Human biology: divisions of nervous system

Afferent division

Sensory neuron fibres carry message to the CNS form receptors

Central Nervous System

Consists of brain and spinal cord

Ventral root

Contains axons of motor neurons that have three cell body in grey matter of brain

Dorsal root

Contains axons of sensory neurons that have thief cell bodies in the dorsal root ganglion

Ganglia

Groups of nerve cell bodies outside the CNS

Fight or flight response

-increased heart rate ect,

Cranial nerves

12 pairs: moves messages to and from the CNS, most are mixed nerves

Spinal nerves

31 pairs of nerves: all are mixed nerves, each joined to spinal cord by two roots (ventral root, dorsal root)

Mixed nerves

A pair of nerves contains both motor (away from) and sensory fibres (to)

Somatic sensory neurons

Afferent division nerves takes information from receptors of muscles and skin to CNS

Visceral sensory neurons

Afferent division nerves that take information from internal organs to the CNS

Divisions of PNS

Afferent: to the CNS visceral, somatic Efferent: away from CNS somatic, autonomic (sympathetic, parasympathetic)

Autonomic motor division

Carries messages to the heart and other involuntary muscles and glands: composed of two division sympathetic parasympathetic

Somatic motor division

Carries messages to the skeletal voluntary muscles

Peripheral Nervous System

Consists of all nerves that connect the CNS to muscles, receptors and glands--> effectors (consists of nerves that carry messages to and form the CNS)

Flight or fight

In threatening situations the sympathetic division becomes dominant and prepares body for increased activity

Efferent division

Takes impulses away from the CNS and is composed of motor neurons