Topic 5 - Homeostasis and Response - Human nervous system Flashcards
(40 cards)
1
Q
Homeostasis definition?
A
- process by which the body maintains a stable internal environment despite changes in both internal and external conditions
2
Q
What is negative feedback?
A
- process where a change in a system is detected - body responds to reverse change - bringing conditions back to normal
3
Q
Example of negative feedback?
A
- receptor dectects a stimulus - level is too high
- coordination centre receives and processes information - organises a response
- effectors produces response - couteracts change - restores optimum level - level decreases
- vice versa
4
Q
What are effectors?
A
- effectors respond to nervous impulses - bring about a change
- muscles and glands known as effectors - respond in different ways
- muscles contract in response to nervous impulse - glands secrete hormones
5
Q
What are receptors?
A
- cells that detect stimuli
- many different types of receptors e.g. taste receptors on tongue and sound receptors in ears
- can form part of larger, complex organs. E.g. retina in the eye covered in light receptor cells
6
Q
What is the Central Nervous System (CNS)?
A
- in vertabrates - consists of brain and spinal cord only
- In mammals - CNS connected to body by sensory neurones and motor neurones
- is a coordination centre - receives information from receptors - coordinates response - reponse carried about by effectors
7
Q
What are sensory neurones?
A
- neurones that carry information as electrical impulses from receptors to CNS
8
Q
What are motor neurones?
A
- neurones that carry electrical impusles from CNS to effectors
9
Q
nervous system order?
A
stimulus - receptor - sensory neurone - CNS - motor neurone - effector - response
10
Q
What is a snynapse?
A
- junction between two neurones
- allows for the tranmission of electric nerve impulses in the nervous system
11
Q
How does information pass a synapse?
A
- neurotransmitters released into synaptic cleft
- neurotransmitters diffuse through synapse - bind to receptors on post-synaptic neurone
12
Q
What are reflex actions?
A
- rapid responses to harmful stimuli - protect body from injury
- don’t involve coscious part of your brain
- there are more synapses in the brain - synapses slow down transmission
- passage of information in a reflex - reflex arc
13
Q
What happens during the reflex arc?
A
- neurones in reflex arc go through spinal cord or unconscious part of brain
- stimulus detected by receptors - impulses sent along sensory neurone to a relay neurone in the CNS
- impulses reach synapse between sensory and relay neurone - neurotransmitters released - cause impulse to be sent along relay neurone
- impulses reach synapse between relay and motor neurone - neurotransmitters released - cause impulse to be sent along motor neuron
- impulses travel along motor neurone to effector e.g. muscle
- muscle contracts to carry out response
14
Q
Reaction time test practical?
A
- person being tested sit with arm resting on edge of table
- hold ruler vertically between their thumb and forefinger - make sure zero and of ruler is level with thumb and finger - let go without any warning
- person tested should try to catch ruler as quickly as possible
- reaction time measured by theon ruler where it is caught - read from top of thumb - further down the ruler caught - slower reaction time
- repeat test several times to calculate mean distance ruler fell
15
Q
Brain function?
A
- along with spinal cord - brain part of central nervous system
- made up of billions of interconnected neurones
- in charge of all of our complex behaviours - controls and coordinates everything we know
- encased in protective membranes called the meninges
16
Q
Cerebral cortex function?
A
- outer wrinkly bit of brain
- responsible for things like consciousness. intelligence, memory and language
17
Q
Cerebellum function?
A
- responsible for muscle coordination and balance
18
Q
Medulla function?
A
- controls unconscious activities liek breathing and heartbeat
19
Q
How can studying patients with brain damage help scientists learn about the brain?
A
- if a small part of the brain is damaged - effect this has on patient can tell scientists what the function of the damaged part of the brain was
20
Q
How can electrically stimulating the brain help scientists learn about the brain?
A
- brain can be stimulated electrically by pushing a tiny electrode into tissue and giving it small zap of electricity
- scientists can observe the effects of stimulating different parts of the brain to get an idea of what these parts do
21
Q
How can MRI scans help scientists learn about the brain?
A
- machine that can produce a very detailed picture of the brains structures
- used to find out what areas of brain are active when people are doing things
22
Q
Problems with the brain?
A
- brain is very complex and delicate - investigation and treatment of brain damage or disease is difficult
- risks such as phsyical damage to the brain or increased problems with brain function
23
Q
What is the sclera?
A
tough supporting wall of the eye - protects the eye
24
Q
What is the cornea?
A
- transparent outer layer found at front of eye
- refracts light into the eye so it can focus on the retina
25
What is the iris?
- contains muscles that allow it to control diameter of the pupil
- controls how much light enters the eye
26
What is the lens?
focuses light onto the retina (which contains receptor cells sensitive to light intenisty and colour)
27
How is the lens held in place?
- held in place by ciliary muscles and suspensory ligaments
- they control the shape of the lens
28
What is the optic nerve?
carries impulses from the receptors on the retina to the brain so the brain can iinterpret them as a visual image
29
What happens in bright light?
- reflex is triggered that make the pupil smaller
- circular muscles in the iris contract and radial muscles relax
- this reduces the amount of light that can enter the eye
30
What happens in dim light?
- reflex is triggered that make pupil wider
- circular muscles in the iris relax and radial muscles contract
- this increases the amount of light that can enter the eye
31
What is it called when the eye focuses light on the tetina by changing the shape of the lens?
accommodation
32
What happens when you look at near objects?
- ciliary muscles contract - slackens suspensory ligaments
- lens becomes fat - more curved
- increases amount by which it refracts light
33
What happens when you look at far objects?
- ciliary muscles relax - allows suspensory ligaments to pull tight
- makes lens go thin (less curved)
- refracts light by smaller amount
34
What is hyperopia?
- long-sighted people unable to focus on near objects
- lengs is wrong shape and doesnt refract light enough or eyeball too short
- images of near objects brought into focus behind retina
35
How do you fix hyperopia?
- uses glasses with convex lens
- lens refracts light rays so they focus on the retina
36
What is myopia?
- short-sighted people unable to focus on distant objects
- lens is the wrong shape and refracts light too much or eyeball is too long
- images of distant objects brought into focus in front of retina
37
How do you fix myopia?
- uses glasses with concave lens
- refract light outward so it can focus on the retina
38
How are contact lenses treatment for vision defects?
- contacts lenses are thin lenses that sit on surface of eye and shaped to compensate for fault in focusing
- popular because lightweight and almost invisible - more convinent than glasses
- 2 types are soft lenses and hard lenses - soft lenses more comfortable - higher risk of eye infections
39
How is lager eye surgery treatment for vision defects?
- laser used to vaporise tissue - changing shape of cornea
- slimming it down makes it less powerful - can improve short sight
- surgeon can precisely control how much tissue laser takes off - completely correcting vision
- risk of complications like eye infection or eye reacting in way that makes vision even worse
40
How is replacement lens surgery treatment for vision defects?
- natural lens of eye removed and artifical lens made of clear plastic fitted
- as involves work inside eye - high risks - possible damage to retina
