Week 5 - nervous system (ANS) (somatic system) Flashcards
What is the autonomic nervous system
Regulates body when not paying attention to it
Overview of NS
- CNS: brain and spinal cord (surrounded by dura), memory cognition, emotion
- PNS: everything outside CNS, afferent/efferent: afferent division is sensory/ visceral stimuli; efferent divides into somatic (running skeletal muscles); autonomic (divides into sympathetic and parasympathetic effecting smooth muscle/cardiac muscle/oxocrine/some endocrine)
Sympathetic
Fight or light
Parasympathetic
Rest and digest
What does the ANS regulate
Activity of Organs - eg. Heart beat faster/slower
Maintian hormeostasis
Regulates activity of glands
What is the ANS a part of?
PNS
How can the ANS operate?
Atuonomically eg. Reflex and central contorl, or stimulate it using a conscious mind (eg. Bringing heart rate down by thinking about it)
What does the sympathetic division control?
- dilates pupil
- inhibits salvation
- accelerates heart
- fascilitates breathing
- inhibits digestion
- stimulates release of glucose
- secretes eponephrine
- relaxes bladder
- inhibits sex organ
What nerves does the sympathetic nerves activate?
Cervical nerves and thoraxic and lumbar nerves
Where do nerves from parasympathetic divsion reach?
Cranial nerves
Sacral nerves
Why does the heart sitll beat if you are paralised from head downwards eg. When breaking neck
Myogenic - tend to have lower heart rate as sympathetic division is no longer engaged
What funcitons can the parasympatehtic impact?
- constrict pupil
- stimulates salvation
- slows heart
- constricts breathing
- stimulates digestion
- stimulates gallbladder
- contracts bladder
- stimulates sex organs
How is the neuron structures in the ANS
Preganglionic neurons (from CNS)
Autonomic ganglion
Postganglionic neurons
Whatr is a autonomic ganglion?
Cluster of neurons
Are preganglionic fibres myelinated?
Yes
Are postganglionic fibres myelinated?
No
Where are sympathetic ganglia usually located?
Close to the CNS
Where are parasympatehtic ganglia usually located to?
Closer to target organ, if not embedded in it
Is there a 1:1 ratio of pre to post ganglionic fibres?
No
How many cellbodies in the ganglia + postganglionic fibres do sympathetic preganglionic axons tent to innervate?
More than 20 cell bodies in the ganglia
Many postganglionic fibres
How many cell bodies in ganglia + postganglionic fibres are innervated by parasympathetic axons?
Smaller extent
- less than 4 cell bodies/ axon
Does sympathetic divisions speeding everything up?
No - does prepare bdy for flight/ flight and shuts of other divisions which are no longer necessary for survival
What are paravertebral ganglia?
Sympathetic ganglia tend to align in a row on each side of the spinal cord
What are prevertebral ganglia?
Located further away from spinal cord.