The Endocrine System

Question 1

hormones

Answer 1

endocrine signaling involves secretion of these directly into the bloodstream
travel to distant target tissues, where they bind to receptors and induce a change in gene expression or cell function

Question 2

peptide hormones

Answer 2

composed of amino acids and are derived from large precursors that are cleaved during post translational modification
polar and cannot pass through plasma membrane
bind to extracellular receptors where they trigger transmission of a secondary messenger
usually have rapid onset but are short-lived
travel freely in the bloodstream and do not require a special carrier

Question 3

steroid hormones

Answer 3

derived from cholesterol
minimally polar and can pass through plasma membrane
bind to intracellular or intranuclear receptors, where they promote conformational change and bind to DNA, affecting transcription of a particular gene
usually have slow onset but are long-lived
cannot dissolve in the bloodstream and must be carried by specific proteins

Question 4

amino acid-derivative hormones

Answer 4

modified amino acids
chemistry shares some features with peptide hormones and some features with steroid hormones; dif ones share dif features with other hormone classes
common ex’s: epinephrine, norepinephrine, triiodothyronine, thyroxine

Question 5

direct hormones

Answer 5

have major effects in non-endocrine tissues

Question 6

tropic hormones

Answer 6

have major effects in other endocrine tissues

Question 7

hypothalamus

Answer 7

bridge between nervous and endocrine systems
release of hormones from here mediated by a number of factors: projections from other parts of brain, chemo- and baroreceptors in blood vessels, and neg feedback from other hormones
stimulates anterior pituitary gland through paracrine release of hormones into the hypophyseal portal system which directly connects the two organs
antidiuretic hormone (ADH or vasopressin) and oxytocin synthesized here

Question 8

negative feedback

Answer 8

final hormone (or product) of a pathway inhibits hormones (or enzymes) earlier in the pathway, maintaining homeostasis

Question 9

gonadotropin-releasing hormone (GnRH)

Answer 9

promotes the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH)

Question 10

growth hormone-releasing hormone (GHRH)

Answer 10

promotes release of growth hormone

Question 11

thyroid-releasing hormone (TRH)

Answer 11

promotes release of thyroid-stimulating hormone (TSH)

Question 12

corticotropin-releasing factor (CRF)

Answer 12

promotes release of adrenocorticotropic hormone (ACTH)

Question 13

prolactin-inhibiting factor (PIF or dopamine)

Answer 13

inhibits release of prolactin

Question 14

anterior pituitary

Answer 14

releases hormones in response to stimulation from hypothalamus
FSH, LH, ACTH, TSH are tropic hormones
prolactin, endorphines, growth hormone are direct hormones

Question 15

follicle-stimulating hormone (FSH)

Answer 15

promotes development of ovarian follicles in females and spermatogenesis in males

Question 16

luteinizing hormone (LH)

Answer 16

promotes ovulation in females and testosterone production in males

Question 17

adrenocorticotropic hormone (ACTH)

Answer 17

promotes synthesis and release of glucocorticoids from adrenal cortex

Question 18

thyroid-stimulating hormone (TSH)

Answer 18

promotes synthesis and release of triiodothryonine and thyroxine from the thyroid

Question 19

prolactin

Answer 19

promotes milk production

Question 20

endorphins

Answer 20

decrease perception of pain and can cause euphoria

Question 21

growth hormone (GH)

Answer 21

promotes growth of bone and muscle and shunts glucose to these tissues
raises blood glucose concentrations

Question 22

posterior pituitary

Answer 22

releases two hormones produced in the hypothalamus

Question 23

antidiuretic hormone (ADH or vasopressin)

Answer 23

secreted in response to low blood volume or increased blood osmolarity and increases reabsorption of water in collecting duct of nephron, increasing blood volume and decreasing blood osmolarity

Question 24

oxytocin

Answer 24

secreted during childbirth and promotes uterine contractions
also promotes milk ejection and may involved in bonding behavior
has a positive feedback loop

Question 25

thyroid

Answer 25

located at base of neck in front of trachea | produces three key hormones

Question 26

triiodothyronine (T3) and thyroxine (T4)

Answer 26

produced by follicular cells and contain iodine increase basal metabolic rate and alter utilization of glucose and fatty acids required for proper neurological and physical development in children

Question 27

calcitonin

Answer 27

produced by parafollicular (C) cells decreases plasma Ca concentration by promoting Ca excretion in kidneys, decreasing Ca absorption in gut, and promoting Ca storage in bone

Question 28

parathyroid glands

Answer 28

release parathyroid hormone (PTH)

Question 29

parathyroid hormone (PTH)

Answer 29

increases blood Ca concentration decreases excretion of Ca by kidneys and increases bone resorption directly to increase blood Ca conc activates vitamin D, which is necessary for Ca and phosphate absorption from gut promotes resorption of phosphate from bone and reduces reabsorption of phosphate in kidney, but vitamin D promotes absorption of phosphate from gut; two effects on phosphate conc somewhat cancel each other out

Question 30

adrenal cortex

Answer 30

produces three classes of steroid hormones: glucocorticoids, mineralocorticoids, cortical sex hormones

Question 31

glucocorticoids

Answer 31

i.e. cortisol, cortisone increase blood glucose conc, reduce protein synthesis, inhibit the immune system, and participate in the stress response release is stimulated by ACTH

Question 32

mineralocorticoids

Answer 32

i.e. aldosterone promote Na reabsorption in distal convoluted tubule and collecting duct, thus increasing water reabsorption also increases K and H ion excretion regulated by renin-angiotensin-aldosterone system

Question 33

cortical sex hormones

Answer 33

i.e. androgens (testosterone) and estrogens in both males and females

Question 34

adrenal medulla

Answer 34

derived from nervous system | secretes catecholamines into bloodstream

Question 35

catecholamines

Answer 35

i.e. epinephrine and norepinephrine (involved in fight-or-flight response) promote glycogenolysis, increase basal metabolic rate, increase heart rate, dilate bronchi, alter blood flow

Question 36

pancreas

Answer 36

produces hormones that regulate glucose homeostasis

Question 37

glucagon

Answer 37

produced by alpha cells, raises blood glucose levels by stimulating protein and fat degradation, glycogenolysis, and gluconeogenesis

Question 38

insulin

Answer 38

produced by ß-cells and lowers blood glucose levels by stimulating uptake by cells and anabolic processes

Question 39

somatostatin

Answer 39

produced by ∂-cells and inhibits insulin and glucagon secretion

Question 40

gonads

Answer 40

produce hormones that are involved in development and maintenance of reproductive systems and secondary sex characteristics

Question 41

testes

Answer 41

secrete testosterone

Question 42

ovaries

Answer 42

secrete estrogen and progesterone

Question 43

pineal gland

Answer 43

releases melatonin

Question 44

melatonin

Answer 44

helps regulate circadian rhythms

Question 45

secretin, gastrin, cholecystokinin

Answer 45

produced by cells in stomach and intestine

Question 46

erythropoietin

Answer 46

secreted by kidneys | stimulates bone marrow to produce erythrocytes (RBC's) in response to low oxygen levels in blood

Question 47

atrial natriuretic peptide (ANP)

Answer 47

secreted by atria of heart | promotes excretion of salt and water in kidneys in response to stretching of atria (high blood volume)

Question 48

thymosin

Answer 48

secreted by thymus | important for proper T-cell development and differentiation