Physiology of PNS Flashcards
2 division of PNS
- somatic nervous system
2. autonomic nervous system
Autonomic Nervous System - 2 divisions
- parasympathetic nervous system
2. sympathetic nervous system
somatic nervous system
controls voluntary movement of muscles
Autonomic Nervous System - 3 principle functions
- regulation of the heart
- regulation of secretory glands (salivary, gastric, sweat, bronchial glands)
- Regulation of smooth muscles (muscles of the bronchi, blood vessels, GU, Gi)
7 functions of PNS - rest and digest
- slowing of heart rate
- increased gastric gases
- emptying of the bladder
- emptying of the bowel
- focusing the eye for near vision
- constricting of the pupil
- contracting bronchial smooth muscle
PNS
Rest and digest - helps control vision and conserves energy by reducing cardiac work
3 functions SNS - sympathetic nervous system
- regulating cardiovascular system
- regulating body temperature
- implementing acute stress responses - fight or flight
- increases cardiac output
- vasoconstriction
- release of epinephrine
SNS - 3 homeostatic objectives
- maintenance of blood flow to the brain
- redistribution of blood flow during exercise
- compensation for loss of blood via vasoconstriction
SNS - regulation of body temp
- regulating blood flow to the skin via dilating (increases heat loss, ) or constricting (conserves heat)
- promoting the production of sweat
- inducing piloerection of hair - hair stands up, conserves heat
SNS - fight or flight
- increase heart rate and blood pressure
- shunting blood from the skin towards skeletal muscles
- dilating bronchi to improve oxygenation
- dilating pupils - enhance visual acuity
- mobilizing energy, thereby providing glucose for the brain and fatty acids for muscles
Most important feedback loop of the Autonomic nervous system
Baroreceptor reflex - these are receptors that sense BP
helps control BP
Baroreceptors
- located in the carotid sinus and aortic arch monitor changes in BP and send info to the brain
- in response, the brain sends impulses along the nerves to the autonomic nervous system, instructing heart and blood vessels to behave in a way that restores BP
Fall in BP - causes vasoconstriction and increases cardiac output
rise in BP - causes vasodilation and reduces cardiac output
Autonomic tone
day to day influence exerted buy the ANS on a particular organ or system, basal level of control of which reflex regulation is superimposed
predominant tone
branch of the autonomic nervous system that controls the organ function most of the time
most organs - predominant tone?
parasympathetic nervous system
