Topic 5 - Homeostasis and Response Flashcards
What are the 6 main hormonal glands in the human body?
Pituitary, thyroid, adrenal, pancreas, ovaries, testes.
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What does the pituitary gland do?
The pituitary gland produces hormones to activate other glands.
What does the thyroid gland do?
The thyroid gland produces thyroxine, which regulates growth.
What do the Adrenal glands do?
The Adrenal glands produce adrenaline.
What does the pancreas do?
In terms of hormones
It produces insulin and glucagon to control blood sugar.
What do the ovaries and testes do?
in terms of hormones?
The ovaries produce estrogen, and the testes produce testosterone.
What are Hormones?
Hormones are chemicals which are secreted by glands that travel through the blood and target/ activate certain cells.
How do Hormones get around the body?
They travel through the blood stream.
Give 3 things which effect blood sugar levels.
1.Eating foods high in carbs
2.Vigorous excercise
3.Normal metabolism of cells (respiration)
What is insulin?
Insulin is a hormone produced by the pancreas, it decreases blood glucose levels.
How does insulin lower blood sugar?
Insulin decreases blood sugar by causing body cells to take up more glucose. Cells in muscles and the liver convert it into glycogen.
What is glycogen?
Glycogen is a storage molecule
What does glucagon do?
- stimulates the liver to break down glycogen to be released as glucose.
- activates gluconeogenesis
- breaks down stored fat into fatty acids.
Where is glucagon produced?
Glucagon is produced by alpha cells in a part of the pancreas known as the islets of langerhans.
What is gluconeogenesis?
Gluconeogenesis is the conversion of amino acids into glucose.
What is Diabetes
Diabetes is a condition that causes a person’s blood sugar to become too high.
What is Type 1 diabetes?
Type 1 diabetes is where the body’s immune system attacks and destroys the cells that produce insulin.
What is Type 2 diabetes?
Type 2 diabetes is where the body doesnt produce enough insulin, or the body’s cells don’t react to insulin anymore.
What are the symptoms of diabetes?
1.Thirst
2.urinating more
3.feeling tired
4.weight loss, loss of muscle
5.cuts or wounds that heal slowly
6.Blurred vision
What causes diabetes?
Diabetes is caused by there not being enough insulin, or the insulin produced is not working.
How can Type 1 diabetes be treated?
Insulin replacement
How can Type 2 diabetes be treated?
Type 2 can be managed with diet change, weight loss and medication/insulin.
What 3 factors affect urine colour?
- Amount of water drunk
- Temperature
- Excercise
What is urine composed of?
1.Water
2.Urea
3.Salts
Which organ produces urine?
The kidneys
Where is urine stored?
The bladder
What is ADH?
Anti-diuretic hormone makes cells in the kidney tubules more/less permeable.
Where is ADH released from?
The pituitary gland
What is Deamination?
Deamination is the process of proteins being converted into fat and carbs which can be stored
What is selective reabsorption?
Selective reabsoprtion is the process in the kidneys where useful substances are absorbed back into the bloodstream.
What substances are usually reabsorbed by the kidneys?
Water, ions and glucose
Describe the process the body undergoes when there is too much water.
- Brain produces less ADH
- Less water reabsorbed by kidneys
- Urine output higher
Describe the process which the body undergoes when there not enough water.
- Brain produces less ADH
- Higher volume of water reabsorbed by kidneys
- Less urine output.
What is Kidney Failure?
It is when your Kidneys are unable to remove waste from blood, and is unable to control water and ion level.
What is dialysis?
Dialysis is when a machine takes the role of the Kidneys.
How does Dialysis work?
- The blood flows past a PPM, which allows ions and waste substances through, but not big molecules like proteins
- The dialysis fluid on the other side of the PPM has the same concentration of dissolved ions and blood, so it won’t be lost.
What are the pros of dialysis?
- No major surgery
- No waiting list
What are the cons of dialysis?
- Diet needs to be controlled
- Restricts life
- Dialysis can not replace all kidney function
- Blood clots
- Expensive for NHS
Where do donated kidneys come from?
From people who died suddenly, or close family
Why does the body reject donated organs?
The antigens on the donor organ aren’t recognised by the person’s immune system.
Pros of Kidney transplant
- Transplant can fully replace kidney
- No diet change
Cons of Kidney transplant
- Major surgery
- Hard to find suitable donor
- Rejection
- Immunosuppressant required
- Bone marrow radiation
- Only lasts 9 years
- can go against religion
What are the 4 hormones which control the menstrual cycle?
1.Oestrogen
2.Pogesterone
3.LH
4.FSH
What does Oestrogen do during the menstrual cycle?
1.Inhibits FSH
2.Causes uterus lining to thicken
3.Causes LH production
What does LH do?
Causes Ovulation
What does progesterone do?
Prepares the uterus lining for an egg to implant
What does FSH do?
1.Stimulates Oestrogen production
2.Makes egg mature
What happens in stage 1 of the menstrual cycle
- Bleeding
- Shedding of uterus lining
- FSH levels rise
What happens in stage 2 of the menstrual cycle
1.Uterus lining builds up
2.FSH falls
3.Oestrogen rises
What happens in stage 3 of the menstrual cycle
1.Ovulation
2.LH levels rise
3.Progesterone starts to rise
What happens in stage 4 of the menstrual cycle
- maintaining of the uterus lining
- if no egg implanted then Progesterone and oestrogen falls.
What are the 6 types of contraceptive?
1.IUD
2.Skin patches, injections and implants
3.Natural methods
4.Surgical methods
5.Barrier methods
6.Oral
How does oestrogen and progesterone work to control fertility?
- Taking oestrogen inhibits FSH, thus stopping the egg from maturing
- Progesterone stimulates production of thick cervical mucus, blocking sperm
What are the pros and cons of the combined pill?
pros - 99% effectuve, reduces risk of cancer
cons - side effects such as headaches, irregular menstrual bleeding and nausea. Doesn’t protect against STDs
What is an alternative to the combined pill?
Progesterone pill.
What barrier methods are there?
Condom and diaphragm
What must be used with a diaphragm contraceptive?
Spermicides
How does sterilisation work?
The oviduct or sperm ducts are cut and tied
What are the downsides to sterilisation?
1.Permanent
2.chance the tubes reconnect
How does the implant work?
Releases continuous amount of progesterone, which stops the ovaries releasing eggs and eggs implanting
What is an IUD
A T-shaped device inserted into the uterus to kill sperm
What is the difference between plastic and copper IUDs?
Plastic releases progesterone, copper kills sperm in the uterus
How can certain drugs increase fertility?
Hormones like FSH and LH can increase fertility by stimulating egg maturation and ovulation.
What are problems with fertility drugs?
- Don’t always work
- Expensive
- Too many eggs can be stimulated
Describe the process for IVF
1.FSH and LH is given to the woman, many eggs mature
2. Mature eggs are collected from the Ovaries, these are fertilised in a lab Petri dish.
3.Fertilised eggs then grow into embryos in an in lab incubator
4.Once the embryos have formed one or two are transferred into the woman’s uterus.
What are ethical issues to IVF?
Unused embryos get destroyed
Genetic testing can mean you can pick and choose a child’s genetic characteristics.
What developments in science have improved IVF?
Improved microscopy, specialised micro tools and time lapse imaging.
What are the cons of IVF
- Expensive
- Physically and emotionally stressful and demanding
- 70% chance of failure under age 35
- Higher chance for multiple births.
What does adrenaline do?
Adrenaline prepares you to fight or flight
How does adrenaline affect you?
It increases the supply of oxygen and glucose to cells in the brain and muscles. Adrenaline increases heart rate.
What does thyroxine do?
1.Regulates metabolic rate
2.Stimulates protein synthesis for growth.
How is thyroxine regulated?
- Thyroxine is released in response to TSH, from the pituitary gland.
- Negative feedback keeps the thyroxine levels normal.
Where is auxin produced?
Auxin is produced in the tips of shoots and roots.
What does auxin do?
Auxin stimulates the cell elongation process, which occurs in the cells behind the tips.
What is phototropism?
Plant growth, in response to light
How is a plants growth influenced by light?
When a shoots tip is exposed to light, more auxin accumulates on the shaded side, so the plant grows towards light.
What is gravitropism?
Plant growth, in response to gravity.
How do is a plants growth influenced by gravity?
Shoots grow away from gravity, auxin is more concentrated on the side of a shoot nearer to the ground, so the shoot grows upwards.
How are roots influenced by gravity?
Roots grow towards gravity, auxin accumulates on the side where gravity is stronger, so the root grows downwards.
How is auxin different in shoots Vs roots?
In roots auxin inhibits growth, in shoots auxin stimulates growth.
What does Gibberellins do?
1.Controls dormancy
2.Induces flowering
3.Helps grow larger fruit
What does Ethene do in plants?
1.Stimulates enzymes to ripen a fruit
2.Controls cell division
Why does body temp need to be kept at 37 degrees?
This is the temp at which the enzymes work best
What does the thermoregulatory centre do?
It receives info about body temp from receptors in the skin, or receptors in the thermoregulatory centre.
Where is the thermoregulatory centre?
Brain, Hypothalamus, thermoregulatory centre
How is body temp controlled?
Using a negative feedback loop
What are 4 ways of correcting poor eyesight?
- Glasses
- Contact lenses
- Laser eye surgery
- Replacement lens
What causes myopia?
The eye is too long or lens is too powerful, so the image forms before the retina.
What causes hyperopia?
The eye lens can’t thicken enough or eyeball too shor tso image forms behind retina.
Which type of lens fixes myopia and hyperopia?
Concave lenses for myopia
Convex lenses for hyperopia
What is accomodation?
The ability to focus on near or distant objects by muscles in the eye changing the shape of the lens.
How do we focus on near objects?
1.Ciliary muscles contract, suspensory ligaments loosen
2.lens becomes fat
3.light is refracted more
How do we focus on far objects?
1.Ciliary muscles relax, suspensory ligaments tighten.
2.lens thins
3.Light refracts less
How does the pupil get smaller?
Radial muscles relax, and circular muscles contract
How does the pupil get larger?
Radial muscles contract, and circular muscles relax
What are effectors?
Muscles or glands which respond to nervous impulses and bring about a response to simuli.
What is the central nervous system?
The CNS is where all the information from the receptors are sent, and where reflexes and actions are coordinated.
What are synapses?
synapses are small gaps at the end of a neuron that allow a signal to pass from one neuron to the next.
What is homeostasis?
The regulation of the internal conditions inside your body to maintain a stable internal environement in response to internal and external conditions.
How does your body cool you down?
1.sweating
2.hairs lay flat
3.vasodilation
How does you body warm you up?
- shivering
- hairs stand on end
- vasoconstriction
What are receptors?
Cells which detect stimuli
What are the 3 types of neurones?
- Motor neurones - carry impuleses from CNS to effectors
- Sensory Neurones - carry impulses from the receptors to CNS
- Relay neurones - transmits electrical impulses from sensory neurones to motor neurones.
What are reflexes?
Rapid, automatic responses to stimuli thay don’t involve the concious part of the brain - they reduce the risk of injury
What are the steps to a reflex arc?
1.Stimulus detected by receptor
2.Impules are sent along the sensory neurone to a relay neurone in the CNS
3.The relay neurone transmits the impuse from the CNS to the motor neurone
4.The impulse then travels along the motor neurone to an effector
5.which then takes action
How can we measure reaction time?
- Person should sit with arm resting on edge of table
- Hold the zero end of a ruler vertically between their thumb and forefinger
- let go without warning
- The person should try to catch it ASAP
- The higher the number the slower the reaction time.
What are the 4 regions of the brain for GCSE?
1.Cerebral cortex
2.Medulla
3.Cerebellum
4.Spinal Cord
What does the cerebral cortex do?
Responsible for consiousness, intelligence, memory and language
What does the Medulla do?
1.unconscious activities like breathing/heartbeat
What does the cerebellum do?
Responsible for muscle coordination
