midterm 2

Question 1

Autonomic nervous system

Answer 1

• influences smooth muscle, glands and the heart
• 2 subdivisions: SYMPATHETIC and PARASYMPATHETIC
• regulates organs to maintain homeostasis
• regulates stress response, reproduction, thermoregulation & enteric system (digestion)

Question 2

Preganglionic neuron

Answer 2

synapses with postganglionic neuron within a ganglion

–> a cluster of neuronal bodies outside the CNS

Question 3

Postganglionic neurons

Answer 3

innervates the effector organ

Question 4

Parasympathetic N.S.

Answer 4

preganglionic neurons originate in the brainstem or sacral spinal cord

• long preganglionic neurons to terminal ganglia near the effector organ
• short postganglionic neurons from ganglia to effector organs

Question 5

Neurotransmitters of the ANS

Answer 5

Preganglionic neurons: release ACh for both sympathetic and parasympathetic
***means they both have receptors for ACh

Postganglionic neurons:

• Sympathetic postganglionic neurons: norepinephrine (adrenergic fibres)
• Parasympathetic postganglionic neurons: ACh (cholinergic fibres)

Adrenal medulla 80% epinephrine and 20% norepinephrine (these move through blood so widespread effect)

Question 6

Receptor types

Answer 6

Neurotransmitters can either:

• stimulate activity in some tissues
• inhibit activity in other tissues

Response depends upon specialization of the tissue (effector organ) cells
–> have one or more of different types of receptor proteins (and within other receptors)

Question 7

Nicotinic cholinergic receptors

Answer 7

• activated by nicotine
• found on postganglionic cells in all autonomic ganglia
• respond to release of ACh from both sympathetic and parasympathetic preganglionic fibres
• channel opening results in depolarization
• effect depends on target
  Two types: N1 & N2

Question 8

Muscarinic cholinergic receptors

Answer 8

• activated by mushroom poison, muscarine
• found on effector cell membranes (smooth muscle, cardiac muscle and glands) –> found on effector cell after postsympathetic neuron
• bind ACh released by parasympathetic postganglionic fibres
• 5 subtypes: M1-M5

Question 9

Adrenergic receptors

Answer 9

• bind epinephrine & norepinephrine

- two classes: Alpha (a1-2) & Beta (b1-b3)

Question 10

Alpha adrenergic receptors

Answer 10

• located in effector organs of sympathetic nervous system
• most common
  usually excitatory and stimulate smooth muscle or glands
• affinity greater for norepinephrine>epinephrine

Question 11

a1 receptors

Answer 11

• excitatory response
  e. g. arteriolar constriction –> reduces blood flow to an area
• when you get into fight or flight, going to inhibit certain activities such as muscle contractions for stomach/blood flow for digestion

Question 12

a2 receptors

Answer 12

• inhibitory response in effector organ

e. g. decreased smooth muscle contraction in digestive tract

Question 13

B1 adrenergic receptors

Answer 13

• located in cardiac muscle and kidneys
• usually excitatory
• equal affinity for norepinephrine and epinephrine

Question 14

B2 adrenergic receptors

Answer 14

• located in some blood vessels and smooth muscle
• usually inhibitory
• greater affinity epinephrine>norepinephrine

Question 15

B3 adrenergic receptors

Answer 15

• not very common
• located in adipose tissue (breakdown of fat molecules) –> energy/produce ATP important for flight or fight
• usually excitatory
• equal affinity for norepinephrine and epinephrine