Homeostasis Flashcards
What is often the efferent of homeostasis?
The ANS
What is the integrator of homeostasis?
The hypothalamus
Decides what efference does
Where are the core temperature receptors?
The spinal cord, not the hypothalamus
What do local temperature sensors cause release of?
Nitric Oxide (vasodilator, increasing surface flow)
How does NO vasodilate?
Activate gaunyl cyclase –> convert GTP to cGMP –> affects potassium currents or MLK to cause relaxation
Increases blood flow
What do core temp sensors send signals to in the CNS?
The sympathetic nervous system
What are the two different types of sweating?
Adrenergic - nervous sweating (norepinephrine)
Cholinergic - eccrine, ACh release
What is pyrogens?
Stimulates hypothalamus to make PGE2
Prostaglandins change the set point of temperature
So you treat by inhibiting prostiglandins
What happens to hypothalamic temp set point?
Nothing, it is never changed
Receives sensors from else place
What receptors are related to blood pressure regulation?
Baroreceptors
In corotid artery and aortic arch
What is BP largely determined by?
Norepinephrine release from sympathetic nerves
What is BP equation?
BP = cardiac output * total peripheral resistance
BP = HRStroke volumetotal peripheral resistance
Cardia output = HR*stroke volume
What happens when sympathetic nerves stimulate Beta1 receptors?
Increase HR and Stroke volume (up cardiac output)
What happens when sympathetic nerves stimulate alpha1 receptors?
Increase total peripheral resistance
What is the other major input to BP?
Vagus nerve (parasympathetic)
How does the vagus nerve affect BP?
Parasympathetic
Releases ACh which stimulate muscarinic receptors and LOWER HR
What to Baroreceptors do?
Sense stretch in the carotid artery and aortic arch
Up BP, Up firing rate
Where are impulses from the Baroreceptors carried to and by what?
Signals are carried to the solitary nucleus (medulla) by the Glossopharyngeal and vagus nerves
How does the NTS lower BP?
By suppressing neurons in the rostral Ventrolateral area which normal excite the sympathetic NS
What produces orthostatic hypotension?
Dehydration
When do the Baroreceptors fire?
When BP is above 50mm
Where is the pacemaker for breathing?
The pre-boetzinger area of Ventrolateral medulla
What does the pre-boetzinger area of the Ventrolateral medulla do?
Stimulus C3-C5 (phrenic nerve) to innervate diaphragm
What neurotransmitter is somatomotor or autonomic therefore stimulated on the diaphragm?
Acetylcholine on nicotinic receptor, sodium channel
What is the main input into the pre-boetzinger area?
Parafacial respiratory center Sense CO2 (actually H) and excites the pre-boetzinger area
This also excites muscles involved in expiration
Where does the H atom come from CO2?
Carbonic anhydrase
What happens with lack of carbon dioxide sensors?
Ondine’s curse
Hypoventilation
Forget to breath when sleep
What is the path of breathing?
CO2 sense by Parafacial respiratory center –> stim of pre-boetzingers area –> stimulation of diaphragm through the phrenic nerve
What part of urination is voluntary?
The external sphincter of skeletal muscle by
ACh stimulating nicotinic
What is the internal sphincter and detrusor (wall) controlled by?
Parasympathetics
ACh stimulating muscarinic
What does bladder filling send signals to?
Prefrontal cortex –> normally suppresses voiding! no it doesn’t
How does urination happen?
Pontine micturition center activates the sacral cord to simulate preganglionic parasympathetics also does interneurons that stim motor neurons controlling the external sphincter
How do you treat urination incontinence?
Anti muscarinic
Muscarinic antagonist
(Like atropine)
What sensor has two neurons?
Temperature
