Studied by 1 person
Looks like no one added any tags here yet for you.
the nervous system consists of 2 parts. what are they?
Central Nervous System (CNS)
Peripheral Nervous System (PNS)
what does the central nervous system consist of?
brain and spinal cord
what is the peripheral nervus system made up of?
nerves that carry information to and from the CNS
what are nerves?
bundles of nerve cells
what are cranial nerves connected to? + how many pairs are there?
- connected to the brain
- 12 pairs
what are spinal nerves connected to? + how many pairs are there?
- connected to the spinal cord
- 31 pairs
what are the 2 types of nerves? + what does each of them do?
a) sensory nerves
- carry information to the CNS
b) motor nerves
- carry info from the CNS to effectors
what are effectors?
muscles and glands
what are glands?
part of the body that secretes a fluid
how does a nerve impulse pass thru a neuron?
dendrites → cell body → axon → synpatic knob
what is a resting neuron? + what is the inside of it like? + what is the outside of it like?
- a neuron that is not in the process of transmitting a nerve impulse
- the inside of the cell membrane of a resting neuron is negatively charged
- the outside of the cell membrane of a resting neuron is positively charged
the cell membrane of a resting neuron is _______
+ what does that mean?
- polarized
- negative on the inside and positive on the outside
where does stimulation of a neuron begin?
at its dendrites
what does a dendrite become as it is stimulated?
depolarized → positevely charged on the inside of the cell membrane and negatively charged on the outside of the cell membrane
what does a depolarization move like?
how?
- like a wave
- dendrites →cell body → axon → synaptic knob
what happens after a depolarization passes part of a neuron?
the cell membrane quickly repolarizes
what are Schwann cells? + what are they shaped like? + what do they do?
- special cells found in the nervous system
- schwann cells are pancake-shaped
- they wrap around the axons of some neurons
an axon that has schwann cells wrappped around it is ________?
myelinated
what is myelin?
layers of white fatty substance
what is multiple sclerosis? + what does it do to the body?
- a condition in which the immune system attacks and damages the schwann cells
- This slows down how fast nerve impulses can pass thru neurons which affects a person’s ability to move
label
answer key
label
answer key
what are the first 2 steps in the transmission of a nerve impulse between neurons at a synapse?
A nerve impulse (= depolarization) reaches the synaptic knob of a neuron
This causes several synaptic vesicles to fuse with the cell membrane of the pre-synpatic neuron release neurotransmitters into the synapse
what are the last 2 steps in transmission of a nerve impulse between neurons at a synapse?
The neurotransmitters diffuse across the synapse and attach to sodium channels on a dendrite of the post-synaptic neurons
This causes the sodium channel to open and allow sodium ions (Na+) to enter the post-synaptic neuron which causes this neuron to become depolarized
label
answer key
label
answer key
what is a neuromuscular junction?
= a special type of synapse between a motor neuron and a muscle cell
can muscle cells contract on their own?
Muscle cells won’t contract on their own, they have to be told. They are told by motor neurons
what is acetylcholine?
the neurotransmitter that’s used in neuromuscular junctions
neurons with schwan cells are _______ neurons
peripheral
what does myelinated means?
it means it has schwann cells around it
the brain consists of 3 main parts. what are they?
brainstem
cerebellum
cerebrum
what is the brainstem & what is it attached to? + what does it control? (6)
- The part of the brain
- attached to the spinal cord
- controls basic psychological functions including:
Breathing
Heart rate
Blood pressure
Sneezing
Coughing
Swallowing
where is the cerebellum? + what does it do? + what is it used for?
- found at the back of the brain
- coordinates voluntary muscle movements
- used for keeping your balance
what is the cerebrum? + what is it responsible for? (6)
- the biggest part of the brain
- initiation of voluntary movement
- touch, vision, hearing
- judgment and reasoning
- problem solving
- emotion
- memory
what organ is used for vision?
the eye
what sends visual information from the eye to the brain?
the optic nerve
what kind of nerve is the optic nerve? (2)
a cranial nerve & a sensory nerve
what is the pupil? (2)
- a hole in the center of the iris
- light enters the eye thru the pupil
what is the iris?
the colored part of the eye
what is the sclera?
the white part of the eye
what is the cornea?
the transparent layer that is at the front of the eye
what is the retina?
a layer at the back of the eye that contains nerve cells that are stimulated by light
what does the lens do?
focuses light entering the eye on the retina
what does the optic nerve do?
it carries nerve impulses from the retina to the brain
what is the ciliary muscle?
a circular ring of muscle that attaches all the way around the lens
what does the ciliary muscle do?
it can change the shape of the lens by streching it at its edges
what is the blind spot?
the blind spot is the region on the retina that contains no rod or cone cells because this is where the optic nerve exits the back of the eye
how many parts does the ear have? + state each of them?
3 parts:
outer ear
middle ear
inner ear
what is irritability?
the ability of a cell to respond to its environment
in complex multicellular animals, what controls the regulation and coordination of responses? (2)
a nervous system & an endocrine system
what is the nervous system?
a network of specialized cells that carry, known as nerve cells, that carry messeges or impulses throughout the organism
along with nerve cells, what are the two other types of body stractures in the nervous system?
receptors and effectors
what are receptors? + what are they also known as?
- receptors are specialized stractures that are sensitive to certain changes, physical forces or chemicals, both inside and outside the organism
- AKA sense organs
what do receptors cause?
receptors cause impulses to be carried over a pathway of nerve cells and these impulses reach an effecor
what is an effector? + what is an example of an effecor?
a specialized structure that responds to the commands of the nervous system
- example: in a human an effecor is either a gland or a muscle
how will an effector respond to an impulse if it’s a gland?
if the effector is a gland, it will respond to the impulse by either decreasing or increasing its activity depending on the nerve path ways the impulse has followed
how does an effecot respond to an impulse if it’s a muscle?
it responds by contracting
what do you call something that causes a receptor to start impulses in a nerve pathway?
a stimulus
what does a stimulus cause? + what does that start?
- the stimulus causes electrical and chemical changes in the receptor
- these changes start the nerve impulses
what are the three basic events in nervous regulation?
a stimulus activates a receptor
impulses are started in associciated nerve pathways
an effector responds to the impulse
impulses reaching an effector are the result of the _______ and ________ of many impulses from many diffferent pathways
- combanations
- interaction
is a nerve pathway a straightforward connection from a praticular recpetor to a praticular effector?
no
in general, each type of receptor is sensitive to a different type of stimulus. give an example
- heat
- cold
- light
- sound
- pressure
- chemicals
what is the brain?
a specialized group of nerve cells that control and coordinate the activities of the nervous system
how does an organism’s complexity affect its brain?
the more complex the organism, the more complex the stracture and functions of the brain
what is a nerve cell? + what is it also known as?
- the basic stracture in the nervous systems in all multicellular animals
- neuron
neurons can send both ______ and _______ impulses?
- electrical
- chemical
what is the main charctaristic of the nerve cell membrane?
to be able to send impulses
what do nerve impulses not pass thru? + how are they trnsmitted?
- cytolplasm of nreurons
- transmitted only along the cell membrane
a nerve cell is usually made up of three basic parts, what are they?
cell body
dendrite
axon
what does a cell body contain? (1) + what does it do? (3)
- a cell body contains the nucleus and the cell organelles
- all metabolic activities that take place in all cells are carried out in the cell body
- also controls the growth of the nerve cells
- materials that are needed for the maintenance of the nerve cell are made in the cell body
what are dendrites? + what do they do?
short, highly branched fibres, that receive impulses
- dendrites generally conduct impulses toward the cell body
- in some neurons, the dendrites branch out around the cell body, giving the cell a bushy appearnce
what is the axon? + what does it do?
- usually, a long thin fiber that extends from the cell body
- axons usually carry impulses away from the cell body and send them either to other neurons or to effectors
what is a nerve fiber?
a sometimes either the axon or the dendrite of a neuron
what are vertabrate axons surrounded by?
surrounded by cells known as schwann cells
on some axons, the scwann cells produce layers of ______? + what is it?
- myelin
- a white, fatty substance called
what does the myelin form?
forms a covering around the axon and axons having such a covering are said to be myelinated
at places along the myelinated axon, there are gaps in the myelin that expose the axon membrane to the surrounding medium, what is it called?
nodes of ranvier
what is the main difference between neurons and other cells of the body? + what is one expetcion?
- the nerve cells of mature animals cannot divide and cannot be replaced unlike other cells of the body
- if however the cell body of a neuron is unhurt, damaged axons and dendrites outside the brain and spinal cordcan grow back
what are terminal brances?
the many branches at the end of an axon of a neuron
what is a synpase?
a place between the terminal branch of a neuron and the membrane of another cell
what is one charctaristic of a synapse?
the synpase has a microscopic gap between the end of the terminal branch and the neighboring cell
what happens in this gap?
impulses are carried across the gap from the axon to the neighbouring cell
true of fsalse? each axon may have one or more synapses with as many as 1,000 other neurons
true
_____ from other neurons may also make _____ with these cells
- axons
- contact
what makes a typical nervous system very complex?
all of the synapses make the interconnections and impulse pathways very complex
what are nerves?
bundles of axons or dendrites that are bound together by connective tissues
when are nerves called sensory nerves?
if they carry impulses from receptors to the spinal cord and brain
when are nerves called motor nerves?
if they carry impulses from the brainand spinal cord to effectors
when are nerves called mixed nerves?
if they are made up of both sensory and motor fibers
how are neurons usually grouped?
they are usually grouped according to what they do
what do the following do?
a) sensory neurons
motor neurons
interneurons + what is another name for this?
a) carry impulses from receptors to spinal cord and brain
b) carry impulses from the brain and spinal cord to effectors, usually muscles
relay impulses from one neuron to another in the brain and spinal cord
- associative neurons
what are most neurons in the human nervous system?
interneurons
what makes the transition of a nerve impulse possible?
the diffference in electrical charge between the outer and inner surfaces of the outer and inner surfaces of the nerve cell
what does it mean when a neuron is resting?
means that it’s not transmitting an impulse
what happens when a neuron is resting?
the outside of the membrane has a net positive charge and the inside has a net negative charge
the cell membrane is said to be _______ because there is a difference in _____ charge between its _____ and _____ surfaces
- polorized
- electrical
- outer
- inner
how is polarization caused in cell membrane?
it’s caused by different concentrations of certain ions outside and inside the cell
how do such differences of concentrations occur?
the differences are the result of active transport of ions across the membrane
Note
Flashcard