Peripheral Nervous system Term 2 Flashcards
Describe the function of the peripheral nervous system? what is it made up of?
Peripheral nervous system takes messages from receptors to CNS and from the CNS to the muscles and glands
composed of:
-nerve fibres that carry information to/from CNS
-groups of nerve cell bodies (ganglia) which lie outside brain and spinal cord
What are the two types of nerves in the body
nerve fibres are arranged into nerves which arise from brain and spinal cord
-cranial nerves
-spinal nerves
Define cranial nerves and function (how many)
PNS made up of 12 pairs of cranial nerves
-optic or auditory
-mixed nerves: contain fibres that carry impulses into the brain(sensory)+fibres that carry impulses away (motor)
Define spinal nerves and function (how many)
PNS made up of 31 pairs of spinal nerves
-mixed nerves: containing both sensory and motor fibres (toward/away)
-each nerve joined by two roots to spinal cord (ventral and dorsal)
Define ventral root
(identify on diagram) pg 94 textbook
Link spinal cord to spinal nerve-Contains the axons of motor neurons that have their cell bodies in the spinal cords grey matter
Define dorsal root
(identify on diagram)
pg 94 textbook
Link spinal cord to spinal nerve-Contains the axons of sensory neurons that have their cell bodies in a small swelling on the dorsal root=dorsal root ganglion=group of nerve cell bodies in dorsal root of spinal nerve
What are the divisions of the PNS
Afferent (sensory), Efferent (motor)
Explain what is meant by the afferent division of the PNS. Define/ distinguish between it’s further divisions
Has fibres that carry impulses into the CNS by sensory neurons from receptors in skin, muscles, and joints
further division
-somatic sensory neurons: impulses from skin and muscles
-visceral sensory neurons: impulses from the internal organs
Explain what is meant by the efferent division of the PNS. Explain/distinguish what the two divisions of the efferent division of the PNS
Has fibres that carry impulses away from the CNS towards effector structure
Subdivisions:
-somatic/SNS: takes impulses form CNS to skeletal muscles
-autonomic/ANS: carries impulses from CNS to heart muscles, involuntary muscles, or glands
ANS can be further subdivided:
-sympathetic: SNS
-parasympathetic: PNS
Explain the role of and effects of the autonomic nervous system
What does the autonomic subdivision of the efferent division of the peripheral nervous system consists of?
Where are it’s control centres located?
part of the nervous system that regulates automatic body functions. Controls the body’s internal environment is involved in many mechanisms maintaining constant
-operates without conscious control
-regulated by groups of nerve cells/control centres in medulla oblongata, hypothal., cereb.cortex
-sympathetic: SNS
-parasympathetic: PNS
List the functions controlled by the autonomic nervous system.
-heart rate
-blood pressure
-body temperature
-digestion
-release of energy
-pupil diameter
-air flow to lungs
-defecation
-urination
Define somatic nervous system
Somatic nervous system responds to the external environment
Compare the autonomic and somatic divisions of the peripheral nervous system
Give the difference in motor pathways between the autonomic and somatic divisions of the peripheral nervous system.
(e, p, n, c, t, e,m)
ANS:
-effectors: heart muscle, involuntary muscle, glands
-general function different
-Efferent pathways: two nerve fibres from CNS to the effectors
-neurotransmitter at effector: (para)acetylcholine or (symp)noradrenaline
-control: involuntary
-nerves to target organ: two sets (parasymp and sympathetic
-effect on target organ: excitation and inhibition
-two motor neurons involved
SNS:
-effectors: skeletal muscles
-general function different
-Efferent pathways: one nerve fibre from CNS to effector
-neurotransmitter at effector: acetylcholine
-control: voluntary
-nerves to target organ: one set
-effect on target organ: excitation
-one motor neuron involved
Define the fight or flight response
a response preparing body for increased activity brought about by stimulation of the sympathetic division of the autonomic nervous system
Describe difference between parasympathetic and sympathetic stimulation
It can be said that sympathetic division tends to produce responses that ready the body for strenuous physical activity and para.=less physically strenuous
Effect of symp and para stimulation on heart
symp.- increase rate and contraction strength
para.- decreases rate and contraction strength
Effect of symp and para stimulation on lungs
symp.- dilates bronchioles
para.- constricts bronchioles
Effect of symp and para stimulation on stomach/intestines
symp.- decreases movement
para.- increases movement
Effect of symp and para stimulation on liver
symp.- increases breakdown of glycogen and release of glucose
para.- increases glucose uptake and glycogen synthesis
Effect of symp and para stimulation on iris
symp.- dilates
para.- constricts
Effect of symp and para stimulation on sweat glands
symp- increase sweat secretion
para.- no effect
Effect of symp and para stimulation on salivary glands
symp- decrease secretion
para.- increases secretion
Effect of symp and para stimulation on blood vessels (all 3 types)
symp
- skin: constricts
-skeletal: dilates
-internal organs: constricts (except in heart/lungs)
para
- skin: little effect
-skeletal: no effect
-internal organs: little effect
Effect of symp and para stimulation on urinary bladder
symp-relaxes muscles of wall
para-constricts
Effect of symp and para stimulation on adrenal medulla
sara-stimulates hormone secretion
para-no effect
Draw flow diagram of PNS
PNS
(1) afferent and efferent (defs)
(2)autonomic and somatic—–somatic sensory and visceral sensory (defs)
(3)parasympathetic and sympathetic
How does sympathetic division cause fight/flight response
-rate and force of heart contraction increase=increase blood pressure
-blood vessels dilate in organs involved in strenuous activity e.g. skeletal muscles, heart, and liver
-lungs dilate and rate/depth of breathing increases
-blood glucose levels rise because liver converts more glycogen into glucose
-secretion from sweat glands increases
-adrenal medulla release adrenaline and noradrenaline which intensify/prolong responses above
