SB7- Animal coordination, control and homeostasis Flashcards
What’s the hormonal system
Another response other than the nervous system - it works more slowly than the nervous system but can cause responses in many parts of the body
What does the hormonal system use
Chemical messengers callee hormones are carried by the blood and so take time to get around the body
Different hormones are released by a range of endocrine glands
What are the endocrine glands
Include pituitary, thyroid, adrenals, ovaries, tested and pancreas
What does the pituitary gland release
Many hormones including
ACTH
FSH
LH
And growth hormone
What does the thyroid gland produce
Several hormones including thyroxine
What gland does the pancreas produce
Some cells produce insulin and other produce glucagon
What hormone do the ovaries produce
The was hormones oestrogen and progesterone
What hormone do the testes produce
Testosterone
What hormone do the adrenal glands produce
Several hormones including adrenalin
What’s a target organ
An organ specially affected by a specific hormone
The hormone affects the organ by changing what the organ is doing - eg growth hormone stimulates cells in muscles and bones to divide, it also stimulates the digestive system to absorb calcium ions - also used to help make strong bones
Tell me about some endocrine glands being the target organs for other hormones
For the sex hormones oestrogen and testosterone which are released by reproductive organs, stimulate the release of growth hormone
The release of sex hormones increases during puberty which helps to increase the growth rate at this time
What’s your metabolic rate
Is the rate at which the energy stored in your food is transferred by all the reactions that take place in your body to keep you alive
How is resting metabolic rate measured
Measured with the body at rest in a warm room and long after the person last had a meal
Tell me about thyroxine and metabolic rate
Thyroxine is taken into, and affects many different kinds of cell
It causes heart cells to contract more rapidly and strongly and it also increases the rate at which proteins and carbohydrates to break down inside cells
Why is thyroxine concentration in the blood an example of negative feed back
An increase in thyroxine concentration directly causes changes that bring a decrease in amount of thyroxine being released into blood
Negative feedback loops
Check pg 144 diagram
What is adrenalin
A hormone that is released from the adrenal glands - normally very little is released into the blood
When do amounts of adrenalin in blood change
In frightening or exciting situations - an increase in impulses from the neurones reaching the adrenal glands from the spinal cord triggers the release of large amounts of adrenalin into the blood
What are the target organs of adrenalin
Including the liver in which causes the breakdown of a storage substance called glycogen
Glycogen is a polymer made of glucose molecules, when glycogen is broken down, the glucose molecules can be released into the blood providing additional glucose for respiration
What’s the fight or flight response
Some of the other target organs and effects of adrenalin together these effects prepare the body to fight or run away from danger
Hear muscle cells contract more rapidly to increase heart rate and more strongly to increase blood pressure
Diameter of blood vessels to muscles increase and to organs decease
Liver cells change glycogen to glucose
What’s the menstrual cycle
A cycle of changes in a woman’s reproductive system
It prepares the body for fertilisation of an egg cell, leading to pregnancy
How long does the menstrual cycle last for
28 days
When does the cycle start and end
Around 12 at puberty and ends in early 50s (menopause)
What happens in days 1 to 5 of the cycle
This is menstruation - when the uterus lining breaks down and is lost with the unfertilised egg cell
Progesterone levels are low
Oestrogen levels are lol
At day 4, low levels of progesterone allow FSh to be released to cause the growth and maturation of egg
When and what happens when menstruation ends
Menstruation ends at day 10, the uterus lining start to thicken again
Oestrogen levels are now rising a lot, progesterone levels still low
Oestrogen levels stimulate release of more LH - LH surge triggers ovulation
When and what happens in ovulation
Days 13-15, the ovary releases the egg
Oestrogen levels are high and progesterone levels begin to rise now
As progesterone begins to be released - this inhibits FSH and LH being released
What happens from days 16 to 28!
Fertilisation lead if to pregnancy is most likely around days 18 to 20
The uterus lining continues to thicken
Around day 25 the egg cell travels along the oviduct to the uterus, progesterone levels high and start to fall around 28 and cycle starts again, oestrogen levels have decreased from day 14 and then stayed the same and now are falling a bit too and cycle ends
What hormones is the cycle controlled by
Oestrogen and progesterone- which are released by the ovaries in to the blood
How can fertilisation occur
During sexual intercourse, sperm cells are deposited in the vagina, they then pass through the cervix to the uterus and into the oviducts - if a sperm cell meets an egg cell fertilisation can occur
What’s contraception
Is the presentation of fertilisation- there are hormones and then physical barriers
What’s the success rate and how does the male condom work
98% succes
It’s placed over an erect penis to prevent sperm entering the vagina
Tell me about the success and how a diaphragm or cap works
92-6% success
It’s placed over the cervix (entrance to the uterus) prevents sperm in the vagina entering the uterus
Tell me about the success and what the hormone pill or implant placed under the skin
> 99% success rate
It releases hormones to prevent ovulation and thickens mucus to the cervix making it difficult for sperm to pass through
What is FSH and LH
Follicle stimulating hormone - FSH and Luteinisong hormone is released from pituitary gland, release of hormones are controlled by concentration of oestrogen and progesterone released after ovulation when egg cell becomes a corpus luteum structure
When do levels of oestrogen increase
Levels increase as the egg follicle matures
When can FSH be released
When there are low levels of progesterone
What does increasing progesterone do to levels of FSH and LH
Increasing progesterone inhibits FSH and LH
What do high levels of oetrogen allow
Stimulate release or more LH
Oestrogen levels are stimulated to rise from maturing follicles
What does increasing oestrogen levels do to uterus lining
It causes it to thicken
What hormone does the corpus luteum release
Progesterone
What do falling levels of oestrogen and progesterone cause
Menstruation
Tell me about hormonal contraception - how does it work?
Uses a progesterone like hormone either on its own or with oestrogen. Raising hormone concentrations in this way prevents the natural fall of concentrations at the end of the menstrual cycle
What’s Assisted reproductive technology (ART) -
which uses hormones and other techniques to increase the chance of pregnancy
Eg clomifene therapy and IVF
Tell me about clomifene therapy
This is useful for women who rarely release an egg during their menstrual cycles - clomifene is a drug that helps to increase the concentrations of FSH and LH in the blood
Tell me about in vitro fertilisation (IVF) - when is it useful?
This can overcome problems such as blocked oviducts in the woman or if the man produces very few healthy sperm cells
Any healthy embryos not used in the first attempt at pregnancy may be frozen and stored for use another time
How does IVF Work?
Egg follicle maturation is stimulated by hormones, egg cells released by many follicles and taken From ovary, sperm cells are taken from the man
Then eggs and sperm are combined to allow fertilisation
One or two healthy embryos are placed in the uterus
What can urine tests be used for
Identifying disease - diabetes
In the Middle Ages the urine may have been tasted, today we use simple chemical tests
Where does glucose come from
It’s released from carbohydrates in our food
Glucose is easily absorbed from the small intestine into the blood and then into cell, where it is broken down during respiration.
Why is there a risk glucose levels may become very high
It takes time for cells to take in the glucose released by digestion - high concentrations can damage organs
In most people this doesn’t happen because blood glucose concentration is carefully controlled
Tell me about the release of insulin
As blood glucose concentrations increase - it stimulated certain cells in the pancreas to release insulin
Insulin causes cells in the liver and other organs to take in glucose which causes a fall in blood glucose concentration
Explain the process of control of glucose concentrations in the blood
Glucose is absorbed from the small intestine after digestion of food, blood glucose concentration rises, pancreas responds by releasing insulin
Insulin causes liver, muscle and other cells to take up glucose and change it to glycogen for storage - blood glucose concentration fell to normal
What happens if blood glucose concentrations in blood fall below a certain level
Cells just stop releasing insulin B)
What’s glucagon and what does it do to glycogen
Glucagon causes liver cells to convert glycogen back to glucose when blood glucose levels fall below a certain level
as blood glucose levels concentrations increases again, the amount of glucagon released from the pancreas falls
Define homeostasis
Maiming constant conditions inside the body
Other examples include temperature and water content
Processes involved in homeostasis help to prevent damage to the body as internal and external conditions change
Tell what type 1 diabetes is
In a few people, the pancreatic cells that should produce insulin do not - this is becusses the cells have been destroyed by the body’s immune system
This means they can’t control rising blood glucose concentration
What’s often the first test for type 1 diabetes
When blood glucose concentrations is too high - some glucose can be detected in URINE
What do people with type 1 diabetes do to fix levels of glucose
Inject insulin into fat layer below the skin where it can enter the blood causing blood concentrations to fall
What is type 2 diabetes caused by
Either insulin releasing cells not producing enough insulin or by target organs not responding properly to the hormone
How do people with type 2 diabetes control insulin and fix it
Just eating healthily and being physically active, eating low amounts of sugar
Being physically active takes glucose out of the blood
People with more severe type 2 diabetes may be given medicines to reduce the amount of glucose that the liver releases into the blood or to increase the sensitivity of the cells in target organs that respond to insulin
What else has increased as the number of people with type 2 diabetes increase
Average body mass
The 2 factors are correlated - more fat on someone body, the more likely they are to develop type 2 diabetes
What is BMI
Body mass index
BMI= mass(kg) divided by height squared(m)
It calculates wether a person has the right mass for their height
There is a correlation between BMI and type 2 diabetes- more people that are obese, higher percentage of them have type 2 diabetes
Tell me about waist:hip ratio
It’s calculated as the waste measurement divided by the hip measurement, as people increase in mass, they tend to develop more fat on their waists compared to hips - which increases their waist:hip ratio
The ratio also correlates with the risk of developing type 2 diabetes
What’s the normal temperature of major organs - heart, liver, brain
37 degrees Celsius
What temperature is a fever
Above 38 degrees c
What’s temperature is hypothermia
Temperatures below36 degreee c
What’s thermoregulation
It’s the control of body temperature which keeps the temperature of the major organs close to 37 degrees c most of the time
What’s the hypothalamus
A small part of the brain that constantly monitors temperature, it receives information from temperature receptors in the dermis of the skin
Receptors inside the hypothalamus detect temperature changes in the brain and the blood
What does the hypothalamus do when blood or brain temp starts to fall below 37 degreee or detects cold environment- 3 things
Shivering , contraction of erector muscles, reduction of blood flow near the skin
Tell me about shivering
Shivering is when muscles contract and relax rapidly - some of the energy released from cell respiration for shivering warms you up
Tell me about contraction of erector muscles
Erector muscles in the dermis of the skin causes body hairs to stand up right - in humans this has little effect but in other mammals it traps air next to the skin for insulation
Tell me about the reduction of blood flow near the skin
Keeps blood deeper inside the body which reduces the rate of transfer of energy to the air by heating
When does sweating happen
When the body temp rises above 37 degreeee c
The hypothalamus causes sweating - how does this cause the body to cool down
Sweat glands secrete sweat
Sweat spreads out as a thin layer over the skin epidermis, where it evaporates - as it evaporates, it transfers energy from the skin to the surroundings by heating, so the skin cools down
What does the hypothalamus do about blood flow when the body is hot
Increases blood flow nearer the surface of the skin so blood can transfer energy to the air so we cool down
What’s vasoconstriction
When it’s cold, the hypothalamus sends nerve impulses to small arteries deep in the skin, causing them to narrow, this reduces blood flow to capillaries near the surface of the skin to help reduce energy transfer to surroundings
What’s vasodilation
When the body is hot, the hypothalamus causes the small arteries to widen - which increases blood flow through skin capillaries, bringing warm blood nearer to the surface of the skin and increasing energy transfer to surroundings
What feedback type is the control of body temperature
Negative feedback
What is osmoregulation
The control of the balance of water and mineral salts in the body, if the balance of water and mineral salts is wrong then cells may take in or lose too much water by osmosis - this can damage cells because water in cells allows molecules in cells reactions to move and around and water is also need to maintain the shape of the cell
What is the function of the urinary system
To remove excess amounts of some substances from the blood - including water and and minerals
Also removes waste products such as urea
How is urea produced
It’s produced in liver cells from the breakdown of amino acids that are in greater amounts than needed - the urea passes into the blood and is carried to the kidneys
What do renal veins do
Carry blood with wastes removed back to the body
What do renal arteries do
Carry blood away from body to the kidneys
What do the kidneys do
Remove substances from the blood and make urine
What do the ureters
Carry urine from the kidneys to the bladder
What does the bladder do
Stores urine
There’s a muscle to keep the exit of the bladder closed until the person wants to urinate
What’s the Urethra
When urine flows to get of the body,
What’s kidney failure
We have 2 kidneys - you can survive with just one
When both stop working properly - that’s kidney failure
Why does kidney failure put people’s lives at risk
The persons life is in danger because waste substances increase in concentration in the blood, the person will need kidney dialysis every few days to keep the concentrations of substances in the blood at safe levels
Tell me about the process of kidney dialysis
Blood carrying wastes passes to the machine from a vein,
The dialysis fluid is containing the same concentration of glucose as blood plasma
There’s a partially permeable membrane separating blood from dialysis fluid, urea and waste diffuses overall to dialysis fluid whilst no glucose is lost and blood returns into the vein
Tell me about organ donation - what is it?
When a kidney from another person is put into a patients body and attached to their blood system
What are problems with kidney donation
Replacing a kidney involved several hours of surgery, which may be too much for weak patients
Kidney cells have antigens on them - cells in the immune system recognise and attack strange antigens, this can cause rejection of the kidney - so antigens on organ must match patients cells, which can take a long time to find a suitable kidney
Where is urine made
In the kidneys - in the thousands of tiny microscopic tubes called nephrons - urine is made in a series of stages
How is urine made in the nephron
Blood flows through a network of capillaries called a glomerulus, which runs inside the bowmans capsule of each nephron
Diffusion and absorption of substances occur
- selective reabsorption of water, mineral ions and glucose
Waste goes to collecting duct to ureter
How are the bowmans capsule and glomerulus adapted
They are adapted to let very small molecules such as water, urea
And glucose through in to the nephron
Large molecules such as proteins and blood cells stay in the blood - this process is called filtration
The capillary cells in the glomerulus and bowmans capsule have spaces between them which makes them “leaky” - small molecules can filter through these spaces
What substances are included in selective reabsorption
- substances the body needs: glucose and some mineral ions
Tell me about the reabsorption of glucose and mineral ions
These substances are pumped through proteins in the cell membranes in the first convoluted tubule of the nephron by active transport - no glucose is usually left in urine
Where is water reabsorbed
Water is reabsorbed by osmosis depending how much body needs, it happens in the loop of Henle and In the collecting duct
What is the substance at the end of the nephron going to the ureter
The fluid contains excess water the body doesn’t need plus urea and other substances - it’s now urine
Tell me how the nephron is adapted in several ways for reabsorption of substances
There is a large surface area of contact between the nephron and capillaries
The membrane of the cells lining in the first convoluted tube has tiny folds - microvilli, these increase surface area to volume ratio of the cells
Cells that have protein pumps in their cell membranes contain many mitochondria
What is ADH
Antidiuretic hormone - is released by the pituitary gland to the kidneys when there is too little water in the blood - ADH changes the permeability of the collecting duct in nephrons and increases the concentration of the urine
What happens when the collecting duct is permeable
Water is absorbed by osmosis from the collecting duct back into the blood, when there is plenty of water in the blood, the pituitary gland stops releasing ADH
What happens when ADH is present
Collecting duct is highly permeable to water
there is high reabsorption of water
Small volume of concentrated urine produced
What happens when no ADH is present
Collecting duct is not permeable to water, a large volume of dilute urine is produced
