homeostasis and control Flashcards
what is homeostasis?
regulation of internal conditions in the body to mantain optimum conditions for body functions
function of cerebrum/ cerebral cortex
- outermost zone of brain
- controls consciousness, intelligence, memory, language and emotion
function of cerebellum
controls coordination, precision, accurate timing
function of medulla
controls unconscious activity eg breathing, peristalsis, heart rate etc.
what are the 2 types of muscles in the iris?
- radial
- circular
what happens to the iris in bright light?
- less light should enter eye to protect retina from damage
- circular muscles contract
- radial muscles relax
- pupil becomes smaller and more contracted
what happens to the iris in dim light?
- more light needs to enter the eye
- radial muscles contract
- circular muscles relax
- pupil becomes bigger (dialated)
function of retina
light sensitive layer which sends signals to optic nerve
function of optic nerve
sends signals to the brain
function of scelra
tough and fibrous > protects interior components of eye from injury
function of ciliary muscles
pull the lens for focusing
function of iris
controls amount of light entering the eye
function of cornea
lets light into eye, begins focusing light onto retina
function of iris (and pupil)
pupil - hole in the iris
iris controls amount of light entering the light through the contraction and relaxation of the radial and circular muscles
function of suspensary ligaments
hold the lens in place
what is accomodation?
when the shape of the lens changes to focus light on the retina
what happens to the eye to look at near object? (4)
- cliary muscles contract
- suspensery ligaments relax
- lens become fat (more curved)
- this increases the amount by which it refracts light
what happens to the eye to look at distants object? (4)
- cilary muscles relax
- suspensary ligaments pull tight
- lens becomes thin (less curved)
- light doesn’t refract as much
what is myopia?
- short sightedness (unable to focus on distant objects)
- lens is wrong shape refracts light too much, focal point is in front of retina or eyeball is too long
how can myopia be treated with glasses?
glasses with a concave lens (curved inwards) so that light focuses on the retina
what is hyperopia?
- long-sightedness (can’t focus on near objects)
- lens is wrong shape and doesn’t refract light enough or eyeball is too short
- focal point is bhind the retina
how can hyperopia be treated with glasses?
glasses with a convex lens (curved outwards) which refracts the light rays so they focus onto the retina
what can be used to treat eye defects? (4)
- contact lenses
- glasses
- laser eye surgery (correct eye defects by shaving off some cornea - most effective for myopia)
- replacement lens sugery (natural lens replaced by artificial one)
how can neuroscientists map the brain? (3)
- studying patients with brain damage eg phineas gage (man with pole through head)
- electrically stimulating the brain
- MRI scans
what are reflexes?
an action which is rapid and automation (doesn’t involve the conscious part of the brain)
how do reflexes work? (7)
(describe reflex arc)
- stimulus detected by sensory receptors
- electrical impulse travels along sensory neurone towards centeral nervous system (cns)
- electrical impulse converted into chemical message at synapse
- relay neurone quickly decides on a response, send a messgae via another synapse to a motor neurone
- motor neurone carries an electrical impulse to an effector
- effector preforms action
- relay neurone also sends a message to the brain, but this takes longer than the actual reaction
what do reflexes do / role of refexes?
protect body from danger and prevent further damage of our tissues
what are the different parts of the nervous system?
- central nervous system (brain and spinal cord)
- sensory neurones
- motor neurones
- effectors
what are sensory neurones?
carry information from the CNS to effectors
what are motor neurones?
neurones that carry electrical impulses from CS to effectors
what are effectors?
all your muscles and glands which respond to nervous impulses
- muscles contract
- glands excrete hormones
what are synapses?
connection (gap) between 2 neurones
what can and can’t travel through synapses?
- electrical impusles cannot travel across
- instead a chemical message (NEUROTRANSMITTER) diffuses across gap to stimulate a new electrical impulse in the next neurone
what are receptors?
- cells that detect stimuli (any change in the environment)
- can also form part of larger organs eg retina is covered in light receptor cells
describe how info is carried from receptors is carried to brain to coordinate the response
- receptors detect stimuli
- sensory neurones carry the info from receptors to CNS
- CNS recieves and processes info
- CNS sends electrical impulse to the effector through the motor neurones
what are the main functions of the nervous system? (2)
