Lecture 13

Question 1

How is homeostasis maintained, what are the 3 different types of responses

Answer 1

through ANS, endocrine, and behavioural systems

Question 2

Describe 3 target organs and their response to sympathetic/parasympathetic influence

Answer 2

Eyes: pupil dilates or contracts
Heart: heart rate increases or decreases
Penis: induced ejaculation either way

Question 3

Describe the 5 differences between the sympathetic and parasympathetic pathways

Answer 3

location in CNS: lumbar/thoracic vs brainstem/sacral
location of ganglion: chain by spinal cord vs close to target cell
length of neurons (pre and post ganglionic): short/long vs long/short
Type of neurotransmitter: Ach/NE vs. Ach/Ach
type of receptor: nicotinic/adrenergic (alpha/beta) or nicotinic/muscarinic
Type of response (same): ionotropic (ionchannels) / metabotropic (GPCR)

Question 4

How do autonomic synapses work

Answer 4

autonomic varicosities are bulges in the axon with lots of neurotransmitter that then release it to the surface of the target tissue. there are chains of varicosities across the surface

Question 5

Describe the adrenal medulla and why is it special

Answer 5

Adrenal medulla acts as a post-ganglionic neuron, it releases neurohormone into the blood in the form of epinephrine, made up of chromaffin cells

Question 6

Describe the adrenergic receptors

Answer 6

coupled to different G proteins
Alpha
1 NE>E Gq activate phospholipase C
(sympathetic tissues)
2 NE>E Gi decrease cAMP levels
(GI tract, pancreas)
Beta
1 NE=E Gs increase cAMP levels
(heart muscle, kidney)
2 E>NE Gs increase cAMP levels
(blood vessels, smooth muscle)
3 NE>E Gs increase cAMP levels
(adipose tissue)

Question 7

Describe the muscarinic receptors

Answer 7

M1, M3, M5 = activate phospholipase C = Gq protein

M2, M4 = decrease cAMP = Gi protein