Neural Signaling Quiz

neurons

cells in the nervous system that carry electrical impulses

how many neurons are in the human body

8.5 billion

structure of a neuron

cell body contains nucleus, dendrites, and axon

dendrites

short branched

axon

long nerve fiber

how to find membrane potential

place electrodes in and out of the lining cell → 10-100 mV

resting potential for a neuron

-70 mV

why is the inside of a neuron membrane more negative

imbalance between net charge inside and outside

resting potential

more K+ inside, more Na+ outside → maintained by the sodium-potassium pump

sodium potassium pump

pumps 3 Na+ out and 2 K+ in

how do ions leak back

facilitated diffusion (K+ more than Na+)

action potential

sudden change in membrane potential

all or nothing (reaches threshold or doesn't)

stereotypical

depolarization

change from negative to positive

repolarization

change back from positive to negative

steps of depolarization

1. stimulus arrives

2. sodium channels open

3. Na+ enters via facilitated diffusion

4. extra positive membrane charges raises membrane potential to +30mV

Steps of repolarization

1. sodium gates close, potassium gates open

2. potassium diffuses out

3. + charges leaving → repolarization back to -75mV

4. now ions are reversed

5. sodium-potassium pump restores Na+ and K+ to og concentrations

Action Potential propagates down the nerve fiber

ion movements that depolarize one part of fiber trigger depolarization in neighboring part

nerve impulse

action Potential that moves along axon

nerve impulse in invertabrates

only goes in one directions, result of local currents

local currents

due to simple diffusion of Na+ inside and outside

lower concentration gradient and increase membrane potential

what does an increase in membrane potential do

open neighboring voltage gated Na+ channels

what does diameter affect

speed in nerve impulses

big diameter → reduces resistance → increases speed

typical diameter and speed

about 1 micrometer and 1 m/s

size and speed of giant squid axons

500 micrometers and 25m/s → allows for quick escape

myelin

coating around nerve fibers

what does myelination do

increase nerve speed

what does alternation Schwann cells w/ nodes of Ranvier do in myelin

prevents ion movements

saltatory conduction

nerve impulse jumps from node to node very quickly because of local currents

how fast does saltatory conduction speed nerve impulses

up to 100m/s

Multiple sclerosis

autoimmune disorder where the body attacks the myelin sheath

symptoms of MS

numbness, limb weakness, lack of coordination, cognitive problems

is there a cure to MS

no, but treatments can improve symptoms

synapses

junction between two cells in the nervous system

how wide are synapses

20-40nm

3 main types of synapses

• between sensory receptor and sensory neuron

• between 2 neurons

• between neuron and effector (muscle or gland)

neurotransmitters

chemicals that carry signals across synapse

what does action potential depolarize

plasma membrane of presynaptic terminal

neurotransmitter example

acetylcholine

excitatory

opens sodium channels

exogenous chemical

enters from outside source

exogenous chemical example

neonicotinoids bind to acetylcholine receptors irreversibly

what is neonicotinoid used as

pesticide → synaptic transmission prevented, causing paralysis + death of insects

cocaine

acts at synapses where dopamine is neurotransmitter and blocks reuptake of dopamine into pre-synaptic neuron

why is cocaine highly addictive

it disrupts the normal reward system and is an excitatory drug

hyperpolarization

some NTs make membrane potential more negative

what does hyperpolarization do

makes it more difficult to reach the threshold potential

example of hyperpolarization

GABA binds to chloride channel → negative ions come in and increase polarization

summation

adds up impacts of NTs arriving at post-synaptic neuron from all pre-synaptic ones

what happens if the summation total is over the threshold

post synaptic will fire

system integration

organisms use multiple, coordinated systems to perform functions of life

hierarchy of subsystems

organelles, cells, tissues, organs, organ systems

tissue

group of the same type of cells to carry out a functions

tissue example

lung tissue is made of AT1 and AT2

how many tissues are in the trachea

5: outer coat, cartilage, trachealus muscle, epithelium

organ systems

group of organs interact to perform the functions of life, most are physically linked

dispersed organ systems

endocrine

11 organ systems

circulatory, digestive, endocrine, gas exchange, integumentary, lymphatic, muscular, nervous, reproductive, skeletal, urinary

emergent properties

whole is more than the sum of its parts

integration of organs by hormonal and nervous signaling

materials and energy transported via blood, all organs provide constant supply of oxygen and nutrients, blood removes waste

what are the endocrine and nervous systems used for

internal communication

why did the brain evolve

we needed muscle fibers to move around and be governed by a network of nerves to adapt to our environment

reflex arcs

induce movement to help jellyfish avoid predators

ganglion

bundles of neurons that equate to a brain for non-vertebrate animals

autonomous movement

organism can move without the presence of touch

spinal cord structures

wides at brain junctions, tapers down to pelvis

how many pairs of spinal nerves do humans have

31

what are the two main tissues of the spinal cord

white and grey matter

function of the spinal cord

white matter conveys signals from sensory receptors to the brain, and from brain to body organs.

coordinates unconscious processes, reflexes

how are unconscious actions coordinated

by the brain and spinal cord, and include secretion by glands and concentrations of smooth muscle

how are conscious actions coordinated

cereebral hemispheres of the brain and include contraction of striated muscle

sensory neuron location

the skin

sensory neuron structure

signals as nerve impulses are carried along the axons of sensory neurons, varying in length

function of the sensory neuron

receptors for touch and heat, pass impulses to sensory neurons, monitor internal conditions

motor neuron structure

signals are nerve impulses located in the gray matter of the cerebral hemisphere

dendrites receive signals and transmit them to the cell body

functions of motor neurons

used for locomotion, posture

tells muscle fibers to contract and gland cells to secrete

nerves

bundles of nerve fibers enclosed in a protective sheath

neurons

single nerve cells that transmit electric signals

pain reflex arc

• stimulus and receptor

• sensory neuron

• interneuron only in central nervous system

• motor neuron goes to muscle or gland

receptors

sense the stimulus - each receptor detects only one type

sensory neurons

receive signals and pass them to neurons in the central nervous system through long axons

interneurons/relay neurons

located in the central nervous system and have branched fibers (dendrites) for nerve impulses to travel

combine impulses and pass them to create a reflex action

motor neurons

receive signals via synapses w/ interneurons

if threshold potential reach → impulse passed along the axon to an effector

effectors

carry out response to stimulus

• muscles contract

• glands secrete

how are we aware of pain

prefrontal cortex

how does consciousness emerge

interaction of individual brain neurons

nociceptor

sensory receptor to pain

types of scales to measure pain

numeral rating scale (0-10), behavioral pain scale

what percent of patients are not given adequate treatment

80%

parts of the brain

left cerebral hemisphere, hypothalamus, arterior pituitary, posterior pituitary, cerebellum, medulla oblongata

cerebellum cord

makes skeletal muscle contraction and balance, not willingly

helps with motor memory

circadian rythyms

depend on 2 cell groups in hypothalamus that control the secretion of melatonin by the pineal gland

• 460-480nm light wavelength signals the hypothalamus of dawn/dusk

Melatonin

high levels cause drowsiness

epinephrine (adrenaline) secretion

prepares body for vigorous activity

binds to target cells and triggers responses

• muscle/liver cells convert glycogen into glucose for respiration/release

• bronchi dilate for easier ventilation → ventilation rate increases

• SA node increases heart rate and cardiac output

• vasodilation in arterioles to muscle/liver or to gut/kidney/skin/extremities

• increases blood flow to skeletal muscle (fight, flight, freeze)

pituitary gland

secretes hormones into blood under direction of hypothalamus

control of endocrine system by hypothalamus

hypothalamus links nervous system to endocrine system via pituitary gland

hypothalamus specialized areas (nuclei)

contains sensors for blood temp, glucose concentration, osmolarity, concentration of various hormones

feedback control of heart rate

sa node

• signals from sympathetic nerve cause increase

• signals from vagus nerve cause decrease

sensory inputs

baroreceptors, chemoreceptors, sa nod

baroreceptors in the aorta

the carotid arteries monitor BP through negative feedback

• a low BP causes an increase in heart rate

chemoreceptors

monitor blood, oxygen, pH (varies with CO2 levels)

• low O2 or pH → increased heart rate