L8. Nervous system structure and function Flashcards
Central Nervous System (CNS)
- Brain and spinal cord
Peripheral Nervous System (PNS)
- Portion of nervous system outside of CNS
- Consists mainly of nerves that extend from brain and spinal cord (spinal nerves and cranial nerves)
Functional divisions of the nervous system
- sensory
- integration/ control
- motor
Sensory (afferent)
- Information from internal and external environment is detected
> Somatic sensory (skin)
> Visceral sensory (internal organs)
Integration
- CNS processes information received and makes decisions as to what will happen next
Motor (efferent)
- Messages goes from CNS to peripheral tissues and organs directing them what to do
ie. carry out an action
> Somatic nervous system (voluntary)- motor innervation of all skeletal muscles
> Autonomic nervous system (ANS- involuntary)- Motor innervation of smooth muscle, cardiac muscle and glands
Autonomic nervous system (ANS) divisions
> Sympathetic division- Fight or flight
> Parasympathetic division- Rest and digest
Neural tissue cells
> Neurons (nerve cells)- cells that send and receive signals
Neuroglia (glial cells)- cells that support and protect neurons
Function of neuroglia
- smaller and more numerous
- support, nurture and protect nerve cells
- insulation
- phagocytosis
- make and circulate fluid
- maintain homeostasis
Structure of neurons
> Cell body (soma)
Short, branched dendrites
Long, single axon
Cell Body contains
> Nucleus
> Organelles
Function of dendrites
- Highly branched
- Receive input from other neurons and convey it to cell body
Function of axon
- Long
- Carries electrical signal (action potential) away from cell body to other neurons or effectors
Role of myelin sheath
- made of glial cells
- fatty white sheath around axons
- electrically insulates axon
- increase speed of transmission
Difference between myelinated axons and unmyelinated axons
- myelinated axons= white matter
- unmyelinated axons= grey matter
