Topic 7 - Animal Coordination, Control And Homeostatis Flashcards
What are hormones?
Hormones are chemical messengers that are made in one part of the body and are carried in the blood to other parts of the body, where they affect.
Hormonal controlled system responses are (faster/slower) than…
Slower than nervous System controlled responses
Describe how endocrine glands communicate with organs around the body (2)
release chemicals called hormones into the blood which carries them around the body to target organs
Metabolism definition
All the chemical reactions that occur in your body
Metabolic rate definition
The overall rate at which chemical reactions occur in your body
Factors that affect metabolic rate
Anything that affects the amount of energy required e.g trying to keep warm, exercise, digesting food
Where and how much adrenaline is released?
The adrenal glands. Very little is released into the blood
Affects of adrenaline
Heart muscle cells contract more rapidly and more strongly.
Diameter of blood vessels leading to muscles widens.
Diameter of blood vessels leading to other organs narrows.
Liver cells change glycogen to glucose and release it into the blood.
Conditions required to measure metabolic rate
Gap in time since eating, warm room, no movement
Negative feedback - definition
A control mechanism that reacts to a change in a condition, such as temperature, by trying to bring the condition back to normal.
What does the hormonal system consist of, and what do they do?
Endocrine glands that produce and release hormones
What does the pituitary gland produce? Where is it found?
ACTH, FSH, LH, growth hormone. Found in the brain (cerebellum)
What does the thyroid gland produce, where is it found?
In the neck, it produces thyroxine.
What do cells in the pancreas produce
Some that produce insulin and others that produce glucagon
What do the adrenal glands produce
Adrenalin
What do the testes produce
Sex hormone - Testosterone
What do the ovaries produce
Sex hormones oestrogen and progesterone
What happens once a hormone has been produced?
Once the hormone has been produced by the endocrine gland, it will travel in the blood to the organ it affects. This is called a target organ.
What are the effects of thyroxine?
- It causes heart cells to contract more strongly and rapidly.
- It increases the rate at which proteins and carbohydrates are broken down inside cells.
Why is thyroxine an example of negative feedback?
- The amount of thyroxine produced by the thyroid gland is controlled by hormones. This is an example of negative feedback.
The Menstrual Cycle length
28 days
When does menopause begin/end?
puberty until menopause
What does the menstrual cycle enable females to be?
fertile
What is the menstrual cycle controlled by (hormones)
Sex hormones oestrogen and progesterone
What are oestrogen and progesterone released by
The ovaries into the blood
What does oestrogen do?
involved in repairing and thickening the uterus lining (leads to ovulation)
What does progesterone do?
maintains the uterus lining
What does FSH do?
causes the maturation of an egg in the ovary
What does LH do?
Stimulates the release of an egg
Where are FSH and LH released from?
The pituitary gland
What is the release of LH and FSH controlled by?
Oestrogen and progesterone
What is contraception?
The prevention of fertilisation
How does fertilisation of the egg occur?
- During sexual intercourse sperm cells enter the vagina.
- They pass through the cervix into the uterus and then into the oviducts.
- If the sperm cell meets an egg cell here, it may be fertilised.
The Sperm’s Journey
Sperm Duct
Penis
Vagina
Cervix
Uterus
Oviduct (where it will fertilise the egg)
Common reasons for infertility
Blocked fallopian tubes
Physical problems with the uterus
Low sperm count
Abnormal or immotile sperm
What does IVF mean and stand for?
In vitro fertilisation: fertilisation in the laboratory outside the mother’s body (Latin: ‘in vitro’ means ‘in glass’)
What happens during IVF?
The woman is given FSH and LH to encourage her ovaries to release eggs.
The eggs are harvested and the man provides a sperm sample.
The sperm is used to fertilise the eggs in a Petri dish.
The fertilised eggs are left to develop into embryos.
What happens when the egg is fertilised?
When they are at the eight cell stage, viable embryos are implanted into the woman’s uterus.
This can result in multiple pregnancies.
Spare embryos can be frozen for future attempts or donated to other couples. They can be destroyed.
Ethical issues surrounding IVF
Do single people have the right to have a child?
Should there be a price on fertility?
What about spare embryos?
Do people over a certain age have the right to have a child?
Clomifene Therapy
- Drug that is taken for 5 consecutive days each month, which promotes ovulation.
- Used for females that do not ovulate at all/not regularly.
- Can increase the chances of having twins
When was the first test tube baby?
1978
What happens when there is high blood glucose?
- The brain detects the level of glucose in the blood.
- The pancreas is stimulated to release insulin.
- The insulin allows glucose to enter the cells of the body, out of the blood. It stimulates the liver to take glucose from the blood and convert into glycogen, which is stored in the liver.
- The level of glucose in the blood decreases, causing the pancreas to stop producing insulin.
Low blood glucose
- Brain detects the level of glucose in the blood.
- The pancreas produces glucagon.
- glucagon stimulates the liver to convert glycogen back to glucose and release this glucose into the bloodstream.
- the level of glucose in the blood increases, causing the pancreas to stop producing glucagon.
What causes Type 1 Diabetes?
When the pancreas cells cannot produce enough insulin, because they have been destroyed by the immune system, therefore the level of blood glucose is high/increases and can be found in the urine.
How to treat Type 1 Diabetes
Inject themselves with insulin before eating to convert glucose to glycogen
What causes type 2 diabetes?
- insulin releasing cells not producing enough insulin
- target organs not responding properly to the hormone.
How to treat type 2 diabetes
A change of diet/exercise or medicine if that doesn’t work.
BMI =
mass/height^2
What BMI is obese
30 and above
Alternative to BMI
Waist:Hip Ratio
The function of the urinary system
To remove excess amounts of some substances from the blood, including water and mineral salts. It also removes waste products such as urea.
Urea is…
Is poisonous so must be removed. It passes into the blood and the kidneys filter it out. When it mixes with water it makes urine. The urine then passes to the bladder until you want to empty it
What happens if the concentration of fluids changes in your body?
It can cause water to move in or out via osmosis. This could destroy your cells.
What is osmoregulation?
The control of water and salt levels in the body.
How can water levels change?
- Breathing out water
- Eating and drinking
- Sweating
Function of the renal veins
Carry blood with wastes removed back to the body
Function of the ureters
Carry urine from the kidneys to the bladder
Function of the bladder
Stores urine
Where does urine flow through?
Through the urethra to the outside of the body
Function of the renal arteries
Carry blood from the body to the kidneys
Function of the kidneys
Remove substances from the blood and make urine
How do you control when to urinate?
A muscle keeps the exit from the bladder closed until a person decides to urinate
How do kidneys work (in a bit more detail)
- Your kidneys filter your blood and then reabsorb everything you need.
- Glucose, amino acids, mineral salts and urea all move out of the blood into the kidneys by diffusion.
How does filtration work
- The Bowman’s capsule and glomerulus are adapted to let very small molecules, such as water, urea and glucose, through into the nephron.
- Large molecules such as proteins, and blood cells, stay in the blood. This process is called filtration.
How does selective reabsorption work
- The filtration fluid flows along inside the nephron, where selective reabsorption of useful substances e.g glucose takes place.
- The substances are pumped through proteins in the cell membranes in the first convoluted tubule of the nephron by active transport.
- No glucose is normally left in urine.
How do sugar and mineral ions move back into the blood?
By active transport to make sure no sugar is left in the urine and the correct amount of mineral ions are reabsorbed
How is the nephron adapted for reabsorption of substances?
- There is a large surface area of contact between the nephron and capillaries.
- The cell membrane of the cells lining the first convoluted tubule has tiny folds called microvilli. These increase the surface area: volume ratio of the cells.
- Cells that have protein pumps in their cell membranes contain many mitochondria.
What 6 different things need to be controlled in the human body?
WASTE PRODUCTS THAT MUST BE REMOVED
1. Removal of CO2
2. Removal of Urea
THINGS TO KEEP AT RIGHT LEVEL
1. Water content
2. Sugar content
3. Temperature
4. Ion content
How does thermoregulation help in the cold?
- Shivering releases heat from respiration
- Subcutaneous fat insulates
- Hairs stand up trapping an insulatory layer of air around the body
- Vasoconstriction - blood vessels get thinner reducing blood flow near to the skin surface
How does thermoregulation help in the heat?
- Sweating - evaporation of the sweat on the skin surface takes heat away from the blood causing it to cool
- Vasodilation - blood vessels get wider increasing blood flow near to the skin surface
What happens if you’re dehydrated?
Dehydration
Decreased water potential of blood
Osmoreceptors cells in hypothalamus lose water (so shrink)
Stimulates nerve cells in the hypothalamus
Increased ADH (antidiuretic hormone) production by posterior pituitary gland
ADH carried in the blood
ADH arrives at the collecting duct
O,A,R,E,V,W
Control of water potential in the blood by negative feedback
6 steps
- Osmoreceptors detect low water content of body fluids
- ADH produced, secreted into capillaries of post pituitary gland
- Presence of ADH detected by receptors in membrane of collecting duct
- Enzyme active phophorylase produced
- Vesicles containing water permeable channels move to and fuse with membrane of the cell
- Water diffuses down water potential gradient out of collecting duct
How drinking alcohol affects the urine production of someone who has been drinking
Alcohol inhibits ADH, meaning water reabsorption in the collecting duct is greatly reduced. Therefore, there is a greater volume of urine produced.
Why is osmoregulation an example of negative feedback?
Because osmoregulation is a reaction to change in water and salt levels in the blood, where water and salt levels are trying to be brought back to normal.
How can the Kidney be damaged?
- Infections
- Genetic problems
- Accidents
What happens if the kidneys are damaged?
If the kidneys are damaged, toxins such as urea could build up. Salt and water balance can be lost.
Process of dialysis (artificial kidney)
- With dialysis the blood leaves their body and flow between a partially permeable membrane.
- On the other side of the membrane is dialysis fluid.
Disadvantages of Dialysis
Have to follow a carefully controlled diet (amount of water)
Have to have long sessions connected to a dialysis machine.
Many years of dialysis means it can become difficult to control the balance of substances.
BUT, the patient survives.
Kidney Transplants
If kidneys fail then they can be replaced by a healthy kidney from a donor.
Disadvantages of Kidney Transplants
Because the kidney comes from a different person, they will have different antigens on the surface.
This means there is a possibility the kidney could be rejected by the immune system.
How to reduce the risk of rejection
- The tissue type is similar between the donor and the recipient
- same blood group.
- the recipient will be given immunosuppresant drugs for the rest of their lives. People who take these drugs can not deal with infectious diseases very well.
What do oestrogen and testosterone do?
Oestrogen and testosterone stimulate the release of human growth hormone. Oestrogen and Testosterone stimulates cells in both muscles and bone cells to divide. It also stimulates the digestive system to absorb calcium ions (used to make bones strong).
What does Dialysis fluid contain/not contain?
- It contains the same concentration of glucose and mineral ions as normal blood plasma.
- It contains normal plasma levels of mineral ions.
- It contains no urea.
Why does Dialysis fluid contain the same concentration of glucose and mineral ions as normal blood plasma?
So there is no net movement of glucose out of the blood.
Why does dialysis fluid contain normal plasma levels of mineral ions?
So no excess ions are lost from the blood.
Why does dialysis fluid not contain urea?
So all of the urea moves from the blood in to the dialysis fluid.
What happens if heart muscle cells contract faster?
Increases the heart rate.
What happens if heart muscle cells contract more strongly?
Increases blood pressure.
What happens if the diameter of blood vessels leading to the muscles widens?
Increases blood flow to muscles.
What happens if diameter of blood vessels leading to other organs narrows?
Reduces blood flow to those organs and increases blood pressure.
What happens if liver cells change glycogen to glucose and release it into the blood?
Increases blood sugar concentration.
