B7 Flashcards
What is the endocrine system ?
A network of glands that produce and secrete hormones into the bloodstream
What is a hormone ?
A cell signalling molecule produced by endocrine glands and released into the blood it then travels to the target organ
What is the pituitary gland ?
It is the “master gland” or a gland that produced hormones wich control other glands
What are the adrenal glands ?
Endocrine gland that produces adrenaline
Were are the adrenal glands located ?
Above the kidney
What is adrenaline ?
A hormone produced by the adrenal gland that is involved in fight or flight response
What are the effects of adrenaline on the body ?
Increases heart rate and blood pressure
How does adrenaline increases heart rate and blood pressure ?
Adrenaline travels into the bloodstream and it then binds to specific receptors on a cell in the heart causing the heart muscle to contract more frequently
What is negative feedback ?
It reverses a change in conditions.
What is the thyroid gland ?
Endocrine gland that produces thyroxine
Where is the thyroid gland located ?
In the neck
What is thyroxine ?
A hormone secreted by the thyroid gland that controls metabolic rate
What is metabolic rate ?
The rate at which biochemical reactions occur in cells
How is thyroxine released ?
Hypothalamus secretes TRH this stimulates the pituitary gland to secrete TSH which then stimulates the release of thyroxine from the thyroid gland
What does TRH stand for ?
Thyrotropin releasing Hormone
What does TSH stand for ?
Thyroid stimulating hormone
How do the overies act as an endocrine gland ?
They secrete oestrogen into the bloodstream
How do the testes act as an endocrine gland ?
They secrete testosterone into the bloodstream
What is the menstrual cycle ?
The cycle in women that involves
1. Shedding of uterus lining
2. Repair of uterus lining
3. Release of an egg
4. Maintenance of uterus lining
Describe what happens days 1-5of the menstrual cycle ?
If fertilisation and implantation do not occur the uterus lining sheds and the egg is expelled with it (menstruation)
What happens day 5-12of the menstrual cycle ?
Uterus lining thickens and blood vessels grow in preparation for the implantation of an egg
What happens day 12-14 of the menstrual cycle ?
The egg is released from the follicle into the oviduct (ovulation)
What happens days 14 - 28 of the menstrual cycle ?
Uterus lining maintained so implantation can occur
What hormones control the menstrual cycle ?
- Follicle stimulating hormone (FSH)
- Luteinising hormone (LH)
- Oestrogen
- Progesterone
What is the role of the FSH hormone in the menstrual cycle ?
Secreted by the pituitary gland
It travels through the bloodstream to the ovaries
Which then triggers the development of a follicle in the ovaries
This then causes the release of Oestrogen
What is the role of oestrogen in the menstrual cycle?
Secreted by the ovaries
Repair and thicken the uterus lining
Inhibits secretion of the FSH from the pituitary gland
Stimulate secretion of LH from the pituitary gland
What is the role of LH in the menstrual cycle ?
Secreted by the pituitary gland
Transported through the bloodstream to the ovaries
Surge in LH triggers ovulation
Stimulates follicle to develop into a corpus luteum which then secretes progesterone
What is a corpus luteum ?
Temporary endocrine structure
Mass of cells that release progesterone
Degenerates after a few days
What is the role of progesterone in the menstrual cycle ?
Secreted by the corpus luteum which
This stimulates the uterus lining to thicken
Inhibits the release of FSH and LH
If there is no implantation then the progesterone levels decrease and uterus long sheds
What are contraceptives ?
A method or device utilised to prevent pregnancy
Which hormones can be taken to prevent pregnancy ?
Progesterone taken on its own
Progesterone combined with oestrogen
How does progesterone prevent pregnancy?
Sperm finds it more difficult to enter the uterus as the cervical mucus is thickened
How does oestrogen prevent pregnancy?
Oestrogen inhibits FSH
How can progesterone be administered?
Mini pill or injection
How is progesterone and oestrogen can be administered as a contraceptive?
Combined pill or skin patch
What are the benefit of hormonal contraceptives methods ?
99% effective when used properly
What are the risks of hormonal contraceptives methods ?
They don’t protect against STI’s
What are the barrier methods of contraception?
Prevent the sperm and egg meeting
E.g condom
What are the benefits of barrier methods of contraception?
Condoms are simple and quick to use and prevent STI’s
What 2 methods are used to treat infertility?
Clomifene therapy
IVF
What is the role of hormones in IVF ?
FSH and LH given to a woman to stimulate egg production and ovulation
Outline clomifene therapy ?
Prescription of clomifene drug to women who do not ovulate regularly
Stimulate secretion of more FSH and LH which triggers egg production and ovulation
What is homeostasis?
The maintenance of a stable internal environment in the body despite fluctuations in the internal or external conditions
Why is homeostasis important ?
To ensure optimum condition for enzymes and cellular precesses in the body
State 3 conditions within the body that must be controlled by homeostasis?
Temperature
Blood glucose concentration
Water level
What is thermoregulation ?
The maintenance of core body temperature
Why must body temperature be controlled?
Enzymes work best at their optimum temperature and Id temperature changes the rate of enzyme controlled reactions
What is the optimum temperature for enzymes in the body ?
37°C
What does the maintenance of an ideal body temperature depend on ?
A negative feedback system
Where are the temperature sensitive receptors located?
Skin (epidermis,outer layer and the dermis,below epidermis)
Hypothalamus
What is the function of the hypothalamus?
It coordinates information from the receptors and sends instructions to the effectors
What happens when the body temperature goes above 37°C ?
Vasodilation, sweating, erector muscles relax so hairs lie flat
How does sweating help to reduce the body temperature?
Heat energy is used to evaporate sweat.
increased heat transfer from the skin to the environment decreases body temperature
What is vasodilation ?
Dilation of the blood vessels near the surface of the skin which allows blood to flow closer to the surface creating greater heat loss
What happens when the body temperature goes below 37°C ?
Vasoconstriction, shivering, hair erector muscles contract so hair stands up on end
How does shivering increase body temperature?
Involuntary contracting of muscle generates heat energy from respiration
What is vasoconstriction?
Constriction of blood vessels near the skin surface so there is less blood flow close to the skin meaning less heat loss to the surrounding
What organ is responsible for the maintenance of the blood glucose concentration?
Pancreas
How are blood glucose levels controlled?
Controlled by the hormone insulin and glucagon which are secreted by the pancreas
What is an antagonistic hormone?
They have opposite effects which counteract one another
True or False insulin and glucagon are antagonistic hormones?
True
What is the role of insulin in the regulation of blood sugar levels ?
Cause the liver and muscle cells to increase their uptake in glucose from the blood
Glucose is converted into glycogen a storage molecule
What is the role of glucagon on the regulation of blood sugar levels ?
Causes the breakdown of glycogen to glucose in the liver
Glucose is released into the blood
What happens when blood glucose levels get to high ?
- The pancreas secretes insulin and stops producing glucagon
- Liver and muscle cells increase uptake in glucose from the
- Glucose is converted into glycogen and stored
What happens when blood glucose levels get to low ?
- Blood glucose concentration decreases below a set point
- pancreas secretes glucagon and stops producing insulin
- Liver cells convert glycogen into glucose which is released into the blood
What is the cause of type 1 diabetes?
Pancreas does not produce enough insulin
How is type one diabetes treated ?
- Daily insulin injections
- Limiting intake of refined sugars
- Regular exercise
What is the cause of type 2 diabetes?
Person develops a resistance to insulin
How is type 2 diabetes treated?
- Balanced diet
- Exercise
- Sometimes medication
What is BMI ?
a value based on height and mass to categorise and individual as under or over weight
How is BMI calculated ?
BMI = mass / height
What BMI indicates obesity and an increase risk type 2 diabetes?
BMI larger than 30
What is osmoregulation ?
The maintenance of constant water levels in the body of an organism
Why is osmoregulation important ?
Prevents cells bursting or shrinking when waters enter or leave cells by osmosis
What happens to an animal cell when it is placed in a solution with a higher water concentration?
Water molecules move down the water concentration gradient by osmosis so the pressure in the cell will increase and cause it to burst
What happens to an animal cell when it is placed in a solution with a lower water concentration?
Water molecules move down the water concentration gradient by osmosis so the pressure in the cell will decrease and cause it to shrink
What is the function of the kidneys ?
Removes toxic waste substance from the body
How is urea produced ?
In the liver, urea is produced from the breakdown of excess amino acids
What is the function of the renal artery?
Supplies blood to the kidney
What is the function of the renal vein?
Drains blood from the kidney
What is the function of the renal vein?
Drains blood from the kidney
What is the function of the ureter ?
Takes urine to the bladder from the kidneys
What is the function of the urethra ?
Releases urine from the bladder out of the body
How is the concentration and volume of urine controlled ?
Controlled by the secretion of anti diuretic hormone
What produces ADH?
Pituitary gland
How does ADH affect the reabsorption of water from the kidney tubules ?
ADH increase the permeability of the collecting ducts enabling more water to be reabsorbed into the blood
How can kidney failure be treated?
Kidney transplant and kidney dialysis
