HOMEOSTASIS Flashcards
What is homeostasis
is the process by which your body maintains a constant internal environment
what internal conditions are controlled by homeostasis
blood glucose
body temperature
water
what does the nervous system consist of
the brain
the spinal cord
neurons
function of the cerebral cortex
responsible for consciousness, intelligence, memory and language
function of the medulla
responsible for unconscious activities such as breathing and controlling your heartbeat
function of cerebellum
responsible for muscle coordination
what happens when your short sighted (myopia)
cant see distant objects and the image focuses in front of the retina
What happens when your long sighted (hyperopia)
cant see close objects and the image focuses behind the retina
what happens to your body when you are cold
your hairs stand up to trap air
your blood vessels vasoconstrict- your blood vessels contract so that theyre further away from the skin, this makes less blood flow to the surface of the skin so less heat is lost
YOUR muscles and the exothermic reactions of respiration needed for muscle contraction raise the temperature
what happens to your body when you are too hot
hairs lie flat
sweating- water will evaporate, leading to heat and energy loss
vasodilation- blood vessels become wider allowing blood to flow closer to the surface of the skin so that heat can be lost
what does the endocrine system consist of (male and female)
pituitary gland secretes FSH
thyroid gland- produces thyroxin which regulates metabolism
adrenal glands- produces adrenaline, it is called fight or flight hormone as it is released when you are stressed or frightened
pancreas- produces insulin
ovaries- produce oestrogen (menstrual cycle)
testes- produce testosterone
how does your body regulate blood glucose (when its too high)
after eating blood glucose levels rise
the receptors in the pancreas recognises this and produces insulin
the insulin causes cells to remove glucose from the blood
liver and muscle cells convert glucose into glycogen and stores it
removing glucose from the blood causes blood glucose levels to fall
how does your body regulate blood glucose (when its too low)
when the blood glucose is too low this is picked up by the receptors in the pancreas
the pancreas starts to produce glucagon
the glucagon turns the glycogen that was stored in the liver and muscles into glucose
the glucose is released back into the blood
this causes the blood glucose levels to rise
type 1 diabetes
pancreas doesn’t work properly so doesn’t produce the right amount of insulin
how can you treat type 1 diabetes
insulin injections
symptoms of type 1 diabetes
loss of weight, increased need to urinate, thirstiness and hunger
type 2 diabetes
cells become insensitive to insulin
how can you treat type 2 diabetes
by controlling diet by eating less carbohydrates and exercise if that doesn’t work drugs can be prescribed- this helps the pancreas make more insulin
why is homeostasis important
it is important for maintaining optimal conditions for enzyme action and all cell functions
where are receptor cells found
in sense organs such as the eye,ear,nose,tongue and skin
the direction of electrical impulses in the nervous system
stimulus—receptor—-sensory neurone—-CNS—–motor neurone—– effector——response
sensory neurons carry……… from the………. to the…….
sensory neurons carry impulses from receptors to the CNS
Motor neurons carry……. from the …….. to the …….
motor neurons carry impulses from the CNS to the effectors
what are effectors and what do they do
effectors are muscles or glands and they respond to impulses, the muscles respond by contracting, the glands react by releasing chemicals
what are reflex actions
they are automatic and rapid reactions that do not involve the conscious parts of the brain
What happens in a reflex
a receptor detects a stimulus
a sensory neurone transmits the impulse to the CNS
a Relay neurone in the CNS passes the impulse on
a motor neurone is stimulated and passes the impulse to an effector
action is taken
what is a synapse
a gap between two neurons
what happens when an impulse arrives at the junction between two neurons
chemicals are released and diffuse across the synapse these chemicals arrive at the receptor sites on the next neurone this starts up a new electrical impulse in the next neurone
what is the brain made up of
interconnected neurons
why is it difficult to study the brain and treat it
drugs do not always pass through membranes surrounding the brain
surgery is difficult because the function of each area of the brain is not fully understood
how have scientists been able to map regions of the brain
electrically stimulating the brain
using MRI scan
what is the sclera
is the tough white outer layer that prevents damage to the eye
cornea
is at the transparent area at the front of the sclera that lets light into the eye and refracts light towards the retina
function of the iris
controls the size of the pupil and the amount of light entering the eye
what happens in dim and bright light
in bright light, the circular muscles contract, radial muscles relax and the pupil constricts to reduce the amount of light entering the eye
in dim light, circular muscles relax, radial muscles contract and the pupil dilates to let in as much light as possible
what do the suspensory ligaments and ciliary muscles do
they change the shape of the lens to focus light onto the retina
what does the optic nerve do
carries impulses from the retina to the brain
how does the eye focus on a distant object
the ciliary muscles relax so the suspensory ligaments are pulled tight and the lens is pulled flat and thin
how does the eye focus on a nearby object
the ciliary muscles contract so the suspensory ligaments loosen. the lens is then thicker and more curved it refracts light more strongly.
how to fix myopia (short sightedness)
concave lens
how to fix hyperopia (long sightedness)
convex lens
what is accommodation
is the process of changing the shape of the lens to focus on near distant objects
what is the endocrine system
is made up of glands that secrete hormones directly into the bloodstream
how does a hormone travel from the endocrine gland to the target organ
the bloodstream
why is thyroxine important
is important for growth and development
what is negative feedback
negative feedback systems work to maintain a steady rate whatever the initial change to the environment is in negative feedback changes take place to restore it to its original level
out of adrenaline and thyroxine which one is controlled by negative feedback?
thyroxine
what happens if thyroxine levels decrease in the blood
there will be an increase in TSH release, the TSH causes an increase in thyroxine level, then the increased Thyroxine level causes a decrease in TSH release.
what does adrenaline cause in your body?
Adrenaline causes your heart rate and breathing rate to increase
stored glycogen in the liver to be converted to glucose for respiration
an increase in the flow of blood containing extra glucose and oxygen to the limb muscles.
What temp does your body need to be kept at
37 degrees
where is your body and blood temperature monitored in the body
the thermoregulatory centre in the brain
how is carbon dioxide produced and removed from the body
produced by respiration and is removed via the lungs when we breathe out
how is urea produced and removed from the body
produced in the liver from the breakdown of excess amino acids and is removed by the kidneys in the urine
how are the amino acids broken down into urea and urine
they are broken down by the process of deamination
an amino group is removed from the amino acid
this forms ammonia which is toxic which is then converted into urea. the urea passes to the kidneys to be excreted
what happens when the water content in the blood is low
the pituitary gland releases a hormone called ADH into the blood, this causes the kidneys to reabsorb more water, resulting in a more concentrated urine
how does ADH work
ADH works by changing the permeability of the kidney tubules so that they reabsorb more water from the urine into the blood
what happens when the water content is too high
less ADH is released into the blood so less water is reabsorbed in the kidneys, resulting in more dilute urine
an increase in ADH leads to a reduction of…..
water in the urine
what are receptors
Receptors are groups of specialised cells. They detect a change in the environment (stimulus) and stimulate electrical impulses in response.
what is the hypothalamus
The hypothalamus, which is the regulating centre for temperature and water balance within the body.
what happens in mri scans
MRI (Magnetic Resonance Imaging) scans, use strong magnetic fields and radio waves to show details of brain structure and function. Patients are asked to perform various tasks and, by looking at the scan, scientists can see which parts of the brain are active when the task is carried out.
what happens when you electrically stimulate the brain
Scientists have stimulated different parts of the brain with a weak electrical current and asked patients to describe what they experienced. If the motor area is stimulated, the patient makes an involuntary movement. If the visual area is stimulated, they may see a flash of colour.
what does the lens and retina do
lens- refracts light to focus on the retina
retina- contains light receptors.
what is a hormone
A hormone is a chemical substance, produced by a gland and carried in the bloodstream, which alters the activity of specific target organs.
what has an important role in detecting and controlling thyroxine levels.
The hypothalamus and pituitary gland
what happens if there is low thyroxine levels
Low thyroxine levels in the bloodstream stimulate the hypothalamus to release TRH and this causes the pituitary to release TSH so the thyroid releases more thyroxine. So blood levels return to normal.
what happens when the thyroxine level is normal
Normal thyroxine levels in the bloodstream inhibit TRH release from the hypothalamus and this inhibits the release of TSH from the pituitary, so normal blood levels are maintained.
what happens when adrenaline is released
When adrenaline is released into the bloodstream it creates multiple effects:
increases breathing rate, heart rate, and conversion of glycogen to glucose so more energy is released in the muscles
it diverts blood away from areas, such as the digestive system, towards the muscles
