B5 Flashcards
what does the CNS protect us from
protects organisms from harm by responding to changes in the environment
what are the CNS components
1)the brain
2)the spinal cord
what do neurones do
carry electrical impulses between receptors, the CNS and effectors
what does the CNS do
coordinates the response of effectors and coordinates responses to stimuli
what are effectors
effectors bring about actions in response to a change in the internal end external environment, like muscles contracting and
what is a synapse
synapses are gaps between neurones and can be found at each junction if a reflex arc
what are neurotransmitters
chemicals that diffuse across synapses and bind to receptors on the next neurone
they initiate electrical impulse into the next neurone
reflex action
an unconscious response that allows a person to respond to a dangerous situation rapid and automatic, by a reflex arc
components of a reflex arc
1)stimulus
2)receptor
3)sensory neurone
4)coordinator
5)motor neurone
6)effector
7)response
what happens when the nerve impulse arrives at the synapse
the electrical impulse reaches the end of the neurone before the synapse
This triggers the release of chemicals called neurotransmitters
how do electrical impulses pass on
the neurotransmitters diffuse across the synapse
The neurotransmitters bind to receptors on the dendrites of receiving neurone
The presence of the neurotransmitter causes the production of an electrical impulse
when enough receptors have been filled a threshold is reached and a electrical impulse made in receiving neurone
after, the neurotransmitter is detaches from membrane of receiving neurone and reabsorbed back into the original neurone
what is a stimulus
A stimulus can be any change in the environment to which the body needs to respond.
what is a receptors
Receptors are found all over the body.
They detect the change in the environment and initiate (start) a signalling process within the body.
The signal is picked up by a neurone (nerve cell).
what are neurones
There are three types of neurone
part of the nerve
a nerve cell
factors that effect reaction time
Caffeine and exercise are factors that could affect human reaction time
what is the medulla
This part is responsible for unconscious activities (e.g. breathing and heartbeat)
what is the cerebral cortex
This part is responsible for conscious thought (e.g. memory, language and intelligence).
what is the cerebellum
This part is responsible for the muscle coordination.
The cerebellum is important for movement, posture, balance and speech.
what are MRI scanners
MRI stands for Magnetic Resonance Imaging.
MRI scanners have allowed us to learn which areas of the brain are active during different activities, such as moving, speaking and listening.
what is electrical stimulation
Electrical stimulation has also allowed us to treat certain disorders of the brain.
Because the nervous system communicates using electrical impulses, electrical stimulation is used to help treat conditions such as Parkinson’s disease (causes tremors).
what is accommodation
lens of the eye changing shape to focus on objects
how can eye defects be treated
Both myopia and hyperopia can be treated using glasses fitted with lenses that refract light rays to allow the image to form on the retina. Contact lenses and laser eye surgery can also correct these issues.
what is myopia
short sighted
Myopia happens when rays of light focus in front of the retina.
what is hyperopia
Hyperopia happens when rays of light focus behind the retina.
long sighted
hwo does the body maintain this constant internal environment
homeostasis
what is homeostasis
to maintain a stable constant internal environment
uses systems of receptors and effectors
why is it important to keep conditions constant
so that other systems are not interrupted by changes in the surroundings
what does the body maintain automatically
ensures that all its inputs and outputs are in balance by regulating the amount of blood sugar, water, ions, and temperature
the body needs to ensure it that there is enough sugar to supply all your cells
with a constant amount of energy
what affects the amount of sugar available for you body
the amount and type of food
why do the cells need sugar
so that there is enough energy to carry out respiration to release energy
what is osmoregulation
the regulation of the amount of water you have in your body
how does water leave the body
lungs through breathing out
skin through sweat
and the kidney through urine
how does the body replace lost water
the body needs to replace lost water and it tell you that it needs water when you are thirsty
how are ions lost
through sweat and urine
what do the kidneys regulate
they monitor the volume of water and ions to be released
what is thermoregulation
regulating body temperature
one of the most important things the body does
why is thermoregulation important
to allow enzymes to work at their optimum rate
what are enzymes
they are chemicals that allow reactions to happen at body temp of 37 degrees
what would happen with out the help of enzymes for the chemical reactions to happen
they would need much higher temperatures to work
when do enzymes work
they are very sensitive and only work when all the conditions are right
how does the body regulate, sugar, ions, water and temperature
communication
negative feedback
what is negative feed back
around the body there are receptors that pick up changes in the environment
once they detect a change they send information to a processing centre usually the brain
always does the opposite
what does the processing centre do (the brain)
coordinates a response
what is the response from the brain
to send a message to the effectors
which are either glands or muscles
these will do something about the change to make the conditions back to normal
what are glands
organs that secrete hormones
what are hormones
chemical messengers that affect how organs work
what are animals with a backbone called
vertebrates
where can the information the CNS come from
eyes
kidneys
skin
entire body
how are the spinal chord and the body organs connected
through nerves
what are nerves
made up of neurones
what are sensory neurones
The sensory neurone carries the signal in the form of an electrical impulse to the central nervous system (CNS).
transmit signal from receptors to the CNS
what are relay neurones
The relay neurone (in the CNS) relays the electrical impulse from the sensory neurone to the appropriate motor neurone.
carry’s impulses between neurons
what are motor neurones
The motor neurone is another type of nerve cell that carries the electrical impulse from the CNS to an effector.
what is the peripheral nervous system
the network of nerves that connects to body organs
how might the body respond to a stimulus
voluntary - brain has to think of a respons
involuntary - body reacts automatically
what are touch receptors
on the skin
they respond to a stimulus that touches the skin
how does the sensory neurone carry impulses to the CNS
through electrical signals that move rapid along sensory neurone to spinal cord
then to the brain
how does the body move after the brain has made a decision
sends a new electrical signal by a motor neurone to body part it wants to move
muscles carry out response
sequence of events for a voluntary response
-stimulated receptor
-sensory neurone
- spinal chord
- brain to make a decision
-sends out new electrical impulse (response signal) by the motor neurone
- to the effector
- effector carries out response
what is the sequence of events in an involuntary response (reflex response)
-stimulated receptor
-sensory neurone
-relay neurone in spinal chord
-connected to motor neurone
-effector carries out response
what are the components of a neurone
very long
have a insulating sheath (myelin sheath) to stop electrical impulses jumping onto other neurones
- the insulation allows impulses to travel across the neurone in little hops which makes it travel faster
dendrites branch out from cell body at one end
the long wire part is called axon when it’s carrying signals away from the body
-but called dendron if it’s carrying signals towards the body
what happens when the electrical impulse reaches the terminal of the axons
causes vesicles in axon to move to the outer edge and release neurotransmitters into the synapse
how are receptors on receiving neurone specific
specific to a particular neurotransmitter
how can you interfere with neurotransmission at a synapse
drugs can block neurotransmitter receptors
so signal can’t be passed on
can cause death
how can you affect re absorbtion of neurotransmitters into the original neurone
with drugs
and further messages can’t be sent
why does the body used electrical signals and chemical neurotransmitters
many advantages
-1if only electrical the messages would be too fast
-false signals which would trigger other messages
-by using neurotransmitters the signal has to reach a threshold before they get passed on
- and they ensure signal only travels in 1 direction (electrical circuits they can travel in either)
what are the advantages of reflex actions on an organism
sustains mess damage
live longer
quick
how are we aware of reflex actions
signals are also sent to the brain
this is why there is a delay in carrying out reflex action and geeking pain
how are cells involved in reflex actions specialised
they transmit electrical impulses quickly
sensory and motor neurones are long
relay neurones are much shorter
why are synapses important
prevent insignificant signals causing us to respond
when we should not
examples of reflex actions
hand moves away from hot object
pupils get smaller when you move from a dark place to a light place
adrenaline is produced when you are scared
what do glands do
secrete hormones
stimulus examples
temp change
light change
what organisms depend on reflexes
more simple than complex
otherwise they would die because they hunt and hide automatically
why does the pupil contract when we move from dark places to light
restricts the amount of light entering the eye
called the pupil reflex
helps prevent damage to light sensitive cells in the retina
what is the rooting reflex in babies
a baby turns toward an object that touches its cheek to find the milk
what is the sucking reflex
if an object is placed in a babies mouth it will automatically suck
what is the stepping reflex in newborns
a baby will make stepping movements when held up
types of sense organs
light is detected by eyes
sound is detected by ears
pressure is detected by the skin
what halpens if a stimulus is too weak
a signal is sent because the impulse doesn’t reach the threshold
why are thresholds improved
would be difficult to differentiate genuine signals and background level of activity
what does the retina contain
thousands of light receptor cells
what receptors detect colour in the retina
cone cells
what receptor cells detect brightness in the retina
rod cells
where does the signal go to when the receptor cells in the eye detect light
passed through the optic nerve
what are organisms that use nerves and electrical impulses
they are multi cellular
do simple organisms have nerves
no, they can’t respond to changes in an environment the same way a multicellular animal can
why do we want to understand how the brain works
we can help people recover from injuries
develop better methods of treatment
better understanding of what it means to be a person (what makes you, you
what is the brain
processing centre of CNS
it coordinates a response after processing and interpreting nerve signals from whole of the body
what is the cerebral cortex
-the outermost part of the brain
-wrinkled
- concerned with intelligence memory and consciousness (awareness of yourself
how did we understand more about the brain overtime
through injuries and their consequences
how can we survive if we damage our brain substantially
if the part of the brain damaged doesn’t control any part of the body
why is mapping the brain by the recording of the effects of injury’s bad
it’s hit and misss
it’s limited to the few people who have had a head injury
what is an invasive method of understanding the brain
stopping parts of the brain and see the effects
- very invasive process
- only done on patients who already have a bad injury and/or voluntarily
what is a non invasive technique for understanding the brain
being improved all the time by new developments in physics
-magnetic fields and electricity to stimulate the brain
-electrodes being attached to the scalp - EEG
-MRI
what happens during magnetic fields and electricity to stimulating the brain
powerful electromagnetic fields that change direction tens of thousands times a second can interfere with parts of the brain
if a high powered magnetic field is positioned over the speech part of the brain, a patient starts to mess up their words
this is because the magnetic fields interfere with the signals being sent to that part of the brain
how do electrodes being attached to the scalp work - EEG
they detect and measure changes of electric current inside the brain
when someone carries out an activity
parts of the brain involved show electrical activity and can be identified
what is MRI
an improvement from EEG to be more specific
stands for magnetic resonance imaging
uses strong magnetic field and radio waves
person is placed in chamber and a magnetic field, which changes direction thousands of times a second is employed over the chamber
with the right MRI scanner we can identify the parts of the brain active when we think about carrying out an action
what do animals that can see have
survival advantage
they have eyes to detect light reflected from objects
what is the sclera
-white
-tough
-holds eyeball together
-outermost part of the eye
-stops light from entering the eye, apart from front of the eye which is transparent
what is the cornea
refracts the light rays so that the light rays focus on the retina to produce the image
front of the eye
what is the iris
behind the cornea
ring of muscle that:
-contracts to minimise the amount of light entering the eye
-relaxes to let in more light
what is the pupil
the hole in the middle of the iris
it is black because the light that hits the retina is all absorbed
aqueous humour
transparent jelly between cornea and the iris
gives shape to front of eye
what is the lens
behind the iris and attached to muscles
these muscles can contract and relax to alter the thickness and the length of the lens
enables fine focusing of the image on the retina
what happens when you alter the lens shape
alters the amount of refraction of light entering the eye
but most of the refraction takes place at the cornea
what is the vitreous body
inside main part of the eyeball, behind the lens
another transparent jelly (a bit thicker)
give the whole eyeball it’s shape
what is the retina
made up of millions of cells
-some are designed to trigger a nerve signal when stimulated by light of a specific wavelength
-cone cells which detect red, blue and green light (colour) (found in centre of retina)
-rod cells detect intensity of light and are scattered over the entire inside of the eye
what is averted vision
example:
-you see faint stars better if you don’t look directly at them
-because it allows the light to land on the part of the retina that contains rod cells but cone cells
-allows you to detect faint light and let’s you see the faint stars more clearly
light journey into the eye
-hits cornea and gets refracted
-aqueous humour
-pupil surrounded by iris
-into the lens and gets refracted a bit more
-vitreous body
-then the retina landing on rod or cone cell
-cell sends message to the brain by the optic nerve
how is long/short sightedness caused
the eyeball or the lens being the wrong shape
how is short sightedness caused
if the eyeball is too large light is focused in the space infront if the retina
how is long sightedness caused
if the eyeball is too small light entering the eye is focused behind the retina
how does the body know the temperature of the body
receptors in the brain monitor the temperature of the blood
receptors on skin that receive information about the external temperature
what is the hypothalamus
section in brain
location of the thermoregulatory system
sets up a series of electrical impulses sent to effectors around the body
what is the thermoregulatory system
coordinates responses to temperature
why does the body need to stay at 37 degrees
so chemical reactions can happen at their optimum rate
why are enzymes useful
they are chemicals that allow reactions to happen at low temperatures
they are very sensitive and only work in very specific conditions (37 degrees
what are the effectors that bring temperature down
blood vessels and sweat glands
what happens to blood vessels near the surface on the skin when hot
the blood vessels that supply the capillaries near the surface of the skin dilate
makes you look redder
this is called vasodilation
what does vasodilation do
higher rate of blood flow to the surface of the skin
this increases the rate of heat loss
what layer of skin produces sweat glands
sweat glands in the dermis layer
how does sweat cool you down
the water in the sweat evaporates using heat energy from your skin which cools you down
what happens after you lose water through sweat
need to drink more to replace the loss of water
what happens to your blood vessels when you are cold
blood vessels near surface of skin constrict
this reduces rate of blood flow and prevents heat loss
called vasoconstriction
what is shivering
shivering is muscles contracting quickly
for your muscles to contract you need to supply them with energy by respiration
every time cells respire they give out heat energy
why do we shiver
to increase respiration in cells which increase heat supply
why do we get goose bumps
caused by hairs standing on end
by hair erector contacting which makes bumps on skin
this helps trap a warm insulating layer of air around skin
