Ch #6: Nervous System (pt.1)

What are the four major nervous system functions?

1. Control the internal environment 

2. Voluntary movement control 

3. Reflexes 

4. Memory and learning

Central Nervous System (CNS) composition

Brain & spinal cord

Peripheral Nervous System (PNS) composition

all neural tissue outside of the CNS (everything else)

What is the SAME pneumonic referring to?

the 2 efferent division of the PNS

Afferent neurons (direction & division)

Sensory division; carries impulses arriving at the CNS

Efferent neurons (direction & division)

Motor division; carries impulses exiting the CNS to effectors

Dorsal horn (location, pathway, mnemonic)

posterior spinal cord: sensory/afferent arrival (incoming) point: SAID

What happens when you injure the dorsal horn of you spinal cord?

loss of incoming sensation

Ventral horn (location, pathway, mnemonic)

Anterior spinal cord; motor/efferent exit (outside) point: MEOV

What happens when you injure the ventral horn of you spinal cord?

loss of outgoing motor control below injury level

Contralateral brain-body control

Each side of the brain controls the opposite side of the body (e.g., left hemisphere controls right leg)

Dendrites function (2)

Transmit impulses toward the cell body; increase surface area for receiving signals

Axon

transmits impulses away from the cell body

Axon terminal

release neurotrasmitters

Schwann cells

Glial cells forming discontinuous myelin around axon

Nodes of Ranvier

accelerate action potential speed

What does down a concentration gradient mean?

ions want to go from a crowded space to a non-crowded one

Sodium Potassium Pumps (job & fuel)

help to maintain/reestablish resting membrane potential : ATP

Voltage-Gated Channels

open when enough Na/K move around and generate electricity (closed at rest)

At rest an axon is_________? This means ______ ion inside & ______ ion outside.

polarized, K (negative), Na (positive)

What charge do fixed proteins have?

negative

Threshold

-55 mV is needed to trigger the voltage-gated Na+ channels 

All-or-None Law

you hit -55 mV and off to the fucking races we go….other than that you aren’t going anywhere

Hyperpolarization

like a leaky old lady the voltage gated ion channels leak out and then shit gets to negative

(-90 mV or greater)

Depolarization causes _______ to open to allow ______ to flow in. This causes the inside to be __________

voltage-gated, na+, polarized

Repolarization allows for ______ channels so open so _____ can flow out

voltage gated ion channels, K