Zusammenfassung der Ressource
Excretion
- The need for Excretion
- Removal of
metabolic waste
from the body
- Carbon Dioxide
- Respiratory acidosis
- Breathing out
- Nitrogenous Waste
- Deamination
- Ornithine Cycle
- Urea
- The Liver
- Rich blood supply to
carry out metabolic
functions
- Deoxygenated blood
- From the digestive system
- Contains varying amounts of
compounds (some potentially
toxic compounds)
- Via hepatic portal vein
- Oxygenated blood
- From the heart
- From aorta via hepatic
artery
- Supplies oxygen for
aerobic respiration
- Blood leaves via
hepatic vein
- Bile duct carries bile
from the liver to the gall
bladder where it is
stored
- Divided into lobes
- Divided into lobules
- Hepatocytes
- Cuboidal with microvilli
- Metabolic functions
- Protein Synthesis
- Transformation + storage of
carbohydrates
- Synthesis of bile
- Detoxification
- Kupffer cells
- Specialies macrophages
- Move about sinusoid and
breakdown/recycle RBCs
- One of the products is bilirubin
- Functions
- Detoxification
- Liver is filled with enzymes with
detoxification functions
- E.g catalase that can convert hydrogen peroxide
into water and oxygen
- Alcohol
- Storage
- Productions of Bile
- Break down of RBCs
- Deamination +
formation of urea
- The Kidney
- The nephron
- About 1 million in each kidney
- Starts in the cortex
- In the cortex capillaries form a knot
(Glomerulus)
- Surrounded by the Bowman's Capsule
- Ultrafiltration pushes the
blood into the Bowman's
Capsule
- Leads to the Nephron
- Narrow gaps
between
endothelium of
capilaries
- Basement membrane
consists of fine mesh of
collagen fibres
- Podocytes have finger-like
projections to ensure gaps
between cells.
- Blood flows from
afferent to efferent
arteriole
- Large to small diameter,
increases pressure
- Four Parts
- Proximal Convoluted Tubule
- Loop of Henle
- Descending limb into medulla
- Ascending limb into the cortex
- Hairpin Countercurrent Multiplier
- Distal Convoluted Tubule
- Collecting Duct
- After short section of DCT where salt
concentrations are altered slightly
- Carries high water potential fluid back through
medulla to the pelvis
- As the water potential of the medulla decreases water
begins to diffuse out by osmosis
- Selective reabsorption
- Mostly occurs in the PCT
- CSM in contact with
tubule fluid has microvilli
- Contains co-transporter
proteins (Glucose/AA +
sodium ions)
- Other membrane also folded
+ contains sodium-potassium
pumps
- Many mitochondria for active processes
- Osmoregulation
- Control of water and salt levels in
the body
- The permeability of the wall of the collecting
duct can be altered
- The walls respond to antidiuretic hormone
(ADH) in the blood
- End result places more aquaporins into the csm by
forming vesicles that attatch/detach from the
memberane
- Concentration of ADH in the
blood can be adjusted
- Water potential monitored by
osmoresceptors in the hypothalamus
- When water potential drops, they lose
water and shrink, stimulating
neurosecretory cells
- Neurosecretory cells are specialised neurones that
produce and release ADH where it is stored in the
pituitary gland until needed
- Kidney Failure
- Once they fail completely the body is unable to
remove excess water and certain waste products
- Treatment
- Dialysis
- Passes the blood across a dialysis membrane to
remove excess fluid, salts + wastes
- Kidney Transplant
- Testing Urine