Endocrine System

Question 1

T/F: endocrine system is the first control system for homeostasis

Answer 1

F, it’s the second

- 1st is nervous system

Question 2

Endocrine system is _____ acting, but lasts ______

Answer 2

• slower than nervous

- lasts longer

Question 3

Endocrine system acts via…

Answer 3

hormones

Question 4

Hormone functions will regulate…

Answer 4

• metabolic rate
• water and electrolyte balance
• cell proliferation
• reproductive organs

Question 5

Hormones control changes to help the body cope with…

Answer 5

stress

Question 6

Hormones are secreted in…

Answer 6

very small amounts by specialized cells

Question 7

How are hormones carried?

Answer 7

via blood

Question 8

Hormones act on…

Answer 8

receptors of target cells to alter function

Question 9

Classifications of hormones by signaling pattern:

Answer 9

• endocrine
• neurocrine
• paracrine
• autocrine

Question 10

How are endocrine hormones produced and how do they travel?

Answer 10

• produced by classical endocrine cells

- travel via blood to target tissue

Question 11

How are neurocrine hormones released?

Answer 11

released by axonal ends of neurons into blood

Question 12

What happens to paracrine hormones?

Answer 12

diffuses to different local cell types through ISF or gap junctions

Question 13

What happens to autocrine hormones?

Answer 13

acts on itself or other identical cells via gap junctions

Question 14

What regulates the release of hormones?

Answer 14

• feedback control (positive, negative, neural)

- chronotropic control

Question 15

Describe negative feedback:

Answer 15

• most common
• brings body back to normal
• ex: relationship between pituitary and target glands

Question 16

Describe positive feedback:

Answer 16

• less common
• amplifies effect of hormone
• brings it farther away from homeostasis
• self-limiting

Question 17

Describe neural control:

Answer 17

• ANS alters hormone secretion

- changes are detected by nervous receptors (visual, auditory, etc)

Question 18

Describe chronotropic control:

Answer 18

hormones are released based on rhythms which are genetically encoded or acquired

Question 19

Examples of chronotropic control:

Answer 19

• circadian (24-25 hours)
• diurnal (day-night)
• ultradian (multiple times a day)

Question 20

Which gland regulates the circadian clock?

Answer 20

pineal via release of melatonin

Question 21

Types of chemicals that can act as hormones:

Answer 21

• amino acids (water or lipid soluble)
• proteins and peptides (water soluble)
• steroids (lipid soluble)
• prostanoids (paracrine/autocrine)

Question 22

Amino acids are derived from…

Answer 22

• tyrosine

- tryptophan

Question 23

Amino acids are released by…

Answer 23

exocytosis

Question 24

Proteins and peptides are synthesized as ______ and accumulates into ______

Answer 24

• large precursor molecules

- vesicles

Question 25

Examples of proteins and peptides:

Answer 25

- insulin - ANP - thyroid regulation hormone (TRH)

Question 26

Steroids are derived from...

Answer 26

cholesterol

Question 27

Steroids require _____ in the blood

Answer 27

protein carriers

Question 28

Prostanoids are derived from...

Answer 28

arachidonic acid (unsaturated fatty acid)

Question 29

T/F: prostanoids are stored

Answer 29

F, are immediately released after synthesis

Question 30

Prostanoids act on....

Answer 30

membrane receptors coupled to G proteins on target tissues

Question 31

What are the forms of hormones that affect the 1/2 life of it?

Answer 31

- free/active hormones - prohormones - carrier bound hormones

Question 32

Describe free/active hormones:

Answer 32

- fast acting - shortest 1/2 life - can be degraded by enzymes

Question 33

Describe prohormones:

Answer 33

- circulates as inactive precursor of water soluble hormones - cleavage turns it into active - prolongs 1/2 life

Question 34

Describe carrier bound hormones:

Answer 34

- longest 1/2 life - slowest response time - binds to specific globulins made by liver - carrier protects hormones from degradation - reduces renal clearance

Question 35

T/f: hormones are reversibly removed from plasma

Answer 35

F, irreversibly removed by target cell uptake, metabolic degradation, urinary and biliary excretion

Question 36

What are the two major sites of hormone extraction and degradation?

Answer 36

- kidney | - liver

Question 37

What types of hormones are filtered?

Answer 37

free hormones

Question 38

In order for hormones to create a response, they must be...

Answer 38

- recognized and bound to specific receptor | - hormone-receptor complex has to be coupled to signal generating mech (2nd messengers) or act on itself

Question 39

Secondary messengers alter...

Answer 39

- enzyme activity or concentration - functional proteins - structural proteins

Question 40

What are the two receptor systems based on solubility?

Answer 40

- membrane | - intracellular

Question 41

Plasma membrane receptors are activated by...

Answer 41

non-lipid soluble (NLS) hormones

Question 42

How fast is the response of plasma membrane receptors?

Answer 42

seconds to minutes

Question 43

Structure of membrane receptors:

Answer 43

large glycoproteins with specific extracellular binding sites - located inside membrane

Question 44

What happens when a hormone occupies a membrane receptor?

Answer 44

change in conformation of receptor

Question 45

What is the % of available membrane receptors that creates the max biological action?

Answer 45

5-10%

Question 46

What is upregulation of membrane receptors and when does it occur?

Answer 46

- increasing the number of membrane receptors - hormones recruit their own receptor and enhance sensitivity of cell - occurs when there is intermittent exposure to a lot of hormones

Question 47

What is downregulation of membrane receptors and when does it occur?

Answer 47

- decrease in number of membrane receptors - occurs when there is a lot of hormones for a sustained period of time - lessens effect of chronic exposure

Question 48

Phosphorylation and dephosphorylation of membrane receptors alters...

Answer 48

affinity of receptor, which can also be altered by pH, osmolarity, ion concentration, and substrate levels