homeostasis - topic 5 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
three main conditions the body needs to regulate
- water levels
- blood glucose concentration
3.temperature
what does a receptor do
detect the stimuli
what does the coordination centre do
receive and process information from the receptors
what does an effector do
bring about a response to restore optimal conditions
what are the two main effectors
nervous system - muscles - contract
endocrine system - glands - release hormones
what are some features of the nervous system
sends electrical impulses
its very fast but its effects are short lived
specific/ precise
what is a neurone
nerve cells that carry electrical impulses, chemicals transmit over the synapses between different neurones
what is the central nervous system (CNS)
the brain and spinal cord
what is the peripheral nervous system (PNS)
all sensory and motor neurones
what is the sensory neurone
the neurone that carries a signal from the receptor to the coordination centre
what is the relay neurone
the neurone that acts as the coordination centre in reflex action. found in the CNS
what is the motor neurone
the neurone that carries a signal from the coordination centre to the effector
what is a reflex action
an automatic and rapid responses of the nervous system. does not involve the conscious part of the brain. it prevents damage and harm.
what is the cerebrum (cerebral cortex)
the part of the brain that controls consciousness, intelligence, memory, language, personality etc
what is the hypothalamus
the part of the brain that controls body temperature by sending signals to the pituitary gland
what is the medulla oblongata
part of the brain that controls unconscious activities (heart rate/breathing)
what is the cerebellum
part of the brain that controls balance and muscle coordination
what is an electroencephalogram (EEG)
a non invasive brain procedure. directs weak electrical current using electrodes and the patient describes what they experience
what is an MRI scan
it uses magnetic waves to detect brain activity, checks which parts of the brain are active whilst people are doing different activities
what are the pros of brain surgery
treatment for disorders, reduces muscle tremors etc
what are the cons of brain surgery
carries risk such as damage or increased problems as the brain is complex and delicate
what is the cornea
the transparent outer layer that refracts light
what is the iris
contains muscles to control diameter of the pupil
what is the pupil
the hole that lets light through
what does the lens do
refracts light to focus on the back of the retina
what are the suspensory ligaments
ligaments that connect to the lens to control its thickness
what do the ciliary muscles do
contract to widen lens and refract more light
what is the sclera
tough, supporting layer
what does the retina do
contains receptors cells sensitive to light intensity and colour
rods - detect black and white
cones - detect colour
what does the optic nerve do
carries impulses from receptors to brain
what do the circular muscles do
contract to make the pupil smaller during bright light
what do the radial muscles do
contract to make pupil dilate during dim light
what is accommodation
when the eye focuses the light on the back of the retina by changing the shape of the lens
what happens when the eye focuses on a near object
- the ciliary muscles contract
- the suspensory ligaments relax
- lens becomes fatter
- more refraction
what happens when the eye focuses on a far object
- ciliary muscles relax
- suspensory muscles tighten
- lens becomes thinner
- less refraction
what happens to the eye in dim light
- radial muscles contract and circular muscles relax
- pupil dilates
what happens to the eye in bright light
- circular muscles contract and radial muscles relax
- pupil constricts
hyperopia (long - sighted)
the lens focuses behind the retina. corrected with a convex lens by narrowing the light rays upon entry to the lens
myopia (near - sighted)
the lens focuses in front of the retina. corrected with a concave lens by widening the light rays upon entry to the lens
