systems and receptors

Question 1

what do G-protein coupled receptors do

Answer 1

activate adjacent enzymes like adenylyl cyclase

Question 2

what happens when adrenaline binds to beta2adrenoceptor

Answer 2

conformational change that allows the alpha subunit to attach to receptor
-then alpha subunit is activated by exchange of GDP to GTP

Question 3

what does alpha subunit do when it has a GTP

Answer 3

attach to adenylyl cyclase which then causes the change of ATP to cAMP

Question 4

when does adenylyl cyclase switch off

Answer 4

when GTP attached turns back into GDP

Question 5

where are alpha 2 adrenoceptors located

Answer 5

gut

Question 6

what happens when adrenaline binds to the alpha 2 adrenoceptor

Answer 6

relaxation of the GI tract

Question 7

what is the principle transduction of alpha 1

Answer 7

Galpha q - activation of phospholipase C increase IP3 and DAG

Question 8

what is the physiological effect of the activation of alpha 1

Answer 8

vasoconstriction of blood vessels

Question 9

principal transduction of alpha 2

Answer 9

Galpha i - inhibition of adenylyl cyclase, decreases cAMP, increase K channels, decreases Ca channels

Question 10

principal transduction of beta 1

Answer 10

G alpha s - stimulation of adenylyl cyclase, increases cAMP

Question 11

physiological effect of beta 1 activation

Answer 11

increased heart rate and cardiac muscle contraction

Question 12

prinicpal transduction of beta 2

Answer 12

Galpha s - stimulation of adenylyl cyclase which increases cAMP

Question 13

physiological effect of beta 2 activation

Answer 13

• dilation of bronchi

- increased HR and cardiac contraction (less than beta 1)

Question 14

principal transduction of beta 3

Answer 14

stimulation of adenylyl cyclase which increases cAMP

Question 15

physiological effect of activation of beta 3

Answer 15

thermogenesis in skeletal muscle and lipolysis

Question 16

what is tyrosine activated by

Answer 16

ATP

Question 17

does tyrosine produce more than one cellular response

Answer 17

yes

Question 18

what is autocrine regulation

Answer 18

chemicals released from the cells bind to receptors on or in the cell that is releasing them

Question 19

what is paracrine regulation

Answer 19

chemicals released from the cells bind to receptors on adjacent cells

Question 20

what is endocrine regulation

Answer 20

chemicals released from the secretory cells are usually transported via the circulatory system

Question 21

what provides the highest level of endocrine control

Answer 21

hypothalamus

Question 22

how does the hypothalamus integrate activities of nervous and endocrine system

Answer 22

• secretion of regulatory hormones
• synthesises hormones and transports them to posterior pituitary via infundibulum
• direct neural control function - control secretion of adrenaline and noradrenaline

Question 23

what are the diurnal control of hormone levels

Answer 23

• external cues evoke fluctuations in hormone secretions

- hormone levels are also influenced by the rate at which they are eliminated by the body

Question 24

what does adrenaline cause the pancreatic alpha cells to do

Answer 24

release glucagon

Question 25

how does stress affect glucose levels

Answer 25

increases them

Question 26

what are the three groups hormones are classed into

Answer 26

- steroid - amine-derived - proteins

Question 27

are steroids hydrophilic or hydrophobic

Answer 27

hydrophobic | -transported in blood by binding to carrier proteins

Question 28

what do steroids initiate to happen?

Answer 28

- activated hormone-receptor complex forms within cell - the complex binds to DNA and activates specific genes - gene activation results in production of key proteins

Question 29

what are amine proteins secreted from

Answer 29

thyroid and adrenal medulla

Question 30

are peptide hormones hydrophilic or hydrophobic

Answer 30

hydrophilic

Question 31

where are peptide hormones secreted

Answer 31

by pituitary, parathyroid, heart, stomach, liver and kidneys

Question 32

what does binding of hormones to carrier proteins make happen

Answer 32

- facilitation of hormone transport - increased half-life of the hormone - a reservoir for the hormone

Question 33

name some important carrier proteins

Answer 33

- cortisol binding globulin - thyroxine-binding globulin - sex steroid binding globulin

Question 34

what hormones does the hypothalamus release

Answer 34

TRH and CRH

Question 35

what hormones does pituitary release

Answer 35

- TSH - ACTH - LH - FSH - Growth hormone - oxytocin - prolactin - MSH - ADH

Question 36

what hormones does thyroid/parathyroid release

Answer 36

- T4 - T3 - CT - PTH