B3.2.1- B3.2.4- The Endocrine System Flashcards
What are hormones
They chemical messengers which travel in the blood
What is an endocrine gland?
A gland which produces and secretes a hormone
Where are hormones made
In endocrine glands
How are hormones transported around the body
The blood transports the hormones in the plasma around the body
What is a target organ
An organ that a hormone has an effect on
What is homeostasis
The maintenance of a constant internal environment
What do hormones do?
They regulate functions of many cells and organs.
They cause a response in specific cells that are found in target organs
They control body processes that need constant adjustment
Where are endocrine glands found
Hypothalamus and the pituitary gland Thyroid gland Adrenal gland Pancreas Ovaries Testes
What are target cells
They are cells with the specific receptors for that hormone and are found on the membranes or in the cytoplasm of cells in the target organ. They produce an effect when the hormone binds
What happens once hormones and their receptors are bound
They stimulate the target cells to produce a response
What is the endocrine system?
It is the name given to all the endocrine glands and the hormones that they produce
What does the endocrine system do?
It controls and co-ordinates body processes with the nervous system.
How are the endocrine system and the nervous system similar?
They both send messages around the body to provide information about changes in your internal and external environment. They also send information about how the body should respond
How are nerves and hormones different?
Nerves are very fast while hormones are slower.
Nerves are short acting while hormones are longer acting.
Nerves target precise areas while hormones target a larger area
What hormones do the pituitary gland and hypothalamus release?
Hormones that regulate the production of other hormones
What hormones does the thyroid gland release?
Thyroxine
What hormone does the adrenal gland release?
Adrenaline
What hormones do the ovaries produce
Oestrogen and progesterone
What hormones do the testes produce
Testosterone
What is thyroxine
The hormone that controls metabolism
It controls the speed at which oxygen and food products react to release energy for the body to use
What is the metabolic rate
The speed at which the body transfers energy from its chemical stores in order to perform its functions
What is the function of the thyroid gland?
To take iodine (found in foods) and convert it into thyroxine by combining it with the amino acid tyrosine
What is adrenaline?
It is the hormone released during stress.
It causes changes which make the body ready for action ( the fight or flight response).
What are the stages in negative feedback?
- Conditions in the body change from set point
- The change is detected by a receptor
- Corrective mechanisms are activated by an effector
- Conditions returned to set point
- Corrective mechanism switched off
What happens when the body requires more energy?
The hypothalamus causes the pituitary gland to release thyroid stimulating hormone (TSH). TSH stimulates the thyroid gland to release thyroxine. This increases the metabolic rate, allowing cells to transfer additional energy
What happens when the cells have enough energy?
The hypothalamus inhibits the production of TSH. The thyroid gland therefore stops releasing thyroxine
How are adrenaline levels controlled?
When you are stressed the brain signals the adrenal gland to secrete adrenaline.
The body responds by:
- respiring more quickly to increase the rate of ATP production
- increasing the rate of breathing to cope with the extra demand for oxygen
- increasing heart rate
- diverting blood away from areas such as the digestive system towards the muscles
What is the menstrual cycle?
A monthly cycle during which a woman’s body gets ready for pregnancy
How long does the menstrual cycle last?
28 days
What happens during the menstrual cycle?
Each month the lining of the uterus starts to thicken, ready to receive a fertilised egg. At the same time an egg starts to mature in one of the ovaries. 14 days later, the egg is released from the ovary. This is ovulation. If the egg is not fertilised the uterus lining and the egg are removed from the body
What happens if the egg it fertilised
It will implant in the uterus lining. Here it is protected and receives nutrients and oxygen from the mother.
What is the ovary
It is where the eggs mature
What if the Fallopian tube ( the oviduct)
It is where the egg is fertilised before travelling along the tube to the uterus
What is the cervix?
It is the entrance to the uterus
What is the uterus (womb)
It is when the foetus develops
What controls the menstrual cycle
It is controlled by 4 hormones that are made in the pituitary gland and the ovaries.
- follicle stimulating hormone (FSH)
- Oestrogen
- luteinising hormone (LH)
- progesterone
What is FSH (follicle stimulating hormone).
This is secreted by the pituitary gland.
It travels to the ovaries where is causes an egg to mature
What is oestrogen?
It is made and secreted by the ovaries.
It causes the lining of the uterus to build up.
How do FSH oestrogen LH and progesterone interact?
- FSH stimulates the ovaries to produce oestrogen
- as oestrogen levels rise they inhibit the production of FSH. this prevents more than one egg maturing. It also stimulates the pituitary gland to release LH
- progesterone also inhibits LH.
What is Luteinising hormone (LH) ?
When LH levels reach a peak in the middle of the cycle ovulation is triggered
It triggers ovulation
What is progesterone?
It maintains the uterus lining,
What is contraception?
A technique used to prevent pregnancy
What are the 2 types of contraception
Non-hormonal- these are barrier methods that prevent a sperm contacting the egg or physical devices that release chemical compounds. These chemicals kill sperm cells or prevent the implantation of fertilised eggs.
Hormonal- these use hormones to disrupt the normal female reproductive cycle
What is negative feedback?
A system that detects a change in condition.
The system then acts to return conditions to the desired level.
A type of homeostasis
What is another term for seedless fruit
Parthenocarpic
What is ADH
A hormone secreted by the pituitary gland which increases water reabsorption in the kidneys making the kidney tubules more permeable to water
It controls the water content of the blood
What is insulin
A hormone produced by the pancreas which controls the body’s blood sugar levels.
It works to decrease glucose levels
What role does the empty follicle play after the egg is released?
It releases progesterone to maintain the uterus lining
What happens to a hormone once it has been used
It is destroyed by the liver
What is insulin
It is secreted from the pancreas and controls blood glucose levels
It increases the conversion of glucose into glycogen for storage
