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.
