Homeostasis - Chapter 11 Flashcards
1
Q
What is homeostasis?
A
The maintenance of constant internal conditions.
This is important as the enzymes in our body work best in these conditions.
2
Q
What are receptors?
A
They detect stimuli in internal and external environments
3
Q
What is a stimulus?
A
A change in the environment
4
Q
What is the coordination centre?
A
Areas that receive and process the information then send out signals and coordinate body response.
This includes brain, spinal cord, and some organs like pancreas.
5
Q
What is an effector
A
A muscle or a gland that produces responses to restore internal conditions.
6
Q
What happens in the nervous system?
A
- Receptor detects stimuli - information is sent to the CNS via the sensory neuron
- Electrical impulse travels to the CNS to the relay neuron where it coordinates a response
- CNS passes this information using impulses via the motor neurons which go to the effector
- The effector - muscle or gland - responds by contracting (muscle), or secreting a hormone (glands)
7
Q
What is the flow chart for what happens in the nervous system?
A
Receptor –> sensory neurone –> CNS (relay neurone) –> motor neurone –> effector
8
Q
2 ways reaction time can be measured?
A
- use ruler drop test
- Investigate different factors that affect reaction time such as talking on the phone, listening to music, drinking cola.
9
Q
What are reflexes?
A
Automatic, unconscious responses.
Reflexes bypass the conscious part of the CNS.
10
Q
Reflex Arc Flowchart
A
Receptor –> sensory –> CNS –> relay (in the spinal cord) –> motor –> effector
11
Q
You realise you have had a reflex after it happens. How?
A
An impulse travels up the spinal cord to the conscious part of the brain so you know the reflex has occurred, but only after it’s happened.
12
Q
What is the 2 things that protect the brain?
A
- The skull
- It is encased in protective membranes called the meninges
13
Q
What disease occurs when the meninges get infected?
A
Meningitis
14
Q
4 different parts of the brain.
A
Cerebral Cortex
Cerebellum
Medulla
Hypothalamus
15
Q
What does the cerebral cortex control?
A
Consciousness, intelligence, memory and language.
16
Q
What does the cerebellum do?
A
Coordinates muscular activity and balance (think of Trisha tiptoeing to ring the koyil bell)
17
Q
What does the medulla do?
A
Unconscious activities –> breathing, heartbeat, movements of the gut
18
Q
What does hypothalamus do?
A
Controls body temperature, and has the pituitary gland which produces many hormones
19
Q
How do we learn about the brain?
A
- MRI Scans (magnetic resonance imaging)
- Comparing a injured person’s brain to a normal brain to see the differences and their possible effects.
20
Q
Go label an nerve cell
A
Well done
21
Q
What is an eye?
A
A sense organ, which contains many receptors that are sensitive to light intensity and colour.
22
Q
9 structures of eye.
A
- Lens
- Cornea
- Pupil
- Iris
- Suspensory ligament
- Ciliary muscles
- Retina
- Sclera
- Optic Nerve
23
Q
What is the sclera?
A
- The white outer layer of the eye
- Relatively tough and strong, to avoid damage to the eye
- Sclera=Safety
24
Q
What is the cornea?
A
- Transparent area at the front of eyeball.
- Allows light into the eye.
- Has curved surface, which is important for changing the direction of light rays coming into the eye.
- It makes sure that light rays which enter the eye are focused on the retina.
25
What is the iris?
- Controls the size of the pupil
- Made up of muscles that contract or relax to change the size of the pupil.
- Control the amount of light reaching the retina.
26
What is the pupil?
The pupil is the opening at the centre of the iris through which light passes.
27
What happens in bright light?
- Pupil constricts ( gets smaller)
- Circular muscles contract
- Radial muscles relax
BRIGHT LIGHT =PC CC RR
28
What happens in dim light?
- Pupils dilate ( get bigger)
- Circle muscles relax
- Radial muscles contract
DIM LIGHT = PD CR RC
29
What happens in the lens?
- Changes the direction of light rays to produce a clear image
30
What is the lens held in place by?
- Suspensory ligament
- Ciliary muscles
31
What happens when light rays hit the retina?
- Light sensitive cells are stimulated.
- They send impulses to the brain, along the sensory neurones in the optic nerve.
- When the brain receives these messages, it interprets them as a visual image.
32
What happens if light is focused behind or in front of the retina?
The image becomes blurry.
33
How does light get focused?
- Light is focused by refractions, where it changes directions are it passes through the eye.
- The cornea changes the direction of the light rays onto the retina.
34
What is the process of accommodation?
- The process of changing the shape of the lens of the eye, to focus on near/distant objects.
35
How can you focus on close object?
- Ciliary muscles contract.
- Suspensory ligaments loosen.
- Lens becomes thicker.
36
What happens to focus on distant objects?
- Ciliary muscles relax
- Suspensory ligament contract
- Lens become thinner.
37
What is a myopia?
- Short sightedness
- Distant objects look blurred.
- Caused because light is focused in
front of the retina.
38
What is hyperopia?
- Long sightedness
- Close-by objects are blurry
- Caused because light is focused
behind the retina.
39
What can myopia be treated with?
Concave lens glasses
40
What can hyperopia glasses be treated with?
Convex glasses
41
What other ways are there to treat eye defects?
- Glasses
- Hard and Soft contact lenses
- Laser surgery
- Replacement lenses in the eye
42
Go label an eye
Well done
43
What is the endocrine system?
The hormone system
44
What are hormones?
chemical messengers (they are also a protein)
45
What is the endocrine system made up of?
glands that secrete hormones directly into the bloodstream
46
What does the blood do to the hormones?
The blood takes the hormones to their target organs/cells where it binds to receptors to produce a response
47
Difference between nervous system responses and hormonal responses?
Hormones can act rapidly, but are a lot slower compared to the nervous system. However hormones have a longer lasting effect
48
What are examples of rapid hormones?
Insulin and adrenaline
49
Examples of slow hormones?
Growth hormones and sex hormones
50
What are all endocrine glands controlled by?
the pituitary gland
51
What is TSH?
Thyroid stimulating hormone --> this hormone stimulates the thyroid gland to release thyroxine, a hormone that is involved in metabloic activity
52
What is glucose?
a sugar used in respiration
53
what is glycogen?
the storage form of excess glucose - can be found in the liver and muscle
54
what is glucagon?
(glucose is gone, glucagon) a hormone that stimulates the conversion of glycogen into glucose
55
where are hormones insulin and glucagon produced?
in the pancreas
56
what does the pancreas do?
The pancreas continuous monitors and controls blood glucose concentration using negative feedback
57
what happens when blood glucose levels get too high?
1. Insulin is secreted -->
2. Insulin allows glucose to move from the blood into cells, where:
3. either, it is used in respiration OR -->
4. insulin stimulates the conversion of excess glucose into glycogen
- When the glycogen stores in our body are full, glucose is converted to and stored as lipids
58
What is Type 1 Diabetes?
when the pancreas doesn't produce enough/any insulin and blood glucose concentration is not controlled. It has a genetic element, and it usually starts in children and teens.
59
what is type 2 diabetes?
when your body cells stop responding properly to insulin
- This disease is linked heavily with obesity and lack of exercise
60
Not having insulin is a problem because
1. glucose cannot get into your cells --> so you lack energy and feel tired
2. Your body breaks down fats and proteins for respiration instead, so you lose weight
61
How is type 1 diabetes treated?
Insulin is injected
Pancreas transplants can cure type one diabetes, however there are not enough pancreas donors, and patients will just be exchanging one medicine for another - after an organ transplant patients take immunosuppressants so that the body does not reject and attack the new organ
62
Why is insulin an injection and not oral?
Insulin is a protein, so if taken orally, the enzymes in the stomach might break this down
63
For type 2 diabetes, many people can restore their glucose balance by:
1. eating a balanced diet with a healthy amount of carbohydrates
2. losing weight
3. doing exercise
Alternatively there are drugs that:
1. help insulin work better on the body cells
2. help the panceras make more insulin
3. reduce the amount of glucose you absorb from your gut
- A last resort for type 2 diabetics is insulin injections
64
Who does type 2 diabetes tend to affect?
older people more, but younger are starting to get it due to being overweight.
65
What is negative feedback?
They maintain a steady state
The response in a negative feedback system normally causes the opposite of the initial change
66
where is the thyroid gland found?
neck
67
what does the thyroid gland use from our diet and what does it produce?
The thyroid gland in the neck uses iodide from our diet to produce the hormone thyroxine
68
What does thyroxine control?
The basal metabolic rate--> how quickly substances are broken down/built up, how much oxygen tissues use, how the brain of a growing child develops
69
How does the thyroxine levels remain stable in adults?
due to negative feedback control of the pituitary gland producing TSH (Thyroid Stimulating Hormone)
70
what occurs when we are stressed/angry/excited/frightened?
the adrenal glands (on top of kidneys) secrets lots of adrenaline which affects lots of organs
71
what does adrenaline cause?
Adrenaline causes:
1. heart rate and breathing rate to increase
2. glycogen in the liver is converted to glucose for respiration
3. the pupils of your eyes dilate to let in more light
4. your mental awareness to increase
5. blood to be directed away from digestive system and towards big muscles of the limbs.
72
B 11.5 - Human Reproduction
New Topic
73
What are primary sexual characteristics?
Sexual characteristics you are born with.
Boys - testes
Girls - ovaries
74
What is oestrogen?
- The main female reproductive hormone
- Produced in the ovaries
- Rising oestrogen levels trigger the development of secondary sexual characteristics.
75
Main changes caused by puberty
Female -
- growth spurt
- pubic hair
- development of breast
- fat deposited on hips and thighs
- menstruation begins
- uterus grows
- brain changes and matures.
Male-
- growth spurt
- pubic hair
- deepening of voice
- facial hair grows
- shoulders and chest broadens
76
How long is the menstruation cycle?
28 days
77
What is ovulation?
The releasing of an egg
78
Give a small overview on the menstrual cycle.
1. egg begins to mature and uterus produces a thickened lining ready for a pregnancy
2. on the 14th day, an egg is released, to be fertilised.
3. If the egg is not fertilised in the next 14 days, the lining of uterus begins to break down and the girl gets her period.
79
What are the four hormones involved in the menstrual cycle?
FSH
LH
Oestrogen
Progesterone
80
What does FSH do?
- Follicles stimulating hormone
- Causes the eggs in ovaries to mature
- Stimulates production of oestrogen
- Secreted by the pituitary gland
81
What does LH do?
- Luteinising hormone
- Stimulates the release of the egg at ovulation
- Secreted in the pituitary gland
82
What does oestrogen do?
- Builds up and thickens the lining of your uterus to prepare for a pregnancy.
- Inhibits production of FSH
- Stimulates release of LH
- Secreted in the pituitary glands.
83
What does progesterone do?
- Maintains the lining of the uterus
- Inhibits production of FSH and LH
84
Draw the graphs, which show the changing levels of the female hormones at different stages of the menstrual cycle
Well done !!
85
Problem with woman having a child close to menopause?
- The woman is less fertile
- The child has a higher risk of having genetic problems.
86
What is the main male reproductive hormone?
Testosterone
87
Function of the lining of the uterus
- Provides protection and food for the developing embryo
88
What are oral contraceptives (contraceptive pills) used for?
To prevent pregnancy
89
What does the contraceptive pill contain?
Low doses of oestrogen, and some progesterone.
- This will inhibit the production + releasing of FSH ( in the pituitary glands).
- This results in no eggs maturing, and no pregnancy.
- The pill also stops the uterus line developing.
- It also makes the mucus thick in the cervix, to prevent sperm from entering.
90
Side effects/Disadvantages of contraceptive pill?
- Raised blood pressure
- Breast cancer
- Thrombosis
91
What do some contraceptive pills only contain?
Progesterone
92
Advantages of taking progesterone- only contraceptive pills?
- Fewer side effects
93
Disadvantages of taking progesterone-only contraceptive pills?
- The pill will have to be taken everyday. If not, the artificial hormone will drop in level in the body and cannot try to stop the release of an egg. So, this can still result in an unexpected pregnancy.
94
What are other ways to deliver hormones into the body to prevent pregnancy? ( Hormone-based contraception)
- A contraceptive implant ( lasts 3 years)
- Contraceptive injection ( lasts 12 weeks)
- Contraceptive patch ( lasts 7 days)
95
What are the chemical methods to prevent a pregnancy?
- Spermicide - kill/disable the sperms ( not very effective at preventing pregnancy.)
96
What are barrier methods to prevent a pregnancy?
- A condom - prevents egg and sperm from meeting
No side effects. Can easily be damaged and still cause a pregnancy.
97
What are intrauterine devices?
- small structures inserted into the uterus and last for 3-5 years
98
What is abstinence?
Avoiding having sex to avoid becoming pregnant.
99
What are the surgical methods to avoid becoming pregnant?
- Sterilisation - where in men, sperm duct is cut and tied and in women, oviduct is cut and tied
100
What causes infertility?
- Lack of female and/or male hormones
- Damaged oviducts
101
Common non-hormonal related reasons for infertility?
- Obesity
- Eating disorders, such as anorexia
- Age
102
What is a lack of ovulation?
When the woman doesn't produce enough FSH to stimulate the maturing of eggs.
103
How is lack of ovulation treated?
Using artificial FSH, as a fertility drug.
104
What is IVF?
- In vitro fertilisation
- a form of fertility treatment, if 1. oviduct has been damaged or blocked, 2. donor has to be used 3. if there is no obvious cause of long-term infertility.
105
How does IVF work?
1. Mother is given synthetic FSH, to stimulate maturing of some eggs. Then, she is given LH, to bring the eggs to ovulation.
2. They collect the eggs from the ovary and fertilise with sperm, in a lab.
3. The fertilised eggs are kept in a special solution, to develop into tiny embryos.
4. 1 or 2 of the embryos are inserted back into the uterus, and in this way they bypass the faulty tubes.
106
Advantages of fertility treatments
1. Allows couples to have children of their own, if struggling with infertility.
2. The mature eggs produced by the woman, using fertility drugs, can be collected and stored, until she wants to be pregnant later.
107
Disadvantages of fertility treatments?
1. Expensive
2. It is not always successful
3. The use of fertility drugs can have some health risks for the mother
4. The process of IVF is very emotionally + physically stressful, because it may not be successful on the first cycle.
5. Increases the chance of a multiple pregnancy ( such as twins and triplets) - this could increase risk for both mother and babies. Multiple births are more likely to lead to stillbirths and premature births.
108
What is phototropism?
A plant's response to light
109
What is gravitropism/ geotropism?
A plant's response to gravity
110
What causes these tropisms?
The hormone auxin
111
Effect of auxins on a plant?
Sunlight hits one side of the plant. So auxin is secreted on the shaded side of the plant. The auxin causes the cells on the shaded side to elongate causing the plant to bend towards the sunlight. once light falls evenly on both sides of the plant, the auxin will be equal on both sides, so it grows straight again
112
What are gibberellins?
- Plant hormones that important in initiating seed germination
- At the start they trigger the breakdown of food stores and stimulate the growth of plant stems
113
What is ethene?
Important in controlling cell division and important in fruit ripening
114
What is auxin useful for?
Auxin is also an effective weedkiller --> when sprayed, it's absorbed, sending the plant into rapid uncontrolled growth, killing it
115
Ways of using gibberellins?
1. brewing industry - speeds up germination of barley seeds (used to make malt)
2. Promote flowering throughout the year, especially in pot plants
3. Increase the size of fruit
116
Describe mitosis?
1. Sub-cellular organelles and DNA duplicates, so that it has 200% of the organelles.
2. Chromosomes in the cells line up along the equator.
3. The chromosome splits into two
4. The cell membrane forms down the middle of the cells and splits, forming two cells
117
What are gametes, in terms of cell types?
Haploid cells
118
What are all other body cells, except gametes, in terms of cell types?
Diploid cells
119
Describe the characteristics of meiosis?
1. 2 cell divisions
2. Form 4 cells
120
Describe the similarities between mitosis and meiosis?
Both involve DNA replication
121
Describe the differences between mitosis and meiosis?
1. Mitosis only consists of one cell cycle. But meiosis consists of two cell cycles.
2. Mitosis produces 2 genetically identical cells. Meiosis produces 4 genetically varying cells.
3. Mitosis produces all other body cells, except gametes. Meiosis only produces gametes.
122
What is negative feedback?
The idea of counteracting a stimuli in the body, through hormones and the endocrine system.
123
What are hormones [2]
Chemical messengers in the blood
124
What is osmoregulation?
Regulating water
125
Where does osmoregulation take place??
In the kidneys
126
What is ADH?
Antidiuretic hormones
127
How is water levels monitored and controlled by the body?
The water level is monitored by the hypothalamus.
It is controlled by the hormone ADH
128
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