excretory system Flashcards
what is excretion
the removal of waste products of metabolism from the body
what are the exctretory organs nd what are their functions
Lungs-CO2 water and heat
Colon/gut- faeces
Kidney- nitrogenous waste
Skin- sweat
what are the nitrogenous waste products
uric acid
urea
creatinine
ammonia
what other useful substances are exctreted out of the body
water
amino acids
hormones
vitamins
salts
ions
glucose
what is the glomerulus
a cluster of capilaries
what is found in the renal corpusle
-bowmans capsule
-glomerulus
what is found in the renal tubule
proximal convulated tubule
loop of henle
distal convulated tubule
what is the microscopic structure that is vital for excretion in the kidney called
nephron
how many nephrons share the same collecting duct
12
how do the kidneys maintain homeostasis
removing unwanted substances from the blood
what is glomerular filtration
when the fluid part of the blood is filtered through a glomerular membrane into the cavity of the bowmans capsule
what is tubular reabsorbtion
when useful substances are reabsorbed back into the bloodstream in the mounts that are needed by the body
what is tubular excretion
when the waste products from the blood are excreted into the tubules
where does glomerular filtration take place
in the renal corpuscle
what is the difference between an efferent arteriole and an afferent arteriole
an efferent arteriole carries blood towards the nephron and the afferent arteriole carries blood away fron the nephron
how does the size of the 2 arterioles influence glomerular filtration
blood enerts through the wider afferent arteriole and and pressure is created because the efferent areriole is more narrow, which means more blood is entering the glomerulus that what can leave
this causes pressure to buld up forcing blood to filter thrugh the glomerular membrane
what is ultrafiltration
filtration of blood in the capilries into the bhowmans capsule while under pressure through the glomerular membrane
what are some non-nitrogenous wastes
toxins and drugs (painkillers, tranquillisers, and nicotine)
alcohol
what is defaecation or egestion
removal of undigested and unabsorbed food material from the gut
is the bladder an excretory organ
no, its only function is to store urine
what type of glands are adrenal glands
endocrine glands
where are the kidneys found
in the abdominal cavity below the diaphragm
where is the nephron in the kidney found
in the cortex and the medulla
what does the renal artery carry
blood that is rich in nitrogenous waste
what does the renal vein carry
purified, deoxygenated blood from the kidney to the inferior vena cava
how much blood is filtered in 1 minute
120ml
how is the glomerular membrane adapted for filtration
it is made up of 2 layers of cells:
endothelial cells- make the wall of glomerular capillaries and they are porous which allows plasma through the pores but not blood cells
flattened podocyte cells - make up the podocyte layer and it has spaces between them called filtration slits that only allow plasma protein through
what makes up glomerular filtrate
Blood plasma without the blood cells or plasma protein with useful substances (water, glucose, amino acids, vitamins, hormones and ions) as well as waste substances such as nitrogenous waste (urea, uric acid & cratinine)
what is the function of the shape of the Bowman’s capsule
large surface area, so that the max amount of filtration can take place
what is glomerular filtration
passive process in which fluids and solutes are forced through the glomerular membrane by means of hydrostatic pressure
what happens to the filtrate as it moves along the renal tubule
the useful substances that are needed by the body are reabsorbed into the blood in the surrounding capillaries
where does the reabsorbtion of useful substances take place
proximal convoluted tubule
what cells are the walls of the PCT made up of
cuboidal epithelial cells
what adaptations are made with the walls of the PCT
microvilli along the border of the tubule= increases surface area for max reabsorption
Outer surface of tubule is folded to increase surface area
A lot of mitochondria for active transport
What is active reabsorption in the PCT
molecules combine carrier molecules and are then able to move against the concentration gradient
what is needed for active reabsorption to take place
ATP- adenosine triphosphate
what is the concentration gradient
the gradual difference in the concentration of solutes in a solution between 2 regions
what substances are reabsorbed
-glucose
-protein
-water soluble vitamins(Vitamin C)
-amino acids
-salts
are there any glucose or protein molecules in normal urine?
No
how is water reabsorbed into the blood
by means of osmosis. 65% of the water is passively reabsorbed
what is the role of the loop of Henle
to create a high concentration of salt in the medulla of the kidney in order to actively transport sodium ions out of the filtrate
what is a sodium pump
salt(nacl) is transported to the surrounding tissue fluid, causing water to move out fo the loop by means of osmosis
what is the final oucome of the loop of henle
water is actively conserved & passed into blood rather than urine
less urine is formed=conservation of water
what does it mean is an organism has a longer loop of henle
encourages more water to be reabsorbed= highly concentrated urine
what is the pH range for urine
6 (weak acid)
what is the pH of blood
7.35- 7.45 (slightly alkaline)
what is a buffer
chemical substance that prevents a great change in pH by binding with H+ when pH drops and releasing H+ when pH rises
what is urine
filtrate containing all substances that the body does not want that flows through the collecting ducts
what can affect the composition, amount and colour of urine
diet
exercise
volume of liquids drunk
health
how much urine is produced daily
1l - 1.5l
what is the process of urine moving out of the kidneys
- passes into the calyx then into the renal pelvis
- moves through the 2 ureters into the bladder
-stored in bladder until it is able to be expelled by the urethra
what is osmoregulation
maintains the correct balance between the water and solute contents of body fluid
what happens is there is too much water in the cell
the cell will burst
what happens when there is too little water in the cell
dehydration of cells
what is osmolarity
the number of solute particles dissolved in 1 litre of water
*the greater the concentration of solutes the greater the osmolarity
