homeostasis and response - biology

last minute biology flashcards

explain the response of sweat glands when body temperature becomes too high

• sweat is produced by the sweat glands

• and evaporates from the skin.

• this transfers energy from the skin to the environment,

• which helps to cool the body,

• and return body temperature to an optimum level (around 37 degrees Celsius)

identify two mechanisms of controlling body temperature that cause a transfer of energy from the skin to the environment

• vasodilation

• sweat production

identify two mechanisms of controlling body temperature that reduce the transfer of energy from the skin to the environment by conserving heat energy

• vasoconstriction

• erector muscles contracting to cause hairs to stand up

why is ammonia immediately converted to urea when it is produced in the liver?

ammonia is a toxic chemical that can cause damage to body tissues so it is converted to urea for safe excretion from the body

what effect does ADH have on the permeability of the kidney tubules, and how does this help to control the water content of the blood?

ADH causes the kidney tubules to become more permeable so that more water is reabsorbed back into the blood during selective reabsorption, keeping the water content of the blood high

identify three substances that diffuse out of the blood and into the dialysis fluid during dialysis

• urea

• excess water

• excess ions

give three benefits of treating kidney failure with a kidney transplant rather than kidney dialysis

• a transplanted kidney cures kidney failure, unlike dialysis

• a kidney transplant is cheaper in the long term

• a kidney transplant allows patients to lead a more normal life as they don’t have to spend frequent hours in and out of the hospital, on dialysis

what is the main role of testosterone in males?

testosterone stimulates sperm production

where is oestrogen produced?

in the ovaries

what effect does oestrogen have on the release of LH?

oestrogen stimulates LH production

what hormone do oral contraceptives (containing oestrogen and progesterone) prohibit?

follicle-stimulating hormone

which method of contraception is inserted the uterus to prevent the implantation of a fertilised egg in the uterus wall?

intrauterine device (IUD)

give three ways that the release of progesterone can reduce fertility

• it stops eggs from maturing

• it prevents ovulation

• it stimulates the production of a thick mucus which prevents any sperm getting through and reaching the egg

give two reasons why some people might think IVF is unethical

• it often results in unused embryos being destroyed, each one representing a potential human life

• the genetic testing of embryos before implantation could lead to the selection of preferred characteristics

how does the increase in heart rate caused by adrenaline prepare the body for ‘fight or flight’?

the increase in heart rate increases the supply of oxygen and glucose to cells in the brain and muscles