hormones Flashcards
Hormones
proteins which are released from glands, called endocrine glands, they travel in bloodstream to their specific target organ and cause a specific change
disadvantages of coordination using hormones
speed of response, effect of hormones is much slower than effect of a nervous response and it occurs over a longer period of time
because they release hormones into bloodstream it is important that glands have a good blood supply so hormones will pass directly into blood to be dissolved in blood plasma and carried to its target organ
homeostasis
maintenance of the internal environment of the body in a relatively constant state
two examples of homeostasis are the control of blood glucose concentration by the hormone insulin and also controlling the water content of the body which is called osmoregulation
Insulin
fuel required for respiration is glucose and without glucose cells will not be able to respire and will soon begin to die
essential that level of glucose in blood is maintained at an appropriate level to ensure cells have a sufficient supply. if blood glucose levels become too low insufficient respiration will result in cell death, while too much glucose will lead to the cells losing water by a process of osmosis which will also damage cells
how is insulin produced
hormone, insulin is produced by specific cells in the pancreas in response to a rise in blood glucose levels to ensure that the level returns to normal
insulin lowers blood sugar by bringing about 3 effects
causes glucose to be converted into glycogen in liver
increases rate of cell respiration
causes more glucose to enter cells
what is glycogen and how does its formation leads to a reduction in blood glucose
excess glucose is converted to glycogen which is stored in the liver
insulin production process
1.blood glucose is normal
______________________________
2. a meal rich in carbohydrates is consumed
_________________________________
3. blood glucose levels rise
__________________________________
4. the pancreas produces more insulin
_______________________________________
5. more respiration, more uptake of glucose by cells , glucose is converted into glycogen.
____________________________________
6. blood glucose levels fall
________________________________–
7. blood glucose level returns to normal
negative feedback
vital in control of blood glucose levels because it is just as important to prevent glucose levels falling too much as it is to prevent them from becoming too high.
glucagon
a second hormone is involved in controlling blood sugar level which is produced by pancreas. it is produced when blood glucose levels are falling and it acts by reversing the changes insulin brings in the liver.
Diabetes
medical condition caused by too little insulin being released by the pancreas. As a result blood glucose levels remain high( hyperglycemia) or too low( hypoglycemia) which is potentially very dangerous in extreme cases and can cause a diabetic coma
most common symptoms
glucose in urine
almost constant thirstiness
frequent toilet visits
lethargy( lack of energy)
irritability and confusion
Treatment
condition cannot be cured, but can be controlled by regular injections of insulin and a carefully controlled diet where carbohydrate intake is closely monitored
why does insulin have to be injected as opposed to taken in tablet form
insulin has to be injected to it can quickly reach the blood directly and control blood sugar levels as opposed to tablet form which has to be digested before it can reach the blood stream.
the hormone wouldn’t stay intact
what should a diabetic person do if they find that their blood glucose levels are too high
give themselves insulin, inject themselves.
Exercise will help lower blood sugar levels
what could happen if a diabetic goes for too long without food
blood glucose levels may fall which may cause a hypo and they may pass out
differences between type 1 and type 2 diabetes
TYPE 1
insulin is not produced by the pancreas
insulin injections( plus controlled diet and exercise)
it is not caused by lifestyle
it is often in childhood
TYPE 2
insulin is produced but stops working properly or the pancreas does not produce enough insulin
usually controlled by diet initially but later requires medication and insulin injections
take regular exercise, reduce sugar intake and avoid obesity
it usually occurs in adults
long term effects
they can damage blood capillaries leading to the major organs including eyes, heart, kidney or brain
this in turn can result in eye damage and potential blindness, kidney and heart disease or stroke
Osmoregulation
example of homeostasis, it is used to control the amount of water in the blood and other body fluids. water has potential to damage our cells if it is not regulated.
kidneys are a part of the excretory system which removes waste from the body and carry out osmoregulation
how do the kidneys work
- Blood enters kidney via renal artery
- liquid and many dissolved substances are filtered out of the cortex
- In the medulla water and some of the substances are reabsorbed back into the blood in a controlled way until normal concentrations are reached
- any water and dissolved substances left over pass into urine which in collects in the renal pelvis
- urine passes into the ureter
- urine is stored in bladder
- urine is passed out via urethra
Blood too dilute
Blood concentration is normal
large amount of liquid is consumed
blood is too dilute
kidney reabsorbs less water back into blood and more urine is produced
Blood too concentrated
Blood concentration is normal
lots of water is lost in sweating during exercise
blood is too concentrated
Kidney reabsorbs more water back into blood and less urine is produced
antidiuretic hormone
if the blood is too concentrated, more ADH is produced this will result in more water reabsorption and less urine produced
if the blood is too dilute, less ADH is produced and this will result in less water reabsorption and more urine is produced
Auxin
produced in cells below the tip of the shoot
If light is spread evenly
the auxin diffuses evenly to and all parts of the tip grow at the same rate.
if light is shone onto one side
the shoot grows towards the light because the light causes auxin to be distributed unevenly across the shoot, migrating away from the lit side of the and towards the shaded side, the auxin causes the cells of the shoot to elongate therefore the cells on the shaded side get longer causing this side to grow more making shoot bend towards light.
hormones as weed killers
need to be eliminated because they can affect crop production by competing for resources such as water, light and space. A range of hormones can be used but most contain artificial auxin( similar in structure and effects naturally occurring auxins in the plant.
They are very effective as they are selective and they work by causing weeds to grow in a rapid and uncontrolled way that they disintegrate.
effective against broad leaved plants such as daisies but not effective against narrow leaved plants such as grass
Hormones used to stimulate flowering and fruit production
can be sprayed onto commercially grown flowers, crops and fruits to ensure production is maximised
however, poor weather in NI lead to
damaged flowers
decrease number of insects for pollination
low pollination and therefore fruit production rates
Hormones in rooting powder and tissue culture
if cuttings of plants are taken, they can be used to grow new plants by placing them in compost and eventually roots and new plants form
this process can be accelerated by dipping the cut stems in rooting powder which contains hormones and stimulates growth known as tissue culture
tissue culture involves
small section of plant tissue called a callus
place them on nutrient agar
add hormones to differentiate and develop new plants
