Homeostasis Flashcards
(125 cards)
1
Q
What is the definition of homeostasis
A
The regulation of internal conditions in a cell or organism to give optimum conditions for it to function in response to internal and external changes
2
Q
What is it in cells or organisms that needs optimal conditions?
A
Enzymes work best in their optimum conditions, most reactions inside cells and organisms involve enzymes
3
Q
What exactly is controlled during homeostatis in humans?
A
Blood glucose concentration, body temperature and water levels
4
Q
What are the automatic control systems in the body for homeostatis?
A
The nervous system and the endocrine hormonal system
5
Q
What is three parts to all control systems have?
A
Receptor cells, coordination centres and effectors
6
Q
What is a receptor cell?
A
Any cell that can detect changes in the environment. These changes are called stimuli, e.g. chemical receptor cells on the tongue
7
Q
What is a coordination Centre?
A
An area of the body that receives and processes the information from the receptors, e.g. brain, spinal cord and pancreas
8
Q
What is an effector?
A
Effectors cause the responses to happen so that the body is return to optimum level is e.g. muscles and glands
9
Q
What is a neuron?
A
A nerve cell they are quite long and thin, and they can transmit information as electrical pulses
10
Q
What is the CNS?
A
The central nervous system is it made of two parts of the brain and the spinal cord
11
Q
What happens at the CNS?
A
The CNS receives impulses from receptors cells, and then sends impulses out to the effectors.
The effect would be a muscle contracting or a gland secreting hormones.
12
Q
What is the order of the pathway of a reflex arc?
A
Stimuli, receptor, coordinator, effector, response
13
Q
What are the three neurons in the reflex arc?
A
Sensory neuron
relay neuron
motor neuron
14
Q
What is the role of a sensory neuron?
A
Sensory neurons transmit an electrical impulse from the receptor cell to the CNS
15
Q
What is the role of a relay neuron?
A
Relay neurons are found in the CNS, usually in spinal cord, it takes the information from the sensory neuron and passes the information to the motor neuron
16
Q
What is the role of a motor neuron?
A
Motoneurons transmit an electrical impulse from the CNS to the effector, e.g. a muscle or a gland
17
Q
What is a synapse?
A
Synapses a tiny gaps between neurons as electrical signal Compas, across the gap. The information is converted into chemicals called neurotransmitters.
18
Q
How does a neurotransmitters cross a synapse?
A
Neurotransmitters move across a synapse by diffusion. When they reach in the next neuron, they cause a new electrical impulse to be sent.
19
Q
Why does the speed is slow down when an impulse reaches a synapse
A
The electrical impulses much faster than the chemical neurotransmitter, so every synapse slows the speed of the overall reaction
20
Q
Why did reflexes help reduce damage by injury?
A
They are automatic and rapid, so don’t involve the conscious part of the brain. The response is quicker than if the impulse travel to the brain so less damage happens.
21
Q
What sort of factors slowdown reaction times?
A
Alcohol, depressant, drugs, tiredness and dehydration can all slow down the speed of a reaction.
Stimulant drugs can speed up reactions too
22
Q
What is the required practical for reaction times?
A
Measuring how fast am on racks by doing a computer reaction test, or by dropping a ruler and measuring how many centimetres have dropped before they catch it
23
Q
What does the brain do?
A
The brain controls complex behaviour
It can do this because it is made of billions of interconnected neurons
24
Q
What are the main areas of the brain?
A
Cerebral cortex
Cerebellum
Medulla
25
What is the cerebral cortex?
This is the outer layer of the cerebrum and is split into two hemispheres and is highly folded
26
What does the cerebral cortex do?
It controls intelligence, personality, conscious, thoughts and high level functions such as language and verbal memory.
27
What is the cerebellum?
This is an area tucked under the cerebrum.
28
What does the cerebellum do?
Controls balance, coordination of movement and muscular activity.
29
What is the medulla
A small swollen area where the spinal cord meets the brain.
It is the one of the most basic brain areas and is found in many animals
30
What does the medulla do?
It’s controls unconscious activities such as breathing rate and heart rate.
31
How do you neuroscientists identify what different regions of the brain do?
They study patients with brain damage.
They also electrically stimulate different parts of the brain during the MRI scanning to identify where the effects of the brain are seen.
32
Why is it so difficult to investigate and treat brain disorders?
The brain is extremely complex so it’s hard to understand.
Also it is very delicate so it’s easy to damage. It is also very difficult to examine without causing damage.
33
What is the eye?
I sense organ containing light receptor cells. They are sensitive to light intensity and to colour
34
What is the retina?
The retina is a layer inside the back of the eye where the light sensitive receptors cells are found.
35
What is the optic nerve?
The nerve that connects each eye to the brain
electrical signals are sent to the area of the brain that identifies what we are seeing
36
What is the sclera?
The tough white layer the outside of the eye. It prevents the eye from being burst by physical damage.
37
What is the cornea?
The front of the sclera is a clear area to allow light to pass through into the eye. The cornea is the name for this clear zone.
38
What is the iris?
The iris is the colours muscle inside the front of the eye that controls the size of the pupil.
This allows enough light in and prevents damage from too much light entering.
39
What are the ciliary muscles?
These are muscles that control the size and the shape of the lens inside the eye
when they contract the lens is rounder when they are relaxed, the lens is pulled thinner.
40
What are the suspensory ligaments?
These are the connecting tissues between the ciliary muscles and the lens. When they pull on the lens, it is stretched flatter.
41
What is accommodation?
accomodation is the changes in the shape of the lens that allows us to clearly see objects both far away and close up.
If this does not work properly you need spectacles.
42
What happens when we focus on a distant object?
Ciliary muscles relax on the suspensory ligaments are pulled tight. The lens is pulled thin, and light rays are only slightly refracted.
43
What happens when we focus a near object?
Ciliary muscles contract on the suspensory ligaments loosen. The lens is a thicker and light rays are refracted strongly.
44
What is the usual treatment for long sightedness hyperopia?
Long sighted people can see far away objects clearly, but not close-up ones. They need convex lenses to refract the light rays, more so they focus more on the retina when reading.
45
What is the usual treatment for short sightedness myopia?
Short sighted people can see close objects clearly not far away ones.
They need a CONCAVE lenses which reduce the effect of the lens refracting the light ray so they focus on the retina.
46
What are the new technologies that can be used to treat vision defects?
Hard and soft contact lenses, laser surgery to reduce the cave of the cornea and replacing the lenses in the eye if necessary.
47
Which part of the brain controls body temperature?
A region called the thermoregulatory centre which is in the hypothalamus just above the medulla.
48
If the skin temperature receptors detect a change, what happens?
Skin temperature receptors send impulses to the thermoregulatory centre, so that a response to be coordinated.
49
Where are the temperature receptor cells in the body?
In the skin, detecting changes in the blood temperature of the surface and also in the thermorgulayory center, detecting changes in the blood temperature in the brain.
50
How to sweating help us to transfer more heat energy to our surroundings
It takes a lot of energy to evaporate water, so when we put sweat into our skin (made in the sweat glands), it transfers our body heat when the water evaporates. we get cooler.
51
If the body temperature is too high what happens?
Vasodilation and sweating help to transfer the heat energy from the body to our surroundings.
52
If the body temperature is too low, what happens?
Vasoconstriction and shivering
Vasoconstriction reduces the amount of heat energy being lost
shivering generates more heat as cells respire also sweating stops.
53
What blood vessels alter diameter during vasoconstriction/dilation?
The artery supplying blood to the capillaries in the skin get wider or narrower.
This changes the amount of blood reaching the skin and alters the amount of heat transferred.
54
What is the endocrine system?
The system of glands that releases the hormones directly into the bloodstream. This leads to slower responses than the nervous system, but the effects last for longer.
55
What is a hormone?
A chemical that travels in the blood to a target organ where it produces an effect.
56
What is a target organ?
The organ of the body where the chemical hormone will have an effect. each hormone has its own target organ.
57
Why is the pituitary gland so important?
The pituitary gland is a master gland it produces several different hormones that can then make other glands produce hormones to which cause effects.
58
Which glands do I need to know/label for GCSE?
Pituitary gland
Pancreas
Thyroid
Adrenal gland
Ovaries
Testes
All these are glands, even though they don’t all have a gland in their name
59
Which hormonal controls do I need to know for GCSE?
The control of blood glucose levels and the control of the human reproductive system (including how we develop contraceptives)
60
What does the pancreas do?
It monitors and controls blood glucose levels
61
What are the hormones produced by the pancreas?
Insulin (when blood glucose is too high)
Glucagon (when blood glucose is too low, remember you produce glucagon when your glucose is gone)
62
When is insulin produced?
When the levels of glucose in the blood are higher than they should be, the pancreas produces insulin
63
What does glucagon do?
Glucagon travels in the bloodstream and causes glycogen stores to be converted back to glucose, which is then released back into the blood.
64
What does insulin do?
Insulin travels in the bloodstream to the liver, its target organ.
which causes liver and muscle cells to take in glucose and convert it to glycogen storage.
65
What is the negative feedback in blood glucose control?
The pancreas is constantly monitoring the glucose levels in the blood, and the two hormones, insulin and glucagon are constantly causing their own in inhibition.
66
What is diabetes?
At disorder where the blood glucose levels are not properly controlled. there are two types of diabetes
67
What is type one diabetes?
A disorder where the pancreas does not produce sufficient insulin - blood glucose levels can get extremely high
68
How is type one diabetes treated?
Regular insulin injections and careful diet control are needed to treat type one diabetes
69
What is type two diabetes?
A disorder where liver and muscle cells no longer respond to insulin produced by the pancreas. Obesity increases the risk of developing type two diabetes.
70
How is type two diabetes treated?
Exercise and careful diet control with limited carbohydrates are usual treatments. Some patients need tablets or injections as well as this
71
When do people get diabetes?
Type one is usually diagnosed in childhood, Type two occurs in older people who have become obese
72
What is the problem of too much or too little osmosis occurs?
If cells gain or lose too much water by osmosis those cells no longer work efficiently
73
How does water leave the body from the lungs?
When we exhale, the air has more water vapour in the air than we inhale
as we breathe out some of the water made during respiration.
74
What substances are lost from the skin when we sweat?
Water mineral irons and urea are lost when we sweat
75
What substances are lost in urine?
Excess water excess ions and urea are lost when the kidneys produce urine.
76
Which of these losses can be controlled by the body?
Losses of water and ions in the urine can be controlled, but losses by lungs and skin (Sweat)cannot be controlled.
77
What is urea?
Urea is formed from the breakdown of excess amnio acids in the liver
78
How does the liver make urea?
The liver deaminates access amnio acids to form ammonia. As ammonia is toxic, it is converted immediately to urea which is safer to excrete.
79
Where does the urea go after it leaves the liver?
Urea is removed by diffusing from liver cells into the bloodstream
80
What is the function of the kidneys?
Kidneys filter the blood to remove wastes and excess water ions.
They produce urea and maintain water balance of the body.
81
How do you kidneys remove waste from the blood?
Firstly, the kidneys carry out ultrafiltration. All small molecules are removed from the blood. The kidneys, then selectively reabsorb useful substances back into the blood
82
Why are some substances selectively reabsorbed?
Some substances are small enough to be ultrafiltrate is out of the blood. But are not wastes, so they need to be reabsorbed back into the blood.
83
What substances are selectively reabsorbed?
Glucose some mineral ions, and some water will be re-absorbed into the blood
84
What is ADH?
Anti diuretic hormone produced by the pituitary gland, and acts on the kidney tubule cells.
85
What does ADH do??
The more ADH that is released by the pituitary gland , The more water is reabsorbed back into the blood. This is very useful if a person is becoming dehydrated.
86
How does urine change when ADH levels are too high? “
Urine becomes more concentrated more deep yellow and the volume decrease as lots of ADH is released. This is because only little water entered the urine.
87
How does urine change when ADH levels are low?
urine becomes less concentrated pale yellow and the volume increases when little ADH is released.
This is because lots of water entered the urine (little was reabsorbed)
88
What controls the level of ADH and the amount of water reabsorbed?
Negative feedback mechanisms ensure that the correct amount of ADH is released, and the body stays hydrated. Osmosis remains in balance because of this.
89
What happens if the kidneys do not work
If the kidneys are permanently damaged an organ transplants is necessary. Patients waiting for a suitable donor can be given kidney dialysis to keep them alive.
90
What is kidney dialysis?
A machine that filters out the waste from the blood if the kidneys are not working
91
How does dialysis work?
Dialysis fluid has the same concentrations as cleaned blood. Diffusion and osmosis cause urea, excess ions and water to be removed from the blood.
92
Can dialysis be used instead of a transplant?
No, a person can only be on dialysis temporarily and will eventually need a transplant. Dialysis is usually done every three days for several hours - often an overnight
93
What are the hormones in the human reproductive system?
Testosterone in men
Oestrogen progesterone, follicle stimulating hormone (FSH) and luteinising hormone LH in women .
94
When did humans start making reproductive hormones?
During puberty, and they cause secondary sex characteristics to develop (breasts, pubic hair etc)
95
What does testosterone do?
It causes men to produce sperm. Sperm production starts during puberty.
96
What is the menstrual cycle?
The development and the release of an egg cell. Plus the development of the uterus lining each month
97
What is ovulation?
The release of an egg from the ovary
98
What does FSH do?
FSH is released from the pituitary gland and causes one egg cell to mature inside the ovary
99
What does LH do?
LH is released from the pituitary glands and causes the mature egg cell to be released
Triggers ovulation
100
What do oestrogen and progesterone to?
Oestrogen (produced by the ovaries) progesterone (produced by uterus) are involved in maintaining the uterus lining (ready for an embryo develop and grow)
101
What order are the menstrual cycle hormones released in?
FSH (from the pituitary) causes production of oestrogen
Oestrogen from the ovary causes FSH production to stop, and LH production to start
LH from the pituitary gland causes egg release
102
When should LH levels be highest?
LH levels will be highest when ovulation occurs
103
What is a contraceptive?
Any method that reduces the chance of a female becoming pregnant
104
What are the non hormonal methods of contraception?
Barrier methods (condoms and diaphragms)
Spermicides
Intra-uterine devices
Abstaining
Surgeries to sterilise the male or the female.
105
What are the hormonal methods of contraception?
Oral contraceptives (these inhibit FSH production, so no egg matures)
106
How do hormones help treat infertility?
Fertility drugs contain FSH and/or LH, which make the woman produce a mature egg. She can then become pregnant naturally.
107
How are hormones used an IVF treatment?
Women are given high doses of FSH and LH, so several eggs mature at the same time
108
How does IVF work once the eggs are mature?
These eggs are collected from the mother and fertilised by the fathers sperm in the lab.
they develop into embryos, and can be inserted back into the mothers uterus
109
What are the benefits of IVF treatment and fertility drugs?
The woman and the man have a chance to have a baby
110
What are the negatives of IVF treatment?
It is emotionally and physically challenging
Success rate are not high
It can lead to multiple births which are high risk for both mother and baby
111
Where is adrenaline produced and when do we, produce it?
Adrenaline is produced by the adrenal glands, when we are stressed, or in times of fear
112
What does adrenaline do in the body?
Adrenaline increases the heart rate and boosts the supply of oxygen and glucose to the brain and to the muscles, preparing the body for ‘fight or flight’
113
Where is thyroxine produced?
Thyroxine is produced by the thyroid gland
114
What does thyroxine do in the body?
Thyroxine stimulates basal metabolic rate (how fast reactions happen in the body) and also plays an important role for growth and development
115
What is the negative feedback in thyroxine control?
Thyroxine levels are controlled by negative feedback, too much thyroxine produced will slow down the production of more thyroxine
116
Why do plants produce chemical hormones?
Plants need to coordinate and control their growth and responses to light and gravity. hormones in plants either stimulate or inhibit growth
117
What are plants growth responses called?
Tropisms, they can be positive (growth towards a stimulus) or negative (grow away from the stimulus)
118
What is the response to light called?
Phototropism
119
What is the response to gravity called?
Geotropism or gravitropism
120
What is auxin?
The plant growth hormone found in roots and shoots
Unequal distribution of auxin will cause unequal growth rates.
121
What can auxins be used for in agriculture and horticulture?
Auxins can be used as…
weedkillers
rooting powder
and to promote growth in tissue culture (artificially grown plant pot in a petri dish)
122
What is gibberellin?
The plant hormone responsible for making seeds begin to germinate
123
What can gibberellins be used for in agriculture and horticulture?
Gibberellins can be used to promote flowering increase fruit size and end seed dormancy, so they start to germinate
124
What is ethene?
The plant hormone that controls cell division, mitosis and ripening of fruits
125
What can ethene be used for in the food industry?
Ethene is used to control fruit ripening during storage and transport so that fruit stays fresh until it reaches the supermarket shelves
