⭐️SB7- Animal Coordination, Control And Homeostasis Flashcards
What is metabolic rate?
Rate at which energy stored in food is transferred by all reactions that happen in the body
What is resting metabolic rate?
Metabolic rate that’s measured when the body’s at rest, in a warm room long after a meal
Name a hormone that effects metabolic rate
Thyroxine as it changes how certain cells work e.g. causing heart cells to contract more strongly
Where is thyroxine released from?
The thyroid gland
What’s negative feedback?
When an action directly triggers an opposite response
How is control of thyroxine level in the blood an example of negative feedback?
As an increase in thyroxine concentration directly causes a change that brings about a decrease in the amount of thyroxine released into the blood
What is homeostasis?
The constant maintenance of internal conditions to maintain optimal conditions for cellular reactions.
What are hormones?
Chemical messengers that take time to get around the body and are transported by the blood to their target organs
What processes require transfer of energy when the body is at rest?
Respiration, digestion, heart rate, mitosis e.c.t
How are thyroxine and metabolism linked?
It is produced when metabolism needs to be higher
What hormone does the hypothalamus make?
TRH
What hormone does the pituitary gland make?
TSH
What does TRH do?
It triggers the pituitary gland to make TSH
What does TSH do?
It triggers the thyroid gland to release thyroxine which goes to its target organs
What hormone do the adrenal glands release and where are they located?
Adrenalin, glands located above the kidneys
What are the three target organs of adrenaline?
The liver, the heart and the blood vessels
What does adrenaline do to the liver?
Causes breakdown of glycogen and when broken down, glucose molecules are released into the body for respiration
What does adrenaline do to the heart?
Causes the heart muscles to rapidly contract, increasing heart rate and pressure of blood flow
What does adrenaline do to the blood vessels?
Either widens the diameter to increase blood flow
Or narrows the diameter to reduce blood flow to muscles increasing blood pressure
Why is it important for adrenaline to trigger liver cells into changing glycogen to glucose?
As it increases blood sugar concentration and can then be used in respiration as energy
How long in a menstrual cycle cycle?
28 days
What happens at the start of the menstrual cycle?
Menstruation that lasts from 3-7 days
What is FSH?
A hormone produced just after menstruation, by the pituitary gland.
What does FSH do?
Matures the edges in the ovaries and stimulates the follicles to produce oestrogen
When does ovulation occur?
Day 13-15
When is a woman most likely to get pregnant?
After the ovary releases the egg in ovulation : between day 16-20 of her cycle
What does increasing oestrogen after being triggered by FSH cause?
The LH hormone surges causing the dominant follicle to rupture and releasing a mature egg from the ovary into the Fallopian tube
What happens to the empty follicle after the LH surge causes the egg to be released?
Progesterone is produced by the follicle inside the ovary
What does progesterone cause?
Further build up in the lining of the womb in preparation for a fertilised egg
What happens at the end of the cycle if the egg isn’t fertilised?
The follicle shrinks, progesterone decreases causing the uterus lining to break down and shed and menstruation starts again
For oestrogen:
Where is it produced?
When is it produced?
What does it trigger?
- produces by the follicles in the ovaries
- at around the middle of the menstrual cycle
- triggers the LH hormone to surge and inhibits FSH
How does a diaphragm or cap prevent fertilisation?
As it’s placed over the cervix and prevents sperm entering the vagina
How does the hormone pill prevent fertilisation?
It releases hormones to prevent ovulation and thickens mucus at the cervix making it hard for sperm to pass through
Why does the pill have a lot of oestrogen?
Use knowledge of hormones to explain
As oestrogen inhibits FSH so no eggs will be matured
What is IVF?
Invetro fertilisation which stands for fertilisation in a Petri dish
When may a couple find it hard to have children?
When a woman is Lowe on oestrogen, when there’s a lack of FSH, if the male has a low sperm count e. c.t
What is Assisted Reproductive Technique? (ART)
A technique that uses hormones and other techniques to increase chances of getting pregnant
Name some ART techniques
Clomifene therapy and IVF
What is clomifene therapy?
A drug that helps increase the concentration of FSH and LH in the blood for women that rarely or never release an egg in the menstrual cycle
What problems can IVF overcome?
Blocked oviducts in the woman, low sperm count for makes
What are the steps to IVF?
- Egg follicle maturation stimulated by hormones
- Egg cell released by follicles taken from ovary
- Sperm cells taken from man
- Egg and sperm combined in Petri dish
- If fertilised, one/two embryos placed in uterus
For LH,
Where is it produced?
When is it produced?
What does it trigger?
Produced in the pituitary gland, middle of the cycle around day 14 and triggers ovulation by causing the dominant follicle to rupture releasing a mature egg
For progesterone,
Where is it produced?
When is it produced?
What does it trigger?
Made by the empty follicle around day 22 of the cycle, causes the uterus lining to thicken in preparation for the fertilised egg
What can urine tests do?
Test for pregnancy and diseases like diabetes
What does insulin do?
A hormone that regulates blood glucose concentration
What food group breaks down into glucose?
Carbohydrates
Why is it important to control blood glucose levels?
If it’s too high, organs can be damaged
What happens once the pancreas produces insulin?
cells in the liver and other organs take in glucose
What happens when blood glucose rises?
It stimulates the pancreas to produce insulin
What happens once cells in liver and elsewhere take in glucose?
The glucose is changed to glycogen for storage which makes blood glucose concentration fall back to normal
What happens when blood glucose falls?
Cells in the pancreas stop releasing insulin altogether
What’s glucagon?
A hormone released by the pancreatic cells
What does glucagon do?
Causes liver cells to convert glycogen back to glucose and so the pancreas releases a lower amount of glucagon until it no longer has to
Give an example of homeostasis?
Maintaining glucose levels in the blood
What is type 1 diabetes?
Where the pancreatic cells that should produce insulin don’t as the cells have been destroyed by the body’s immune system
What is the first test for type 1 diabetes?
To see if there’s glucose in urine
How can type 1 diabetes be treated, what’s the advantages and disadvantages for each of them?
Via insulin injections
Adv:cheap and discreet
Dis adv. greater chance in sudden increase or decrease of blood glucose concentration and uses more insulin per day
-or by an insulin pump:
Adv: controls glucose concentration better
Disadvantage: expensive and must be worn all the time
What is type 2 diabetes?
Caused by an insulin resistance as the liver cells don’t respond to the insulin or respond very poorly
How can the conditions of type 2 diabetes be improved?
By eating healthily, exercising more or with medicine to reduce amount of glucose the liver releases into the blood
What makes people more likely to develop type two diabetes?
The amount of fat in their body, genetic factors
How do you calculate BMI?
Mass (kg)/height squared in meters
Give an alternative measurement to BMI and how it’s calculated
waist to hip ratio
Calculated by taking the waist measurement and dividing it by the hip measurement
What does the regulatory centre do and where is it?
senses the temp of blood flowing through the hypothalamus
How does the hypothalamus detect heat?
From heat receptors in the skin
Sensory neurones
The regulatory centre
What is vasodilation
It’s when the rate of heat loss is increased
When is vasodilation triggered?
When core body temp starts to increase
What are the steps to allow vasodilation?
- Smooth muscles in the arteriole walls relax and the wall itself dilates
- More blood then flows through the capillaries near the skins surface
- This increases the rate if heat loss in the body
What’s vasoconstriction?
A decrease in the rate of heat loss
What triggers vasoconstriction?
When the core body temp decreases
What are the steps that allow vasoconstriction?
- Smooth muscles in the arteriole walls contract so the arteriole is constricted
- Less blood is then allowed to flow through the capillaries close to the skins surface as blood
- Instead, blood is redirected to lower layers of skin
- Rate of heat loss from body is decreased
How is vasoconstriction and vasodilation an example of negative feedback?
As it helps keep conditions in the body under control at the right levels
What’s thermoregulation?
Controlling body temp. so it stays at 37°C
Why does your hair stand on end when you’re cold?
As when rate of heat loss increases, the pilli erector muscles contract which makes the hair stand on end so that there’s an insulating layer of air between the hair to reduce heat loss rate
Why is pili erection more effective in mammals?
As their hair is much thicker and so the air layer will be more insulating
Describe the role of the sweat gland in thermoregulation [2]
Sweat gland releases water onto the skin’s surface [1]
This water then evaporates [1] removing heat from the skin’s surface [1]
Why do we shiver?
As the muscles contract repeatedly so the rate of respiration in the muscles increases and more heat is generated
What happens when blood temp rises, what responses are triggered?
Change detected by the hypothalamus triggered the responses of vasodilation and sweating
What happens when blood temperature falls, what responses are triggered?
The change of temp is detected by the hypothalamus triggering vasoconstriction, goosebumps and shivering
What is osmoregulation?
The control in the balance of water and mineral salts in the body
Why is it important there is the right balance of water and mineral salts in cells?
As the cells may be caused to loose or take in too much water by osmosis
Why is water in cells important?
It allows molecules in the cell’s reactions to move around and its needed to maintain cellular shape
What is the urinary system for?
To remove excess amounts of some substances from the blood
What do renal veins do?
Carry clean blood back to the body
What do the ureters do?
Carry urine from the kidneys to the bladder
What does urine flow through to exit the body?
The urethra
What do the kidneys do?
Remove substances from the blood and make urine
What are the two problems that can cause happen to the kidneys?
Kidney stones and renal damage / faliure
How can kidney failure or renal damage be treated?
With dialysis or kidney transplant
Give 2 advantages of a kidney transplant
- patients can lead a more normal life without having to watch what they eat
- cheaper for the NHS overall
What are the disadvantages of a kidney transplant?
- the kidney only lasts 8-9 years on average
- the operation carries risks
- shortage of organ donors
- immune suppressant drugs have to be taken which increase risk of infection
What are the advantages of dialysis?
- No need for immune suppressant drugs
- available to all kidney patients
What’s the disadvantages of dialysis?
- Patient must limit their salt and protein intake
- dialysis sessions are regular
- expensive for the NHS
How does a dialysis machine work?
Blood flows through a tube of semi permeable membrane in a dialysis fluid and excess salts and urea move out of blood by diffusion along a concentration gradient though the semi permeable membrane
In dialysis, why is there no net movement of sugar?
As the concentration of sugar in the dialysis fluid is the same as that in the blood of the patient
Why is it important for someone who has a kidney transplant to take immune system suppressant drugs?
As the cells in the patients immune system may attack the antigens in the kidney and cause the body to reject it despite the kidney donors antigens and the patients antigens have been matched as there’s still a risk
What is the glomerulus in the kidney?
what does it do?
Why is it able to do this?
A capillary network that runs through the bowman capsule
It filters blood by squeezing it through
This happens because the waste products that must be filtered like urea are small enough to be pushed through while proteins and blood cells are too big
What happens in the convoluted tuble in the kidney and why?
Selective reabsorption as glucose and mineral ions that are needed re enter the blood via active transport
What happens at the loop of Henle in the kidney, how and why?
Where water is reabsorbed out of urine
Happens via osmosis through a semi permeable membrane
This is to get remaining water out of urine to get as much water as possible
What happens at the collecting duct in the kidney, how and why?
Where water is reabsorbed back into the blood through osmosis
It happens by ADH changing the permeability of the collecting duct so it’s easier to release the water into the blood
What is ADH?
A hormone that changes permeability of the collecting duct in the kidney
What happens if water in the blood is too low?
- Pituitary gland secrets ADH
- collecting duct becomes more permeable to water
- Water passes back into the blood
What are the structural features of the nephron in chronological order?
The glomerulus
First convoluted tube
Loop of henle
Collecting duct
Why do reptiles lie in sunlight for a long period of time? [2]
Because reptiles are ectothermic [1]
This means they cannot generate heat to maintain their own body temp [1]
What does the hypothalamus do to body temperature?
It controls it
How can excessive cause body temperature to increase? [2]
Because the muscles contract and relax [1]
And they release heat energy by respiration [1]
Explain how the capillaries are adapted to allow water and ions into the Bowman’s capsule
As they only let small molecules like urea, water and glucose through but keep larger molecules like blood cells and proteins in the blood
Explain one disadvantage of using hormones to stimulate ovulation to treat infertility [2]
More than one egg is fertilised [1]
This could increase risk of complications [1]
High levels of what hormone prevent ovulation during pregnancy?
Progesterone
Explain how the blood entering a nephron is filtered to remove excess sodium ions and water [3]
Ultrafiltration occurs in the glomerulus where the liquid part of the blood passes into the bowman’s capsule [1]
Reabsorption takes place as it travels through the proximal convoluted tuble into the loop of Henle [1]
Urine production then occurs in the collecting duct and excess fluid and sodium ions are removed [1]
Explain why a doctor might advise someone with type two diabetes to increase their daily excessive [2]
As excessive reduces blood sugar levels [1] because the muscle cells will use up more glucose [1] in aerobic respiration
