Topic 7 - Animal coordination, control and homeostasis Flashcards
Where are hormones produced and transported around the body
- Hormones produced by ENDOCRINE glands, released into blood
- travel around body in blood until reaching target organ
- hormone causes target organ to respond, eg by releasing another chemical substance
- different hormones, different target organs, different responses
Describe all the hormones and their target organs
TRH and CRH - pituary gland
TSH - thyroid gland
ADH - kidney
FSH and LH - ovaries
INSULIN and GLUCAGON - liver, muscle and adipose tissue
ADRENALIN - various organs, eg heart, liver, skin
PROGESTERONE - uterus
OESTROGEN - ovaries, uterus, pituary gland
TESTOSTERONE - male reproductive organs
Explain the main differences between hormones and nerve impulses
HORMONES:
- chemical signal
- transported in bloodstream
- cells in particular tissues (more specific)
- slow
- long duration
NERVES:
- electrical signal
- transmission between/through nerve cells
- muscles or glands
- very rapid
- short duration
Explain the effects of adrenalin and what its in response to
—> ADRENALIN released from adrenal glands, response to stress. Causes fight or flight
Effects:
- increases heart rate
- constricts some blood vessels, make blood pressure higher
- dilates other blood vessels, increases blood flow to muscles
- causes liver to convert glycogen -> glucose, which is released into the blood
Explain what thyroxine controls and how it controls it
—> THYROXINE controls metabolic rate (rate of cells respire - rate of energy transfers)
How it controls metabolic rate:
- low levels stimulates TRH production in hypothalamus
- causes TSH release from pituitary gland
- TSH acts on thyroid to produce thyroxine
- when normal levels thyroxine stops the release of TRH and the production of TSH
Describe the stages in the menstrual cycle
MENSTRUATION - break down of uterus lining - begins on day 1 of the cycle and usually lasts about 5 days
second week - the lining of the uterus is gradually built up
OVULATION - release of egg from ovary - day 14
Days 14 to 16 - fertilisation most likely
lining continues to build up - weeks 3 and 4
If fertilisation occurs, uterus lining is maintained and menstruation doesn’t happen
Which two hormones control the menstrual cycle and their roles and where are they produced
OESTROGEN - causes growth and repair of lining of uterus wall. Oestrogen inhibits FSH, produced in the ovaries
PROGESTERONE - produced by adrenal cortex, ovaries and testes. triggers lining to thicken
Explain the interactions of oestrogen, progesterone, FSH and LH in the control of the menstrual cycle
- FSH secreted from pituitary gland, causes a follicle in ovary to mature
- As matures, secretes oestrogen which inhibits FSH and starts thickening lining
- high concentration of oestrogen —> surge in LH from pituitary
- ovulation caused when egg is released from follicle
- ruptured follicle becomes a corpus luteum - secretes progesterone, oestrogen - cause more thickening of lining
- Progesterone inhibits FSH and LH. If egg isnt fertilised —> corpus luteum breaks down, progesterone concentration falls
- triggers menstruation, FSH not inhibited, can be secreted from pituitary gland
Explain the two types of contraception
HORMONAL - releasing hormones to prevent ovulation, thicken mucus at the cervix, preventing sperm
Eg :
Hormone pills, implants or injections
BARRIER - stops sperm reaching egg
Eg :
Male and female condoms, the diaphragm, caps and sponges
Give one advantage and one disadvantage of hormonal contraceptives compared with condoms
Hormonal contraceptives more effective than condoms ( >99%) at preventing pregnancy.
condoms protect STD’s, hormonal contraceptives do not
Explain how fertility drugs can be used to help fertility
CLOMIFENE can be used to cause + FSH and LH
- Fertility drug given to stimulate eggs to mature
- Eggs taken from ovaries
- Eggs + sperm in dish for fertilisation
- Fertilised eggs —> embryos
- When embryos are tiny balls of cells, one or two placed in mothers womb to develop
Define IVF (in-vitro fertilisation)
Fertilisation outside a woman’s body
Offered to those with conceiving problems
Follicle-stimulating hormone (FSH) is used to stimulate ovulation in a woman undergoing IVF treatment, even if she ovulates naturally, explain why. (2 marks)
stimulate the maturation of many eggs. Normally only one egg would mature in a normal cycle.
What is an advantage of using FSH in IVF treatment
Stimulating more eggs -> more embryos can be produced.
means enough embryos for woman to undergo several cycles if necessary
Explain homeostasis
Maintains conditions in body, constant level, response to internal/external change.
NEGATIVE FEEDBACK mechanisms respond change, help restore normal level
Define the relationship between thermoregulation and body temperature
THERMOREGULATION keeps core body temperature steady (around 37 degrees)
Controlled by hypothalamus (Thermoregulatory centre monitors and controls temp) , triggers change in skin and muscles
What corrections does the body make to a hot temperature environment
INCREASES energy transferred to surroundings by:
- changes triggered - blood flow so more blood flows near skin surface (dilate or constrict to change blood flow)
- sweat glands release more sweat onto skin surface to evaporate
- sebaceous glands produce oil that helps sweat spread out on skin
What corrections does the body make to a cold temperature environment
REDUCES energy transferred -> surroundings by:
- less blood near surface
- sweat stopped produced by glands
- body hairs raised by erector muscles in skin (goosebumps)
Explain why its important for the enzymes in our bodies that our internal temperature is fairly constant (2 marks)
Enzymes work fastest @ optimum
lower or higher, aren’t active, chemical reactions arent carried out as normal, causing harm to body
Define osmoregulation and its effect on animal cells
Controls amount water lost in urine, controls amount water in body
Stops animal cells swelling up/shrinking by osmosis if body water content changes
Explain the structure of the skin in thermoregulation
Vasodilation/vasoconstriction changes blood flow in surface capillaries depending on temperature in dermis
Sweat glands in dermis release sweat when warm to lose heat through evaporation
hair muscle contracts when cold to pull hairs upright, trapping layer of air, when warm hairs lie flat
Describe the role of the dermis and epidermis of the skin in cooling the body (4 marks)
Sweat glands in the dermis secrete sweat on to the epidermis. This evaporates, cooling the body down.
Muscles in dermis relax, hairs can lie flat. there is thinner layer of insulating air trapped against epidermis
Explain and describe vasoconstriction and the structure when a cold temperature is detected
More blood flows through deep skin blood vessels so less blood flows through surface capillaries
This keeps warm blood deeper in the skin so less heat is transferred to air. Little heat loss from skin
Explain and describe vasodilation and the structure when a hot temperature is detected
Less blood flows through deep skin blood vessels and more blood flows through surface capillaries.
This increases heat loss by radiation
Increases blood flow of warm blood near skin so heat can transfer easily to air
Explain how shivering affects body temperature when a cold environment is detected
Muscles quickly contract and relax in succession (causing shivering) releasing energy to warm the body
Describe osmoregulation in terms of a negative feedback system (3 marks)
If there is too much water in the body this means that more water is excreted in urine. If there isn’t enough water then less water is excreted in urine, helping to increase water levels again. This is an example of negative feedback because the body works to restore the balance
A pale skinned person may look pink after exercise.
Identify what causes this change (1 mark)
Describe and explain what effect this has on body temperature (2 marks)
They look pink because more blood is flowing near the surface of the skin as a result of vasodilation (1)
This increases the rate of transfer of heat energy from the body to the environment and so reduces body temperatures
Explain how the hormone insulin controls blood glucose concentration
If the blood glucose concentration is too high, the pancreas produces the hormone insulin, this causes glucose to move from the blood into the cells.
In liver and muscle cells excess glucose is converted to glycogen for storage
Insulin controls the storage of glycogen in your liver and muscles
Explain how blood glucose concentration is regulated by glucagon
When blood glucose levels fall, the pancreas releases glucagon
This causes your liver to break down the glycogen back into glucose
Explain the importance of glucose and pancreas
GLUCOSE is vital for respiration, allowing the body to release energy
The PANCREAS monitors and controls blood glucose concentration using insulin and glucagon
Explain the effect of low glucose on the pancreas, liver and blood glucose levels
PANCREAS - insulin not secreted into the blood
LIVER - doesn’t convert glucose into glycogen
BLOOD GLUCOSE LEVEL - Increases
Explain the effect of high glucose on the pancreas, liver and blood glucose levels
PANCREAS - insulin secreted into the blood
LIVER - converts glucose into glycogen
BLOOD GLUCOSE LEVEL - decreases
Explain the cause of type 1 diabetes
Caused when the immune system has damaged the persons insulin-secreting pancreatic cells, person doesn’t produce INSULIN
Explain how type 1 diabetes can be controlled
Inject insulin into the fat below the skin
They have to work out the right amount of insulin to inject so that the blood glucose concentration is kept within safe limits
Explain the cause of type 2 diabetes
Person doesn’t produce enough insulin but their liver and muscle cells have become RESISTANT to it
Explain how type 2 diabetes can be controlled
Most people eat less sugary foods and exercise
Medication can be used if needed
Evaluate the correlation between body mass and type 2 diabetes including waist:hip calculations and BMI
Measurements of fat, estimations used:
- BMI : mass (kg) / height^2 (m)
(Assumes that the mass of the body tissues is in proportion to height) - Fat closely linked to cardiovascular disease is abdominal fat
Divide waist by hip measurement to get waist:hip ratio
Describe the structure of the urinary system
RENAL VEINS - carry cleaned blood back to the body
URETERS carry URINE from the kidneys to the bladder
BLADDER stores urine
Urine flows through the URETHRA to the outside of the body
RENAL ARTERIES carry blood from the body to the kidneys
KIDNEYS remove substances (urea) from blood and makes urine
A muscle keeps the exit from the bladder closed until we decide to urinate
What is the difference between urea and urine, and the ureter and urethra
Urea is produced from the breakdown of excess amino acids in the liver, its toxic in excess however urine contains urea, water and salts.
Ureters are tube-like structures that connect the kidneys with the urinary bladder however urethra is a tube that connects the urinary bladder to the outside of the body
Explain how the structure of the nephron is related to its function in filtration in the glomerulus and Bowman’s capsule
Filtration of small molecules from blood into tubule, including water, glucose, salts and urea in the glomerulus and bowmans capsule
Glomerulus - small knot of capillaries
Bowman’s capsule - cup shaped
Explain how the structure of the nephron is related to its function in selective reabsorption of glucose
Selective reabsorption of glucose from tubule back into blood by active transport
(Selective reabsorption - useful molecules absorbed back into blood, other molecules left in tubule)
Explain how the structure of the nephron is related to its function in reabsorption of water
Reabsorption of water that the body needs from the tubule back into the blood (osmoregulation)
This happens in the COLLECTING DUCT
Explain the effect of ADH on the permeability of the collecting duct in regulating the water content of the blood
ADH - increases permeability of cell membranes in collecting duct of nephron
So more water reabsorbed from urine by osmosis
Explain the function of the hormone ADH
Amount of water reabsorbed from the nephrons is controlled by ADH (Antidiuretic hormone)
Regulates water content of blood (osmoregulation)
Explain what is meant by a negative feedback mechanism, using ADH production as a example (4 marks)
As increase in blood water content causes the pituitary gland to secrete less ADH. This causes less water to be reabsorbed by the collecting duct in the kidneys so more water is excreted by kidneys. A decrease in blood water content causes the pituitary gland to secrete more ADH, which causes less water to be excreted by the kidneys. This is a negative feedback mechanism because a change in blood water content causes an opposite change that restores the ‘normal’ blood water content
Describe kidney dialysis as a treatment for kidney failure
KIDNEY FAILURE is when it stops working so excess water, mineral ions and urea build up
KIDNEY DIALYSIS is carried out every 2 or 3 days
It uses diffusion which restores which restores normal dissolved substance concentrations in the blood.
Urea then diffuses out of the blood into the dialysis fluid
Dialysis fluid contains the same concentration of useful substances as blood so glucose and mineral ions aren’t lost
Describe kidney transplant as a treatment for kidney failure
Healthy kidney connected to blood circulation to replace
PROBLEMS :
Antigens on transplanted kidney cells different to patients. Antibodies in patient attack kidney and reject it
PREVENTING REJECTION:
- antigens must be as similar as possible
- drugs for life to reduce effects of immune system (patient may get more infections than usual)
