Homeostasis

Question 1

What is the bigger risk for thermoregulation: hyperthermia or hypothermia?

Answer 1

hyperthermia

Question 2

What is the LOCAL mechanism to avoid hyperthermia?

Answer 2

local temp sensors cause release of nitric oxide, which causes vasodilation and thus increases surface blood flow

blood being closer to the surface means it loses heat more readily

Question 3

What is the response to body temp below 37?

Answer 3

vasoconstriction to reduce surface blood flow

shivering to make heat

Question 4

What neurotransmitter causes sweating?

Answer 4

It’s ACh released form the postsynaptic sympathetic neuron (unusual)

Question 5

What neurotransmitter is released to cause vasoconstriciton and decreased surface blood flow?

Answer 5

norepinephrine

Question 6

What is unusual about thermoregulation in postmenopausal women?

Answer 6

their thermoregulatory zone is extremely narrow so they always feel too hot or too cold

Question 7

Blood pressur is usually determined by what NT release from what type of nerves?

Answer 7

norepinephrine from sympathetic nerves

Question 8

What receptors does NE work on to stimulate heart rate and stroke volume?

Which does NE work on to increase peripheral resistance?

Answer 8

beta 1 for heart rate and stroke volume

alpha1 for resistance

Question 9

How do you decrease blood pressure?

Answer 9

through the vagus nerve you get release of ACh to interact with muscarinis receptors in the heart to slow heart rate

Question 10

Where are the receptors that recognize an increase in BP?

Answer 10

the stretch receptors in th ecarotid bodies

Question 11

An increase in carotid bocy stretch will cause an ____ in firing rate in what nerves?

Answer 11

increase in firing rate in CN9 and 10

Question 12

Where do the glossopharyngeal and vagus nerve bring the BP information?

Answer 12

the NST

Question 13

What do the NST neurons do in order to increase BP?

Answer 13

they inhibit the rostral ventrolateral medulla, which is a sympathoexcitatory area

this means you get a decrease in sympathetic release of NE, so you don’t get an increase in heart rate, stroke volume, or resistance

this leads to a decrease in BP

Question 14

What NT will the vagus nerve release directly on the heart to decrease heart rate?

Answer 14

Ach on muscarinic receptors

Question 15

When BP is low, what is the signalling pathway to increase it?

Answer 15

1. carotid body firing decreases (no stretch)
2. Decreased firing in CN9 and 10
3. Dereased stimulation of the NST
4. No inhibition of the rostral ventrolateral medulla
5. stimulation of preganglionic sympathetics
6. release of NE
7. beta 1 - increase stroke volume and HR; alpha1 - increase resistance
8. blood pressure increases

Question 16

What two things are required for inspiration to occur?

Answer 16

1. pacemaker to initiate breathing
2. contraction of the diaphragm (and external intercostals) to generate pressure differentials

Question 17

Where is the pacemaker for breathing located?

Answer 17

in the Pre-Boetzinger area of the ventrolateral medulla

Question 18

Through what nerve does the pacemaker innervate the diaphram?

Answer 18

the phrenic nerve (C3-C5)

Question 19

What type of nerve is the phrenic nerve? What NT on what receptor?

Answer 19

a somatomotor nerve under conscios control

releases ACh on nicotinic receptors

Question 20

What are the inputs to the Pre-boetzinger area?

Answer 20

• from the parafacial respinratory center sensing CO2 (actually H+)

more CO2 - increase respiratory rate to get the CO2 out

Question 21

What happens if you don’t have CO2 receptors in the parafacial nucleus?

Answer 21

you have Ondyne’s curse

you hypoventilate when you sleep and it’s fatal when untreated

Question 22

A spinal cord transection above what level would require the patient to be on a ventilator?

Answer 22

above C3

their phrenic nerve wouldn’t be able to get the diaphragm to move

Question 23

What part of urinary control is voluntary?

Answer 23

the external sphincter consists of skeletal muscle under voluntary control

Question 24

What NT is involved in keeping the external sphincter contracted?

Answer 24

ACh on nicotinic receptors

Question 25

What branch of the autonomic nervous system is involved with the involuntary control of urination?

Answer 25

parasympathetic nervous system on the internal sphincter and detrusor (wall)

Question 26

What NT on what receptor is involved in the involuntary control of urination?

Answer 26

ACh on muscarinic receptors

Question 27

Bladder filling sends afferent signals to what part of the brain, which usually does what?

Answer 27

afferent signals to to the medial prefrontal cortex

the medial prefrontal cortex usually supresses voiding, but when it receives the afferent signals, it turns off that inhibition to encourage urination

Question 28

WHat brain region is normally supressed by the medial prefrontal cortex to inhibit urination?

Answer 28

pontine micturition center

Question 29

What does the pontine mictrurition center stimulate?

Answer 29

it activates the sacral cord to stimulate preganglionic parasympathetic nerves to….

release ACh on the muscarinic receptors of the internal sphincter and wall, causing bladder contraction

activate an inhibitory interneuron influencing motoneurons innervating the external urethral sphincter, causing sphincter relaxation

urination

Question 30

How can you pharmacologically treat the inability to initiate urine flow?

Answer 30

give a muscarinic agonist