Nervous System + Brain

central nervous system function

processes incoming information and stimulates a response

CNS consists of

brain and spinal cord

CNS types of neuron

interneurons

peripheral nervous system function

transmits info to and from the CNS

PNS types of neuron

sensory neurons, motor neurons

sensory neuron

travel to the CNS with stimulus information; has specialized receptor ends to monitor pain and temperature

motor neuron

travel from the CNS to effectors or other motor neurons; controls muscle contraction and secretion of glands

interneurons

inside brain and spinal cord that conduct impulses from one part of the brain/spinal cord to another; direct sensory impulses for processing/interpreting

sensory division of PNS

transmits impulses from sense organs to the CNS; detects changes and monitors external factors

motor division of PNS

somatic nervous system and autonomic nervous system; conducts impulses from CNS to effectors (causes a response)

somatic nervous system

controls skeletal muscles, voluntary motions; responses always excitatory (involves reflexes)

autonomic nervous system

controls smooth and cardiac muscle, involuntary motions; response can be excitatory or inhibitory (involves actions like breathing)

sympathetic division (ANS)

fight or flight response; prepares the body to deal with stress

parasympathetic division (ANS)

rest and digest response

reaction

information goes to brain for processing; voluntary response

reflex

information only goes to spinal cord and an involuntary response occurs

sodium-pottasium pump

pottasium pumped out, sodium pumped in (utilizes energy)

inside of the cell

more negative

pumping sodium into cell

cell becomes more positive (neutral first, then positive)

depolarization

process of sodium flowing into the cell and causing the inside to become more positive

resetting after depolarization

potassium channels open causing potassium to exit, sodium channels close; cells become negatively charged again (repolarization)

action potential

a neural impulse; a brief electrical charge that travels down an axon

3 major aspects of the nervous system

Sensory input, integration and processing, and motor output.

makeup of the nervous system

brain, spinal cord, nerves, sense organs

neuron function

conduct impulses that pass information to another neuron and then other tissues

neuroglia function

protect, support, insulate, provide nutrients

Neurotransmitters

Chemicals that transmit information from one neuron to another

endocrine system

uses hormones to maintain homeostasis (long lasting)

regions of a neuron

cell body, dendrites, axon

functions in the cell body

protein synthesis, energy production, metabolism

dendrites

Branchlike parts of a neuron that are specialized to receive information.

axons

a part of a neuron that carries impulses away from the cell body

nodes of ranvier

Gaps in the myelin sheath to which voltage-gated sodium channels are confined and replenishes the positive charge

schwann cells

Supporting cells of the peripheral nervous system responsible for the formation of myelin.

myelin

a fatty substance that helps insulate neurons and speeds the transmission of nerve impulses

why can't an infant's nervous sytem function as effectively?

axons aren't fully myelinated; deficiencies in nutrients can limit the formation of myelin

blood brain barrier

tightly attached capillaries selectively allow some substances to go through while blocking others (protect from toxic compounds/biochemical fluctuations)

downside of blood brain barrier

prevents uptake of needed drugs and antibiotics

Which part of the nervous system relaxes the body to calm it down after stress?

parasympathetic

Two main types of cells in the nervous sytem

neurons and glial cells

What can change the way a nerve sends their action potential?

frequency

overall charge of body

neutral

Difference in charges on the inside and outside of cell

membrane potential

ion channels that open at a specific membrane potential

voltage gated channels

what happens if the stimulus cannot hit the threshold?

no action potential is generated

Why does the charge move down the axon?

repulsion of positive charge, attraction to the negative charge

why does the positive charge decrease as it moves down the axon?

leakage; spreading out (diluting)

what happens if the positive charge runs out?

the signal dies out and there won't be a response

damage to schwann cells

signals are slowed down/lost; appears as scarring/sclera in brain and spinal cord (hardening of tissue)

how does the damage to schwann cells occur?

the blood brain barrier gets damaged; immune cells sneak in and attack the myelin

symptoms of damage to schwann cells

tingling/numbness, speech/vision problems, muscle weakness, cognitive impairment

multiple sclerosis

autoimmune disease attacking myelin in the CNS

risk factors for multiple sclerosis

mutations in DNA, exposure to viruses, toxins in cigarettes

treatment for multiple sclerosis

immune system suppressants

signaling through a neuron

electrical signal

signaling between neurons

chemical signal

where does the action potential reach during synaptic transmission?

the presynaptic terminal from the axon

what happens after the A.P. reaches the terminal?

ion channels open due to depolarization, calcium ions flow into cell

what happens when the calcium enters the cell?

releases neurotransmitters from vesicles

what happens after neurotransmitters are released?

the neurotransmitter binds to the receptor sites on the postsynaptic membrane

what happens after the binding of neurotransmitters?

the binding triggers an opening and closing of the channels, which changes the postsynaptic membrane potential (exciting or inhibiting the response)

what happens after the response?

the action potential starts again in the next cell

what happens after the response is no longer needed?

neurotransmitters are broken down by enzymes, diffuse away from synapse, or are transported back into the presynaptic terminal (reuptake)

what does it mean when the membrane response is graded?

the action potential will or will not fire depending on the summation of excitatory or inhibitory signals

medication enhancing effect on neurotransmitter activity

mimics the neurotransmitter which influences strength and duration; blocks reuptake of neurotransmitter; blocks enzymatic breakdown after signal

medicine inhibiting effect on neurotransmitter activity

binds/blocks receptors in postsynaptic cell; speeds up reuptake/enzymatic breakdown

dopamine

A neurotransmitter associated with movement, attention and learning and the brain's pleasure and reward system.

synaptic cleft

The narrow gap that separates the presynaptic neuron from the postsynaptic cell.

synapse

composed of the terminal button, synaptic cleft, and dendrite of the next neuron

cerebellum function

coordination of voluntary movements and balance

brain stem function

eye/ear/eating reflexes, breathing, heart rate, consciousness/sleep, blood pressure

cerebrum

largest part of the brain; split into right and left hemispheres

frontal lobe function

motor control, problem solving, speech (on left side)

parietal lobe function

process touch and temperature, proprioception, pain sensory input

temporal lobe function

auditory processing, language comprehension, memory

occipital lobe function

visual reception and interpretation

frontal lobe

parietal lobe

temporal lobe

occipital lobe

corpus callosum

connects the hemispheres of the brain

corpus callosum function

coordination of thought process and decision making

corpus callosum

diencephalon function

relay information to correct lobes; homeostasis of water, appetite, and temperature

diencephalon

amygdala function

memory and emotion; receives smell information

amygdala

hippocampus function

short term memory --> long term; emotion processing

hippocampus

gray matter

neuron cell bodies

white matter

myelinated axons

wrinkling in the brain

increases surface area for more neurons

meninges

three protective membranes that surround the brain and spinal cord

dura mater

loose superficial sac; avascular; attaches to bone

arachnoid and pia mater

2 deep membranes that create cerebrospinal fluid (cushion and nutrients); highly vascular

meningitis

inflammation of the meninges from bacteria/viral infection

symptoms of meningitis

stiff neck, severe headache, typical illness symptoms

possible result of meningitis

brain damage, stroke

subdural hematoma

collection of blood under the dura mater by head injury

why is a subdural hematoma dangerous?

puts pressure on brain; cuts off circulation (can lead to death)