Topic 7- Animal Coordination, Control And Homeostasis Flashcards
Hormones
Chemicals released directly into the blood affecting particular cells in target organs to control organs/cells need for constant adjustment.
What system is involved in the secretion of hormones?
The endocrine system
What glands produce hormones?
Endocrine glands
Examples of endocrine glands
The pituitary gland Thyroid gland Adrenal glands Ovaries Testes Pancreas
Pituitary gland
Location and function
Located in brain
master gland
Produce many hormones regulating body conditions and acting on other glands to release hormones that bring about change.
Thyroid gland
What does it produce?
THYROXINE (controlling metabolism, heart rate, temperature)
Ovaries
What do they produce?
OESTROGEN (involved in menstrual cycle)
Testes
What does it produce?
TESTOSTERONE (controls puberty and sperm production)
Adrenal glands
What does it produce?
ADRENALINE (prepares body for ‘fight or flight’ response)
pancreas
What does it produce?
INSULIN (regulates blood glucose levels)
Difference between hormones and neurones
Neurones = fast while hormones = slow action
Neurones= short time while hormones= long lasting
Neurones act on precise area while hormones act in a general area
Where are adrenal glands located?
Just above kidneys.
How does adrenaline prepare your body for, ‘flight/fight’?
Binds to specific heart receptors, causing heart muscle to contract more frequently w more force so heart rate/blood pressure increase.
Increases blood flow to muscles (more oxygen/glucose for respiration)
Also binds to receptors in liver, causing liver to break down glycogen stores and release glucose, increasing blood glucose level
What does your brain do when it detects a stressful situation
Sends nervous impulses to the adrenal glands which secrete adrenaline.
How does the body uses negative feedback systems?
When it detects a substance level has gone above/below the normal level, it triggers a response to bring the level back to normal again.
Metabolic rate
The speed at which chemical reactions in the body occur.
What happens when your blood thyroxine level is lower than normal?
The hypothalamus is stimulated to release THYROTROPIN RELEASING HORMONE.
What does thyrotropin releasing hormone do?
Stimulates the pituitary gland to produce thyroid stimulating hormone which stimulates the thyroid gland to release thyroxine so the thyroxine level rises back to normal.
What happens when the blood thyroxine levels are higher than normal?
TRH production in the hypothalamus is inhibited .
The menstrual cycle
The monthly sequence of events in which the female body releases an egg and prepares the uterus in case the egg is fertilised.
Stage 1 of menstrual cycle
Uterus lining breaks down and is released
Uterus lining
Endometrium
Stage 2 of menstrual cycle
Uterus lining is repaired (day 4 to 14)
Until becomes spongy layer of blood vessels ready for fertilised egg to implant there.
Stage 3 of menstrual cycle
Egg develops and is released from ovary
Ovulation
Day 14
Stage 4 of menstrual cycle
Lining is maintained until day 28 (w no fertilised egg)
Spongy lining breaks down again
Whole cycle repeats
4 hormones controlling menstrual cycle
FSH (follicle stimulating hormone)
Oestrogen
LH (luteinising hormone)
Progesterone
Where’s follicle stimulating hormone produced ?
Function?
Pituitary gland
Causes a follicle to mature in ovaries and stimulates oestrogen production.
Follicle
An egg and its surrounding cells
Where’s oestrogen released?
Function?
Released by ovaries
Causes uterus lining to thicken / grow
Stimulates LH surge
Where’s luteinising hormone released?
Function?
Pituitary gland
Stimulates ovulation at day 14 so follicle ruptures and egg is released.
Stimulates remains of follicle to be a corpus luteum (secretes progesterone)
Where’s progesterone released?
Corpus Luteum (after ovulation ) Maintains uterus lining/ inhibits release of FSH and LH Fall in progesterone levels = endometrium breakdown = FSH increase
What will happen to progesterone levels if a fertilised egg implants in the uterus?
Progesterone levels will stay high to maintain endometrium during pregnancy
Infertile
Unable to reproduce naturally
2 ways in which an infertile couple can become pregnant
Clomifene therapy
IVF (in vitro fertilisation)
Clomifene therapy
Drug causing more FSH/ LH release, stimulating egg maturation/ovulation.
IVF
Collecting eggs and lab fertilising them w sperm, growing into embryos.
Transferred to uterus to improve pregnancy chance. FSH/LH given before to stimulate egg production.
Example of assisted reproductive technology
Assisted reproductive technology
Fertility treatment involving egg fertilisation outside of body.
Contraceptives
Hormones (eg, progesterone/ oestrogen) to prevent egg release, minipill, injection, patch or barrier methods (condoms/diaphragms )
How does oestrogen contraceptive work?
Keeps levels high to inhibit FSH production so egg development/production stops
How does progesterone hormone work?
Stimulates thick cervical mucus production, preventing sperm getting through uterus entrance.
What does the combined pill and patch contain?
Oestrogen and progesterone
What does the mini pill/ injection contain?
Progesterone
Pros of hormonal contraceptive methods
More effective at preventing pregnancy.
Don’t have to worry about contraception each time before sex.
Cons of hormonal contraceptive methods
Can have bad side effects (headaches, acne and mood changes)
Don’t protect against STI’s
Homeostasis
Maintaining a constant internal environment. Meaning the body needs to respond to both internal/external changes whilst balancing inputs with outputs.
Why is homeostasis important?
Cells need the right conditions in order to function properly, including enzyme action.
Is dangerous if conditions vary too much from normal.
Examples of homeostasis
Osmoregulation
Thermoregulation
Blood glucose regulation
Osmoregulation
Regulation of water content
Balancing water input w water output.
Thermoregulation
Process your body uses to keep its internal temperature steady.
Blood glucose regulation
So amount of glucose in blood doesn’t get too high/low.
Negative feedback systems in homeostasis
If condition changes away from normal level, response triggered to counteract change.
What controls blood glucose concentration
Insulin/glucagon
What puts glucose into the blood, from where?
Carbohydrates
From small intestine
What removes glucose from the blood?
Metabolism of cells
Vigorous exercise
Where’s excess glucose stored?
As glycogen in liver/muscles.
When stores are full, stored as lipid in tissues.
What monitors changes changes in blood glucose ?
Pancreas
Using insulin/glucagon
What happens when blood glucose concentration is too high?
Insulin is added from pancreas
Insulin pushes blood into liver to turn into glycogen for muscles/liver
What happens when blood glucose concentration is too low?
Glucagon is secreted from pancreas
Makes live turn glycogen to glucose
Type 1 diabetes
Condition where the pancreas produces too little/no insulin, resulting in a person’s blood glucose rising to a level that can kill them.
How are type 1 diabetics treated?
Using insulin therapy (injecting insulin in blood)
After meals so glucose is reduced quick after meal digestion.
Where is insulin usually injected?
Into subcutaneous tissue (fatty tissue under skin)
What does the amount of insulin injected depend on?
A person’s diet/activity
What do type 1 diabetics have to do
Limit simple carbohydrates intake
Take regular exercise
Type 2 diabetes
Condition where pancreas doesn’t produce enough insulin or when a person becomes resistant to insulin, causing blood glucose levels to rise.
BMI
weight(kg)/ height (m) squared
Obesity correlates w diabetes
Waist to hip ratio
Waist circumference (cm)/hip circumference (cm)
Male / female abdominal obesity measures
Above 1 for men and 0.85 for women
What can type 2 diabetes be controlled by?
Healthy diet Regular exercise Weight loss Medication Insulin shots
What temp do enzymes in the human body work best at?
37 °C
Below, enzyme activity slows down
Above, enzymes start to denature so they can’t work
Where’s the thermoregulatory centre?
hypothalamus
How does the thermoregulatory centre work?
Contains receptors sensitive to blood temperature in brain
Receives impulses from skin receptors in the epidermis/ dermis, providing info on the external temperature
Where are skin receptors?
In the epidermis (outer-layer of skin)
Dermis (deeper layer of skin just below epidermis)
What happens when you are too hot?
Erector muscles?
Sweat glands?
Blood vessels?
Erector muscles RELAX (hairs lie flat)
Sweat forms in sweat glands released onto surface of skin through epidermis pores, evaporates to transfer energy from skin to environment.
Blood vessels near skin dilate (vasodilation) to allow more blood to flow near surface to transfer energy to surroundings.
Sweat
Water and salts
What happens when you are too cold?
Erector muscles CONTRACT (hairs stand up to trap insulating layer of air near skin surface)
V little sweat is produced.
Skin blood vessels constrict (vasoconstriction) so less blood flows near surface to transfer heat.
You also shiver (automatic muscle contractions) to increase respiration rate to transfer more energy to warm body
What will happen if there’s a too high concentration of water in the blood?
Water will move into the body cells via osmosis, too much will cause them to burst.
What happens if water concentration in the blood is too low?
The water will move out of the cells into the blood via osmosis, causing the cell to shrink.
What organ helps to regulate water content?
The kidneys regulate how much water is reabsorbed/lost through urine.
Why do animal cells burst when they contain too much water?
They don’t have a rigid cell wall, unlike plant cells which become turgid instead.
What are the three main roles of kidneys?
Removal of urea from blood
Ion level adjustment in blood
Water content adjustment in blood
What’s urea?
Excess amino acids broken down in the liver
How do kidneys carry out their functions?
By filtering out things from the blood in high pressure and then reabsorbing useful things.
End product = urine
What does the urinary system consist of?
Renal artery/vein Right/left kidney Ureter Bladder Urethra
Nephron
Filtration units in kidneys
What happens in each nephron while they filter things out of the blood?
Liquid blood is forced out of glomerulus into Bowman’s capsule at high pressure (ultrafiltration).
Bigger molecules/blood cells can’t pass through membranes so aren’t forced out.
Liquid part of blood
Water, urea, ions and glucose
Ultrafiltration
Liquid blood being forced out of glomerulus into Bowman’s capsule at high pressure while bigger molecules can’t pass through.
What happens during reabsorption at the nephron?
Glucose is selectively reabsorbed back into blood against gradient.
Sufficient ions are reabsorbed
Sufficient water is reabsorbed according to ADH hormone
What controls reabsorption of water?
Where does this occur?
ADH hormone
In the henle
Why do animals in droughts have longer loops of henle?
To reabsorb more water
What happens to whatever isn’t reabsorbed?
It continues out of the nephron via the collecting duct, passes into ureter and down to bladder as urine released through urethra
What controls water reabsorbed in the kidney nephrons ?
Anti-diuretic hormone (ADH)
What releases ADH into the blood?
The pituitary gland
How does ADH work ?
Makes collecting ducts of nephrons more permeable so more water reabsorbs into blood.
Stops dehydration
Body
Negative feedback system of water content regulation
Water LOSS > brain detection> pituitary gland makes more ADH>ADH means kidney reabsorbs more water.
Water GAIN > brain detection> pituitary gland releases less ADH> less water reabsorbs
Function of a dialysis machine
Filters blood, keeping substances at right concentration/removing waste
Why aren’t the salts/glucose removed from the blood during dialysis?
Dialysis fluid is the same concentration of salts and glucose as blood plasma.
Characteristic of dialysis barrier
Permeable to ions/waste substances but not larger molecules such as proteins.
Only cure for kidney disease
A kidney transplant
What precautions are taken to prevent rejection to a liver transplant?
Only donors w similar tissue type are chosen.
Patient is treated w drugs to suppress immune system (so won’t attack kidney)
