SB7 Flashcards
What is the definition of homeostasis?
- Maintaining constant conditions inside the body
Where are hormones produced?
- Hormones are produced in the endocrine glands, which are found all over the body
- Examples of endocrine glands are the pituitary and hypothalamus (found in the brain), as well as the adrenal, ovaries, testes and pancreas
What are three differences between the hormonal system and the nervous system?
- Nervous system carries signals much faster than hormonal system
- Nervous system carries signals through electrical impulses; whereas hormonal is through chemical messages in the blood
- Hormonal system has a much longer effect than nervous system
What is a target organ?
- This is an organ that is affected by a hormone, such as the ovaries or kidneys
What is adrenaline?
- This is a hormone released by the adrenal glands, with the target organs consisting of the heart, liver, lungs and eyes
- Large amounts of adrenaline is released in exciting or frightening situations
What is the ‘fight or flight’ response?
This is what occurs when a person feels as though they are in danger and the release of extra adrenaline aids this
- An increase in heart rate, blood pressure and blood flow to working muscles allow there to be more Oxygen at the working muscles, so that more respiration can occur
- Increased respiration releases more energy for the person to either fight or run away
How does adrenaline raise blood sugar levels?
- One of its target organs is the liver, where it breaks down glycogen (a polymer of glucose), into glucose
- The extra glucose is used for increased respiration, so that more energy can be released for the fight or flight response to occur
What is meant by negative feedback?
- This is a control mechanism that reacts to a change in a condition by trying to bring it back to normal levels
What is metabolic rate and how is it measured?
- This is the rate at which the energy stored in your food is transferred by all reactions in your body that keep you alive
- Resting metabolic rate is measured with the body at rest, in a warm room and long after the person has eaten
Explain the process of negative feedback in controlling metabolic rate
- Hypothalamus releases TRH, which travels to the pituitary gland
- Pituitary gland releases TSH, which travels to the thyroid gland
- Thyroid gland releases thyroxine, which travels to the target organs
- If levels of blood thyroxine are too high, the pituitary gland and hypothalamus are inhibited
- If levels are too low, hypothalamus is stimulated
What is the menstrual cycle and what happens on each day?
- Cycle of changes in women’s reproductive system, that occurs from puberty to menopause
- On day 1-5, menstruation occurs, where uterus lining and unfertilised egg cell are lost
- On day 5-13, uterus lining begins to rebuild
- On day 15, ovulation occurs ( the release of an egg cell from ovary)
- On day 16-23, uterus lining continues to thicken
- On days 23-28, egg travels along oviduct to the uterus
What is the role of the hormones oestrogen and progesterone?
- Oestrogen stimulates thickening of the uterus lining (from maturing egg follicle)
- Progesterone leads to the uterus lining being maintained ( released from empty follicle)
What is the role of the hormones LH and FSH?
- LH stimulates release of the egg cell
(Oestrogen cause pituitary gland to start LH) - FSH stimulates growth of the egg follicle
(Released by pituitary gland after uterus lining brakes down)
How do hormones work in negative feedback in the menstrual cycle?
- FSH levels are high, causing release of oestrogen
- Oestrogen levels are high, which causes the release of LH but stops FSH
- LH levels are high, which causes release of progesterone but stops oestrogen
- Progesterone levels are high, which causes release of FSH but stops LH (if no fertilisation occurs)
How do hormonal contraceptive pills work?
- Contains high levels of oestrogen and progesterone, which inhibit the release of FSH and LH, meaning that the egg follicle cannot mature and release
What are the advantages of physical contraceptives compared to hormonal?
- Can prevent STDs as there’s no contact between sexual fluids
- Doesn’t have side effects
- However, success rate at prevented pregnancies are lower as they may tear or slip
How does clomifene therapy work in increasing likelihood of pregnancy?
- Helps to overcome problem of releasing no or few eggs
- Increases concentration of LH and FSH in blood, helping to mature and release an egg to then be fertilised
How does IVF work?
- Helps to overcome problems such as a blocked oviducts or low sperm count
1- Egg follicle maturation is stimulated by hormones
2- Egg cells released by many follicles are taken from ovary, and sperm is taken from man
3- Eggs and sperm cells are combined (in vitro) so fertilisation can occur
4- One or two healthy embryos are placed in the uterus
Why is maintaining a constant internal environment important?
- This is to ensure enzymes in the body work at their optimum rate and don’t get denatured
- Also protects cells from absorbing too much or too little water, for activities to occur
What are the roles of the hypothalamus and dermis in thermoregulation?
- The hypothalamus in the brain receives information from temperature receptors in the dermis of the skin
- This is then used when deciding when and whether changes will occur to control temperature
What might occur if the body is too cold (below 37 degrees)?
- SHIVERING, which contracts and relaxes muscles repeatedly, to release energy to heat up
- Contracting of ERECTOR muscles, causing hairs to stand up and traps air for insulation
- VASOCONSTRICTION, which restricts blood flow near skin o reduce rate of energy transfer to outside the body
What might occur if the body is too hot?
- SWEATING, which forms a thin layer of sweat on the epidermis, which then evaporates: transferring heat energy to the surroundings
- VASODILATION, which increases blood flow to the skin, resulting in more heat energy being lost through transfer
What is the role of insulin?
- It is found in the liver and decreases blood glucose concentration by causing cells to take in glucose
What is: insulin, glucose, glycogen and glucagon?
- Glucose is a simple sugar monomer, found in foods and in the bloodstream
- Insulin converts glucose to glycogen, which is a polymer and is stored in liver cells
- If blood glucose concentration is too low, glucagon (released by pancreas) converts glycogen back into glucose