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
How is type 1 diabetes caused?
- Pancreatic cells that produce insulin have been destroyed by the body’s immune system, meaning blood glucose levels cannot be maintained
How can type 1 diabetes be controlled?
- By injecting insulin into the fat layer below the skin, where it can be used to control levels of blood glucose
How is type 2 diabetes caused?
- By insulin-releasing cells not producing enough insulin or target organs not properly responding to the insulin
How can type 2 diabetes be controlled?
- Eating less sugar and doing more exercise both reduce the amount of glucose in the blood stream
- Medicines may be given to reduce the amount of glucose released by the liver, or to increase sensitivity of cells in target organs
What does BMI stand for?
Body Mass Indicator
What is the roles of the urinary system?
- Remove waste products in blood
- Regulate levels of ions
- Regulate water levels
What is the role of the renal veins and arteries?
- Renal arteries carry blood from body to kidneys
- Renal veins carry blood with wastes removed back to the body
What is the role of the kidneys?
- Remove excess and waste substances from blood and make urine
What is the role of ureters?
- Carry urine from kidneys to bladder
What is the role of the bladder?
- To store urine before it is excreted
- Contains a muscle that keeps the exit closed until person is ready to take a piss
What are nephrons?
- Long tubule found in the kidney where filtration and reabsorption of blood occurs and urine is formed
What is the glomerulus and Bowman’s capsule?
- The glomerulus is a network of capillaries, which runs inside the Bowman’s capsule
- They are both adapted to let very small molecules such as water, urea and glucose through, but keep larger molecules such as proteins and blood cells in
- This process is called filtration
What happens in the nephrons after blood passes through the Bowman’s capsule?
- Selective reabsorption of useful substances such as glucose and mineral ions occur
- Active transport then pumps these substances through proteins in cell membrane of FIRST CONVOLUTED TUBULE, through active transport
What happens in the nephron after the first convoluted tubule?
- Water is reabsorbed by osmosis in the LOOP OF HENLE and COLLECTING DUCT
What happens in the nephron after the loop of Henle and collecting duct?
- Remaining fluid flows into ureter, containing excess water and other substances not needed, such as urea
What are some ways in which the nephron is adapted to reabsorption?
- Large surface area of contact between nephron and capillaries
- Cell membrane of cells lining the first convoluted tube have microvilli, which increase SA:V ratio
- Cells that use active transport contain many mitochondria
What is the role of ADH in controlling blood water content?
- When pituitary gland detects that there is too little water in blood, it releases ADH
- ADH makes the collecting duct in nephrons more permeable, so that osmosis can occur
- When water content is sufficient, no more ADH will be released, meaning collecting duct is impermeable
What is kidney dialysis and how does it work?
- Involves the exchange of substances between the person’s blood and a dialysis fluid
- This is done as the person’s kidneys no longer operate, so waste products build up
- Diffusion across the dialysis membrane occurs, which is partially permeable for small molecules
What is organ donation and some of the drawbacks?
- Kidney from another person is given to patient and attached to blood system
- Cells have antigens that may lead to rejection
- Surgery is long and may not be suitable for weaker patients
- Patient will require life-long medication, which also leads to infection =s being more easily caught
What is urea?
- It is a waste substance that is poisonous, formed from the breakdown of amino acids
