BIOLOGY 12 NERVOUS SYSTEM

how is a nerve impulse transmitted.

1. Polarization of the neuron's membrane: Sodium is on the outside, and potassium is on the inside. 2. Resting potential gives the neuron a break. 3. Action potential: Sodium ions move inside the membrane. 4. Repolarization: Potassium ions move outside, and sodium ions stay inside the membrane. 5. Refractory period puts everything back to normal: Potassium returns inside, sodium returns outside. (RESTING POTENTIAL)

name and define the 2 divisions of autonomic nervous system

1. sympathetic-fight or flight (accelerates hear rate) 2. parasympathetic-non-emergency situations (lowers heart rate)

Label A-H (see Synapse diagram)

A. axon B. axon terminal /bulb C. synaptic vesicle D. presynaptic membrane E. receptors F. neurotransmitters G. synaptic cleft H. postsynaptic membrane

Label A-H (See Neuron diagram)

A. nucleus B. axon C. axon terminal D. schwann cell E. node of ranvier F. nucleus of schwann cell G. cell body H. dendrites

what is ACTION POTENTIAL

a rapid change in polarity across an axomembrane as the nerve impulse occurs (an ALL OR NONE response)

where is adrenaline produced?

adrenal medulla

define excitation

causes an action potential to happen in the postsynaptic neuron

function of axon

conduct nerve impulses AWAY from the cell body to other neurons or effectors.

function of cell body

contains nucleus and other organelles

functions of dendrites

receive signals from other neurons and conduct nerve impulses TOWARDS the cell body

function of central nervous system

sensory information is received and motor control is initiated

what does the somatic system control

skin, skeletal muscles, and tendons

what does the autonomic system control

smooth muscles

define inhibition

stops an action potential from happening in the postsynaptic neuron

function of peripheral system

takes impulses to the CNS

sensory neurons structure (lengths of dendrites and axons) and function

-LONG dendrite and SHORT axon -takes a message from a sensory receptor to CNS

motor neurons structure (lengths of dendrites and axons) and function

-SHORT dendrites, LONG axon -takes message away from the CNS to an eddector

interneurons structure (lengths of dendrites and axons) and function

-dendrites and axons may be long or short -completely contained within CNS (spinal cord/brain). conveys messages from sensory and other interneurons, sums up messages received before communicating with motor neurons.

how an impulse travel across a synaptic cleft

1. Calcium gates open 2. Releasing a neurotransmitter. 3. The neurotransmitter binds with receptors on the neuron. 4. Excitation or inhibition of the membrane occurs.