Endocrine system Flashcards
Define hormone?
Mammalian hormones are substances that stimulate target cells via the blood.
How does a hormone work?
Hormones are released directly into the blood plasma from endocrine glands. Each hormone has specific target cells on which it acts.
Once the hormone reaches a target organ, it affects the target cells by attaching onto specific receptors either on the surface of, or within the cells.
Hormones are part of the endocrine system, which produces slow, long-lasting and widespread responses.
How does the nervous system differ from the endocrine system?
Endocrine system produces slow, long-lasting and widespread responses.
However the nervous system produces faster, but shorter lasting responses.
Role of thyroid gland?
Produces thyroxine which controls rate of metabolism
Role of adrenal gland?
Produces adrenaline which prepares the body for rapid activity by increasing the heart rate and level of sugar in blood and diverting blood to muscles and brain.
Role of pancreas?
Produces insulin which controls blood sugar level
Role of testes?
Produces testosterone which causes the changes at puberty and stimulates sperm production
Role of ovary?
Produces oestrogen which causes changes at puberty and helps control the menstrual cycle
Role of the brain?
Contains a sensitive centre called the hypothamalus, which controls the pituitry gland.
Define negative feedback:
When the body responds to a negative change to bring it back to normal values.
What two hormones do the islets of langerhan (in the pancreas) produce?
Insulin (produces by beta cells)
and
Glucagon (produced by alpha cells)
Whats the function of glucagon?
Stimulates the liver when glucose levels in the blood are low
The glucose has GONE so GlucaGON is released
Converts Glycogen back into Glucose
Describe the negative feedback loop of the endocrine system if there was an increase in glucose levels:
1) Normal glucose levels of blood
2) Increase in level of glucose in blood eg:after meal
3) Receptors in pancreas detect change
4) Insulin is released by beta cells in the islets of langerhan
5) Muscle and liver absorb glucose and store it as glycogen
6) This is known as glycogenesis.
Describe the negative feedback loop of the endocrine system if there was a decrease in glucose levels:
1) Normal glucose levels of blood
2) Decrease in level of glucose in blood
3) Receptors in pancreas detect change
4) Glucagon is released by alpha cells in the islets of langerhan
5) Glucagon converts glycogen back into glucose
6) This is known as glycogenolosis.
Whats a gland?
A gland is an organ which secretes substances such as hormones or enzymes.
Why are blood glucose levels important ?
Glucose is essential for respiration, therefore it is important that the amount of glucose in the blood is kept at a fairly constant level.
Whats the function of insulin?
Insulin – they take glucose INto cells for energy
Stimulates liver to convert glucose into GLYCOGEN – the stored version
some causes of increases in blood glucose are…
Digestion of carbohydrates
Breakdown of GLYCOGEN called GLYCOGENOLYSIS
Producing glucose from non-carbohydrate compounds called GLUCONEOGENESIS
Causes of decreases in blood glucose:
When demand for energy increases e.g. Exercise, respiration levels increase and therefore glucose levels decrease.
Lack of intake of carbohydrates/sugars (Starvation)
Glucose is Converted/Stored as glycogen GLYCOGENESIS
What is diabetes?
Diabetes mellitus is a disorder that affects the body’s ability to regulate blood glucose levels. There are two different types – type 1 and type 2.
Whats type 1 diabetes?
Also known as insulin-dependent diabetes, normally occurs suddenly in childhood.
The body is not able to produce its own insulin. This is thought to be caused by the immune system attacking the insulin-producing beta cells.
Type 1 diabetes can be controlled with regular insulin injections and the careful management of diet and exercise
Whats type 2 diabetes?
Also known as insulin-independent diabetes, occurs mainly in people over 40, however it is becoming increasingly common in adolescents.
This condition is caused by glycoprotein receptors on the body cells losing their responsiveness to insulin, or an inadequate supply of insulin from the pancreas.
Type 2 diabetes can be controlled by careful regulation of diet and exercise.
What are hormones secreted by?
Endocrine glands
