsulin
16
Q
Some hormones are inactive until
A
- activated by target cells
- E.g. thyroxine (T4) is inactive until converted to T3 in target cells
17
Q
Both NS & endocrine system use
A
chemicals to communicate
18
Q
Difference between NTs & hormones:
A
- transport in blood
- more diversity of effects in hormone targets
19
Q
Common Aspects of Neural & Endocrine Regulation
A
- Some chemicals are used as hormones & NTs
(e. g. norepinephrine) - Targets for both NTs & hormones must have specific receptor proteins
- Must be way to rapidly inactivate both
20
Q
Hormone Interactions
A
A tissue usually responds to # of hormones
21
Q
2 hormones are synergistic if
A
- work together to produce an effect
- produce a larger effect together than individual effects added together
22
Q
A hormone has permissive effect if
A
if it enhances responsiveness of a target organ to 2nd hormone
23
Q
antagonistic
A
If action of 1 hormone inhibits effect of another
24
Q
Normal tissue responses are produced
A
only when hormones are in physiological range
25
High (pharmacological) doses
- can cause # of side effects; probably by binding to receptors of other hormones
26
Priming effect (upregulation)
occurs when a hormone induces more of its own receptors in target cells; results in greater response in target cell
27
Desensitization (downregulation)
occurs after long exposure to high levels of polypeptide hormone
28
Subsequent exposure to high levels of polypeptide hormone
produces a lesser response due to decrease in # of receptors on targets
29
Most peptide hormones have
pulsatile secretion
30
pulsatile secretion
(in spurts rather than continuously) which prevents downregulation
31
Target cell receptors show
- specificity (specific receptors)
- high affinity (high bonding strength), &
- low capacity (saturation) for a hormone
32
Lipid hormones have
receptors in target cell's cytoplasm &/or nucleus because can they diffuse through plasma membrane
33
Receptors for water-soluble hormones are
on surface of target cell
34
Lipid hormones
(steroids and thyroid hormones) travel in blood attached to carrier proteins
35
Lipid hormones dissociate from
carriers to pass thru plasma membrane of target
36
Lipid hormones receptors are called
nuclear hormone receptors
37
Nuclear Hormone Receptors
serve as transcription factors (Activate transcription) when bound to hormone ligands
38
Nuclear Hormone Receptors Constitute a
a "superfamily" composed of steroid family & thyroid hormone family
39
Nuclear Hormone Receptors have
ligand (hormone)-binding & DNA-binding domains
40
Nuclear Hormone Receptors bind
hormone & translocate to nucleus
41
Nuclear Hormone Receptors binds to
hormone-response element (HRE) on DNA located adjacent to target gene
42
Nuclear Hormone Receptors consists of
of 2 half-sites; 2 ligand-bound receptors have to bind to each HRE (dimerization), which stimulates transcription of target gene
43
Thyroid gland secretes
- 90% T4 (tetraiodothyronine = thyroxine = inactive form)
| - 10% T3 (triiodothyronine = active form)
44
99.96% of T4 in blood is bound to
- carrier protein (thyroid binding globulin - TBG)
- but only free T4 can enter cells, so bound is reservoir
- T4 converted to T3 inside cell
45
T3 binds to
receptor protein located in nucleus bound to DNA…
46
T3 & receptor bind to 1 half-site
| Other half-site binds
retinoic acid (vitamin A derivative)
47
Two partners form heterodimer
that activates hormone response element (HRE) =
| Stimulates transcription of target gene
48
Pituitary gland is located
beneath hypothalamus at base of forebrain
49
Pituitary gland Is structurally & functionally
into anterior & posterior lobes
50
Anterior pituitary (adenohypophysis)
produces own hormones and is controlled by hypothalamus
51
Posterior pituitary (neurohypophysis)
stores & releases hormones made in hypothalamus
52
Anterior Pituitary secretes
- 6 trophic hormones that maintain size of targets
| - High blood levels cause target to hypertrophy and low levels cause atrophy
53
6 trophic hormones
- Growth hormone (GH = somatotropin)
- Thyroid stimulating hormone (TSH =thyrotropin)
- Adrenocorticotrophic hormone (ACTH = corticotropin)
- Follicle stimulating hormone (FSH = folliculotropin)
- Luteinizing hormone (LH = luteotropin)
- Prolactin (PRL)
54
Growth hormone (GH = somatotropin)
promotes growth, protein synthesis, & movement of amino acids into most cells
55
Thyroid stimulating hormone (TSH =thyrotropin)
stimulates thyroid gland to produce & secrete T4 & T3
56
Adrenocorticotrophic hormone (ACTH = corticotropin)
stimulates adrenal cortex to secrete cortisol, aldosterone
57
Follicle stimulating hormone (FSH = folliculotropin)
stimulates growth of ovarian follicles & sperm production
58
Luteinizing hormone (LH = luteotropin)
causes ovulation & secretion of testosterone in testes
59
Prolactin (PRL)
stimulates milk production by mammary glands
60
Feedback Control of Anterior Pituitary
- Involves short feedback loop and Negative feedback
61
short feedback loop
in which retrograde flow of blood & hormones from ant. pit. to hypothalamus inhibits secretion of releasing hormone
62
Anterior Pituitary Involves negative feedback
of target gland hormones
63
Anterior Pituitary during menstrual cycle
estrogen stimulates “LH surge” by positive feedback
64
Hypothalamus receives input from
higher brain centers that can affect A. Pit. secretion
| - E.g. psychological stress affects circadian rhythms, menstrual cycle, & adrenal hormones
65
Posterior Pituitary Stores & releases
2 hormones produced in hypothalamus:
- Antidiuretic hormone (ADH/vasopressin)
- Oxytocin
66
Antidiuretic hormone (ADH/vasopressin)
which promotes H20 conservation by kidneys
67
Oxytocin
which stimulates contractions of uterus during parturition (labor)
- & contractions of mammary gland alveoli for milk-ejection reflex
68
Hypothalamic Control of Posterior Pituitary:
| Supraoptic nuclei of hypothalamus produce
ADH
69
Hypothalamic Control of Posterior Pituitary:
| Paraventricular nuclei
produce oxytocin
70
Supraoptic nuclei of hypothalamus and Paraventricular nuclei both
- Both transported along hypothalamo-hypophyseal tract to posterior pituitary
- Release controlled in hypothalamus by neuroendocrine reflexes
71
Adrenal Glands
Sit on top of kidneys
72
Adrenal Glands each consists of
outer cortex (glandular tissue) & inner medulla (derives from neuronal tissue)
73
Adrenal cortex secretes
steroid hormones called corticosteroids (corticoids);
74
Adrenal cortex controlled by
Adrenocorticotrophic hormone (ACTH) from ant. Pit. & secretes:
75
3 categories of corticoids
- Mineralocorticoids
- Glucocorticoids
- & some supplementary sex steroids
76
Mineralocorticoids
regulate Na+ and K+ balance ex: Aldosterone which stimulate kidneys to reabsorb Na+ and water and secrete K+
77
Glucocorticoids
regulate metabolism of glucose and other organic molecules ex:Cortisol which inhibits glucose utilization & stimulates gluconeogenesis
78
Functions of adrenal medulla
Medulla synthesizes & secretes 80% Epinephrine & 20% Norepiphrine,
79
effects of Epi
- last 10X longer than NE;
| - Innervated by preganglionic Symp fibers
80
Functions of adrenal medulla Activated during
- "fight or flight" response:
- ↑ respiratory rate and HR & cardiac output; general vasoconstriction which increases venous return, and glycogenolysis & lipolysis
81
Thyroid Gland Is located
just below the larynx w/ each lobe on either side of trachea
82
Thyroid Gland Secretes
T4 & T3 which set basal metabolic rate & are needed for growth, development
83
Thyroid Gland Consists of
microscopic thyroid follicles and the outer layer is follicular cells that synthesize T4
84
Outer parafollicular cells secrete
calcitonin = ↓ blood [Ca2+] levels by stimulating secretion and osteoblast activity
85
Parathyroid glands
4 glands embedded in posterior surfaces of lateral lobes of thyroid gland
86
Parathyroid glands Only secrete
Parathyroid hormone (PTH)
87
Parathyroid hormone (PTH)
- Most important hormone for control of blood Ca2+ levels
- Release stimulated by decreased blood Ca2+
- Acts on bones, kidney, & intestines to increase blood Ca2+ levels
88
pancreas
has both exocrine (discharge of secretions through a duct) and endocrine functions (secretion of hormones into circulation)
89
Endocrine portion of pancreas
scattered clusters of cells = pancreatic islets (islets of Langerhans)
90
pancreatic islets (islets of Langerhans)
- 2 cells types in the pancreatic islets:
- Alpha Cells
- Beta Cells
91
Alpha cells secrete
glucagon
92
Beta cells secrete
insulin
93
Glucagon
- released in response to low blood glucose
- stimulates glycogenolysis (occurs at the liver to ↑ blood glucose)
- stimulates lipolysis (↑ free fatty acids) and helps with conversion of fatty acids to ketone bodies
94
Insulin
- released in response to high blood glucose which promotes:
- entry of glucose into cells
- conversion of glucose into glycogen & fat causing decreases blood glucose
95
Pineal gland
located in basal forebrain near thalamus
96
Pineal gland Secretes
melatonin in response to activity of hypothalamus
97
melatonin
nvolved in aligning physiology with sleep/wake cycle & seasons
secreted at night & is inhibited by light
98
Thymus
Is located around trachea below thyroid and behind manubrum
99
Thymus Produces
T cells of immune system & hormones that stimulate them
100
Sex & Reproductive Hormones
Gonads (testes & ovaries)
101
Gonads (testes & ovaries) secrete
steroid hormones testosterone, estrogen, & progesterone
102
Autocrine regulatory molecules
produced & act within same cell type in which they were produced
103
All autocrines control
gene expression in target cells
104
Paracrine regulatory molecules
are produced within one tissue & act on different tissue in same organ.
