Autonomic Nervous System (ANS)

Question 1

Autonomic nervous system (ANS)

Answer 1

part of the nervous system that controls the internal (visceral) organs of the body (i.e. the viscera)

not normally under conscious control

• bladder control, crying

3 main divisions of the ANS:

1. Sympathetic Nervous System (SNS)
2. Parasympathetic Nervous System (PSNS)
3. Enteric Nervous System (ENS - the gut)

Question 2

ANS function

Answer 2

primary role is to maintain homeostasis

SNS and PSNS work together to maintain homeostasis

it helps regulate:

• heart rate
• blood pressure
• body temperature
• gastrointestinal and bladder motility
• gland secretions (hormones, sweat)
• regulates blood glucose levels
• sexual function

Question 3

ANS organization visual receptors

Answer 3

homeostasis is the relatively constant condition of the internal environment of the body

sensory receptors monitor internal environment/organs

Question 4

ANS organization sensory afferent fibers

Answer 4

these receptors send signals back to CNS through sensory afferent fibers

Question 5

ANS organization integration centers

Answer 5

CNS integration centre interprets signals and activates hypothalamus

Question 6

ANS organization hypothalamus

Answer 6

hypothalamus master controller of ANS

Question 7

ANS organization SNS & PSNS

Answer 7

output through branches of the ANS:

1. sympathetic nervous system (SNS)
2. parasympathetic nervous system (PSNS)

Question 8

ANS organization smooth/cardiac muscle glands

Answer 8

the ANS exerts its actions by controlling target organs (effectors):

• smooth muscle in blood vessels, digestive tract
• specialized cardiac tissue and cardiac muscle
• glands; salivary, sweet, adrenal gland, etc.

Question 9

ANS peripheral efferent nerves

Answer 9

Question 10

general characteristics of peripheral (efferent) nerves

Answer 10

• preganglionic neurons (cell body in CNS, terminates on ganglion)
• ganglion
• postganglionic neurons (cell body in ganglion, terminates on target tissue)
• target tissue/organ)

Question 11

somatic and autonomic motor system

Answer 11

Question 12

pathways of peripheral (efferent) nerves

Answer 12

a) parasympathetic pathway
b) sympathetic pathway
c) adrenal sympathetic pathway

Question 13

PSNS vs SNS - anatomical differences

Answer 13

both contain:

• preganglion neurons
• ganglion
• postganglionic neurons
• target tissue/organ

differences:

• location of ganglion
• length of preganglionic neuron and postganglionic neuron
• types of neurotransmitters released

parasympathetic: long pre-ganglionic neuron (Ach); short post-ganglionic neuron (Ach)

sympathetic: short pre-ganglionic neuron (Ach); long post-ganglionic neuron (NE)

Question 14

adrenal sympathetic pathway

Answer 14

there is only one SNS preganglionic neuron to adrenal gland

adrenal gland secretes epinephrine (adrenaline) with a little norepinephrine

Question 15

innervation of SNS and PNS

Answer 15

Question 16

innervation of upper body, heart and lungs (SNS)

Answer 16

fight or flight

more light entering eye

thick mucus

increases blood output by the heart

move air in & out of lungs easily

Question 17

innervation of digestion (SNS)

Answer 17

fight or flight

shut down digestion

Question 18

innervation of adrenal glands, kidneys and bladder (SNS)

Answer 18

fight or flight

releases epinephrine (adrenaline)

holds in urine

Question 19

innervation of adrenal glands, kidneys and bladder (PSNS)

Answer 19

rest and digest

no PSNS innervation for the kidney

contracts bladder

Question 20

innervation of upper body, heart and lungs (PSNS)

Answer 20

rest and digest

less light entering eye

watery saliva and enzymes for digestion

decreases blood output from heart

Question 21

innervation of digestion (PSNS)

Answer 21

rest and digest

increases digestion and absorption of nutrients

Question 22

innervation reproductive organs (PSNS & SNS)

Answer 22

sexual activity

sexual responses are mediated by the coordinated activity of both SNS and PSNS