topic 7 - animal coordination, control and homeostasis

location of pituitary gland

brain

hormones produced in pituitary gland

• FSH

• LH

• ADH

• TSH

role of FSH hormone

• stimulates oestrogen production

• stimulates growth of follicles in ovaries

role of LH hormone

stimulates ovulation

location of thyroid gland

neck

hormone produced in thyroid gland

thyroxine

role of thyroxine

stimulates the metabolic rate

how does thyroxine control the metabolic rate

• controls rate at which

• oxygen and food products react

• to release energy for the body to use

location of pancreas

abdomen

hormone produced in pancreas

insulin

role of insulin

• stimulates muscles and liver

• to take up excess glucose

• from the bloodstream

• to store as glycogen

what is glycogen

glucose polymer

location of adrenal gland

abdomen

hormone produced in adrenal gland

adrenaline

role of adrenaline

• increase heart and breathing rate

• divert blood flow towards muscles

• dilation of blood vessels inside muscles

• breaking down glycogen to glucose

• dilation of pupils

how does adrenaline increase the heart and breathing rate

• ensures glucose and oxygen

• delivered to muscles cells

• and carbon dioxide taken away

• from muscles cells

• at increased rate

why does adrenaline divert blood flow towards muscles

• ensures an increased supply of reactants of respiration

• reach the muscles

• to prepare the body for movement

why does adrenaline dilate blood vessels in muscles

• ensures an increased supply of reactants of respiration

• reach the muscles

• to prepare the body for movement

why does adrenaline break down glycogen into glucose

• to increase blood glucose concentration

• for increased respiration

• in muscle cells

why does adrenaline dilate the pupils

• to allow as much light as possible

• to reach the retinas

• so more information can be sent to the brain

location of testes

scrotum

hormone produced in testes

testosterone

role of testosterone

stimulates sperm production

location of ovaries

lower abdomen

hormone produced in ovaries

oestrogen

role of oestrogen

grows and repairs uterine lining

hormone produced in corpus luteum

progesterone

role of progesterone

• maintains the uterine lining

• creates a mucus plug in cervix

state thyroid gland negative feedback loop

• hypothalamus detects low levels of thyroxine

• and releases more TRH

• stimulating release of TSH in pituitary gland

• stimulating thyroid gland to release thyroxine

• normal or high levels of thyroxine inhibits release of TRH

• which inhibits the release of TSH, inhibiting the release of thyroxine

role of TRH

stimulates the release of TSH

role of TSH

stimulates thyroid gland to release thyroxine

menstrual cycle stages

1. day 1-7 menstruation

2. day 7-14 uterine lining thickens

3. day 14 ovulation

4. day 14-28 lining is maintained in case of pregnancy

why contraception is used

• to keep families small

• limit the increase of the human population

state natural forms of contraception

• abstinence

• rhythm method

state chemical forms of contraception

• IUD

• contraceptive pill/implant/injection

explain how IUDs work to prevent contraception

• release progesterone

• causes mucus plug to form in cervix

• makes it difficult for sperm to enter uterus

• also thins uterine lining

• so fertilised egg are less likely to implant

evaluate IUDs

explain how contraceptive pills/implants/injections work to prevent contraception

• contains progesterone

• progesterone inhibits FSH and LH

• FSH is inhibited meaning no new eggs are produced by ovary follicles

• LH is inhibited meaning ovulation cannot occur

• meaning the sperm can’t fuse with an egg

state barrier forms of contraception

• condom

• femidom

• diaphragm + spermicide

explain how a condom/femidom works to prevent contraception

physically prevents sperm from meeting the egg

explain how diaphragm + spermicide work to prevent contraception

• diaphragm physically prevents sperm from entering the uterus through the cervix

• spermicide kills any sperm present

state advantages of hormonal contraception

• effective when taken regularly

• more effective than barrier methods as it prevents ovulation

state disadvantages of hormonal contraception

• doesn’t protect from STIs

• lacks effectiveness when not taken regularly

• can produce unwanted side effects

state advantages of barrier method contraception

• protects from STIs

• no side effects on the body (e.g. affecting the menstrual cycle)

state disadvantages of barrier contraception

• less effective than hormonal methods

• barrier methods are only effective when used correctly

infertility definition

when a couple find it difficult or unable to conceive naturally

causes of infertility

• issues with female reproductive system

• insufficient levels of reproductive hormones affecting the development of gametes

explain use of hormones in Assisted Reproductive Technology (ART)

• IVF is an example of ART

• IVF gives the female FSH and LH to stimulate the development and release of matured egg cells

• the egg cells are collected from the female and fertilised with the male’s sperm in a lab

• fertilised eggs develop into embryos

• the embryos are inserted into the female’s uterus

explain use of hormones in clomifene therapy

• clomifene drug is given to the female to cause more FSH and LH to be released

• which stimulates the development and release of matured egg cells

state advantage of fertility treatment

can provide an infertile couple with a baby

state disadvantages of fertility treatments

• expensive

• risk of multiple births

• low success rate

• ethical issues as it could increase the risk of eugenics

explain the importance of maintaining internal conditions in response to internal/external factors

ensures that reactions in bodily cells can function normally

thermoregulation definition

maintenance of core body temperature

explain the importance of homeostasis in thermoregulation

• human body needs to maintain optimum temperature

• for optimum enzyme activity within bodily cells

state example process of thermoregulation

• respiration

• releases thermal energy from the body

• into the surroundings

state body part where thermoregulation occurs

hypothalamus

explain what occurs if body temperature is too high

• hair erector muscles relax

• vasodilation (blood vessels dilate)

• causing sweat to be secreted by sweat glands into the skin

• sweat evaporates, cooling the skin

• thermal energy from the body is lost

explain what occurs if body temperature is too low

• hair erector muscles contract

  • erected hair traps air which acts as an insulator

• vasoconstriction (blood vessels constrict)

• causing sweat to stop

• and skeletal muscles to contract (shivers)

osmoregulation definition

maintenance of water and salt concentrations across membranes within the body

explain the importance of homeostasis in osmoregulation

• maintaining water concentration in the body is important

• to prevent harmful changes occurring to bodily cells due to osmosis

explain what occurs if water concentration is too high

• causes cells to be in a hypotonic solution

• where excess water enters them due to osmosis

• causing the cells to swell and eventually lyse (burst)

explain what occurs if water concentration is too low

• causes cells to be in a hypertonic solution

• where cells lose excess water due to osmosis

• causing the cells to shrivel and cause cell death

explain the role of the dermis in thermoregulation

• dermis contains sweat glands, hair erector muscles and blood vessels

• which change to maintain the optimum core temperature of the body

explain the role of the hypothalamus in thermoregulation

• the hypothalamus maintains the optimum internal temperature of the body

• by making changes in the body based on internal changes in temperature

explain how insulin controls blood glucose concentration

• hypothalamus detects high blood glucose concentration

• triggering the pancreas to release insulin

• insulin stimulates the liver and muscles cells to take up excess glucose from the blood

• and store it as glycogen

explain how glucagon controls blood glucose concentration

• decreased blood glucose concentration triggers the pancreas to release glucagon

• glucagon stimulates the liver to break down glycogen into glucose

• which is released into the bloodstream

what is glycogen

glucose polymer

explain the cause of type 1 diabetes

• the patient’s pancreas fails to produce sufficient insulin to control blood glucose concentration

• causing uncontrollable high blood glucose concentrations

explain how type 1 diabetes is controlled

• insulin injections

• to decrease blood glucose concentrations

explain the cause of type 2 diabetes

• the patient’s cells become resistant to insulin produced by the pancreas

• causing uncontrollable high blood glucose concentrations

explain how type 2 diabetes is controlled

• low-carbohydrate diet

• regular exercise

evaluate the correlation between body mass and type 2 diabetes

• obesity is a major risk factor for type 2 diabetes

• because an obese person is more likely to eat a carbohydrate-dense diet

• causing the over-production of insulin

• resulting in the development of insulin-resistance

evaluate the correlation between waist: hip ratio and type 2 diabetes

• a waist: hip ratio closer above 0.85/0.9 indicates fat being stored abdominally

• which suggests obesity caused by a carbohydrate-dense diet

• causing the over-production of insulin

• resulting in the development of insulin-resistance

evaluate the correlation between BMI and type 2 diabetes

• a BMI above 30 indicates that a person is obese

• which suggests obesity caused by a carbohydrate-dense diet

• causing the over-production of insulin

• resulting in the development of insulin-resistance

state how to calculate BMI

mass (kg) / height² (m)

state how to calculate waist: hip ratio

waist circumference (cm) / hip circumference (cm)

state the waist: hip ratio obesity indicator in men

0.9 +

state the waist: hip ratio obesity indicator in women

0.85 +

state functions of urinary system

• ultrafiltration of blood

• selective reabsorption

• osmoregulation

• excretion of metabolic waste products

state what urinary system consists of

• two kidneys

• joined to the bladder

• by two tubes (ureters)

• and to the vena cava by the renal vein

• the renal artery supplies oxygenated blood to the kidneys

• and a urethra carries urine from the bladder outside of the body

kidneys function

• osmoregulation of water in blood (vital for maintaining blood pressure)

• excrete metabolic waste products

• ultrafiltration of blood

• selective reabsorption of key substances

kidneys structure

• cortex - outer region

• medulla - inner section

• renal pelvis - tube linking kidney to the ureter

state location of nephrons

kidneys

state what nephrons are made of

kidney tubule

state sections of a kidney tubule

• glomerulus

• Bowman’s capsule

• proximal convoluted tubule

• loop of Henlé

• distal convoluted tubule

• collecting duct

state the small molecules filtered by the nephron

• urea

• amino acids

• salts

• glucose

• water

state which small molecule is not reabsorbed by the nephron

urea

state the large molecules which are not filtered by the nephron

• proteins

• cells

explain how the nephron is related to filtration in the glomerulus and Bowman’s capsule

• nephron contains capillaries that are ‘leaky’ due to small spaces between cells in their walls

• Bowman’s capsule is the first part of the nephron and the cells which make it up have spaces between them

• this means molecules can enter from the capillaries

• blood flow through high pressure glomerulus causes small molecules to pass through capillary walls

• where the larger molecules remain in the blood

explain how the nephron is related to the reabsorption of water

• water is filtered out of the blood through small gaps between cells in the walls of the glomerulus and Bowman’s capsule

• in the loop of Henle, water and salts are reabsorbed due to osmosis and active transport

• due to the high concentrations of salts and mineral ions in the surrounding tissue

explain the effect of ADH on the permeability of the collecting duct when water content in the blood is too high

• osmoregulation is controlled by ADH

• which is released by the pituitary gland

• the hypothalamus detects that water content in the blood is too high

• signalling the pituitary gland to inhibit ADH release

• making the collecting duct becomes less permeable and thus reabsorbs less water

explain the effect of ADH on the permeability of the collecting duct when water content in the blood is too low

• osmoregulation is controlled by ADH

• which is released by the pituitary gland

• by controlling the permeability of the collecting duct

• the hypothalamus detects the water content in the blood is too low

• signalling to the pituitary gland to release more ADH

• making the collecting duct more permeable

• allowing more water to be reabsorbed by the blood through osmosis

what does ADH stand for

antidiuretic hormone

causes of kidney failure

• severe blood loss (in an accident)

• high blood pressure

• diabetes

impacts of kidney failure

• toxins build up in the kidneys

• which can enter the bloodstream

• and cause death

describe the process of kidney dialysis to treat kidney failure

• unfiltered blood is taken from an artery in the arm (containing urea)

• and pumped in the dialysis machine where it returns to a vein in the arm

• dialysis fluid and the blood are separated in the machine by a partially permeable membrane

• the blood flows in the opposite direction to the dialysis fluid

• allowing the exchange of molecules between concentration gradients to exist

• urea will diffuse across the partially permeable membrane

• due to the large concentration gradient (caused by the fluid having no urea)

• meaning clean, filtered blood is now being pumped back into the vein

describe the process of kidney donation to treat kidney failure

• one healthy kidney is taken from a genetic match

• and transplanted into the patient to replace BOTH of their unhealthy kidneys

state what dialysis fluid contains

• glucose concentration similar to normal blood level

• concentration of salts similar to normal blood level

• no urea

what process produces urea

breakdown of excess amino acids in the liver

describe ultrafiltration in the kidneys

• blood enters a series of capillaries called the glomerulus at high pressure

• this causes small molecules to be forced out of the blood through the glomerulus’ leaky walls

• from here, they enter the nephron through the bowman’s capsule

• glucose is selectively reabsorbed back into the blood from the proximal convoluted tube by active transport

• at the loop of henlé, necessary salts are selectively reabsorbed back into the blood by diffusion

• this lowers the water concentration in the blood, causing the selective reabsorption of water by osmosis

• at the collecting duct, some water may be selectively reabsorbed back into the blood based on the permeability of the collecting duct, controlled by ADH

• after this, the remaining urea and water exits the nephron to the bladder