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B11. - Coggle Diagram
B11.
Plant hormones and
using plant hormones:
Plants are sensitive to light and gravity.
Plant responses to light and gravity are brought about by the plant hormone auxin.
The responses of roots and shoots to stimuli of light and gravity are the result of the unequal distribution of auxin.
Shoots grow towards light and against the force of gravity
Roots grow in the direction of the force of gravity.
Plant hormones are used in agriculture and horticulture.
Auxins are used as weed killers, rooting powders, and in tissue culture.
Ethene is used to control fruit ripening.
Gibberellins can be used to increase fruit size, end seed dormancy, and promote flowering in the malting process, and increase the yield of sugar cane.
Control of blood glucose levels:
Blood glucose concentration is monitored and controlled by your pancreas.
The pancreas produces the hormone insulin, which allows glucose to travel from the blood into the cells and be stored as glycogen in the liver and muscles.
The pancreas also produces glucagon, which allows glycogen to be converted back into glucose and released into the blood.
Glucagon interacts with insulin in a negative cycle to control glucose levels.
In type 1 diabetes, the blood glucose may rise to fatally high levels because the pancreas does not secrete enough insulin.
In type 2 diabetes, your body stops responding to its own insulin.
The endocrine system and glands:
The system is comprised of glands that secrete chemicals called hormones directly into the blood stream. The blood carries the hormone to a target organ where it produces an effect.
Compared to the nervous system, the effects of hormones are often slower but longer lasting.
The pituitary gland is the master gland and secretes several hormones into the blood in response to body conditions. Some of these hormones act on other glands and stimulate them to excrete hormones for specific effects.
Key endocrine glands are the pituitary, thyroid, pancreas, adrenal glands, ovaries and testes.
Negative Feedback:
Thyroxine from the thyroid gland stimulates the basal metabolic rate. It plays an important role in growth and development.
Adrenaline is produced by the adrenal glands in times of fear or stress. It increases the heart rate and boosts the delivery of oxygen and glucose to the brain and muscles, preparing the body for "fight or flight"
Thyroxine is controlled by negative feedback whereas adrenaline is not.
IVF:
FSH and LH can be used as a fertility drug to stimulate ovulation in women with low FSH levels.
In Vitro Fertilization FSH and LH are used to stimulate maturation of ova that are collected, fertilized, allowed to start development, and replaced in the uterus.
IVF is stressful and often unsuccessful, it can lead to risky multiple births.
Treating diabetes:
Type 1 diabetes is normally controlled by injecting yourself with insulin to replace the hormone that is not made in the body.
Type 2 diabetes is often treated by a carbohydrate controlled diet and taking more exercise. If this doesn't work drugs can be used these:
Help insulin work better on the body cells.
Help your pancreas make more insulin.
Reduce the amount of glucose you absorb from your gut.
Human Reproduction:
Oestrogen is the main female reproductive hormone produced by the ovary. At puberty eggs begin to mature in the ovary and one is released every 28 days at ovulation. Testosterone is the main male reproductive hormone produced by the testes and stimulates sperm production.
Hormones involved in the menstrual cycle include: FSH, LH, oestrogen and progesterone.
Hormones in the Menstrual cycle:
FSH: From the pituitary stimulates the eggs to mature in the follicles of the ovary and the ovary to produce oestrogen.
Oestrogen: secreted by the ovaries stimulates the growth of the lining of the uterus and the release of LH and inhibits FSH.
LH stimulates ovulation.
Progestorone is produced by the empty follicle after ovulation. It maintains the lining of the uterus for around 10 days and inhibts FSH and LH.
Contraception:
Oral contraceptives, hormonal injections, implants and patches, barrier methods such as condoms and diaphragms, intrauterine devices, spermicidal agents, abstinence, and surgical sterilisation.