Homeostasis

Question 1

difference between the nervous system and the endocrine system

Answer 1

nervous system:
- electrical impulses
- responses last a short time
- near instant transmission of signals
Endocrine system:
- chemical impulses
- longer lasting effect
- slow transmission of messages

Question 2

what does homeostasis mean

Answer 2

the regulation of the internal conditions of a cell or organism to maintain optimum conditions for functions in response to internal and external changes
(AKA the maintenance of a constant internal environment)

Question 3

what is a negative feedback loop

Answer 3

if something is too high or low from the optimum a receptor detects it and works to counteract it back to optimum

Question 4

why is it important to have a narrow temperature range

Answer 4

so that enzymes act most effectively changes in temperature are detected by receptors all around the dermis (skin) and the hypothalamus detects blood temperature

Question 5

body reactions when its too cold

Answer 5

• shivering (skeletal muscles contract indirectly releasing heat via respiration)
• Erector pili muscles contract causing hairs to raise and trap heat
• vasoconstriction reduces blood flow to the surface of the skin so less heat is lost via radiation plus conserves heat from/ around the core

Question 6

body reaction when its too hot

Answer 6

• erector muscles relax so heat dissipates easier
• vasodilation so heat is lost easier via radiation
• sweat produced by sweat glands and heat is transferred due to the sweat evaporating and evaporation being endothermic

Question 7

what is thyroxine

Answer 7

TSH secreted from the pituitary gland stimulates the thyroid gland and produces thyroxine which controls the base metabolic rate (how long digestions takes to break down nutrients). In adults its used to regulate oxygen to tissues and in children it is a part of growth and development

Question 8

negative feedback loop for thyroxine

Answer 8

when blood thyroxine levels are too high it is detected by hypothalamus the production of TSH is inhibited by the pituitary gland causing thyroxine levels to return to optimum
(reverse when too low)

Question 9

testosterone

Answer 9

male sex hormone produced in the testes and controlls male characteristics

Question 10

adrenaline

Answer 10

the stress hormone that triggers the fight, flight or freeze response (increased awareness). It is secreted from the adrenal gland (above your kidneys). ADRENALINE DOES NOT REQUIRE A NEGATIVE FEEDBACK LOOP

Question 11

effects of adrenaline

Answer 11

• increased heart rate
• glucagon in liver is converted to glucose
• blood diverted from digestive system to muscles and limbs
• pupils dilate

Question 12

blood glucose levels

Answer 12

detected by the eyelets of langerhan
when too high insulin released converting glucose into glycogen and storing it in the liver
when too low glucagon converts glycogen into glucose

Question 13

difference between type 1 and type 2 diabetes

Answer 13

Type 1 is caused by an autoimmune response where the body attacks the cells in the pancreas causing no more production of insulin
Type 2 is caused by the body becoming less sensitive to higher glucose levels hence needing more insulin to convert glucose into glycogen

Question 14

reasons for different diabetic symptoms

Answer 14

• tiredness- less aerobic respiration
• thirst/frequent urination- to balance glucose levels body consumes more water to remove the excess sugar
• blurred vision- water may leave the retina and lens due to the high glucose
• loss of weight- the body relies of fats and protiens to respire

Question 15

excretory system

Answer 15

• Renal vein and artery (takes blood to and away from kidney)
• kidneys
• Ureter (carry urine from kidney to bladder)
• bladder
• bladder outlet
• Urethra (lets urine out of the body)

Question 16

deamination

Answer 16

the removal of amino group from an amino acid turning it into ammonia, which becomes urea when combined with CO2. when this is moved to the kidney and combined with other waste products it is called urination

Question 17

two sections of the kidney

Answer 17

outer bit- cortex
inner bit- medulla

Question 18

the nephron

Answer 18

the glomerulus allows small molecules (e.g glucose, urea, salts,water and ions) to diffuse across the capillaries into the bowman’s capsule in a process called ultrafiltration. Small useful ions are then selectively reabsorbed into the bloodstream while waste products (and some water to dilute them) are excreted out

Question 19

causes of kidney failure

Answer 19

• drug abuse
• alcoholism
• diabetes
• high blood pressure
• bacterial infection
• issues with blood supply
• anaphylactic shock

Question 20

haemodialysis

Answer 20

must happen 4 hours a day 3 days a week and removes waste products from the blood so they are at a healthy level. Dialysis fluid and blood flow travel counter current to maintain the largest possible concentration gradient fro stuff like urea

Question 21

kidney transplant

Answer 21

a more permanent solution to kidney failure. A donor organ (usually from a close relative for blood type and tissue match) is connected to renal vein and artery and ureter
because it is a foreign tissue the recipient will have to take immunosuppressant drugs to prevent immune system from attacking it (can increase chances of diseases and cancer)

Question 22

phases of the menstrual cycle

Answer 22

days 1 - 5 - menstrual phase
8 - 12- follicular phase
13-15 ovulation phase
16-27 luteal phase

Question 23

reproductive hormones

Answer 23

The pituitary gland secretes FSH causing an egg to mature in the ovaries this causes oestrogen to be secreted to build the lining of the uterus. when enough oestrogen has been secreted it inhibits the production of FSH and stimulates the production on LH which causes ovulation. When the the follicle is empty it releases progesterone which inhibits the FSH and LH. Progesterone maintains the lining of the uterus. As the follicle degrades it stops producing progesterone causing the lining of the uterus to degrade

Question 24

types of contraception

Answer 24

• barrier
• chemical
• hormonal
• abstinence
• surgical (vasectomy/ hysterectomy)

Question 25

barrier methods

Answer 25

• condoms& femidoms(up to 98% effective)- prevents STIs
• IUD (up to 99% effective)- up to 10 years+ block & disable sperm
• Diaphragm(up to 92%)- reusable but ust be let in for at least 6 hours afterwards for spermicide to work

Question 26

hormonal methods of contraception

Answer 26

• vaginal ring (can be over 99% effective)keep it is 3 week one week without
• injections (up to 99% effect) can help if forgetful
• hormone patch
• pill

Question 27

stimulating pregnancy

Answer 27

some women just have low levels of FSH so they take medication such as clomiphene and Tamoxifen which stimulates FSH and LH

Question 28

IVF

Answer 28

in vitro fertilisation occurs when a woman can’t get pregnant naturally. She is given LH to release a large amount of eggs which can be extracted using a aspirating needle and then the gg is fertilised with the sperm in a petri dish for the next 16-20 hours and monitored for about 5 days(blastocyst) at which it will be placed in the uterus. If it fails the couple can have another go after hormones have settled

Question 29

Ethical issue with IVF

Answer 29

• some say its not natural
• can lead to multiple births (higher risk)
• embryos not used are eventually destroyed
• can become pseudo eugenics when picking a donor
• allows older people to have children which may be unfair to the child