Homeostasis fundamentals (FSL) Flashcards
what is homeostasis
the regulation of the internal conditions of a cell or organism to maintain optimum conditions for function in response to internal and external changes
what does exercise do to the body
places demand on the body,,, respiration uses glucose to produce energy, this can cause the blood glucose concentration to fall. The athletes body temp will rise and hell lose water through sweating.
homeostasis consists of ____ making sure that the internal conditions of the body stay as constant as possible
automatic control systems
what can the automatic control systems in the human body involve
nervous system or hormones
receptor cells detect changes in what
the environment,, such as the bodys internal conditions eg the glucose concentration
other than internal conditions, what else do receptor cells detect change in?
bodys external conditions eg the temperature of the skin
what do scientists call a change to the environment
a stimulus
what do the receptors pass information to?
a coordination centre
whats an example of a co-ordination centre
the brain, spinal cord or the pancreas
what does the co-ordination centre do
receives and processes the information from the receptor cells then sends instructions to the effector
whats an effector is a muscle or a gland
the job of the effector is to carry out the response / restore the optimum level
whast the nervous system cycle
receptors detect a stimulus and send electrical impulses down neurones to the central nervous system this sends electrical impulses to the effector to bring about a response.
what are effectors usually?
a muscle which contracts or a gland which secretes a hormone
what happens when you touch a hot thing
first a stimulus is detected by a receptor, electrical impulses now pass from the receptor along a sensory neurone to the central nervous system, the chemical then diffuses across to a relay neurone in the cns where it triggers an electric impulse , this then passes across the relay neurone b4 reaching another synapse then another chemical is released,, the chemical; triggers and electrical impulse in the motor neurone,, the electrical impulse now passes down the motor neurone to an effector ,, the muscle now contracts and pulls away from the heat.
what does the brain contain
billions of interconnected neurones
the function of the cerebral cortex include what
language, memory and consciousness
what does the cerebellum control
balance and co-ordinates our movements
what does the medulla control
our heart rate and our breathing rate
why is studying/treating the brain difficult ?
its protected by the skull so is v tricky to access ,, the structures of the brain are v complex & the brain is extremely delicate and easy to damage
how can we look at the effects on a persons behaviour
by electrically stimulating different parts
what does the eye contain
receptors sensitive to both light intensity and also the colour of light
What is the first step of the eye
light rays pass through the transparent front of the eye called the cornea
whats the job of the cornea
start the focussing of the light rays
whats the 2nd step of the eye
the light rays then pass through the pupil in the centre of the eye
whats the job of the lens
to focus the light rays onto the back of the eye
what is accomodation
the lens changing shape to allow it to focus on distant or near objects
what does the retina contain and what do they do
receptor cells for light, they allow us to detect light intensity and light colour,, the receptor cells sent electrical impulses to the optic nerve to the brain
whats the white part of the eye an what does it do?
the sclera and its the tough outer structure protects the eye
what do the ciliary muscles and suspensory ligaments do?
allow us to focus on distant/ near objects
whats the job of the iris
to control the sizeof the pupil
what happens when you enter a dark room (in the eye)
the amount of light entering the eye is low. this drop in light intensity is sensed by light receptors in the retina and these send electrical impulses to the brain. The brain then sends electrical impulses to specific muscles in the iris. These msucles contract causing the pupil to become larger , allowing more light into the eye
by contracting or relaxing, the ciliary muscles can do what?
the thickness of the lens
when the cilliary muscle contracts, the suspensory ligaments do what?
loosen,, the lens is now thicker and refracts light rays more strongly
when the ciliary muscle relaxes, the suspensory ligaments do what?
They pulled tight; the lens is now pulled thin and only slightly refracts light rays b
what happens regarding focus on objects that are far away?
light from distant objects needs to be focused only a relatively small amount so ciliary muscles relax and suspensory ligaments are pulled tight so the lens is pulled thin,, bc of this,, the light rays are only slightly refracted ,, light rays are now focused to a point on the retina
what happens in hyperopia
long sight is also called hyperopia ,, the eyeball is too short so the light is focused behind the retina, in some cases, the lens becomes less elastic ,, in this case the lens cant become thick enough to focus on near objects
how can hyperopia be treated
convex lenses , these partially focus the light before it enters the eye
what happens in myopia
the eyeball can be too long so the light is focused at the point in front of the retina, it can also be caused when the lens is too thick , the light is focused infront of the retina
how can myopia be treated
concave lenses to partially unfocus the light before it enters the eye
what do scientists call the part of the brain that controls temp
the thermoregulatory centre
what does the thermoregulatory centre contain
receptors which are sensitive to the temperature of the blood,, the skin also contains these receptors
what do receptors in the skin do
these send electrical impulses down sensory neurones to the thermoregulatory centre
what is flushing
under the surface of the skin, we have a fine network of blood capillaries, these are supplied with blood by the blood vessels, if we get too hot the blood vessels dilate (get wider) this is vasodilation,, due to dilation, more blood is flowing through he capillaries , heat can transfer out of the blood so body temp returns to normal
what happens if the body temp falls to low
blood vessels supplying the capillaries constrict in other words they become narrower, this is vasoconstriction ,, less blood now flows through the capillaries and less heat is lost from the body
other than vasoconstriction,, what else happens when our body temp drops too low
shivering,,, when we shiver our skeletal muscles contract,, to generate energy for this contraction the muscle cells increase their rate of respiration, this releases heat
what happens if our body temperature falls too low
we also stop sweating
