Homeostasis and response Flashcards
(103 cards)
1
Q
What is a stimulus ?
A
A change in the environment
2
Q
What stimuli do the nose receptors detect ?
A
odours ( chemicals in the air)
3
Q
What stimuli do skin receptors detect ?
A
touch, temperature, pain
4
Q
What stimuli do ear receptors detect ?
A
Sound
5
Q
What stimuli do eye receptors detect ?
A
Light and movement
6
Q
What stimuli do your tongue receptors detect ?
A
Chemicals in food and drink
7
Q
What are the two sections of the nervous system ?
A
Central nervous system and peripheral nervous system
8
Q
What is the central system made up of ?
A
Brain and spinal cord
9
Q
What is the peripheral nervous system made up of ?
A
Neurons ( nerve cells) that carry information to or from the CNS
10
Q
What does the nervous system enable us to do ?
A
Enables us to react to our surroundings and coordinate our behaviour
11
Q
What is an effector ?
A
An organ that does something in response to a stimulus
12
Q
What are the two types of effectors and what do they do ?
A
Muscles - contract and relax
Glands - release / produce hormones
13
Q
How is information in the nervous system carried ?
A
Carried as electrical impulses
14
Q
How are electrical impulses transmitted ?
A
Transmitted by nerve cells
15
Q
What is the role of the sensory neuron ?
A
Carries nerve impulses from sense organs towards the central nervous system
16
Q
What do relay neurons do ?
A
carry nerve impulses within the central nervous system
17
Q
What does the motor neuron do ?
A
Carries nerve impulse away from CNS towards an effector organ ( muscle or gland )
18
Q
What are receptors and what do they do ?
A
cells which are clustered together in sense organs such as your eyes
They detect stimuli and send information to CNS through sensory neurons
19
Q
Describe the normal impulse route
A
A stimulus is detected by a receptor.
The receptor converts this information into a nerve impulse
This impulse is transmitted from the receptor to the CNS along sensory neurons
The CNS coordinates the information and sends another impulse in response.
This impulse passes along motor neurons to the relevant effector (normally a muscle or a gland) to bring about a response.
20
Q
What is a reflex action ?
A
A rapid, automatic response of the nervous system which bypasses the brain
21
Q
What is the impulse route for reflex actions called ?
A
The Reflex Arc
22
Q
Why is the reflex Arc important ?
A
- allows us to avoid danger or harm
- allows us to coordinate everyday bodily functions ie eating, seeing, walking, sleeping etc
23
Q
Describe the reflex Arc
A
A stimulus is detected by a receptor
The receptor converts this information into a nerve impulse
The impulse is transmitted to the spinal cord along sensory neurons
Spinal cord will transfer the impulse to relay neurons
Relay neurons transfer impulse to a motor neurons
Motor neurons carries impulse to an effector which will bring about a response
24
Q
What are the adaptations of a neuron ?
A
- long fibre ( axon) so they can carry impulses up and down body over long distances
- branched connections called dendrites which receive incoming nerve impulses from other neurons ( allows neurons to communicate)
- axon is insulated by a fatty myelin sheath which increases the speed of the nerve impulses along the neuron
25
What is a synapse ?
The gap between two neurons
26
How do nerve impulses cross the gap between two neurons ?
- when electrical impulse hits the end of a nerve, causes the release of chemical messengers called neurotransmitters
- these diffuse across the synapse to the next nerve cell where they can trigger another electrical impulse
- new impulse continues along the new nerve cell to the other end, where it will hit another synapse and process repeats
27
What are the two coordinators in the nervous system ?
brain and spinal cord
28
What is the role of brain and spinal cord
To receive and process information from receptors around the body
29
What is reaction time ?
The amount of time it takes to respond to a stimulus
30
what are some factors affecting reaction time ?
age, gender, physical fitness, fatigue, distraction, alcohol, personality type, and whether the stimulus is auditory or visual.
31
What are the steps for investigating human reaction times ? ( required practical 7)
Step 1: Person A sits on a stool with good upright posture and place the forearm of their dominant hand across the table with their hand overhanging the edge
Step 2: Person B holds the ruler vertically with the 0 cm mark between person A's thumb and index finger
Step 3: Person B drops the ruler at a random time and person A has to catch the ruler with their thumb and index finger as quick as possible
Step 4: Person B records the measurement on the ruler which is level with the top of person A's thumb
Step 5: Experiment is repeated and a mean reaction distance is calculated. Results can be converted into reaction times using a conversion table
Step 6: Person A and B switch places with person A now testing the reaction time of person B ( steps 1- 5 repeated )
32
What are some control variables for practical affecting reaction time ?
Starting distance between thumb and index finger should be kept constant
Measurement of reaction distance should always be measured from top of the thumb
Conditions in room should be kept the same ie lighting and background noise
33
What is the role of the cerebral cortex ?
Controls consciousness, intelligence, memory and language
34
What is the role of the cerebellum ?
Controls balance, coordination of movement and muscular activity
35
What is the role of the medula ?
controls unconscious activities such as heart beat and breathing rate
36
What is the role of the hypothalamus ?
It is the regulating centre for temperature and water balance in the body
37
What are the four main areas of the brain ?
Cerebral cortex, cerebellum, medula and hypothalamus
38
What are three methods used to map areas of the brain to their functions ?
CT scans , MRI and EEG scanner
39
What does MRI stand for ?
magnetic resonance imaging
40
How does an MRI scanner work ?
- Magnets in the machine create a strong magnetic field
- scanner then sends radio waves through your body
- When radiowaves are turned off , the scanner picks up energy signals from your body
- energy signals are then used to form pictures/ images of regions of your body
41
What are the advantages of MRI ?
- non invasive ( ie doesn't involve putting a camera inside of you )
- Doesn't use ionising radiation ( high dose of IR can cause cancer)
- Safer than CT scans
42
What are some disadvantages of MRI ?
- You can't have MRI if you have any metal device or implant in your body ie a pacemaker
- scanners can be very noisy
- scanning speed is slow
- patients have to be very still as any slight movement can cause distorted images
43
What does CT stand for ?
Computed tomography scans
44
How does a CT scanner work ?
CT scan combines a series of X-ray images taken from different angles around your body and uses computer processing to create cross-sectional images (slices) of the bones, blood vessels and soft tissues inside your body.
45
What are the advantages of CT scans ?
- fast scanning speed
- Cheaper than MRI
- less stringent about remaining motionless
- non invasive
- relatively quiet
46
What are the disadvantages of CT scans ?
- can cause harm to person due to exposure to ionising radiation
- risk of allergic reaction to contrast material
47
What is a contrast material ?
A Special dye used to highlight areas of the body being examined
48
What does EEG stand for ?
Electroencepthalography
49
How does an EEG scanner work ?
- Works by attaching small sensors all over the scalp to detect electrical signals produced when brain's cells communicate
- highly trained specialists can read the signals to detect unusual activity
50
What are the advantages of an EEG scanner ?
- noiseless
- non invasive technology
- doesn't aggravate claustrophobia
- tolerant of movement
51
What are the disadvantages of an EEG scanner ?
- Poor spatial resolution
- can't be used to detect cancer
- doesn't specify where in the brain activity comes from
52
What can an EEG scanner detect ?
epilepsy, fits and memory problems
53
What is epilepsy ?
Sudden bursts of electrical activity in the brain which can cause seizures/ fits
54
What can an MRI scanner detect ?
cancer cells, blood clots, abnormal blood flow and internal injuries
55
What are three things a CT scanner can do ?
- can be used to diagnose conditions ie damage to bones, strokes, cancer, and abnormal blood flow
- can help determine the location, size and shape of a tumour before having radiotherapy/chemo
- can be used to monitor conditions ie checking tumour size during and after cancer treatment
56
What is a brain implant useful for ?
Helps diagnose and treat a range of brain pathologies ie Parkinson's disease
57
One advantage and disadvantage of brain implant
- Your brain may get damaged in the process
| - It can help your brain function properly again
58
What is brain surgery used for ?
Used to remove as much of a brain tumour as possible
59
What are the disadvantages of a brain surgery ?
- May cause brain damage ie speech, memory loss
| - may cause infection and the possibility of a stroke
60
What is an advantage of brain surgery ?
Can save/prolong a person's life
61
What is the difference between radiotherapy and chemotherapy ?
Radiotherapy uses rays to destroy cancer cells
Chemotherapy uses drugs to destroy cancer cells
62
What is an advantage and disadvantage of using radiotherapy/chemotherapy ?
- Removal of tumour can save lives
| - Risk of normal cells getting damaged in the process
63
What are monoclonal antibodies ?
Identical copies of antibodies that have been made in labs, that are able to bind to cancerous cells and help immune system destroy them
64
What is an advantage and disadvantage of monoclonal antibodies ?
- offers hope in the treatment of cancer/ tumours
| - can cause sore, red skin or an itchy rash
65
What can stem cell therapy do ?
helps in repairing damaged nervous system and produces cancer killing molecules
66
What is an advantage or disadvantage of stem cell therapies ?
- repairs damage to nervous system tissue
| - stem cells may be rejected by the immune system
67
What is neurology ?
A branch of medicine that deals with disorders in the nervous system
68
The eye is a _____ _____ containing ________ sensitive to ______ _______ and ______.
Sense organ
receptors
light intensity
colour
69
What is the retina ?
A light sensitive tissue that lines the back of the eye
70
What are the two light sensitive receptor cells that make up the retina ?
Cones and rods
71
What are cones sensitive to...
Colour
72
What are rods sensitive to...
Light
73
What is the purpose of the retina ?
- To receive light that the lens has focused
| - Convert the light into neural signals and send the signals to brain via the optic nerve
74
What does the iris do ?
It has sets of muscles that control the size of the pupil and regulate the light reaching the retina
75
What happens to the muscles in the iris when there is dim lighting ?
- radial muscles in iris contract
- circular muscles in iris relax
This causes pupil to dilate ( become larger) to allow in more light
76
What happens to the muscles in the iris when there is bright lighting ?
- radial muscles in iris relax
- circular muscles in iris contract
This causes pupil to contract ( become smaller) to allow in less light
77
What is accomodation ?
Process of changing the shape of the lens to focus on near or distant objects
78
What exactly is refraction ?
The bending of light rays as they travel from one medium to another
79
How does the eye create an image ?
Light passes through the cornea and is refracted through pupil onto the lens
As light passes through the lens, it refracts again onto the retina where an image is formed
This double refraction causes the image to turn upside down
The inverted image travels as an impulse along the optic nerve to the brain's occipital lobe. The brain turns the image right side up.
80
What is the cornea ?
Transparent region of the sclera at the front of the eye
81
What is the sclera ?
The tough outer layer of your eye ( the white of your eye)
82
What does the lens do ?
Focuses light rays onto the retina
83
What is the pupil ?
The hole in the centre of the iris that allows light to pass through
84
What do the ciliary muscles and suspensory ligaments do ?
Change the shape of the lens to precisely focus light rays onto the retina
85
What does the optic nerve do ?
Carries impulses from the retina to the brain
86
How does the eye focus on near objects ?
Ciliary muscles contract which causes the suspensory ligaments to loosen
This makes the lens shape thick and round
This causes the light rays to be refracted more strongly, bringing them into perfect focus onto the retina
87
Light from distant objects ... (focus)
Only needs to be focused a small amount ( only a slight refraction of light needed)
88
How does the eye focus on distant objects ?
Ciliary muscles relax which causes suspensory ligaments to be pulled tight
The lens is pulled thin and flat
Because the lens is thin, light rays are only slightly refracted, and light is focused to a point on the retina
89
Light from near objects...
Needs be focused a large amount ( large refraction of light needed)
90
What is myopia ?
Shortsightedness, when people can see objects at short distances but struggle to see objects at a distance
91
Where is the image formed with normal vision ? Why ?
On the back of the retina
Light is correctly refracted by the cornea and lens in the eye
92
Where is the image formed with myopia ? Why ?
In front of the retina
Eyeball is too long or cornea is too sharply curved or lens is too thick
93
Where is the image formed with hyperopia ? Why ?
Behind the retina
Eyeball is too short or cornea isn't curved enough or lens is less elastic ( can't become thick enough to focus on near objects)
94
What is hyperopia ?
When people can see objects at long distances away, but struggle to see near objects
95
How can myopia be treated ?
Wearing glasses with a concave lens ( diverging lens )
This spreads out the light rays from distant objects before it enters the eye, so light can be bought into perfect focus onto the retina
96
How can hyperopia be treated ?
Wearing glasses with a convex lens ( converging lens )
this brings the light rays together more before they reach the eye, so light can be bought to perfect focus on retina
97
What does converging mean ?
Light rays move towards each other
98
What does diverging mean ?
Light rays spread out
99
What are the two techniques for replacing lenses ?
1- Permanent contact lens is implanted in the eye and natural lens is also left in
2- Faulty lens is removed ans artificial lens is implanted
100
What do contact lenses do ?
Carry out the same job as glasses but cannot be seen
101
what is the difference between hard and soft contacts ?
Hard contacts are more durable whereas soft contacts are more flexible and comfortable but not as durable
Both must be kept sterile to avoid infection
102
How can laser eye surgery be used to treat myopia and hyperopia ?
For myopia, lens thickness reduced so cornea refracts light less strongly
For hyperopia, lasers change curve of the cornea so it refracts light from nearer objects more effectively
103
why can laser surgery only be used for adults ?
It can cause damage to developing eyes of children
