Homeostatasis And Responce - Nervous System Flashcards
What is Homeostasis
Regulation of internal conditions to maintain a stable environment, in response to internal and external changes
What are control systems
Both nervous and hormonal communication systems that regulate internal environment
All contain 3 components: receptors, coordination centres and effectors
What is a stimulus
A change in the environment you need to respond to
What do receptors do
They detect the stimulus when the level of somthing is too high or low and send this info to the coordination centre.
What do effectors do
Respond the conteract the change, bringing levels back to the optimum
What is the nervous system made of and why is it important
Neurones and allows you to react to your surroundings
Give some examples of receptors
Taste receptors on the tounge
Sound receptors in the ear
Light…
Smell..
What is the cns and what does it do
Brain and spinal cord
It’s where reflexes and actions are coordinated
Connected to the body via sensory neurones and motor neurones.
What are effectors
Muscles wich contact
Glands wich secreate hormones
What type of nurone carrys electrical impulses through the cns
Relay neurons
What is a synapse and how do they work
The connection between 2 neurones. The signal is transferred by chemicals wich diffuse across the gap. Theses chemicals set off a new electrical signal in the next neutrone.
What are reflexes
Fast automatic responses to certain stimuli that bypass your brain completely.
What is the passage of information called from the receptor to effector
Reflex arc
Cerebral cortex
Outer layer of brain.
Responsible for consciousness, intelligence, memory and language
Medulla
Base of the brain, top of spinal cord
Controls unconscious activitys
Cerebellum
Back of the brain
Muscle coordination
How do neuroscientist study patients with brain damage
The effect on the penitent after a certain part if the brain is damaged can tell you what that part of the brain does
How do neuroscientist study the brain through electrical stimulation
Pushing a tiny electrode into the tissue and giving it a small zap if electricity. Observing what stimulating certain parts of the brain does gives you an idea of what those parts do
MRI scans
Magnetic resonance imaging is a tube machine that provides a detailed picture of the brain. Can use it to find wich area of the brain are active when people are doing different things
Why is treating the brain dangerous
Its complex, delicate so can cause physical damage to the brain or increased problems with brain functions
What is the sclera
Tough supporting wall of eye
What is the cornea
Transparent outer layer at front of eye
It retracts light into the eye
What is the pupil
Hole in centre of the eye through wich light enters
What is the iris
Contains musles that control diameter of the pupil
What is the retina
Layer at back of eye that contains receptor cells. One sensitive to light intensity and the other to colour
What is the lens
Focuses the light onto the retina
What is the optic nearve
Carrie’s implises from the receptors on the retina to the brain
What does the iris do when light intensity increases
The circular muscles contact and the radial musles relax
What is accommodation
The reflex which gives you the ability to focus on near and distance objects. The eye focuses light on the retina by changing the shape of the lens
What happens if you looks at a close by object
Ciliary musles contract
Suspensory ligaments relax
This increases the amount the light refracts so the lens is fatter.
When looking at distant objects the lens go thin and less curved
When does long sightedness (hyperopia) occur, what is it and how can it be fixed
Unable to focus on near objects
Happens when lens doesn’t bend the light enough
Or the eyeball is to short
The image is brought into focus behind the retina
Convex lens to bend light outwards
What is myopia when does it occur and how can it be fixed
Inability to focus on far away objects
When lens reflects light too much or eyeball is too long
Image brought into to focus in front of retina
Concave lens wich bends inwards
What are contact lenses
Thin lenses that sit on surface of eye
Lightweight and almost invisible
More convenient than glasses
Soft lenses are more comfortable but carry a higher risk of infection
What is lazer eye surgery
Laser used to vaporized tissue, changing the shape of the cornea. Thinning it down can make it less powerful and improve short sight
Risk of complications such as infections or the eye reacting
What is replacement lens surgery
A lens made of clear plastic is put in.
Treats long sightedness
Higher risk than laser eye surgery eg possible damage to retina
How does the body detect chang in temperature
Receptors in thermorengulatory centre are sensitive to temp of blood
Receptors in skin send info about skin temps via nervous impulses
How di we respond to a change in temperature
Impules are send the thermoregulatory centre wich acts as the coordination centre. It triggers effectors automatically. The effectors produce a response
What are some responses to body temp getting too high
Hairs in skin lie flat so their isn’t an insulating layer
Sweat is produced by glands. When it evaporates off the skin it transfers energy to the environment. Vasodilation gets the capillaries wider so more blood flows closer to the surface of the skin.
What are some responses to a drop in body temperature
Hairs on skin stand up creating an insulating layer
No sweat
Vacoconstriction
Shivering to create respiration wich transfers energy to warm body
