B7 | homeostasis Flashcards
definition of homeostasis
the process of maintaining constant internal environment
which gland secretes adrenaline?
adrenal gland
how does adrenaline work?
binds to receptors in the heart causing it to beat faster and with more force
what does adrenaline cause your body to do?
- increased heart rate
- increased blood pressure
- increased blood flow
- increased oxygen/glucose supply to cells
- increased respiration
- increase in energy needed for muscle contractions
- allows you to “fight or flight”
which gland secretes thyroxine?
thyroid gland
what does thyroxine do?
regulates basal metabolic rate
basal metabolic rate definition
the speed of chemical reactions in the body while it is at rest
what happens when there are low levels of thyroxine in the blood?
- hypothalamus releases TRH
- pituitary gland releases TSH
- thyroid produces thyroxine to increase metabolic rate
what happens when there are high levels of thyroxine in the blood?
- hypothalamus inhibits production of TRH
- pituitary gland reduces production of TSH
- thyroid produces less thyroxine to decrease metabolic rate and for thyroxine concentration in the blood to drop
what happens when you have an underactive thyroid (hypothyroidism)?
- less thyroxine produced
- metabolic rate drops
- less energy available
- more fat stored
- weight gained
what happens when you have an overactive thyroid (hyperthyroidism)?
- more thyroxine produced
- metabolic rate increases
- more energy available
- less fat stored
- weight lost
which gland produces FSH and LH?
pituitary gland
which gland produces oestrogen and progesterone?
ovary glands
what happens during day 1-5 of the menstrual cycle?
- uterus lining breaks down
- pituitary gland releases follicle stimulating hormone (FSH) causing concentration of FSH in the blood to increase
what happens during day 5-14 of the menstrual cycle?
- FSH targets the egg follicle in the ovary, causing it to start to mature and prepare an egg cell for release
- as the egg follicle matures, oestrogen is released causing concentration of it in the blood to increase
- as levels of oestrogen increase, levels of FSH decrease and pituitary gland releases luteinising hormone (LH) instead
- high levels of oestrogen also cause uterus lining to thicken in preparation for a fertilised egg
what happens during day 14 of the menstrual cycle?
- levels of FSH and LH peak causing an egg cell to be released (ovulation)
what happens during day 14-21 of the menstrual cycle?
- empty egg follicle (corpus luteum) in the ovary releases oestrogen and progesterone to maintained the thickened uterus lining
- as levels of progesterone increase, pituitary gland stops production of FSH and LH to prevents the maturing of another egg/ovulation
what happens during day 21-28 of the menstrual cycle?
- if the egg cell is not fertilised, progesterone levels decrease in order for the uterus lining to break down
- levels of FSH increase and the cycle starts all over again
- if the egg is fertilised, progesterone levels stay high in order to maintain the lining of the uterus for pregnancy
how does the pill act as contraception?
- contains oestrogen which inhibits production of FSH preventing egg cell from maturing and being released (ovulation)
- contains progesterone which thickens cervical mucus preventing sperm from getting into the uterus
side effects of hormonal methods of contraception
headaches, nausea, irregular period, mood swings
how does clomifene therapy work?
- taken by women who don’t ovulate (regularly) during days 1-5 of the menstrual cycle
- contains FSH which stimulates egg to mature in follicle and stimulates release of oestrogen
- also contains LH which initiates ovulation of mature egg
how does IVF (in vitro fertilisation) work?
- woman is given FSH and LH to stimulate egg maturation and ovulation
- eggs cells are collected and fertilised with sperm cells
- the fertilised eggs mature into embryos and are implanted back into the mother’s uterus (more than one is implanted to improve chances of pregnancy)
disadvantages of IVF
- more than one embryo implanted can lead to multiple births which can lead to pregnancy complications (especially for women over 40)
- hormones gives at the start of the treatment can have side effects, and stopping these hormones reduces the chance of pregnancy
optimum body temperature
37 C
how does shivering maintain body temperature?
- muscles contract and relax rapidly
- cells are required to respire more
- respiration produces heat energy which is transferred to the blood to warm you up
how do muscles cause hairs to stand up/flatten?
erector muscles at base of hair contract/relax
what is glycogen?
large insoluble store of glucose
what is glucagon?
hormone which turns glycogen back into glucose
what happens if there is a high concentration of water INSIDE a cell and a low concentration of water OUTSIDE of it?
water moves out of the cell via osmosis and the cell shrinks/becomes smaller
what happens if there is a high concentration of water OUTSIDE a cell and a low concentration of water INSIDE of it?
water moves into the cell via osmosis and cell swells/becomes bigger
cell could even burst (lysis) and die
how are high levels of water in the blood regulated?
- high levels of water detected by hypothalamus
- pituitary gland releases less ADH
- drop in ADH detected by kidney which becomes less permeable and less water is reabsorbed into the blood
how does vasoconstriction help to regulate body temperature?
- blood vessels get smaller/constrict
- this prevents blood from travelling to the skins surface
- which prevents heat from being radiated from your blood
- which keeps you warm
how does vasodilation help to regulate body temperature?
- blood vessels get wider/dilate
- this increases amount of blood from travelling to the skins surface
- which increases amount of heat from being radiated from your blood
- which cools you down
what is the epidermis?
outer layer of skin
what is the dermis?
deep layer of skin
how does the hypothalamus monitor body temperature?
receptors in the hypothalamus detects any changes in body temp from 37°C and initiates a negative feedback to return the body temp back to normal
what happens when blood glucose levels are too high?
- pancreas detects high levels of glucose and secretes insulin into the blood
- liver detects insulin and absorbs excess glucose
- this excess glucose is converted into glycogen and stored in the liver
- blood glucose levels return to normal
what happens when blood glucose levels are too low?
- pancreas detects low level of glucose and secretes glucagon into the blood
- liver detects glucagon and converts glycogen back into glucose which is passed back into the blood
- blood glucose levels return to normal
how is type 1 diabetes caused?
when the pancreas is unable to produce insulin
this leads to excess glucose which isn’t converted into glycogen
leading to build of glucose
leading to hyperglycaemia
how is type 1 diabetes treated?
- insulin injections
- limit glucose intake (less carbs and sugars)
- regular exercise to lower blood glucose levels through using this sugar for metabolism/cell respiration
how is type 2 diabetes caused?
when a person’s body becomes resistant to insulin
typically in 40+ year olds and makes up most cases of diabetes
obesity & constant intake of high glucose foods tires the pancreas out leading to less production of insulin and eventually insulin resistance
how can type 2 diabetes be treated?
- losing weight which will lead to an increased insulin production
- reduce glucose intake to prevent sharp rises in blood sugar levels
- exercise regularly to increase metabolism/cell respiration which will use up excess glucose in the blood
