Hormonal coordination in humans (5.3) (M) Flashcards
What is a hormone?
A chemical messenger synthesised by an endocrine gland and released into the blood to affect specific target tissue
How does the endocrine system work?
The endocrine system is composed of glands which secrete chemicals called hormones directly into the bloodstream.
The blood carries the hormone to a target organ where it produces an effect
Compare the effects of the nervous system with that of the endocrine system
Compared to the nervous system, the effects are slower, but act for longer
also via blood instead of electrical impulse
What is the pituitary gland referred to as?
the ‘master gland’
Where is the pituitary gland found?
the brain
Why is the pituitary gland called the master gland?
It secretes several hormones into the blood in response to body conditions.
These hormones in turn act on other glands to stimulate other hormones to be released to bring about effects.
Label these components on the body: pituitary gland, pancreas, thyroid, adrenal gland, ovary, testes.
- Ignore pineal gland, parathyroid gland*
- thyroid = thyroid gland*
What does the pancreas monitor and control in the human endocrine system?
blood glucose concentration
What does the pancreas (and liver/muscle cells) do if the blood glucose concentration is too high?
The pancreas detects high blood glucose
The pancreas produces the hormone insulin that causes glucose to move from the blood into the cells.
In liver and muscle cells, excess glucose to be converted to glycogen for storage.
What is type 1 diabetes?
a disorder in which the pancreas fails to produce sufficient insulin
often genetic
What is type 1 diabetes characterised by?
uncontrolled high blood glucose levels
How is type 1 diabetes normally treated?
with insulin injections
What is type 2 diabetes?
a disease in which the body cells no longer respond to insulin produced by the pancreas
not genetic
What are common treatments for type 2 diabetes?
a carbohydrate controlled diet and an exercise regime
What is a risk factor for type 2 diabetes?
obesity
What does the pancreas do if blood glucose concentration is too low?
pancreas detects low blood glucose
the pancreas produces the hormone glucagon that causes glycogen to be converted into glucose and released into the blood
Describe (via a diagram) how glucagon interacts with insulin in a negative feedback cycle to control blood glucose (sugar) levels in the body
What bodily fluids are lost during exhalation?
Water leaves the body via the lungs during exhalation
What bodily fluids are lost during sweating?
Water, ions and urea are lost from the skin in sweat.
There is (…) control over water, ion or urea loss by the lungs or skin.
no
What/how are bodily fluids lost in urine?
Excess water, ions and urea are removed via the kidneys in the urine.
What happens if there is a greater water concentration inside the cell after osmosis?
the cytoplasm pushes against the cell wall and becomes turgid
What happens if there is a lower water concentration inside the cell after osmosis?
the cytoplasm pulls away from the cell wall and becomes flaccid
What do you call it when the concentration of water molecules inside and outside the cells are equal?
isotonic
What happens if body cells lose or gain too much water by osmosis?
the body cells do not function efficiently.
What does the digestion of proteins from the diet result in…
excess amino acids which need to be excreted safely
excess amino acids may lead to abdominal cramps, diarrhoea, etc
What does the liver do to reduce excess amino acids in the blood?
In the liver these amino acids are deaminated to form ammonia
What is the issue with ammonia and how is it solved?
Ammonia is toxic
and so it is immediately converted to urea for safe excretion
How do the kidneys maintain water balance in the body?
The kidneys produce urine by filtration of the blood and selective reabsorption of useful substances such as all of the sugar, some of the ions (as needed by body) and some of the water (as needed by body).
Extra info (for 5/6 markers): Urea is present in urine - reabsorption of water by osmosis
The water level in the body is controlled by… (+ what it acts on)
the hormone ADH which acts on the kidney tubules
By what and when is ADH released?
ADH is released by the pituitary gland when the blood is too concentrated
What does ADH cause?
it causes more water to be reabsorbed back into the blood from the kidney tubules
So more concentrated urine is produced
What is the effect of ADH on the permeability of the kidney tubules?
They become more permeable to water (molecules absorbed more easily)
What is the reabsorption of water from kidney tubules into blood controlled by?
negative feedback
2 needed
What are treatment for kidney failure?
- organ transplant (is rare/expensive)
- kidney dialysis
6 marker
How is water content in the blood controlled?
- If water content too low, ADH released
- from pituitary gland
- into the blood
- causing kidneys to reabsorb more water
- so more concentrated/smaller volume urine produced
- if water content too high, ADH lowered/not produced
- less water reabsorbed by kidney
- more dilute/larger volume urine produced
Describe the basic principles of dialysis
- Use of partially permeable membrane
- use of dialysis fluid, which has ideal concentrations of solutes
- diffusion of waste substances (dissolved in water) out of blood
- then there will be equilibrium of water and ions between plasma and dialysis fluid
- People have to be connected into system for several hours (can be done at home), this may reduce quality of life
Why is it important that negative feedback brings a raised blood glucose concentration down?
Too much glucose in blood increases solute (glucose) concentration
Which draws out water from the body cells into the blood via osmosis
Which leads to cells not functioning efficiently (as become flaccid)
What organ makes the urea?
The liver
What does urea contain?
excess amino acids
6 points for 6 marks
Explain how the two hormones keep the blood glucose concentration at the correct level in a healthy human body
- Pancreas produced insulin and glucose
- if blood glucose levels are too high, insulin is produced/released
- allowing glucose to move from the blood into the cells / named eg liver
- glucose is converted to glycogen
- if blood glucose levels fall, glucagon is produced / released
- glycogen is converted to glucose
- causing glucose to be released into the blood
- This is negative feedback (not part of this mark scheme but have seen it form part of one on similair
5 marker
Explain how the body responds if slightly too much insulin is injected into the body?
blood glucose concentration goes too low
blood glucose concentration detected by pancreas
pancreas releases glucagon
glucagon causes cells to convert to glycogen into glucose
glucose released into blood
5 marker
How do the hormones insulin and glucagon control an increased blood glucose concentration?
- Insulin produced and released into the blood stream by pancreas
- Insulin causes glucose to enter cells
- glucose conversion to glycogen
- so blood glucose concentration decreases causing glucagon production and release into the bloodstream by pancreas
- glucagon causes glycogen to be converted to glucose
- raises blood glucose concentration
The body cells of a person with Type 2 diabetes do not respond to insulin
Why might a person with Type 2 diabetes have a higher blood insulin concentration than a non-diabetic person?
cells absorb less glucose
so glucose concentration in blood remains high
(This causes) the pancreas to release more insulin
Why would protein not be found in urine?
Too large
so cannot pass through filter
There are more not on this list - 3 needed
What are some substances found in urine?
- Water
- Ions
- Urea
- hormones
A diabetic person’s blood often stains high concentrations of glucose
Why would the urine of a diabetic person contain glucose?
Not all glucose reabsorbed
because not enough time
4 needed
Why might someone’s urine contain a higher concentration of mineral ions and urea on a hot day than a cold day?
More sweating occurred, so more water loss, so more water reabsorption by the kidney, so lower volume of urine produced
accept less water in urine for last marking point
Why must urea be excreted from the body?
Urea is a waste product and is toxic
4 markers - indicative content (exhaustive)
Give advantages and disadvantages of kidney transplant over dialysis
Advantages of kidney transplant
no need for regular / long hospital visits or is a long-term solution
flexible lifestyle, such as can go on holidays
may not live near a hospital or reference to transport costs
no risk of infection from frequent needles / treatment
less / no need to control diet
maintains correct concentration of substances in blood / body
cheaper long term for NHS / hospital
Disadvantages of kidney transplant
may be rejected
have to keep taking anti-rejection drugs or immunosuppressants
(suitable) donor may not be available or need for tissue matching
risk from surgery (e.g. anaesthesia or infection)
recovery from surgery will take a long time
does not last forever (therefore further surgery needed)
Give 2 biological reasons (with reason) to why one should use a kidney transplant over dialysis
- Changes in concentrations/urea are minimised so no/less chance of damage to body cells/tissues
- Not repeatedly puncturing skin so no/less chance of infection
What is a way in which doctors try to prevent kidney rejection?
Tissue typing
can have ‘treat with immunosuppressants’
After dialysis, the urea concentration in the blood will (…)
decrease
After dialysis, the glucose concentration in the blood will (…)
remain constant
assume this is similar for water/ions, get checked
5 marks
Describe how the kidney produces urine
The kidney filters the blood
Then the kidney reabsorbs all of the glucose
reabsorbs some of the ions
reabsorbs some of the water
release urine (in urea)
Why is a blood test more accurate than a urine test when testing blood glucose concentration?
there is not always glucose in urine
5 points
What happens to amino acids that can not be stored in the body? Describe fully
amino acids broken down
amino acids form urea
amino acids broken down/converted in liver or urea formed in liver
urea/broken down amino acids removed/filtered by kidney
urine/urea/broken down amino acids stored/held in bladder
