B5 Flashcards
what does the nervous system allow us to do
allows us to react to our surroundings and co-ordinate actions in response to stimuli
what is a stimuli
a change in the environment
describe what happens in response to a stimuli
- receptor cells convert a stimulus into an electrical impulse
- the electrical impulse travel along cells called sensory neurones to the CNS
- the information is processed and the appropriate response is coordinated resulting in an electrical impulse being sent along motor neurones to effectors
- the effectors carry out the response
what are receptor cells
cells that detect the stimulus
what do sensory neurones detect
- change in temperature
- level CO2 in blood
what is a sensory neurone
neurones that carries impulses from the sensory organs to the CNS
name two examples of an effector
muscles or glands
what is an effector
areas that bring about responses in the body
what is a reflex arc
the pathway of information from a sensory neurone through an inter neurone to a motor neurone
what is a reflex/reflex action
rapid automatic response of the nervous system that do not involve a conscious thought
describe a reflex arc
- stimulus is detected by the receptors
- impulses are sent along a sensory neurone
- in the CNS the impulse passes to a relay neurone
- impulses are sent along a motor neurone
- the impulse reaches an effector resulting in the appropriate response
give an example of reflex arcs
- pupils getting smaller to avoid damage from bright light
- moving your hand from a hot surface to prevent damage
what are synapses
gaps between two neurones
how is information passed from one neurone to another
chemicals released from a neurone, they diffuse across the synapse
what is a reaction time
how long it takes you to respond to a stimulus
what is the CNS made up of
brain and spinal chord
what does the hypothalamus do
regulate body temperature and send signals to the pituitary gland
what does the cerebral cortex do
control consciousness, intelligence, memory, language, senses
where is the cerebral cortex found
outer part of the brain, split into two hemispheres
what does the cerebellum do
control fine movement of muscles and balance
where is the cerebellum
rounded structure near the bottom/back of the brain
what does the medulla do
control unconscious actions such as breathing and heart rate
where is the medulla found
in the brain stem in front of the cerebellum
why is investigating brain function and treating brain damage and disease difficult
- the brain is complex and delicate
- the brain is easily damaged
- drugs given to treat diseases cannot always reach the brain due to the membranes that surround it.
- not fully understood which part of the brain does what
how can neuroscientists map out the regions of brains
- studying patients with brain damage
- electrically stimulating different parts of the brain
- using MRI scanning techniques such as CT, PET, MRI
what is accommodation
the process of changing the shape of the lens to focus on near or distant object
what is the retina
a layer of light sensitive cells found at the back of the eye
what is the process of accommodation to focus on a distant object
- ciliary muscles relax
- the suspensory ligaments loosen
- the lens then becomes thinner - light is refracted less
what do the suspensory ligaments do
control the shape of the lens
what do the ciliary muscles do
hold the lens in place
what can the lens do
can change its shape
what does the pupil do
its a gap that allows light to pass through it to the lens
what does the optic nerve do
carries the impulses from the retina to the brain to create an image
what is the sclera
white outer layer which supports and protects the structures inside the eye
what is the cornea
a see-throuh layer at the front of the eye
there are no blood vessels in the cornea so how does it get oxygen
the oxygen is diffused through it
what is the optic nerve
a nerve that leaves the eye and leads to the brain
what is the cornea
a see-through layer at the front of the eye
what is the iris
muscles that surround the pupil
what does the iris do
contract or relax to alter the size of the pupil
in bright light, what happens to the circular muscles and radial muscles
the circular muscles contract and the radial muscles relax to make the pupil smaller (constricted)
what is the eye
a sense organ containing receptors sensitive to light intensity and colour
what is the technical term for short sightedness
myopia (the lens are too curved and so distant objects appear blurry. concave lens)
what is the technical term for long sightedness
hyperopia (the lens are too flat and so it cannot refract light enough. concave lens)
name four treatment methods for myopia/hyperopia
- spectacle lenses (concave lenses to spread out the light to. convex lenses to bring the rays together)
- contact lenses (same as spectacle lenses)
- laser eye surgery (myopia - reduce the thickness of the cornea, refracts light less. hyperopia - change its curvature, refracts light more)
- replacement lens (hyperopia - replace lens with an artificial one made out of clear plastic or by adding the plastic on top. however can lead to cataracts developing or damage to the retina)
what is the thermoregulatory centre part of
the hypothalamus
what does the thermoregulatory centre do
monitor and control body temperature found in the brain
what do the receptors in the thermoregulatory centre do
monitor the temperature of the blood and sends impulses to the thermoregulatory centre
if the temperature becomes too high what happens
- sweat is produced from sweat glands which evaporates to increase the energy transfer away from the body
- vasodilation (opposite is vasoconstriction) which means more blood flows closer to the surface of the skin
- hairs fall flat to prevent trapping warm air and creating an insulating layer
when temp gets to low, opposite but skeletal muscles also contract rapidly to generate heat from respiration
what two communication systems does the human body have
nervous system and endocrine system
what does the endocrine system send around the body
hormones
what glands are in the human endocrine system and what do they secrete
- pituitary - hormones (either have an effect on the body to to make other glands produce different hormones)
- pancreas - insulin (controls blood glucose levels)
- thyroid - thyroxine (controls metabolic rate, heart rate and temperature)
- adrenal - adrenaline (flight and fight response)
- ovary - oestrogen (menstrual cycle and puberty)
- testes - testosterone (production of sperm and puberty)
the hormonal system is much slower compared to the nervous system but
it acts for longer
why does the concentration of glucose in your blood needs to be kept within a certain limit
glucose is needed by cells for respiration
eating foods that contain carbohydrates increases
glucose levels in the blood
if glucose levels are too high what happens
- pancreas produces hormone insulin
- insulin binds to cell in target organs
- glucose move from the blood into muscle cells for respiration
- excess glucose is converted into glycogen which is stored in the liver
- blood glucose concentration is reduced
what is glycogen
stored form of glucose is made up of many connected glucose molecules
what is glucagon
a hormone that is involved in controlling blood sugar (glucose) levels
if glucose levels are too low what happens
- pancreas produces glucagon
- glucagon binds to liver cells causing glycagon to be broken down into glucose
- glucose is released into the blood, increasing blood glucose concentration
when does type 1 diabetes occur
when the pancreas cannot control your blood glucose level
when does type 2 diabetes occur
when your body cells no longer respond to insulin
how is type 1 diabetes treated
- insulin injections at meal times
- advised to limit the intake of simple carbohydrates which contain lots of glucose
how is type 2 diabetes treated
- reduce the number of simple carbohydrates in diet
- lose weight
- increase exercise
- drugs to make insulin more effective
if the water concentration of the blood increases
- cells in body take up water
- because concentration of water in the bloodstream is higher than the concentration of the water in the cells due to osmosis
- cells expand as they take up more water and eventually burst
what organs are very important in maintaining the balance of water and other substances in the body
kidneys
how does the kidney make urine
- filters out waste products
- selectively reabsorbs useful substances such as glucose, ions and water
name three waste products and how they leave the body/taken in
- water (lungs due to exhalation or sweat or urine)
- ions (taken in via food, lost in sweat)
- urea (lost in sweat and urine)
amino acids are the products of what
digestion of proteins
amino acids are DEAMINATED in the liver to form
ammonia
is ammonia toxic
yes therefore its converted to urea
ADH is a hormone involved in what
the control of the loss of water as urine
ADH is released into the pancreas by the [] when a receptor in the brain detects that the blood is too concentrated
pituitary gland
Describe the negative feedback loop when the concentration of the blood increases leading to more ADH being secreted to reverse the change
- ADH travels in bloodstream to the kidney tubules
- increased amount of ADH reaching tubules increase their permeability to water so more moves out of the tubule and back into the bloodstream
- smaller volume of more concentrated urine and the blood becomes less concentrated as more water moves into it
what is kidney failure
when your kidneys stop working due to waste products building up
what two ways can you treat people with kidney failure
- dialysis
- kidney transplants
how does dialysis work
the function of the kidneys is carried out using artificial membrane. the blood moves between partially permeable membranes surrounded by dialysis fluid
how does kidney transplants work
provides the individual with a healthy kidney
advantages of dialysis
- useful ions and glucose aren’t lost from the blood but urea, excess ions and water diffuse across the membrane
- acts as an artificial kidney and keeps people alive while they wait for a transplant
disadvantages of dialysis
- has to be done three times a week, each time taking 3-4 hrs
- possibility of blood clots forming
- have to follow a strict diet
- unpleasant experience
- build up of waste products between sessions can make you feel ill
disadvantages of kidney transplants
- can be rejected from the body
- drugs taken to try and prevent that can make them vulnerable to other diseases
- do not last forever
- only cure
advantages of kidney transplants
- cheaper than overall cost of dialysis
- do not need to visit the hospital as regularly
how does the thermoregulatory centre send information to the sweat glands in the skin
neurones/nerves
If the reaction time decreases what does it mean?
we respond quicker
