excretion?
removal of metabolic waste products to maintain metabolism and homeostasis
egestion?
removal of undigested food by defection
structure of the liver?
consists of lobules:
- hepatic artery
- hepatic portal vein
- hepatic venule
- bile duct
- hepatocytes
- kuffer cells
- sinusoid
histology of the liver?
central vein - large, white, circular shape
hepatocyptes - red dotted nuclei
sinusoids - white spaces
how does the liver regulate BGC?
hepatocyptes convert glucose into glycogen when responding to insulin
they also respond to glucagon
both can be found in the hepatic artery blood
how does the liver break down RBCs?
kupffer cells break down haemogloblin into bilitubin (brown pigment) where it is then excreted as a part of the bile.
deamination?
- removal of amine group/ excess amino acids
- this produces ammonia and organic acids
- ammonia + CO2 can form urea via the ornithine cycle (mitochondria + cytoplasm)
- this is then transported to the kidneys
- organic acids such as keto acid can be converted into pyruvate for the link reaction
detoxification?
alcohol
- ethanol loses H+ to NAD and forms ethanal (via alcohol dehydrogenase)
- ethanal is oxidised by NAD to form ethanoate which enters kreb cycle
hydrogen peroxide
- enzyme catalase splits hydrogen peroxide into oxygen and water to prevent cell damage (toxic)
siusoid?
a mixture of HA (oxygenated blood) and HPV (deoxygenated blood)
so? increase in O2 content for hepatocyptes
gets drained into the HV after processing nutrients like glucose and amino acids in HPV blood
how is bile transported to the bile duct?
- hepatocyptes surround the canaliculus and produce bile
- bile is drained into the canaliculus and travels to the bile duct where they are emulsified and transported to the gall badder
structure of the kidneys?
- 2
- just below ribcage
- supplied blood throgh renal artery + drained by renal vein
- ureter
- pelvis (collects urine into ureter)
- medulla
- cortex
- renal pyramids
- nephrons
histology of the kidneys?
CORTEX
bowman’s capsule - white area surrounding glomerulus
PCT/DCT - surrounding by purple blobs ( squamous epithelium nuclei)
MEDULLA
loop of henule - white
RBCs - red dots
ultrafiltration?
CORTEX - nephrons
- blood in the glomerus is under high hydrostatic pressure as afferent ateriole is widen than efferent arteriole
- water is forced into blood and small substances like glucose, ions and urea
- these enter through pores in the capillary endothelium and through basement membrane into bowman’s capsule
- large molecules such as plasma proteins cant pass through
- small molecules move through the Bowman’s capsule epithelium, which has podocytes that wrap around capillaries forming filtration slits
glomerular filtrate rate?
glomerular filtration rate (GFR) measures the volume of glomerular filtrate formed per minute
glomeular filtrate?
contains peptide hormones, amino acids, inorganic mineral ions, water, glucose, urea
selective reabsorption?
PROXIMAL CONVOLUTED TUBULE
- Sodium ions actively transported into blood capillaries, reducing the Na+ concentration in epithelial cells lining the PCT
- Na+ enters via co-transort with glucose from the PCT lumen into the epithelial cells, down its concentration gradient
- These reabsorbed molecules can then diffuse into blood capillaries.
DISTAL CONVOLUTED TUBULE
- reabsorption of any remaining useful substances, primarily through active transport.
- alteration of DCT membrane permeability to regulate further reabsorption of water and solutes.
- regulation of blood pH by selectively reabsorbing certain ions.
adaptions of PCT?
Microvilli - small, finger-like projections that greatly increase the surface area for reabsorption
Basal infoldings - structures further increase the surface area for moving substances into surrounding blood capillaries
Numerous mitochondria - ATP for the active transport processes
Co-transporter proteins in the plasma membrane - These allow co-transport of substances from filtrate into epithelial cells
describe the role of the loop of henle in reabsorption of water
- Na+Cl- is actively transported out of the ascending limb (impermeable to water) into surrounding medulla
- water potential is lowered in medulla
- water moves out of the descending limb and the cllecting duct by osmosis into the medulla
- water is reabsorbed back into the capillaries
- countercurrent system concentrates urine, and ensures that there is always a water potential gradient drawing water out of the collecting duct
osmoregulation?
homeostatic control of the water potential of the blood in the kidneys
how is the countercurrent multiplier system produced?
- water potential is loered in filtrate moving down the collecting duct
- water potential in medulla is also low as ions are actively transported out of the ascending limb
- water constantly moves out of filtrate to medulla in the collecting duct
Describe the coordinated role of osmoreceptors, hypothalamus and pituitary gland when there is low water potential
- water is reabsorbed into the blood:
1. low water potential in the blood stimulates osmoreceptors in the hypothalamus
2. hypothalamus sends nerve impulses to POSTERIOR pituitary gland
3. ADH is released into the blood via neurosecretory cells
4. this stimulates walls of the collecting duct and DCT to be more permeable to water
5. more water is reabsorbed into medulla and move into capillaries via osmosis
6. smaller, more concentrated volume of urine is produced
explain how the release of ADH causes greater water permeability in the DCT and collecting duct?
- ADH attaches to receptors on the surface of cells in the DCT and collecting duct.
- This triggers the activation of cyclic AMP
- a series of reactions that lead to the phosphorylation of aquaporins occurs.
- Aquaporin vesicles merge with the cell-surface membrane.
- Water moves through aquaporins by osmosis from the DCT and collecting duct into the surrounding medulla tissue.
- Water is then reabsorbed into the surrounding blood vessels.
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causes of kidney failure?
infections - can lead to inflammation and swelling, damaging the cells responsible for filtering and reabsorption.
High blood pressure - can damage the glomeruli capillaries, so proteins and blood leak into the urine.
how does kidney failure effect the glomerular filtration rate?
A low GFR indicates less effective blood filtration
A blood test can measure the level of creatinine in the blood, which is used to estimate the GFR.
A high level of creatinine is a signal that the kidneys are not working properly and may indicate kidney disease.
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Key Terms (Whole course)10
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Module 1 - Development of Practical Skills Practical Skills17
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Module 2: Section 1 - Cell Structure52
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Module 2: section 1 - Microscopes39
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Module 2: Section 2 - Biological Molecules62
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Module 2: section 3 - Nucleotides And Nucleic Acids40
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Module 2: Section 4 - enzymes43
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Module 2: Section 5- Biological membranes40
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Module 2 Section: 6 - Cell division51
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Module 3: Section 1 - Exchange and Transport54
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Module 3: Section 2 - Transport in Animals74
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Module 3: Section 3 - Transport in plants44
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Module 4: Section 1 - Disease and the Immune System68
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Module 4 : Section 2 - Biodiversity43
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Module 4: Section 3 - Classification and Evolution29
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Module 5: Section 3 - Neuronal Communication47
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Module 5: Section 2 - Excretion35
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Module 5: Section 5 - Plant and Animal Responses and Hormones43
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Module 5: Section 6 - Photosynthesis19
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Module 5: Section 6 - Respiration23
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Module 6: Section 1 - Cellular Control50
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Module 6: Section 2 - Patterns and Inheritance38
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Module 6: Section 4 - Manipulating Genomes20
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Module 6: Section 5 - Cloning and Biotechnology42
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Module 6 : Section 6 - Ecosystems42
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Module 6: Section 7 - Populations and Sustainability0
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Module 5: section 1 - Homeostasis and communication17
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Module 5: section 4 - Hormonal communication23
