Topic 5 - Homeostasis and response Flashcards
1
Q
What is homeostasis
A
The regulation of internal conditions in your body and cells to maintain an optimum conditions for function in response to internal and external changes
2
Q
What are the three main components of your automatic controls systems
A
receptor (cells), coordination centre and the effectors
3
Q
Why do the internal conditions of your body need to be regulated
A
To maintain the right conditions for cells to function properly and for enzyme action
4
Q
Name the component of a control system which detects the stimuli
A
Receptor (cell)
5
Q
Outline the stages in the negative feedback mechanism when blood pressure becomes too high
A
The receptor detects the blood pressure is too high and sends a signal to the coordination centre, the CC processes the info and organises a response/stimulates the effector. The effector produces a response to bring the blood pressure back down
6
Q
What part of the nervous system do the brain and spinal cord form
A
The central nervous system (CNS)
7
Q
What is the job of the CNS
A
It receives info from the receptors and coordinates a response to be carried out by an effector
8
Q
What is the function of the nervous system
A
It allows organisms to react to their surroundings and coordinate their behaviour based on it
9
Q
What are the two main neurones outside the CNS
A
Sensory neurone and Motor Neurone
10
Q
Name two effectors and how they respond to changes in the environment
A
Muscles - contract
Glands - secrete hormones
11
Q
What is the function of a receptor
A
To detect a stimuli
12
Q
What is the connection between 2 neurones called
A
A synapse
13
Q
What is the nerve signals between 2 synapses transferred by
A
Chemicals, known as neurotransmitters, which diffuse between the gap
14
Q
What causes the neurotransmitters to be released
A
The action potential (Electrical signal)
15
Q
State the steps of a reflex action
A
electrical impulses come from the receptor along the sensory neurone. It then travels through the relay neurone. Lastly, it travels through the motor neurone and then to the effector
16
Q
Name parts of the brain and what they do
A
Cerebral Cortex - Outer wrinkly bit. It’s responsible for things like consciousness, intelligence, memory and language
Medulla - Controls unconscious activities like breathing, heart rate and blood pressure
Cerebellum - Responsible for muscle coordination
Hypothalamus - Controls body temp/homeostasis
Pituitary Gland - Stimulates/inhibits hormone production
17
Q
What part of the CNS controls reflex reactions
A
The spine, the actions are unconscious
18
Q
Name all the parts of the eye (there are 9)
A
1 - Sclera 2 - Retina 3 - Cornea 4 - pupil 5 - iris 6 - lens 7 - suspensory ligaments 8 - ciliary muscle 9 - optic nerve
19
Q
What is the function of the sclera?
A
It’s the tough, supporting wall of the eye
20
Q
What is the function of the retina?
A
It has light receptors on it, sensitive to light intensity and colour, which send signals to the optic nerve which sends signals to the brain
21
Q
What is the function of the cornea?
A
a transparent outer layer of the eye which refracts light into the eye
22
Q
What is the function of the lens?
A
It focuses light on the retina
23
Q
What is the function of the optic nerve?
A
It receives signals from the receptors on the retina and sends them to the brain
24
Q
What are the function of the ciliary muscles and suspensory ligaments?
A
to change/adjust the shape of the lens
25
What is the function of the iris?
Changes shape depending on how much light is detected as the brain contracts muscles contained in the iris
26
What is accommodation?
The ability to change the shape of the lens to focus on near or distant objects
27
What happens to your eyes when focusing on near objects?
The ciliary muscles contract and the suspensory ligaments relax making the lens fatter and more curved which refracts light stronger
28
What happens to your eyes when focusing on distant objects?
The ciliary muscles relax and the suspensory ligaments contracts making the lens thinner and less curved which refracts light only a little bit
29
What causes long-sightedness (hyperopia) ?
The lens is too thin so the light isn't refracted enough to hit the retina or the eyeball is too short and focuses the light behind the retina. In the elderly, this can be caused because the lens becomes elastic and is unable to be thick enough to focus on near objects
30
How can you correct long-sightedness (hyperopia)?
By placing a convex lens in front of the eye as these partially focus the light before it enters the eye
31
What causes short-sightedness (myopia)?
The lens is too fat and curved so the light is refracted too much or the eyeball is too long and focuses the light in front of the retina.
32
How can you correct short-sightedness (myopia)?
By placing a concave lens in front of the eye to bend the light so it hits the retina by partially unfocusing it before it enters the eye
33
What are the three alternatives to using glasses?
- contact lenses
- laser eye surgery
- replacement lens surgery
34
Why is homeostasis important for your body?
It maintains the right conditions for your cells to function and for enzyme action
35
What part of the homeostasis control system detects the stimuli?
the receptor
36
What is the function of the nervous system in humans?
Allows organisms to react to their surroundings and coordinate a response
37
Name the two main types of neurones outside of the CNS
Sensory neurone
| motor neurone
38
Name the two types of effectors and how they respond to nervous impulses
muscle - contracts
| glands - secretes hormones
39
Name the type of cell which makes up most of the brain's material
neurones
40
Which region of the brain controls the unconscious activities?
the medulla
41
Which region of the brain controls things like intelligence, language and memory?
the Cerebral cortex
42
What does the cerebral cortex control?
Intelligence, memory and language
43
What does the medulla control?
the unconscious activities
44
What does the cerebellum control?
Muscle coordination
45
Suggest two reasons why it's difficult to investigate treatments for brain diseases
the brain is complex
| the brain is delicate
46
State three ways scientists map regions of the brain to their function
MRI's
Studying patients with brain damage
Electrically stimulating the brain
47
Why is changing the size of the pupil in the eye important?
so that the amount of light entering the eye can be controlled so not too much light enters an damages the eye or lots do so the person can see
48
How do the spectacle lens' correct the sight of a person?
They refract light rays so it focuses on the retina
49
Where is the thermoregulatory centre located?
in the brain
50
What are the receptors in the thermoregulatory centre used to monitor?
The temp of the blood flowing through the brain and the temp of the skin
51
How does the thermoregulatory centre receive info about the temp of the body?
the skin has receptors in them which send impulses to the brain when it gets too hot
52
What responses does your body carry out when it gets too hot?
vasodilation - the blood vessels of your skin capillaries dilate so more blood flows to the capillaries near the surface of your skin so more energy is released into the surroundings
Sweating - sweat, produced by your sweat glands, evaporate and carry energy with it
53
What responses does your body carry out when it gets too cold?
vasoconstriction - the blood vessels of your skin capillaries constrict so less blood flows to the capillaries near the surface of your skin so less energy is lost to the surroundings
Shivering - your skeletal muscles contract which requires respiration to generate energy which releases heat to warm the body
We stop sweating
54
What hormones do the ovaries secrete and what is their function?
Oestrogen and progesterone which are involved in the menstrual cycle
55
What hormone does the thyroid gland secrete and what is its function?
Thyroxine - regulates the rate of metabolism, heart rate and temp
56
What hormone do the testes secrete and what is its function?
Testosterone - controls puberty and sperm production
57
What hormone does the adrenal gland secrete and what is its function?
Adrenaline - to prepare the body for 'fight or flight' response
58
Which gland controls the rate of metabolism, heart rate and temperature?
The thyroid gland
59
What are the key differences between hormones and nerves?
Hormones are slower
Hormones act for longer
Hormones don't really target a specific area of the body
60
Which two hormones are involved in controlling your blood glucose levels?
Insulin
| Glucagon
61
How does your body control your blood glucose levels when it gets too high?
You eat carbohydrate-rich foods which increase BG levels
Your brain detects this and the pancreas secretes insulin
This insulin travels with the glucose in the bloodstream
It tells the liver to store the excess glucose into glycogen
Your blood glucose levels return to normal
62
How does your body control your blood glucose levels when it gets too low?
You don't eat enough carbohydrate-rich foods which decrease BG levels
Your brain detects this and the pancreas secretes glucagon
This glucagon travels with the glucose in the bloodstream
It tells the liver to turn the stored glycogen back into glucose and release it into the bloodstream
Your blood glucose levels return to normal
63
What is type 1 diabetes?
When a person's pancreas can't produce enough insulin for their BG levels to drop to normal and can kill them.
64
What can people with type 1 diabetes do to keep themselves alive?
go through insulin therapy where they inject themselves with insulin throughout the day near the time of a meal to ensure the glucose is removed from the blood so the BG levels don't get too high
These people can also eat less carb-rich foods or exercise more often
65
What is type 2 diabetes?
When a person becomes resistant to their own insulin, meaning their body cells don't respond to it, so their blood glucose levels rise to a fatal level
66
What can help people with type 2 diabetes?
Eating less carb-rich foods and exercising more often
| Obesity can increase your chances of developing type 2 diabetes
67
What is the job of your kidneys?
The kidneys produce urine by taking the waste products out of your blood
68
How does filtration in the kidneys work?
substances are filtered out of the blood and through the kidneys. Useful substances - water, ions, glucose - are absorbed back into the blood through the process of selective reabsorption. The substances are removed from the body as urine
69
How is ammonia filtered out of the blood?
Proteins are broken down, by the liver through deamination, into amino acids which are converted into fats and carbs. This process releases ammonia which is toxic so is converted into urea and is filtered out and excreted as urine
70
How are ions filtered out of the blood?
Ions such as sodium are taken in through food and absorbed into the blood. if the ion/water content is wrong it could upset the balance meaning too much/little water is drawn into the cells by osmosis which can damage the cells and cause them not to work anymore. Some ions are lost in sweat, but this isn't regulated, so your kidney filters out the right amount and the blood reabsorbs any needed
71
How is water filtered out of the blood?
We lose water from our skin in sweat and lungs through breathing. We can't control this so the right amount is filtered out by the kidney and some are reabsorbed back into the blood
72
How is the concentration of urine controlled?
If there is too much water detected in the blood less ADH is secreted by the pituitary gland which means less water will be reabsorbed into the bloodstream after it has been filtered. This makes the urine more concentrated
If there is too little water detected in the blood a hormone called ADH is secreted by the pituitary gland which means more water will be reabsorbed into the bloodstream after it has been filtered. This makes the urine less concentrated
73
How do neurotransmitters move?
When the electrical impulse reaches the end of the neurone, chemicals called neurotransmitters are released. The chemicals diffuse across the synapse and bind to receptors on the next neurone
74
Can neuroscience help people with Parkinson's disease?
Since the nervous system communicates using electrical impulses, electrical stimulation can be used to help treat Parkinson’s disease.
75
What happens to your eyes when there is a change in light intensity?
The iris relaxes and the radial muscles contract causing the pupil to dilate when there's low levels of light and vice versa when there are high levels of light.
76
What happens to your body at puberty?
It starts releasing sex hormones which trigger secondary sexual characteristics e.g facial hair or breasts growing
77
What is the main reproductive hormone in women?
oestrogen
78
What are the four stages of the menstrual cycle?
Stage 1 - menstruation starts and the uterus lining breaks down for four days
Stage 2 - uterus lining builds up again from day 4-14 into a thick spongy layer full of blood vessels ready to receive an egg
Stage 3 - and egg develops and is released from the ovary on day 14 (ovulation)
Stage 4 - the wall is maintained from 14-28 says and breaks down if no fertilised egg has landed on the uterus wall by then. Layer breaks down and the cycle starts again
79
What hormones are involved in the menstrual cycle and how?
1) FSH - secreted by the pituitary gland and causes the egg to mature in one of the ovaries in a follicle. Stimulates oestrogen production
2) Oestrogen -secreted by the ovaries and causes the lining of the uterus to grow. Stimulates LH and inhibits FSH
3) LH - secreted by the pituitary gland and causes the release of an egg at day 14
4) Progesterone - produced in the ovaries by the remains of the follicle after ovulation and maintains the lining of the uterus until the level of P falls and the lining breaks down. Inhibits release of FSH and LH
80
How can oestrogen be used as a form of contraception?
if taken every day to keep the levels of oestrogen high it can prevent the release of an egg as it inhibits the production of FSH which would release a mature egg
81
How can progesterone be used as a form of contraception?
It can be taken to stimulate the production of thick mucus in the uterus which prevents any sperm from getting through and reaching an egg
82
What does 'the pill' consist of and what are two side effects of it?
contains both oestrogen and progesterone and is 99% effective at preventing pregnancies but can cause side effects e.g nausea, and headaches. Also, it doesn't protect against STD's
83
Why might the progesterone-only pill be considered to be better than 'the pill'?
because it causes less side effects but is just as effective
84
Explain the 'flight or flight' response
Your brain detects danger/fear and sends nervous impulses to the adrenal gland where adrenaline is secreted triggering an increase in the production of oxygen and glucose to the cells in the brain and muscles
85
Other than metabolic rate, what does thyroxine control?
protein synthesis for growth and development
86
Where in the plant is auxin produced?
In the tips and shoots of the plant
87
What does auxin control in a plant?
The growth of a plant in response to light and gravity
88
What would happen if the tip of a shoot is removed?
As auxin is produced in the tips of the shoot no auxin would be available and the shoot may stop growing
89
How does cell elongation work?
Auxin in the tips moves backwards to stimulate cell elongation which occurs the cells behind the tips
90
What happens to the amount of auxin when a shoot tip is exposed to the light?
More auxin accumulates in the shaded side than the side exposed to light which makes the cells grow faster on that side and cause the shoot to bend towards the light
91
What happens to the auxins when a shoot grows sideways?
gravity produces an unequal distribution of auxin in the tip with more on the lower side which causes it to grow faster and bend towards the light
92
What happens to the auxins when a root grows sideways?
the root will always have more auxin on the lower side which inhibits the growth meaning the cells on top elongate faster and the root bends downwards
93
Describe the Plant Growth investigation
Investigate: EFFECT OF LIGHT ON THE GROWTH OF CRESS
1) you place 10 cress seeds into 3 different labelled Petri dishes with moist filter paper in it
2) Shine a light onto one of the dishes from above and the others from different directions
3) leave your cress seeds for one week until observations can be made
4) results should show that the cress bends towards the direction of light
5) you will know its light that affects the direction of growth if other factors are controlled e.g temp, water, light intensity and the number and type of seeds
