Homonal Coordination Flashcards
What is the human endocrine system?
Composed of glands that secrete chemicals called hormones into the bloodstream. Blood carries hormones to a target organ where an effect is produced.
Compare the effects of the endocrine system to the effects of the nervous system?
Slower
Act for longer
What organ is blood sugar concentration monitored and controlled by?
Pancreas
What is the pituitary gland?
Master gland in brain
Secretes several hormones
These hormones act on other glands to stimulate the release of other hormones, and bring about effects
What is the negative feedback loop for when blood glucose is too high?
Pancreas releases insulin which moves from the blood into cells
Excess glucose is converted into glycogen in the LIVER and MUSCLE CELLS for storage
Blood glucose falls
What is the negative feedback loop for when blood glucose is too low?
Pancreas releases glucagon
Glycogen converted into glucose and released into blood
Amino acids and fats are broken down
Blood glucose rises
What is diabetes?
Diabetes is a non-communicable disease in which the body either cannot produce or respond to insulin, leading to uncontrolled blood glucose concentrations
What is Type 1 Diabetes (3 things)?
Early onset
Pancreas stops producing sufficient insulin
Commonly treated through insulin injections, also diet control and exercise
What is Type 2 Diabetes (3 things)?
Later onset, often as a result of obesity
Body doesn’t respond to insulin produced
Commonly treated through a carbohydrate-controlled diet and exercise
Maintaining water and nitrogen balance
Water leaves the body through the lungs via exhalation
Water, ions and urea are lost through the skin from sweat
Excess removed by kidneys as urine
Why must levels of water in the body be balanced?
Cells do not function efficiently if they lose or gain too much water
How do the kidneys produce urine?
Filtration of the blood and selective reabsorption of useful substances, such as water, glucose and some ions
How is the water level in the blood controlled?
Hormone ADH
Affects the amount of water absorbed by the kidney tubules
Negative feedback cycle
What is the negative feedback loop for ADH?
Water concentration too high/ low
Pituitary
Less/ more ADH released
Kidney tubules absorb less/ more water
Lots of/ little urine produced
Blood restored to normal
What is dialysis (6 steps)?
Blood temporarily removed from patients body
Filtered through machine
Patients blood passes over dialysis fluid
Dialysis fluid has no urea
Urea and waste products diffuse from high concentration to low concentration
Patients blood returned to body
What is deamination?
Digestion of proteins from food results in excess amino acids
Amino acids are delaminated to form ammonia
Ammonia is toxic so it is immediately converted to urea for safe excretion
What is a negative feedback loop?
Work to maintain a steady state
What is adrenaline?
Produced by adrenal glands in times of stress and fear
Increases heart rate
Boosts delivery of oxygen and glucose to brain and muscles
Prepares the body for fight or flight
Does not involve negative feedback
Why is adrenaline not negative feedback?
Adrenal glands stop producing adrenaline
What is thyroxine?
Produced by thyroid gland
Regulates how quickly your body uses energy and makes proteins = metabolic rate
Important for growth and development
Controlled by negative feedback
What is oestrogen?
Main female reproductive hormone
Produced in the ovary
At puberty, eggs begin to mature, and one is released every 28 days
Causes lining of uterus wall to thicken
Inhibits release of FSH
Stimulates release of LH
What is testosterone?
Main male reproductive hormone
Produced by testes
Stimulates sperm production
What is FSH?
Released by pituitary gland
Causes eggs to mature
Stimulates ovaries to produce oestrogen
What is LH?
Released by pituitary gland
Stimulates the release of mature eggs = ovulation
What is progesterone?
Released by ovaries
Maintains thick uterus lining
Inhibits release of LH and FSH
What is the change in the ovary across the menstrual cycle?
Egg matures until around the 14th day when ovulation occurs
After ovulation a yellow body forms until day 21 when it begins to break down
What are the levels of pituitary hormones?
Rise for first five days and then fall to day 14
Spike at day 14 (LH)
Steady rate
What are the blood oestrogen levels over 28 days?
Steady low for 5 days
Rise until day 14 when drops
Gently rises to day 21 before falling again
What is the blood progesterone level?
Steady for 14 days before rising and then falling to day 28
What are oral contraceptives?
Inhibit FSH using chemicals
No eggs mature
What is an injection/ implant/ skin patch?
Slow release of progesterone to inhibit maturation and release of eggs
What is barrier contraception?
Prevent sperm reaching egg
E.g condom or diaphragm
What are intrauterine devices?
Prevent the implantation of an embryo or can release hormones
What are spermicidal agents?
Kill or disable sperm
What is abstaining?
Not having sex
What is another non-hormonal contraceptive method?
Male or female sterilisation
What is IVF?
Mother given LSH and FH to stimulate maturation of several eggs
Eggs collected from mother and fertilised by sperm in a laboratory
Fertilised eggs develop into embryos and are inserted into the mothers uterus
Disadvantages of IVF
Emotional and physical stress
Low success rate
Multiple births which are a risk to mother and babies
What is phototropism?
Orientation and growth of plants in response to light
What is geotropism or gravitropism?
Growth of plants in response to gravity
What are auxins?
Plant growth regulator
Unequal distributions lead to unequal growth rates in plants roots and shoots
What are auxins used for?
Weed killer
Roofing powder
Promoting growth in tissue cultures
What is ethene?
Acts as a hormone to control cell division
What is ethene used for?
Controls ripening of fruit
What are gibberellins used for?
End seed dormancy
Promote flowering
Increase fruit size
What are gibberellins?
Regulate developmental processes including initiating seed germination
What is the hypothalamus?
Responds to signals
Releases hormones to pituitary gland
What is the pituitary gland?
Stimulates other hormones
Regulated body functions
What is the thyroid gland?
Controls body’s metabolism
Produces thyroxine, using iodine
T-shirts gives negative feedback loop
What is the pancreas?
Produces enzymes
Produces insulin and glucagon
What are the adrenal glands?
Stress response
Produce adrenaline
Causes tired glycogen in the liver to be converted to glucose for respiration and increase mental awareness
Pupils dilate to let in more light and blood is diverted away from digestive system to limbs
Not a negative feedback loop
Why can surgery on brain be done on conscious patients?
No pain receptors or sensory nerve endings
Electrical stimulation
How can we use insulin from other animals?
Extracts of animal pancreas
Animal insulin from cows and pigs
Genetic engineering
What is core temperature?
36-38 degrees
Needs to be right temp for enzymes
What happens when too hot?
Sweat - evaporation causes cooling
Low metabolism
Vasodilation - heat loss via radiation
Hairs lie flat
Drink more
What happens if too cold?
Shiver
Goosebumps
Hairs stand up
Vasoconstriction
Raises metabolism
Sweat less
Where does carbon dioxide dissolve?
Cytoplasm to make acidic conditions, affecting enzyme activity
What is urea?
Breakdown of excess protein in liver into amino acids
Deamination to from toxic ammonia
Converted instantly to urea
Filtered from blood in kidney
Excess water and salts combine to make urine
What do the kidneys do?
Ultrafiltration: urea, water, salt and glucose diffuse from the blood through the nephron
Red blood cells and large proteins are too big
Selective reabsorption: In the first tube, 2/3 of the water and salts are reabsorbed. Glucose moves out via active transport. These substances go back into the blood
Loop of Henle: The down part is permeable to water and not salt, water will diffuse into blood so more is reabsorbed. The up part is permeable to salt, increasing the salt concentration. Some may diffuse back into blood.
Collecting duct: the remainder of the salts and water move into the collecting duct, permeable to water and controlled by ADH
All the urea, non absorbed water and salt travel to the bladder to from urine and are removed from the body
Can kidneys be replaced?
Yes, usually from a dead donor
As close a tissue match as possible
What is negative feedback loop for ADH?
Water concentration too high/ low
At pituitary, less/ more ADH released
Kidney tubules reabsorb less/ more water
Lots/ little urine produced
Blood restored to normal
What is a transplant?
No special diet
No dialysis
Relatively inexpensive
Need donor
Need tissue match
Immunosuppressants
