Homeostasis And Response Flashcards
1
Q
What is Homeostasis?
A
The regulation of the internal conditions of a cell
It maintains optimal conditions for enzyme action and all cell functions
2
Q
What does homeostasis control?
A
-Blood glucose concentration
-Body temperature
-Water levels
3
Q
Negative feedback loop
(Counteracts change)
-too high
A
- Receptors detects a stimulus (levels is too high)
- The coordination centre receives and processes the information and organises a response
- Effector produces a response, which counteracts the change and restores the optimum level
- Levels decrease
4
Q
Negative feedback loop
(Counteracts change)
-Too low
A
- Receptor detects a stimulus, level is too low
- The coordination centre receives and processes the information, then organises a response
- Effector produces a response, which counteracts the change and restores the optimum level
- The level increases
5
Q
Why is the nervous system important?
A
Enables humans to react to their surroundings and coordinate their behaviour
6
Q
What is the Central Nervous System (CNS) made up of?
A
-The brain
-The spinal cord
7
Q
How does the Central Nervous System (CNS) coordinate a response?
A
Coordinates a response of effectors which may be muscles contracting or glands secreting hormones
8
Q
The CNS response…
A
Stimulus-> receptors-> coordinator-> effector-> response
9
Q
Reflex Arc (depth)
A
- Stimulus (pain)
- Impulse travel along sensory neurone
- Impulses are passed along a relay neurone via a synapse
- Impulse travel along a motor neurone via a synapse
- Effector (muscle or gland) contracts
- Response
- Quicker as it bypasses the brain
10
Q
Reflect arc (simple)
A
- Stimulus
- Sensory neurone
- Relay neurone
- Motor neurone
- Effector
- Response
11
Q
What is a reflexes arc?
A
Automatic and rapid response which bypasses the conscious part of the brain. This prevents injury.
12
Q
What is a synapse?
A
-Junction between neurones -The nerve signal is transferred by chemicals which diffuses across the gap
-These chemicals then set off a new electrical signal in the next neurone
13
Q
Required practical- reaction time
Explain the method to carry it out…
A
- Person 1 sit down on the chair with good posture
- Place the forearm of your arm across the table with your hand overhanging the edge of the table
- Person 2 hold the ruler vertically so the zero mark is level with the top of your thumb
- Person 2 tells Person 1 to prepare to catch the ruler
- Person 2 drops the ruler at a random time
- Person 1 must catch the ruler as quickly as possible
- Record the number that is level with the top of the thumb on the ruler
- Have a short rest and repeat (Person 1)
- Swap and repeat
14
Q
What safety precaution do you need to do when carrying out the reaction time practical?
A
Wear safety goggles to avoid the possibility of the ruler hitting the floor and bouncing back up into the eyes
15
Q
What is the cerebral cortex?
A
- outer wrinkly bit
- responsible for intelligence, memory, language and consciousness
16
Q
What is the cerebellum?
A
- pom pom thing at the back of the brain
- responsible for muscle coordination
17
Q
What is the Medulla?
A
- controls unconscious activities eg breathing and heartbeat
18
Q
What is the functions of the spinal cord?
A
Transmitting electrical impulses between the brain and the rest of the body
19
Q
MRI Scans
A
Provides a detailed picture of the brain’s structure. Used to find out what areas of the brain are active when people are doing things like listening to music or trying to recall a memory
20
Q
Why is investigating and treating the brain difficult?
A
As the brain is extremely complex and delicate
21
Q
How is body temperature monitored and controlled?
How does it work?
A
-By the thermoregulatory centre in the brain
-Contains receptors sensitive to the temperature of the blood
-Also receives impulses from thr temperature receptors in the skin, giving information about skin temperature
22
Q
What happens if the body temperature is too high?
A
- Temperature receptors detects too high
- The thermoregulatory centre acts as a coordination centre and triggers effectors
- Effectors produce response eg blood vessels vasodilate or sweat
- Body cools down
23
Q
What happens if the body temperature is too low?
A
- Temperature receptors detects core body temperature is too low
- The thermoregulatory centre acts as a coordination centre and triggers effectors
- Effectors produce response eg vasoconstriction, sweating stops, skeletal muscles contract (shiver), hairs erect (trap an insulating layer of air)
24
Q
What are hormones?
A
-Chemical molecules released directly into the blood
-Produced and secreted by glands
-Relative long-lasting effects
25
The pituitary gland
-Regulates body condition
-Known as the 'master gland' because these hormones simulate other hormones to bring about effect and growth hormones in children
-In the brain
26
Thyroid
-Produces thyroxine
-Regulates the rate of metabolism, heart rate and temperature
-Found in the neck
27
Adrenal gland
-Produces adrenaline
-Prepares the body for 'fight or flight'
-Above the kidneys
28
The pancreas
-Produces insulin
-Regulates the blood glucose levels
29
Ovaries (fem only)
-Produces oestrogen
-Involved in the menstrual cycle
30
Testes (male only)
-Produces testosterone
-Controls puberty and sperm production in males
31
What are the differences between nerves and hormones?
Nerves:
-Very fast
-Act for a very short time
-Act on a very precise area
Hormones
-Slower action
-Act for a long time
-Act in a more general way
32
What happens if the blood glucose level is too high?
1. Pancreas produces the insulin.
2. The liver moves the glucose into your blood in cells into glycogen so it can be stored
3. Blood glucose is decreased
33
What happens if the blood glucose level is too low?
1. The pancreas secretes glucagon
2. Glucagon makes the liver turn stored glycogen into glucose
3. Glucose is released into the blood by the liver
4. Blood glucose levels increase
34
What is type 1 diabetes?
Treated?
Symptoms?
-Where the pancreas produces little or no insulin
-This means the person's blood glucose level can rise to a level that can kill them
-Treated by insulin injections, machines that monitor glucose levels, pancreatic transpant
-Occurs in childhood
-Symptoms = tiredness, thirst, weight loss
35
What is type 2 diabetes?
Symptoms?
Treated?
-When a person becomes resistant to their own insulin (they still produce insulin, but their body's cells don't respond properly to the hormone)
-This can cause blood sugar levels to rise to a dangerous level
-Being overweight can increase your chances
-Symptoms = thirsty, weight loss or gain, tired, blurred vision
-Controlled by eating a carbohydrate-controlled diet and getting regular exercise
36
How do the kidneys make urine?
By taking waste products (and other unwanted substances) out of your blood.
Substances are filtered out of the blood as it passes through the kidneys as it contains lots of nephron. This is called filtration.
37
What substances are absorbed back into the blood in selective reabsorption?
-Glucose
-Ions
-Water
38
Digestion of proteins
1. When you eat too much results in excess amino acids which needs to be excreted safely
2. In the liver these amino acids are deminated to form fats and carbohydrates but ammonia is a product of this
3. Ammonia is toxic and is immediately converted to urea for safe excretion
39
Ions
This is regulated by the kidneys so the right amount is reabsorbed, and the rest is removed in your urine
The kidneys also produce urine by filtration
40
What happens if water content is too high?
1. A receptor in the brain detects it it too high
2. The coordination centre in the brain receives the information and coordinates a response
3. The pituitary gland releases less ADH, so water less reabsorbed from the kidney tubules (less permeable)
4. Water content decreases and urine output increases (pale)
41
What happens if the water content is too low?
1. A receptor in the brain detects that the water content is too low
2. The coordination centre in the brain receives the information and coordinates a response
3. The pituitary gland releases more ADH, so more water is reabsorbed from the kidney tubules (more permeable)
4. Water content increases and small urine output (dark)
5. Example of a negative feedback loop
42
How can people who suffer from kidney failure be treated?
-Organ transplant
-Kidney Dialysis
43
What would happen if the kidneys failed?
-Waste substances would build up in the blood stream
-Unable to regulate water and ion levels
44
How is starch broken down?
Broken down into glucose by carbohydrase enzymes and into the blood
45
Why do glucose levels need to be controlled?
As too high, water will not leave cells by osmosis
Too low, respiration will not occur
46
What is diabetes?
A non-communicable disease where the amount of glucose in your blood cannot be controlled
47
Formation of urine
1. Filtration- blood is filtered at the start of the nephron (kidney)
2. Molecules like water, ions, urea, glucose can be filtered out but red blood cells and proteins cannot as they are too big
3. Selective reabsorbtion- all glucose reabsorbed back into the blood by diffusion, some water by osmosis, some ions by active transport, no urea
4. Molecules that are not reabsorbed into the blood continue along the tubule as urine, which is excreted
48
Explain the sets of dialysis...
1. Blood goes out of the patient into the dialysis machine
2. In the tubing, there is a partially permeable membrane which is surrounded by dialysis fluid which contains ideal concentration of fluids
->same concentration of glucose
->normal levels of water and ions so movement by diffusion / osmosis until equilibrium is reached
-> no urea so it moves by diffusion from high to low concentration
49
Advantages and disadvantages of dialysis
Advantages- no shortage of machines
Disadvantage- frequent treatments
- controlled diet
- expensive long term
50
Advantages and disadvantages of transplant
Advantages- normal life
-only expensive initially
Disadvantages- shortage of organs and donors
- have to take anti rejection drugs for the rest of someone's life
- risk of rejection
51
Menstrual cycle
1-4: the uterus lining breaks down, and menstruation occurs
4-14: the uterus lining builds up again ready to recieve a fertilised egg
14: ovulation (egg released from ovary's)
14-28: the wall is maintained, if no fertilised egg, it will begin to break down again
52
What is FSH (pituitary gland) role in the menstrual cycle?
Maturing of the egg and stimulates oestrogen
53
What is the role of oestrogen (ovaries) in the menstrual cycle?
Thickens the uterus lining and stimulates LH, which stops FSH
54
LH (pituitary gland)
Stimulates the release of an egg
55
Progesterone (ovaries) role in the menstrual cycle
Maintains the uterus lining, when levels fall the lining breaks down, stops FSH and LH
56
MR OM FLOP
Menstruation
Rebuilding
Ovulation
Maintained
FSH
LH
Oestrogen
Progesterone
57
Explain how IVF works?
1. Mother is given FSH and LH to stimulate the maturation of several eggs
2. Eggs are collected
3. They are fertilised by the sperm from the father in a laboratory
4. Fertilised eggs develop into an embryo
5. One or two are inserted into the mothers uterus
6. Helps people to have children when they are having fertility problems
58
Advantages and disadvantages of IVF
Advantages- let's people have children
-control timing
-unused eggs donated to research
Disadvantages- side effects from drugs
- possible multiple births
-low success
- birth effects and premature
59
Methods of contraception...
-oral contraceptives: contain horomons to stop FSH so no egg matures
-Injection, implant or patch: slow the release of FSH to stop maturation or release of egg
-barrier methods: prevent sperm reaching the egg
-spermicides: kill or disable sperm
-The pill
- Abstinence
60
Pros and cons of contraception
Pros: -some more long term
-some prevent STDs
-All help to prevent pregnancy
Cons: -Some don't prevent STDs
-Side effects if release hormones
-Last several years
61
What is a tropisms?
Directional growth response
-> plants grow in certain directions to respond to stimuli
62
What is phototropism?
Light
63
What is geotropism?
Gravity
64
What is hydrotropism?
Water
65
Roots (tropism)
Positively geotropic
Positively hydrotropic
Negativity phototropic
66
What is auxin?
The plant hormone for growth, and is produced in the tips of roots and shoots. It stimulates growth above, but inhibits growth for the roots. It is unevenly distrubuted and goes to the darker side.
67
Upwards growth
1. The auxin diffuses to the darkest side of the shoot
2. This cause the cells to elongate
3. This causes upwards growth
68
Direct sunlight to the side
1. The aucin diffuses to the darkest side
2. This causes the side of cells to elonage but the other side stays the same (sun side)
3. This changes the direction of growth
69
What happens if you cut the shoot off?
It would not grow as there would be no auxin
70
Sponge between tip and stem
Still grow as the auxin would be able to diffuse through the sponge
71
Cover over the tip
Would mot be able to grow as the auxin would not be able to diffuse toward the light
72
Auxin in the roots
Auxin will concentrate at the bottom, causing the cells at the bottom to elongate less, making it bend down
73
Gibberellins
Required for seed germination, stem growth and flowering. It can be used to control dormancy, induce flowering and grow larger fruits
74
Ethene
Important for cell division and ripening. Used for fruit that is picked when it isn't ripe.
