Chapter 19- Endocrine System

Question 1

general characteristics

Answer 1

• chronic regulation of homeostasis
• -slow and prolonged responses
• -acute=nervous system
• interrelated with nercous system
• -hypothalamus and posterior pituitary
• ductless system
• -hormones produced by specialized cells
• -carried in blood stream

Question 2

hormones

Answer 2

• substance synthesized by a specific organ or tissue and secreted:
• -secreted into extracellular spaces=paracrine signaling (no blood needed)
• -blood carries it to other sites=endocrine signaling
• act on target cells
• -have specific receptors for specific hormones

Question 3

chemistry of hormones: categories

Answer 3

1. steroids: made from cholesterol, non polar
2. peptides: polar
3. amines
   - derived from amino acids
   - polar and non-polar
4. eicosanoids
   - most are non-polar
   - paracrine signals (prostaglandins)

Question 4

steroid hormones

Answer 4

• lipid soluble therefore can cross cell membrane
• -transduction=regulation of DNA transcription
• examples
• -estrogens like estradiol
• -androgens like testosterone
• -aldosterone
• -cortisol

Question 5

amine hormones

Answer 5

• derived from either tyrosine or tryptophan
• some are membrane soluble (thyroxine)
• some are not (epinephrine)
• most important ones are made by:
• -thyroid
• -adrenal medulla

Question 6

other hormones

Answer 6

peptide hormones
-short chains of amino acids
--cannot cross cell membrane
-all pituitary hormones
eicosanoids
-derived from fatty acids
--most cross cell membranes
-coordinate functions in extracellular fluid
--ex. prostaglandins

Question 7

control of hormone secretion

Answer 7

negative feedback

• gland is sensitive to concentration of substance
• concentration exceeds limits–> prevents gland from secreting hormone
• concentration decreases->secretion increases
• results in relatively stable concentration of both substance and hormone

Question 8

hypothalamus

Answer 8

• sends signals to the body and the pituitary gland
• -really 2 separate glands: developmental origins are key to function
• pituitary is the most important endocrine gland for regulation
• basically runs endocrine system

Question 9

pituitary gland

Answer 9

2 lobes
posterior (neural)
-does not make any hormones
-mostly hypothalamic axons
anterior (endocrine)
-5 types of endocrine cells
-controlled by hypothalamic regulatory hormones
--releasing hormones
--inhibiting hormones

Question 10

posterior pituitary hormones

Answer 10

Oxytocin

ADH

Question 11

oxytocin

Answer 11

-posterior pituitary
-causes contraction of muscles in uterine walls
-causes muscles associated with milk ejection to contract
-cause contraction of prostate gland
-significant in emotional bonding
–familial
–romantic
does NOT make milk, just causes release

Question 12

antidiuretic hormone

Answer 12

• causes kidney to decrease water excetion

- increases blood volume-> rise in BP

Question 13

anterior pituitary hormones

Answer 13

1. melanocyte stimulating hormone (MSH)
2. follicle stimulating hormone (FSH)
3. luteinizing hormone (LH)
4. growth hormone (GH)
5. thyroid stimulating hormone (TSH)
6. prolactin (PRL)
7. adrenocorticotropic hormone (ACTH)

Question 14

melanocyte stimulating hormone

Answer 14

-increases melanin secretion

Question 15

follicle stimulating hormone

Answer 15

• testes to produce sperm
• follicular development in ovary
• stimulate secretion of estrogen

Question 16

luteinizing hormone

Answer 16

• promotes secretion of sex hormones

- release of oocyte

Question 17

growth hormone

Answer 17

• GH
• increase size and rate of reproduction of body cells
• targets muscles and bones-mobilizes fat and glucose
• enhances movement of amino acids through membranes
• secreted throughout life, increases at puberty

Question 18

thyroid stimulating hormone

Answer 18

• TSH

- controls secretion of thyroid hormone

Question 19

prolactin

Answer 19

• PRL
• targets mammary tissue
• milk production/secretion

Question 20

Adrenocorticotropic hormone

Answer 20

• ACTH

- stimulates adrenal cortex to produce corticosteroids

Question 21

thyroid gland

Answer 21

• 2 lobes and isthmus
• -inferior to larynx
• Follicular cells
• -line follicle cavities (filled with thyoglogulin colloid)
• -remove Iodine from blood
• -secrete T3 and T4
• Parafollicular cells
• -produce calcitonin

Question 22

thyroid hormones: follicular cells

Answer 22

Thyroxine (T4)
-increase glycogenolysis
-increase protein synthesis
-increase growth
Triiodothyronine (T3)
-same as T4 but 5x's more potent

Question 23

thyroid hormones: parafollicular cells

Answer 23

calcitonin

• DECREASE blood calcium and phosphate
• increase renal excretion
• increase osteoblast activity

Question 24

parathyroid glands

Answer 24

posterior surface of thyroid

• many tightly packed secretory cells
• -oxyphil and transitional cells=immature
• -chief cells=produce parathyroid hormone

Question 25

parathyroid hormones

Answer 25

parathyroid hormone (PTH) - INCREASE blood calcium - decrease renal calcium and phosphate excretion - increase osteoclast activity - increase calcitriol=intestinal calcium absorption

Question 26

thymus

Answer 26

thoracic cavity, posterior to sternum - produces thymosin - -enhances lymphocyte production and competence - -most active in infancy and childhood

Question 27

adrenal glands

Answer 27

adrenal cortex | adrenal medulla

Question 28

adrenal cortex

Answer 28

- glomerulosa - -aldosterone: sodium retention - fasciculata - -cortisol: glycogen formation - reticularis - -androgens: secondary sexual characters

Question 29

adrenal medulla

Answer 29

- chromaffin cells which are modified postganglionic cells of the SNS (neurons) - -epinephrine and norepinephrine - only gland directly stimulated from brain

Question 30

kidneys

Answer 30

- renin: start cascade to increase blood pressure - erythropoietin (EPO): erythrocyte production - calcitriol: increases absorption of digested calcium

Question 31

heart

Answer 31

atrial natriuretic peptide (ANP) - suppresses aldosterone and ADH - decrease blood volume and blood pressure

Question 32

pancrease

Answer 32

``` posterior to stomach -attaached to duodenum by duct -exocrine and endocrine function islets of langerhans=endocrine function -alpha cells --glucagon=increases blood sugar -beta cells --insulin= decreases blood sugar -delta cells --somatostatin: inhibits glucagon and insulin secretion --antagonizes GH ```

Question 33

male gonads

Answer 33

``` interstitial cells -secrete androgens --testosterone ---stimulate nurse cells ---secondary sex characteristics nurse cells -secrete inhibin --decrease FSH from anterior pituitary --stimulate spermatogenesis ```

Question 34

female gonads

Answer 34

``` follicles=pre-ovulation -estrogens: --maturation of oocyte -- endometrial development -inhibin: --decrease FSH from anterior pituitary corpus luteum: post-ovulation -estrogens (estradiol) -progesterone --prepares body for pregnancy ```

Question 35

pineal gland

Answer 35

pineacytes in epithalamus - melatonin - -circadian rhythms - -possible role in puberty