The Endocrine System Part I Study Guide

Question 1

endocrine system vs nervous system

Answer 1

• endocrine system’s responses are much slower than the nervous system, but endocrine’s effects are longer lasting.
• Endocrine system works w nervous system to coordinate and integrate the activities of all the body’s cells

Question 2

What does the endocrine system control and integrate?

Answer 2

• Reproduction
• Growth and development
• Maintenance of electrolyte, water, and nutrient balance
• Regulation of cellular metabolism and energy balance
• Mobilization of the body’s defenses

Question 3

exocrine glands

Answer 3

• Produce non hormonal substances (sweat, saliva)
• Have ducts to carry secretions to membrane surfaces

Question 4

endocrine glands

Answer 4

• Produce hormones
• Lack ducts

Question 5

Hormones

Answer 5

long-distance chemical signals; travel through blood or lymph
- Circulate systemically, but only cells w receptors for a specific hormone will be affected
- Alter target cell activity

Question 6

Autocrines

Answer 6

chemicals that exert effects on the same cells that secrete them

Question 7

Paracrines

Answer 7

locally acting chemicals that affect cells other than those that secrete them

Question 8

target cell

Answer 8

Tissues with receptors for a specific hormone

Question 9

water soluble hormones

Answer 9

All amino acid based hormones except thyroid hormone
- Cannot directly enter a cell
- Act on plasma membrane receptors
- Typically, receptors are couples to 1+ intracellular second messengers via regulatory molecules called G proteins

Question 9

ways that a hormones can create change

Answer 9

• Alter plasma membrane permeability and/or membrane potential by opening/closing ion channels
• Stimulate synthesis of enzymes or other proteins
• activate/deactivate enzymes
• Induce secretory activity
• Stimulate mitosis

Question 10

Does thyroid hormone function like a water-soluble or lipid-soluble hormone?

Answer 10

lipid soluble hormone

Question 10

Lipid soluble hormones

Answer 10

Steroid and thyroid hormones
- Can directly enter a cell
- Act on intracellular receptors that directly activate genes

Question 11

purpose and function of a second messenger system

Answer 11

The hormone never enters the cell; it activates the second messenger (on the inside of the cell), to make the changes to the cell internally. Second messenger helps amplify the hormones effects

Question 12

two 2nd messenger systems

Answer 12

Cyclic AMP
PIP2-Calcium

Question 13

5 steps for activating a second messenger

Answer 13

Hormone (1st messenger)
Receptor
G protein
Enzyme
2nd messenger

Question 14

5 steps for activating second messenger in depth

Answer 14

1. Hormone (1st messenger) binds receptor
2. Receptor activates G protein
3. G protein activates adenylate cyclase
4. Adenylate cyclase converts ATP to cAMP (2nd messenger)
5. cAMP activates protein kinases → triggers responses of target cell (activates enzymes, stimulates cellular secretion, opens ion channels, etc.)

Question 15

In the cAMP pathway, G protein activates the enzyme ____________ . In the PIP2-Calcium pathway, G protein activates the enzyme ___________

Answer 15

adenylate cyclase
phospholipase C

Question 16

What happens when a lipid-soluble hormone enters a cell

Answer 16

They bind with their intracellular receptors

Question 17

Where does the lipid soluble hormone go to create change?

Answer 17

enters the nucleus + bind to specific regions of the DNA

Question 18

Creation and release of most hormones is regulated by _____________

Answer 18

negative feedback loops

Question 19

3 ways endocrine glands are stimulated to synthesize and release hormones

Answer 19

• humoral stimuli
• neural stimuli
• hormonal stimuli

Question 20

humoral stimuli + example

Answer 20

(Changing blood levels of ions and nutrients directly stimulates secretion of hormones) → Example: Level of Ca2+ in Blood
- Declining blood Ca2+ concentration stimulates parathyroid glands to secrete parathyroid hormone (PTH)
- PTH stimulates osteoclast activity and causes Ca2+ concentrations to rise; the stimulus is removed

Question 21

neural stimuli + example

Answer 21

(Nerve fibers stimulate hormone release) → Example: in times of stress, fibers of the sympathetic nervous system stimulate the adrenal medulla to secrete catecholamines

Question 22

hormonal stimuli + example

Answer 22

(Hormones can stimulate other endocrine glands to release their hormones) → Example: the hypothalamic-pituitary-target endocrine organ feedback loop

Question 23

hypothalamic-pituitary-target endocrine organ feedback loop

Answer 23

- Hypothalamic hormones stimulate the release of most anterior pituitary hormones - Anterior pituitary hormones stimulate their targets to secrete still more hormones - Hormones from the final target organs inhibit the release of anterior pituitary hormones

Question 24

How does the nervous system modulate the activity of the endocrine system? Why is this useful?

Answer 24

It adjusts hormone levels when needed – can modify stimulation/inhibition of different endocrine glands – can override mechanical endocrine controls Ex. under severe stress, the hypothalamus and sympathetic nervous system override insulin controls to allow blood glucose levels to rise

Question 25

3 types of interactions between hormones affecting the same target cell

Answer 25

- permissiveness - synergism - antagonism

Question 26

permissiveness

Answer 26

- one hormone cannot exert its effects without another hormone being present Ex: reproductive hormones need thyroid hormone to have effect

Question 27

synergism

Answer 27

more than one hormone produces the same effects on the target cell – causes amplification Ex: glucagon and epinephrine both cause the liver to release glucose

Question 28

antagonism

Answer 28

one or more hormones oppose(s) the action of another hormone Ex: insulin and glucagon