hormone activity and mechanism

Question 1

“Output” = efferent pathway

Answer 1

Control center sends signal to effector

Question 1

“Input” = afferent pathway

Answer 1

Receptor sends signal to control center

Question 2

endocrine system response time

Answer 2

Slow: Seconds to hours or days

Question 3

nervous system response time

Answer 3

Rapid: Milliseconds to seconds

Question 4

ligand

Answer 4

signalling molecule

Question 5

neurotransmitters are released into the

Answer 5

Synaptic cleft

Question 6

endocrine response duration

Answer 6

Long-lasting: Minutes to weeks

Question 7

nervous system response duration

Answer 7

Short-term: Milliseconds

Question 8

exocrine

Answer 8

Exocrine glands secrete their products
into ducts which empty into body
cavities or body surfaces

Question 9

exocrine examples

Answer 9

E.g., sudoriferous (sweat) glands,sebaceous (oil) glands, mucous glands,
digestive

Question 10

Some organs also secrete hormones in addition to their main function

Answer 10

E.g., hypothalamus, thymus, pancreas, ovaries,
testes, kidneys, stomach, liver, small intestine,
skin, heart, adipose tissue and placenta

Question 11

Target Cells

Answer 11

Target cells contain specific protein receptors for hormones
– The shape of the hormone must fit the shape of receptor
– Bind hormone and respond by initiating or inhibiting selective cellular
metabolic activities

Question 12

Steroids

Answer 12

• 4 rings
  – Formed from cholesterol
  – All lipid soluble

Question 13

amino acid derivatives

Answer 13

– Carboxyl group removed
– Amino group remains
– All water soluble, except thyroid hormones

Question 14

steroid examples and locations

Answer 14

-(adrenal cortex; aldesterone, cortisol, androgens)(reproductive organs; testosterone, estrogen, progesterone) (calcitrol; kidneys)

Question 15

amino acid derivative examples and locations

Answer 15

-epinephrine and norepinephrine from the adrenal medulla
-thyroid hormones from the thyroid gland
-serotinin from platelets
-melatonin from the pineal gland
-histamine from mast cells

Question 16

Peptides and Proteins

Answer 16

– Amino acid polymers
– All water soluble

Question 17

the hypothalamus makes

Answer 17

All releasing and inhibiting hormones

Question 18

posterior pituitary makes

Answer 18

Oxytocin, antidiuretic hormone

Question 19

anterior pituitary makes

Answer 19

Follicle-stimulating hormone, Luteinizing hormone, Adrenocorticotropic hormone,
Growth hormone, Prolactin, Thyroid-stimulating hormone

Question 20

pancreas makes

Answer 20

Insulin, Glucagon, Somatostatin, Pancreatic polypeptide

Question 21

parathyroid gland makes

Answer 21

parathyroid hormone

Question 22

thyroid gland makes this protein

Answer 22

Calcitonin

Question 23

protein in digestive system

Answer 23

Gastrin, secretin, cholecystokinin, GIP (glucose-dependent insulinotropic peptide)

Question 24

protein in kidneys

Answer 24

Erythropoietin

Question 25

adipose tissue makes

Answer 25

leptin

Question 26

lipid soluble hormones

Answer 26

-REQUIRES transport proteins
-Intracellular Receptors
-Initiates transcription of mRNA that results in a new protein that alters cellular activity

Question 27

water soluble hormones

Answer 27

-DOES NOT require transport proteins
-Transmembrane Receptors
-Activates signal transduction pathways

Question 28

water soluble hormone interactions

Answer 28

The binding of water-soluble hormones to a transmembrane receptor initiates a series of events called a signal transduction pathway
– Hormone is the signaling molecule = first messenger
– Transmembrane receptor = G-protein coupled receptor (GPCR)

Question 29

Lipid-Soluble Hormone Interactions

Answer 29

-activated receptor-hormone complex alters gene expression
-newly formed mRNA directs the synthesis of specific proteins on the ribosomes

Question 30

types of g proteins

Answer 30

The different signal transduction pathways are determined by the
different types of G proteins
– Gs activates adenylate cyclase (AC) pathway
– Gq activates phospholipase C (PLC) pathway

Question 31

Gs protein activates the Adenylate Cyclase (AC) pathway

Answer 31

1. Activated Gs protein binds to and activates the plasma membrane enzyme
   adenylate cyclase.
2. Adenylate cyclase converts ATP molecules to cAMP molecules
3. cAMP serves as the second messenger by activating protein kinase A
4. Protein kinase A adds a phosphate to other molecules, which may be
   activated or inhibited as a result

Question 32

Gq protein activates the Phospholipase C (PLC) pathway

Answer 32

1. Activated Gs protein binds to and activates the plasma membrane enzyme
   phospholipase C.
2. Phospholipase C splits PIP2 into two second messengers: DAG (diacylglycerol) and IP3
   (inositol triphosphate)
3. a) DAG activates protein kinase C (a phosphorylating enzyme)
   b) IP3 increases Ca2+ in cytosol by stimulating its release from the endoplasmic
   reticulum
   c) Ca2+ acts as a third messenger to activate other protein kinase enzymes or alter
   activity of ion channels on the plasma membrane.

Question 33

Degree of Cellular Response

Answer 33

• Amount of hormone can
  influence number of receptors on
  target cell for that hormone
  – Helps maintain normal level of cellular response

Question 34

upregulation

Answer 34

– Increases number of receptors
– Increases hormone sensitivity
– Occurs in response to LOW blood
hormone concentrations

Question 35

downregulation

Answer 35

– Decreases number of receptors
– Decreases hormone sensitivity
– Occurs in response to HIGH blood
hormone concentrations