Endocrine System II

Question 1

simple endocrine pathway

Answer 1

• stimulus received by endocrine cells
• stimulates endocrine cells -> secretes hormone
• hormone travels via bloodstream -> interacts with target cells -> physiological response

Question 2

simple neuroendocrine pathway

Answer 2

• stimulus received by sensory neuron
• stimulates neurosecretory cell -> secretes neurohormones
• hormone travels via bloodstream -> interacts with target cell -> physiological response
• ex: milk release during nursing

Question 3

hypothalamus

Answer 3

• regulates MANY hormones
• neuroendocrine gland
• links NS and endocrine systems
• connected to pituitary gland by portal vessels

Question 4

Releasing Hormones (RH)

Answer 4

trigger Anterior Pituitary (AP) to secrete certain hormone

Question 5

Inhibiting Hormones (IH)

Answer 5

inhibit AP from secreting hormones

Question 6

hormone cascade pathway

Answer 6

• RHs trigger AP to secrete Stimulating Hormones (SH)
• SHs trigger gland to secrete specific hormones
• Negative feedback: higher hormone levels -> less RH and SH. lower hormone levels -> more RH and SH

Question 7

tropic hormone

Answer 7

stimulate production of other endocrine hormones

Question 8

nontropic hormone

Answer 8

stimulate target cells directly

Question 9

antidiuretic horomone (ADH) and oxytocin

Answer 9

• peptide neurohormones
• produced by neurons in hypothalamus
• sent to Posterior Pituitary (PP)
• stored in vesicles in PP until needed

Question 10

what are the two lobes of pituitary glands in humans?

Answer 10

Posterior Pituitary and Anterior Pituitary

Question 11

Posterior Pituitary (PP)

Answer 11

-neuroendocrine gland
-stores and secretes:
[ADH - water retentio in kidneys]
[oxytocin - milk, contrations, care, bonding]

Question 12

Anterior Pituitary

Answer 12

Endocrine gland - hormones released into blood

• produces and secretes both tropic and nontropic hormones
• every AP hormone controlled by at least 1 RH (some also by an IH)

Question 13

thyroid hormones

Answer 13

endocrine gland - hormones stimulate cellular metabolism in virtually all cells

• maintain normal BP, reproductive functions
• regulate digestive, reproductive function

Question 14

SEQ Thyroid Hormone Regulation

Answer 14

hypothalamus ->Thyrotropin Releasing Hormone (TRH) -> AP -> Thyroid Stimulating Hormone (TSH) -> Thyroid Gland -> Thyroid Hormones: T3 (3 Iodine) and T4 (4 Iodine) -> all cells -> response

Question 15

hyperthyroidism

Answer 15

• too much thyroid hormone
• high body temp, profuse sweating, weight loss, irritability, high BP
• ex: Grave’s Disease (antibodies bind to TSH receptors, trigger T3 and T4 production)

Question 16

hypothyrodism

Answer 16

• too little thyroid hormone
• weight gain and lethargy, slower metabolism, intolerance to cold, goiter
• ex: Hashimoto’s Thyroiditis (immune destruction of thyroid cells, inability to produce T3 and T4)

Question 17

molting (ecdysis)

Answer 17

• larva grows in discrete stages
• molts in between
• endocrine pathway between begins in larval brain

Question 18

Juvenile Hormone (JH)

Answer 18

• produced in brain

- “remain a larva”

Question 19

Prothoracicotropic Hormone (PTTH)

Answer 19

• produced in brain

- “make ecdysteroids”

Question 20

ecdysteroids

Answer 20

• produced in prothoracic gland

- “molt”

Question 21

pathway of invertebrate endocrine control

Answer 21

• after hatching, larva has high levels of JH, no PTTH and no Ecdysteroids
• larva eats -> grows -> internal body presses organs and exoskeleton
• pressure against exoskeleton = stimulus for PTTH production

Question 22

what happens when JH levels are high?

Answer 22

grow and molt into larva

Question 23

what happens when JH levels are low?

Answer 23

molt into pupa -> metamorphosis into adult

Question 24

what are some applications of hormones?

Answer 24

can be used as insecticides

• synthetic ecdysteroids: premature molting -> death
• synthetic JH: larva would never become adults

Question 25

parathyroid

Answer 25

4 glands in connective tissue surrounding thyroid

Question 26

parathyroid hormone (PTH)

Answer 26

- regulates blood Ca2+ levels | - secreted by parathryoid

Question 27

what two hormones does blood calcium regulation involve? what is special about these two?

Answer 27

- parathyroid: secretes PTH to increase Ca2+ - thyroid: secretes calcitonin to decrease Ca2+ the two hormones are anatagonistic

Question 28

SEQ low blood Ca2+ regulation

Answer 28

stimulus: low blood Ca2+ -> parathyroid -> PTH -> Multiple effects -> response (increase in blood Ca2+) Multiple effects: - bone releases Ca2+ - kidneys reabsorb Ca2+ - liver produces Vitamin D -> increase Ca2+ from intestines

Question 29

is blood calcium regulation an example of positive or negative feedback?

Answer 29

negative

Question 30

SEQ high blood Ca2+ regulation

Answer 30

stimulus: high blood Ca2+ -> thyroid -> calcitonin -> multiple effects -> response (decrease in blood Ca2+) multiple effects: - bone retains Ca2+ - kidneys excrete Ca2+

Question 31

adrenal glands

Answer 31

- small glands on top of each kidney - 2 parts: (1) central - adrenal medulla (2) outer - adrenal cortex - function as distinct glands but both regulate metabolism, response to stress

Question 32

adrenal medulla

Answer 32

- neuroendocrine gland - short-term stress response (fight or flight) - secretes epinephrine and norepinephrine (water soluble hormones) - activated by nerve impulses

Question 33

what is the benefit of the nervous system involvement and release of water-soluble hormones

Answer 33

it's fast

Question 34

during stress, what happens with the adrenal medulla?

Answer 34

- hypothalamus activates adrenal medulla via nerve impulse - adrenal medulla releases epinephrine, norepinephrine (1) more blood to brain, muscles, heart (2) glycogen breakdown to glucose (3) increase metabolic rate (up to 100%) (4) increase O2 delivery - higher HR, stroke volume, breathing rate - short-term response

Question 35

adrenal cortex

Answer 35

- endocrine gland - responds to chronic stress - secretes corticosteroids (lipid-soluble) - activated by endocrine signal - long-term response

Question 36

SEQ stress in adrenal cortex

Answer 36

stress -> hypothalamus -> CRF -> AP -> ACTH -> Adrenal Cortex -> response (corticosteriods) response: - glucose synthesis from non-carb sources - muscles broken down -> increase blood glucose - immune suppression