Topic 11 - Hormonal Coordination Flashcards
What is the endocrine system?
The endocrine system is made up of glands that secrete chemicals called hormones directly into the blood stream. The blood carries the hormone to its target organ where it produces an effect. The target organ has receptors on the cell membranes that pick up hormone molecules, triggering a cellular response.
What is a hormone?
Hormones are regulatory substances produced in an organism and transported in tissue fluids such as blood or sap to stimulate specific cells or tissues into action. They are proteins and have a similar receptor-active site system to enzymes.
What does insulin do?
Insulin acts to reduce glucose concentration by increasing glucose absorption from the blood by the liver and muscles; converting excess glucose to glycogen. It can be broken down to glucose when sugar reserves are low.
What does adrenaline do?
It prepares the body for fight or flight by heightening strength, increasing reaction times and transfering glucose to the different parts of the body.
What is the pituitary gland?
The gland control most of the secretion of hormones throughout the body, often referred to as a master gland. It also
-Controls growth in children.
-Stimulates the thyroid gland to make thyroxine and control metabolism.
-In women - stimulates the ovaries to produce and release eggs and make the female sex hormone oestrogen.
-In men - stimulates the testes to make sperm and the male sex hormone testosterone.
What does FSH do?
Follicle Stimulating Hormone stimulates the ovaries to make the female sex hormone oestrogen.
What does TSH do?
Stimulates the thyroid gland to make thyroxine, a hormone that helps control the rate of your metabolism.
What does the pancreatic gland do?
Controls the levels of glucose in the blood.
What does the adrenal gland do?
Prepares the body for stressful situations - by making the body in a hyper state.
What do the ovaries do?
Controls the development of the female secondary sexual characteristics and is involved in the menstrual cycle.
What do the testes do?
Controls the development of the male secondary sexual characteristics and is involved in the production of sperm.
What is glucagon?
When the blood sugar concentration level goes too low, glucagon is secreted which makes the liver break down glycogen, converting it back into glucose. Stored glucose is released back into the blood.
What causes type 2 diabetes?
-The older you get the more likely you are to develop it since metabolism slows.
-It is linked to lack of exercise, excess eating, obesity and more.
-There can also have a genetic tendency to develop type 2 diabetes.
-Your body cells stop responding properly to the insulin you make.
What causes type 1 diabetes and what are the consequences of it?
If your pancreas does not make enough (or any) insulin, your blood glucose concentration is not controlled.
Without insulin your blood glucose levels get very high after you eat.
Eventually your kideneys excrete glucose in your urine. You produce lots of urine and feel thirsty all the time. Without insulin, glucose cannot get into the cells of your body, so you lack energy and feel tired. You break down fat and protein in the body as fuel instead of glucose, losing weight.
How do you treat type 1 diabetes?
You take replacement insulin before meals. Insulin is a protein that would be digested in your stomach, so it usually given as an injection to get into the blood stream.
This injected insulin allows glucose to be taken into your body cells and converted into glycogen in the liver. This stops the concentration of glucose in your blood from getting too high. Then, as the blood glucose levels fall, the glycogen is converted back to glucose. As a result, your blood glucose levels are kept as stable as possible.
If you have type 1 diabetes you need to control the amount of carbohydrate intake and have regular meals. Moreover, exercise requires more planning. Like everyone else, you need to exercise to keep your heart and blood vessels healthy.
How is type 1 diabetes cured?
-Doctors can transplant a pancreas successfully, however, this operation is risky and difficult. Only a few hundred pancreas transplants take place each year. There are not enough pancreas donors to help the 250,000 people with type 1 in the UK.
How do you treat type 2 diabetes?
-Eating a balanced diet with controlled amounts of carbohydrates.
-Losing weight
-Doing regular exercise
There are also drugs that:
-Help insulin work better on the body cells
-Help your pancreas make more insulin
-Reduce the amount of glucose you absorb by the gut.
What is negative feedback?
If a factor in the internal environment increases, changes take place to reduce it and restore the original level.
If a factor in the internal environment decreases, changes take place to increase it and restore the original level.
This is done to keep the level within narrow limits.
How does negative feedback work with thyroxine?
The thyroid gland uses iodine from your diet to produce the hormone thyroxine. This controls the basal metabolic rate of your body. Thyroxine plays an important part in growth and development. In adults, thyroxine levels remain relatively stable. This happens as a result of negative feedback. If thyroxine in the blood begin to fall, it is detected by sensors in the brain. As a result, the amount of TSH released from the pituitary gland increases. TSH stimulates the production of thyroxine by the thyroid gland. As the level of thyroxine increases, it is detected by sensors and in turn the level of TSH released falls.
What does the secretion of adrenaline cause?
-Your heart rate and breathing rate increase.
-Stored glycogen in the liver is converted to glucose for respiration.
-The pupils of your eyes dilate to
let more light in to see more easily.
-Your mental awareness increases.
-Blood is diverted away from the digestive system to the large muscles.
-Delivery of oxygen and glucose to your brain and muscles is boosted, preparing your body for intense situations.
What happens during puberty?
The reproductive hormones control the development of secondary sexual characteristics.
How does puberty work in females?
The hormone Oestrogen is secreted, triggering the development of secondary sexual characteristics in the early teen years. The main changes are:
-A growth spurt
-Growth of underarm hair
-Growth of pubic hair
-Breasts develop
-External genitals grow
-Skin darkens
-The brain changes and matures
-Fat is deposited on the hips, buttocks and thighs
-Mature eggs form each month
-The uterus grows and becomes active and menstruation begins.
What is the menstrual cycle?
A monthly cycle that a woman that has gone through puberty will experience. Each month, eggs mature in the ovary. At the same time the uterus produces a thickened lining ready for pregnancy. Every 28 days a mature egg is released. This is ovulation. If the egg is not fertilised, around 14 days later the lining of the uterus is shed, along with the egg. Hormones involved include:
-FSH which causes the eggs in the ovaries to mature.
LH which stimulates the release of the egg at ovulation
What is the menopause and when do women go through it?
The menopause happens after the age of 40 and happens since the woman stops producing eggs. This means she cannot get pregnant.
What happens during puberty to males?
The male reproductive hormone testosterone triggers many different change in the body in the early teenage years. The main changes include,
-A growth spurt
-Pubic hair growth
-Underarm hair growth
-Facial hair growth
-Larynx gets bigger
-Voice breaks
-Skin gets darker
-Testes grow and become active, producing sperm throughout the man’s life.
-Chest and shoulder muscles areas broaden as muscle develops
-The brain matures
What is the order of hormones in the menstrual cycle?
- FSH is secreted by the pituitary gland. It makes eggs mature in the ovaries, also stimulating hormones like oestrogen to be produced.
- Oestrogen is made and secreted by the ovaries as a response to FSH. It stimulates the lining of the uterus to grow again after menstruation in preparation for pregnancy. High levels of oestrogen inhibit the production of more FSH and stimulate LH release.
- LH from the pituitary gland stimulates the release of a marure egg from the ovary. Once ovulation has taken place, LH levels fall again.
- Progesterone is secreted after ovulation, it helps to maintain pregnancy if the egg is fertilised. Progesterone inhibits both FSH and LH production and secretion, maintaining the uterus lining.
- FSH and LH are then suppressed and the body is kept ready for pregnancy until it becomes clear the egg isn’t fertilised.
- The levels of all hormones then drop and the lining pulls away and is lost from the body. At this stage a new cycle begins and the FSH and Oestrogen levels build up again.
What is contraception?
The control of pregnancy using physical or chemical methods.
What is the contraceptive pill?
It is taken by women and uses female hormones to control pregnancy. The mixed pill contains low doses of oestrogen and progesterone. The hormones inhibit the production and release of FSH by the pituitary gland, affecting the ovaries, so no eggs mature, preventing pregnancy. They also make the mucus in the cervix thick to prevent sperm from getting through. The contraceptive pill is easy to use but there is a slight risk of side effects like raised blood pressure, thrombosis and breast cancer.
