The Nervous System

Nervous system is split up into

Peripheral Nervous System

• relay information to and the from the CNS

  
  

• cranial nerves → to the brain; concern head, neck and face, can be sensory only, motor only, or mixed nerves

• spinal nerves → come from spinal chord, - all mixed nerves and carry both sensory/motor neurons

• enter through dorsal side, form dorsal root ganglion, leave through ventral, ventral root (in spinal chord)

  • serve somatic (voluntary)

  • autonomic (involuntary

advantage of autonomic nervous system

• involuntarily and automatically control internal and involuntary activities

visceral reflex

• involuntary response - maintains homeostasis

what is ANS controlled by

• medulla oblongata and hypothalamus

What do both divisions of the autonomic system have

1. automatic and subconscious

2. nerve connections with internal organs

3. two motor neurons and one ganglion for each impulse

preganglionic neuron and postganglionic neuron

• pre → relays information to the ganglia from the CNS - myelinated

• post → relays information to effector from ganglia - unmyelinated

what does ANS consist of

• 2 antagonistic divisions

  • parasympathetic

    • sympathetic

Parasympathetic Nervous System (not responses)

• slows down activity of visceral organs

• activated during rest and digest

• response is localized

• neurotransmittor released from nerve ending is acetylcholine

• ganglia is close to organs being innervated

• preganglionic neurons start from cranium and tip of spinal chord

Responses of Parasympathetic Nervous System

• slower heart rate

• stimulation of flow of saliva

• bladder contracts

• stimulates peristalsis and secretion

• release of bile

Sympathetic nervous system

• accelerates activity of all visceral organs

• during fight or flight → stress response

• ganglia are far from organs being innervated

• neurotransmitter is noradrenaline

• preganglionic neurons originate from spinal chord

• response is diffused

  
  

Responses of sympathetic Nervous System

• dilates pupils

• accelerates heartbeat

• stimulates conversion of glycogen into glucose

• inhibits peristalsis

• inhibits flow of saliva

• inhibits bladder contraction

• dilates bronchi

central nervous system is protected by

• bones

• Meninges

• CSF - cerebrospinal fluid

Bones

• cranium and vertebrae

Meninges

• 3 layered membrane

• line skull and cover brain

  • protect it from being bruised + friction

  • nourish CNS tissues (grey + white matter)

  • bacterium → meningitis (inflammation)

where is csf produced

• choroid plexus -network of blood vessels and epithelial cells in the ventricles of the brain

• produce csf

Cerebrospinal Fluid

• central canal between spinal chord and also in ventricles of brain

• fills space between meninges

  • blood vessels which supply nutrients and oxygen to brain

  • lymphocytes → immunity

  • lubrication

  • removes waste from brain and spinal chord

  • shock absorbed