5.3 Hormonal coordination

Define endocrine system

A system that works with the nervous system to help coordinate and control the body. It is made up of glands that release hormones into the bloodstream

Define hormone

a chemical that is released by glands, which travel around the body until they reach the target organ where they cause an effect or response. They travel in the bloodstream

Define target organ

The organ that has receptors that bind to the hormone molecules, which leads to a response

What glands are in the body?

-Pituitary gland

-Thyroid gland

-Adrenal gland

-Pancreas

-Ovary

-Testis

What hormones does the pituitary gland release and what are their roles?

-Growth: controls growth in children

-TSH: Stimulates the thyroid gland to make thyroxine

-FSH: in women - stimulates the ovaries to mature eggs and make the female sex hormone oestrogen

-LH: in women - stimulates the ovaries to release eggs

-ADH: affects the amount of urine produced by the kidney

-n/a: in men - stimulates the testes to make sperm and the male sex hormone testosterone

What hormone does the thyroid gland release and what is it’s role?

-Thyroxine: controls the metabolic rate of the body - how quickly substances are broken down and built up, how much oxygen tissues use, how the brain of a growing child develops

-Insulin: controls the level of glucose in the blood

-Glucagon: controls the level of glucose in the blood

What hormone does the adrenal gland release and what is it’s role?

-Adrenaline: prepares body for stressful situations (flight or fight response)

What hormone does the ovaries release and what is it’s role?

-Oestrogen: controls the development of the female secondary sexual characteristics and is involved in menstrual cycle

What hormone does the testes release and what is it’s role?

-Testosterone: controls the development of the male secondary sexual characteristics and is involved in the production of sperm

How do hormones travel through the body?

through the bloodstream where they reach the target organ where hormones bind to the receptors on the organ because they are complimentary which causes a response

What is the role of negative feedback?

-Works to maintain a steady state

-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

-Whatever the initial change, in negative feedback the response causes the opposite

Examples of negative feedback in the body

-control of body temp

-control of water in blood

-thyroxine levels

-blood glucose levels

where is the thyroid gland found?

neck

What does the thyroid gland make?

uses iodine from the diet to make the hormone thyroxine

How are thyroxine levels controlled?

When levels rise, the pituitary gland releases less TSH so less thyroxine will be released. This means a change in levels causes the opposite effect

Where is adrenaline made?

in the adrenal gland, found at the top of the kidneys

When is adrenaline released?

prepares body for action when stressed, angry or excited

What effects does adrenaline have on the body?

-Heart and breathing rate increases: more oxygen to blood to allow increased rate of aerobic respiration - prepares muscles and removes carbon dioxide faster

-Stored glycogen in the liver to be converted into glucose for respiration: more glucose in blood for increased rate of respiration for energy

-Pupils dilate: let more light into eye to reach retina - improving perception of danger

-Mental awareness increases: better perception of treats and problem solving

-Blood diverted away from digestive system: allows blood to be diverted to muscles and brain instead

-Blood diverted to skeletal muscles: more blood carrying oxygen to muscles so increased aerobic respiration to release energy for more muscle contractions

-Blood diverted to brain: more blood carrying oxygen to brain - allows increased mental awareness

What does the pancreas do when glucose levels are too high?

-It releases insulin which causes:

1. Excess glucose is converted and stored as insoluble glycogen in the liver and in muscles

2. Cells take up glucose and use it for respiration

-Therefore blood glucose levels fall

What does the pancreas do when glucose levels are too low?

-Pancreas releases the hormone glucagon which causes the liver to break down stored glycogen into soluble glucose, which is released back into the bloodstream for cells to use in respiration

-Glucose levels then rise

What is the function of insulin?

hormone that decreases blood sugar by converting glucose to glycogen

What is the function of glucagon?

hormone that increases blood sugar by converting glycogen to glucose

What is the function of glycogen?

storage molecule found in mammals

What is diabetes?

A disease where a person is unable to properly control their glucose levels

Causes of type 1 diabetes

When the pancreas doesn’t make enough or any insulin so blood glucose concentration is not controlled

Causes of type 2 diabetes

the pancreas still makes insulin, but less than the body needs and cells stop responding properly to the insulin made

Symptoms of type 1 and 2 diabetes

-Lack energy

-Feel tired

-Lose weight (because fat and protein broken down for fuel)

Treatments of type 1 diabetes

-Replacement insulin before meals - usually given as injection into blood

-Need to be careful of levels of carbohydrates eaten

-Have regular meals

-Exercise but needs to be planned to keep blood glucose levels steady)

This helps to keep blood glucose levels as stable as possible

Treatment of type 2 diabetes

Restore normal blood glucose balance by:

-Eating a balanced diet with carefully controlled amounts of carbohydrates

-Losing weight

-Doing regular exercise

If this doesn’t work drugs can:

-Help insulin work better on the body cells

-Help pancreas make more insulin

-Reduce the amount of glucose absorbed from gut

If these don’t work than insulin injections used

What are the advantages of multiple insulin injections?

-Discreet: injection syringe or pen can be carried around in a bag and used in privacy

-Equipment in cheaper

What are the disadvantages of multiple insulin injections?

-Greater chance of extreme high or low blood glucose concentration

-Uses more insulin per day than a pump

What are the advantages of an insulin pump?

-Better control of blood glucose concentration

-Uses less insulin per day

What are the disadvantages of an insulin pump?

-Must be worn all the time

-More expensive equipment

Advantages of injected insulin

with practice pain free and simple

Disadvantages of injected insulin

Absorption affected by:

-site of injection (absorbed quickest from abdomen)

-using the correct injection technique (if too shallow into the skin or too deep into muscle won’t be absorbed properly

-smoking causes inconsistent blood glucose as nicotine causes changes in small blood vessels which may affect absorption

Advantages of inhaled insulin

-produces regular concentrations of insulin

Disadvantages of inhaled insulin

-timing of doses difficult to asses, as the response to a dose may not be easy to predict

-expensive due to large doses required

-may have potential to cause lung cancer

What are the two main types of hormones?

-Proteins: have short term effects

-Steroids: have long term effects by interacting with genes in DNA

define puberty

the period in which adolescence start to develop secondary sexual characteristics

What hormones trigger puberty?

in females oestrogen

in males testosterone

Changes during puberty

males: height increases, deepening voice, more muscle mass, testes start to produce sperm, pubic hair

females: height increases, breasts grow, hips become wider, menstrual cycle starts, pubic hair

What is the menstrual cycle?

a cycle of changes in hormone production and uterus structure

Where is FSH made and what is it’s function?

-Pituitary gland

-causes the eggs in the ovary to mature, stimulates oestrogen release in ovaries

Where is oestrogen made and what is it’s function?

-ovaries

-Stimulates the womb lining to build up, inhibits FSH release, stimulates LH release

Where is LH made and what is it’s function?

-pituitary gland

-stimulates the release of the egg at ovulation (day 14)

Where is progesterone made and what is it’s function?

-ovaries (the empty egg follicle)

-stimulates the womb lining to build up and remain

What is stage 1 of the menstrual cycle (days 0-4)?

menstruation - a period of bleeding where the uterus lining breaks down caused by drop in progesterone

What happens in stage 2 of the menstrual cycle (day 5-14)?

the uterus lining builds up and gets thicker

what is stage 3 of the menstrual cycle (day 14)?

ovulation - egg released

What is stage 4 of the menstrual cycle (days 15-28)?

uterus lining is maintained

what happens after stage 4 of the menstrual cycle if no fertilised egg implants into the uterus lining?

the cycle repeats

what happens after stage 4 of the menstrual cycle if a fertilised egg implants into the uterus lining?

the menstrual cycle will pause and the lining will be maintained to allow the fertilised egg to develop

What does FSH stand for?

Follicle stimulating hormone

What does LH stand for?

Luteinising hormone

define contraception

designed to prevent pregnancy by either:

-preventing an egg and sperm meeting

-preventing a fertilised egg implanting in the uterus