7) Homeostasis Flashcards
What does the endocrine system do?
Coordinate the body’s responses to changes in the environment
How does the endocrine system coordinate the body?
With chemical messengers
What is the process of chemical messengers reaching their targets?
1) Hormones released by glands
2) Hormones in bloodstream
3) Travel to target organs
What are the 6 endocrine glands?
Pituitary Thyroid Pancreas Adrenal Testes Ovaries
What do the testes produce?
Testosterone
What is the pituitary gland linked with?
The hypothalamus
What do the ovaries produce?
Oestrogen
What does oestrogen control?
Puberty
What do the adrenal glands produce?
Adrenaline
What does the pancreas produce?
Insulin
Glucagon
What are insulin and glucagon used for?
Regulating blood glucose levels
What does the thyroid produce?
Thyroxine
What does thyroxine regulate?
Metabolism
Heart rate
Temperature
What are features of the CNS?
Rapid response
Electrical signals carried by neurones
Very short response
Acts on a precise part of the body
What are features of the endocrine system?
Slow response
Chemcial messengers carried by blood
Long-lasting response
Acts on large areas of the body`
What order does the CNS and endocrine system follow?
Receptor cells –> coordination centre –> effectors
What happens when the body has low thyroxine?
1) Hypothalamus produces TRH
2) Pituitary gland releases TSH
3) Thyroid secretes thyroxine
What happens when the body has high thyroxine?
1) TRH secretion reduced
2) TSH reduced
3) Thyroxine reduced
What effect does adrenaline have on bluud glucose?
Liver converts glycogen into glucose increasing blood sugar levels
What effect does adrenaline have on heart rate and blood pressure?
Vasoconstriction increases heart rate and blood pressure
What effect does adrenaline have on the lungs?
Enlarged air passages and metabolism changed to boost delivery of oxygen and glucose to brain and muscles
What does thyroxine increase?
Basal metabolic rate
What are features that appear during puberty called?
Secondary sex characteristics
What are male responses to puberty?
Testosterone rises, stimulating sperm production
Underarm, facial, pubic hair
Voice deepens
What are female responses to puberty?
Oestrogen rises and triggers menstrual cycle
Underarm and pubic hair
Breasts enlarge
What hormones control the menstrual cycle?
Follicle stimulating hormone (FSH)
Oestrogen
Luteinising hormone (LH)
Progesterone
When are all a females egg’s ready?
At birth
What produces FSH?
Pituitary gland
What does FSH do?
Causes an egg in the ovaries to mature
Stimuales oestrogen production
What does oestrogen do in the menstrual cycle?
Causes the development of the thick, spongy uterus lining
Stimulates LH
Inhibits FSH
What produces LH?
Pituitary gland
What does LH do?
Stimulates ovulation on day 14
What does progesterone do?
Maintains uterus lining during days 14-28
Inhibits FSH and LH
What causes the breakdown of the uterus lining?
A drop in progesterone levels
What is stage 1 of the menstrual cycle?
The uterus lining breaks down, resulting in a ‘period’
What is stage 2 of the menstrual cycle?
The uterus lining starts to build up again into a thick, spongy layer full of blood vessels
What is stage 3 of the menstrual cycle?
Ovulation happens. This is when an egg is released from one of the ovaries
What is stage 4 of the menstrual cycle?
The uterus lining is maintained, which means that it is now ready for the arrival of a fertilised egg (which will eventually grow into a baby). If no fertilised egg is attached to the uterus lining, the lining breaks down and the cycle begins again
What are the 2 main types of contraceptive pill?
Combined pill
Progesterone only pill
What does the combined pill contain and do?
Oestrogen and progesterone
Oestrogen builds up and inhibits production of FSH so no eggs mature
How does the progesterone only pill work?
Production of thick, sticky mucus prevents sperm penetration
Inhibits release of FSH
What are benefits of the progesterone only pill over the combined pill?
Just as effective but with fewer side effects
What does the contraceptive patch/ injection/ implant contain?
Progesterone
How long does the contraceptive implant last?
3 months
How long does the contraceptive implant last?
3 years
How long does the contraceptive patch last?
1 week
What do diaphragms do?
Prevent sperm from reaching the egg by beeing place inside the vagina at the entrance to the uterus (covered in spermicide)
How are intrauterine devices (IUDs) used?
inserted into uterus to prevent implantation of an embryo (some can release progesterone)
How often are contraceptive pills taken?
Daily
How are condoms used?
Worn on penis during sexual intercourse
What are benefits of condoms?
Contains spermicide
Prevents sperm from reaching an egg
Protects agaisnt STIs
What are the natural methods of contraception?
Abstinence
Timing
What is abstinence?
Not having sex until you are ready for a baby
What is the contraceptive method of timing?
Avoiding sex when females are ovulating
What are drawbacks of timing?
Sperm can last up to 6 days inside a woman
When does a female’s body temperature rise in the menstrual cycle?
During ovulation
What is sterilisation?
Underoing a permanent procedure to remove any chance of getting pregnant
What is sterilisation for females?
Cutting the fallopian tubes so an egg cannot reach the uterus
What is sterilisation for men?
Cutting the sperm ducts so no sperm is released on ejaculation
What causes a woman to be infertile?
Not having high enough levels of FSH to stimulate the maturation of eggs
What are the 2 main reproductive technologies?
Clomifene (fertility drugs)
In Vitro Fertilisation
What does clomifene do?
Trigger ovulation by increasing release of FSH
Increases LH concentration to cause ovulation
What is the process of IVF?
1) Given fertility drugs to stimulate FSH and LH and grow large numbers of eggs
2) Eggs collected and fertilised in a dish in a lab using sperm from the father
3) Fertilised eggs grow into embyros and one is implanted into the woman’s uterus (sometimes two are implanted to increase the chance of pregnancy)
What are disadvantages of fertiltiy treatments? (3)
High levels of stress
Chance of multiple pregnancies puts mother and children at risk
Expensive and not guranteed to work
What does homeostasis describe?
All of the process that can happen in a cell or orgnaism to keep conditions optimal
Why must we regulate our body’s internal conditions?
To make sure our enzymes and cells function well
What happens to our enzymes if conditions are not optimal?
They can denature which reduces their ability to catalyse metabolic reactions
What internal conditions need to be regulated? (5)
Blood sugar levels Carbon dioxide levels Water levels Urea concentration Temperature
What 3 parts make up control systems?
Effectors
Receptors
Coordination centres
What do coordination centres do?
Receive and process information arriving from receptor cells
What do receptor cells do?
Detect changes in the environment
What do effectors do?
Carry out a response to a stimuli that helps to restore optimum levels
What is the body’s optimal temperature?
37 degrees
What receptors monitor temperature for the body?
Skin receptors monitor body surface temperature
Hypothalamus montiors interal body temperature
What happens if your body is too cold?
Muscles contract- shivering
Hairs stand on end
Vasoconstriction
What happens if your body is too hot?
Sweat is released from sweat glands under the skin
Hairs lie flat
Vasodilation
How does shivering warm the body?
Muscles contract automatically when we are cold
This process needs energy from respiration
Respiration produces heat which warms us up
How does sweating cool the body?
Sweat glands release sweat which covers epidermis
Heat energy is transsferred to water and evaporates
This takes heat with it and lowers body temperature
What happens to body hairs when we are cold?
Hair erector muscles cotnract and causes the hair to stand on end and pull on the skin (goosebumps)
This traps an insulating layer of air around the body
What happens to body hairs when we are hot?
Hair erector muscles relax
Hairs lie flat
What happens to blood vessels when we are hot?
Muscular walls relax
Vasodilation
More blood flows through capillaries close to the skin surface which is transferred to the environment
What happens to blood vessels when we are cold?
Muscular walls contract
Vasoconstriction
Reduced blood flow to skin surface keeps heat energy inside the body
What is glucose important for?
Respiration
What happens when we have too little glucose?
We cannot produce enough energy
What happens if we have too much glucose?
Negative impact on osmosis as concentration gradients will be affected
What detects blood glucose levels?
The pancreas
What happens if blood glucose is too low?
1) Pancreas releases glucagon
2) Liver detects glucagon and converts glycogen into glucose and releases into bloodstream
What happens if blood glucose is too high?
1) Pancrease releases insulin
2) Liver detects insulin and converts excess glucose into glycogen
What is glycogen?
A form of glucose that is insoluble and stored for later use
What does insulin do?
Converts excess glucose into glycogen
What does glucagon do?
Converts glycogen into glucose
What is type 1 diabetes?
When sufferers are unable to produce enough insulin
What is type 2 diabetes?
When sufferers still produce insulin but their body no longer responds to it
When does type 1 diabetes develop?
During childhood
What is treatment for type 1 diabetes?
Injecting insulin when blood glucose levels rise too high
Managing diet and exercise keeps levels steady
When does type 2 diabetes develop and why?
Later in life
Old age and being overweight
What is treatment for type 2 diabetes?
Manging diet and exercising regularly
Why must water levels be kept constant in the body?
To control the amount of water and ions diffusing in and out of cells
What factors disrupt the body’s water balance? (4)
Sweating
Illness
Too much salt
Exhalation
What is lost in sweat?
Water
Ions
Urea
What does an isotonic solution mean?
Same water and ion concentration as cells
What does a hypertonic solution mean?
Solution has lower water concentration and a higher ion concentration than cells
What happens to cells if blood becomes hypertonic?
Cells lose water by osmosis and shrink
What does a hypotonic cell mean?
Solution has a higher water concentration and a lower ion concentration than cells
What happens to cells if blood becomes hypotonic?
Cells gain water by osmosis and burst
What do kidneys control?
Water and ion levels in the blood
What monitors the volume of water in the blood?
The hypothalamus
Why must urea be removed from the bloodstream?
It is toxic and too much can harm cells and tissues
What forms urea?
An excess of amino acids from digested proteins
What happens to excess amino acids in the liver?
Deamination with the waste product ammonia
Where does deamination happen?
The liver
What is the waste product of deamination?
Ammonia
What is converted into urea?
Ammonia
What is the process of producing urea?
1) Digested proteins have excess amino acids
2) Amino acids unergo deamination in the liver and ammonia is a waste product
3) Ammonia is converted to urea
What are the 2 stages of urine production?
Ultrafiltration
Selective reabsorption
Where does urine production happen?
Nephrons in the kidneys
What is the process of ultrafiltration?
1) Blood capillaries form a knotted cluster called a glomerulus in the Bowman’s capsule
2) Blood is filtered and water, urea and salts move into nephron tubule
3) Blood cells and proteins remain in the blood as they are too big to move across the capillary walls
What is the process of selective reabsorption?
1) Useful substances such as glucose and some water are reabsorbed from the tubule back into the bloodstream
2) This leaves urea, excess salts and excess water in the nephron tubule
3) Thix mixture forms urine which is collected by the kidneys and travels to the bladder to be stored and excreted
What is urine made up of?
Urea
Excess salts
Excess water
How does the body respond to too little water?
1) Hypothalamus tells pituitary gland to release ADH
2) Increases permeability of kidney tubules so more water can be reabsorbed back into the bloodstream
3) Small volume of concentrated urine
What does ADH do?
Increase permeability of kidney tubules
increase water levels
How does the body respond to too much water?
1) Hypothalamus tells pituitary gland to stop the release of ADH
2) Reduces permeability of kidney tubules and less water is reabsorbed back into the bloodstream
3) Large volume of dilute urine
What are possible treatments of kidney failure?
Transplants
Dialysis
When is dialysis used?
When the kidneys cannot keep the concentrations of urea and salt at an optimum levels to ensure tissue damage does not occur
What is the dialysis fluid designed to have?
Optimum concentrations of salts and glucose as a healthy person’s blood
How does dialysis work?
1) Patient’s blood passes over a partially permeable membrane in the machine that is designed to replicate kidney tubules
2) Dialysis fluid on the other side establishes a concentration gradient and allows excess ions and urea to diffuse from an area of high concentration in the patient’s blood to an area of low concentration in the dialysis fluid
What are disadvantages of dialysis? (3)
Lasts 3-4 hours and is needed 3 times a week
Increases risk of blood clots and infections
Expensive
What are advantages of dialysis? (2)
Life-saving process
Gives a patient time to find a donor kidney
Why are close relatives often organ donors?
They have a higher chance of being a tissue match
When can organs be transplanted from people who have recently died?
When they are a tissue match and are registered on the organ donor register
What do immunosuppressants do?
Suppress the immune system to prevent it from destroying the foreign cells of the transplanted organ
What are advantages of kidney transplants? (2)
Time consuming dialysis treatment is not required
Transplants are cheaper than dialysis in the long run
What are disadvantages of kidney transplants? (3)
Kidney may be rejected by the body
Can be a long waiting list for transplants
Immunosuppressant drugs can make a patient more prone to other infections
