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Homeostasis + Kidney - Coggle Diagram

- - - - Increased surface area for reabsorption
      - Capillaries are in close contact with tubule
        
        Reduces diffusion distance
        
        Constant blood flow, increasing conc. grad.
    - - Increasing surface area for transport out of PCT cells
      - Concentration increases in channels, so increases conc. grad.
    - - ATP synthesis for active transport
    - - Production of proteins for facilitated diffusion and active transport
  - - - Then transported out of cells by facilitated diffusion or active transport
- - - - (Thick ascending tubule)
  - - - Therefore water will leave by osmosis > surrounding tissue > vasa recta
  - - - Water is reabsorbed from the lumen of collecting duct into the tissue fluid via intrinsic, channel-forming proteins called aquaporins
        
        Permanent - Enables constant flow of water into and out of cells
        
        Temporary - Can be inserted or removed from cell membrane, to control vol. of water entering / leaving
    - - Membrane-bound vesicles with temporary aquaporins fuse with cell membrane
        
        The cell membrane on the side of the collecting duct cells that are also in contact with the filtrate (luminal side)
        
        The temporary aquaporins are embedded into the membrane of the vesicle
        
        The water potential in cytoplasm is lower than filtrate, and the insertion of aquaporins into the luminal membrane, more water can pass in via osmosis
- - - - Constant internal state adapting to changes in external environment
    - - Deviations from point are adjusted by negative feedback
        
        To restore set point
    - - Stimulus
      - Sensor
        
        Detects stimulus (with sensory cells)
        
        Response lowers effect of stimulus
        
        Negative feedback reduces the level of response
      - Control
      - Effector
  - - - Osmoregulation
        
        Regulation / Balance of water and dissolved solutes in plasma
        
        Part of homeostasis in body
      - Removal of urea from the body - excretion
    - - Oxygenated blood with high urea conc. flows from heart > kidneys - via aorta + renal arteries
      - Deoxygenated blood with lower urea conc. returned to heart - via renal veins and vena cava
      - Urine with high conc. of urea passed via ureter to urinary bladder then through the urethra
        
        Urine stored in urinary bladder until passed out through urethra
  - - - Cortex - The outer region
        
        Renal arteries divide into tiny arterioles linked to a nephron
        
        Ultrafiltration occurs
        
        Filtration of blood under high pressure
        
        Selective reabsorption occurs
        
        Removes useful substances from filtrate
        
        Most of the water is also reabsorbed into the blood
      - Medulla - central region
        
        Site of osmoregulation
        
        Controls volume of water and ions lost from blood
      - Renal pelvis - Origin / Core
        
        Collects the urine formed and passed onto ureter for transport to bladder
  - - - How to distinguish in detailed / microscope diagrams
        
        Cells of proximal convuluted tubules are cuboidal with distinct nuclei
        
        Cuboidal cells are square in cross sections
        
        Capillaries of glomerulus are stained as a dark group of cells
        
        Bowman's capsule appears as a clear zone surrounding glomerulus
    - - How to distinguish
        
        Cross sections of different tubular structures with different diameters + thickness of walls
        
        Blood in capillaries stain as solid mass
        
        Collecting ducts appear larger than other structures
        
        Thin and thick parts of descending and ascending limbs of loop of Henle are different
    - - Large numbers of tubules cut in longitudinal section - along the tubule
      - Sometimes you may see tubules emptying into a space
        
        This space is the origin of the ureter
- - - - They work together to filter the blood supply leading to the glomerulus under high pressure
        
        6.7Kpa
      - Blood supply to the glomerulus enters through afferent arteriole and leaves through the efferent arteriole
        
        The efferent arteriole is narrower than the afferent arteriole
        
        Efferent also leads to two other capillary networks
        
        Capillaries surrounding the loop of Henle
        
        Also known as the "vasa recta"
        
        Capillaries surrounding the proximal and distal convoluted tubules
        
        Can also be worded as afferent arteriole is wider than the efferent arteriole
        
        This difference increases the hydrostatic pressure of the blood plasma
        
        Afferent - going to
        
        Efferent - going out
    - - These "pores" may also be called fenestrations or filtration slits
        
        Filtration slits, allow filtrate to pass from the blood into the lumen of the renal capsule
        
        Proteins and cells are too large to pass through these gaps
        
        Selectively permeable membrane
    - - Podocytes wrap around the capillaries of the glomerulus
    - - Allowing only water and small molecules to pass from the blood to the nephron
      - The pores in the basement membrane are the main filtration sites
        
        The pores are smaller than fenestrae and filtration slits
    - - Podocytes
        
        Channels between the "feet" of the podocytes increase conc. grad. between tissue fluid
        
        The "feet" of the podocytes increase surface area for filtration
      - Short diffusion distance between podocytes and the capillary
  - - - This means small soluble molecules are forced out of plasma
        
        These molecules enter channels between podocytes "feet" and the capillary walls
        
        Increasing concentration of these molecules
    - - Like a molecular sieve, only allowing small-sized molecules to pass
        
        No cells and plasma proteins can pass through, as they are too large
        
        This works as hydrostatic pressure of plasma is high due to difference of diameters
        
        Osmotic pressure of plasma is lower than filtrate, therefore water will move back into plasma
        
        The osmotic pressure is lower from the presence of plasma proteins
        
        Fluid pressure in Bowman's capsule increases as volume increases
    - - This is called "net filtration pressure"
- - - - High protein causes more urea levels which can be converted into uric acid
        
        Can crystallise and form kidney stones, causing damage to tissues and bleeding
        
        This leads to small proteins being excreted by kidneys
        
        Blood plasma proteins maintain the osmotic pressure of the blood
        
        Low dietary protein results in accumulation of fluid in tissues, lowering blood pressure and reduction of kidney function
    - - High blood pressure causes excessive filtration by glomeruli and loss of nutrients
      - High blood pressure can damage glomerulus, if severe, leads cells and plasma proteins being lost in urine
    - - K+ is required for transmission of nervous impulses and is actively transported into all cells
        
        If too high / low, can disrupt nervous transmission
      - Can be dietary or taking drugs, to reduce or increase reabsorption of K+
      - Excessive loss of Ca2+ leads to brittle bone disease (osteoporosis)
      - Reduced loss of Ca2+ can lead to problems with hormonal production and the disposition of calcium salts in tissues.
        
        Tissues such as the retina (leading to blindness), muscle (pain on contraction), joints (pain during movement)
  - - - Chronic
        
        Kidney failure develops over years, irreversible at the end
        
        Possible causes
        
        Secondary to high blood pressure and / or diabetes
        
        Chronic bacterial inflammation of the kidneys
        
        Cystic kidneys
        
        Various autoimmune diseases
      - Acute
        
        Kidney failure develops over hours - days, including chance of kidney function recovery
        
        Possible causes
        
        Acute intoxications
        
        Part of multi-organ failure
        
        Various other diseases (e.g. infections)
        
        Traumatic (e.g post surgical)
    - - Haemodialysis - using a dialysis machine to remove excess water, urea and ions from plasma
      - Peritoneal dialysis - Using selectively permeable membranes in the body to achieve the same result