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Human Physiology - Coggle Diagram

- - - - Therefore muscle shortening does not mean muscle contraction
      - Also means you can produce tension without changing the length of the muscle
      - Relaxation of a muscle = return of muscle fibers to a low tension state
    - - do not contain sarcomeres but use actin and myosin contraction to constrict blood vessels and move the contents of hollow organs in the body
    - - contain actin and myosin filaments that power contraction and are organized into repeating arrays, called sarcomeres, with a striated microscopic appearance
      - contain INDIVIDUAL muscle fibers inside of which are smaller units called myofibrils made of parallel think and thick filaments
        
        The filaments are arranged longitudinally in small units known as sarcomeres which give the muscle a striated appearance under microscopy
        
        thick filaments made of the protein myosin and at the tail of the thick filament two heavy chains are intertwined in a helical formation. At the other end of the thick filament, each heavy chain is paired with two light chains giving rise to two heads. The myosin heads have an actin-binding site that helps them attach to the thin filaments
        
        The thin filaments are composed of actin, tropomyosin, and troponin. Actin is a globular protein that combines with other actin globules to form two intertwined strands with positive and negative ends. The double-stranded actin filaments are covered by tropomyosin, which blocks the interaction between myosin and actin when the muscle is inactive. The troponin group comprises troponins I, T, and C and is located along the actin filaments next to tropomyosin.
    - - Starts with an action potential. the action potential causes depolarization in the myocyte membrane (the membrane of a muscle cell)
        
        Depolarization of the T tubules causes a conformational change in the dihydropyridine receptors, which causes the opening of nearby ryanodine receptors on the sarcoplasmic reticulum (SR), the storage site for calcium within muscle cells. [ryanodine receptors open causing calcium to be released into the muscle cell's cytoplasm]
        
        When calcium is released from the SR, it binds to troponin C. This causes a conformation change, which shifts tropomyosin, allowing the myosin heads to attach to the actin filaments creating what is known as a cross-bridge.
        
        Cross-bridge cycling begins when ATP binds to an ATP-binding domain on the myosin head. Myosin dissociates from the actin, breaking the cross-bridge. ATP is then hydrolyzed into ADP and P, which causes the myosin heads to change conformation and move toward the positive end of the actin, cocking the myosin head. The phosphate is released, and the ADP-bound myosin binds to a new location on the actin filament. ADP is then released, which causes the myosin to return to its original position, pulling on the actin filament and causing the sarcomere (and, therefore, the muscle fiber) to contract. These cycles continue until calcium levels in the myocyte fall, causing tropomyosin to cover the actin filaments' myosin-binding sites
        
        does have the troponin complex required for skeletal muscle contraction
    - - does not have the troponin complex required for skeletal muscle contraction
      - Controlling Ca entry into the muscle cells (mytocyte)
        
        Voltage-gated (carrier proteins or maybe channel proteins which require energy to open) that allow Ca channels are activated by membrane depolarization, allowing Ca to enter the cell.
        
        Hormones or neurotransmitters can open ligand-gated channels on the cell membrane.
        
        Hormones and neurotransmitters such as norepinephrine and angiotensin II can, via the phospholipase-C (PLC) pathway, cause an increase in intracellular inositol triphosphate (IP3).
      - IP3 can bind to receptors on the SR and cause Ca to be released. Once Ca is released, it binds to a calmodulin protein instead of binding to troponin C as it does in striated muscle.
        
        Calmodulin then activates myosin light chain kinase (MLCK), which, as the name suggests, phosphorylates the myosin light chain. The phosphorylated myosin light chain has ATPase activity which hydrolyzes ATP, increasing its affinity to actin. The myosin can then readily bind to actin. From this point, cross-bridge cycling is the same as in striated muscle. The smooth muscle will remain contracted as long as Ca is bound to calmodulin and the MLCK is phosphorylated. This allows for prolonged periods of vasoconstriction in blood vessels
  - - - Striated muscle
  - - - Smooth muscle.
  - - - Striated muscle
- - - - Open: skin break
        Closed: no skin break
        
        Oblique fracture is a fracture that is diagonal
      - For long bones:
        And one incidence: Simple (two pieces) and Comminuted fracture (several pieces)
        And over use injury: Stress fracture
    - - BONE REMODELLING
        
        Bone Cells:
        
        Osteoblasts (produce bone)
        
        Osteoclasts (remove/demineralise bone) (from bone marrow)
        
        Bone lining cells (inactive osteoblasts)
        
        Osteocytes (former osteoblasts)
        
        Activation–resorption–formation model (ARF)
        
        Blood clotting or haematoma formation and inflammation
        
        lasts 3–4 days maybe longer if it is a bad fracture
        
        fractures always disturb the medullary vessels and internal bleeding (extravasation)
        
        Although contraction and thrombosis of the disrupted vessels minimise blood loss
        
        leads to ischaemic necrosis of bone (bone cell death?)
        
        Granulation tissue is replaced with soft (cartilaginous) and then hard callus of WOVEN bone
        
        Osteoblasts (creating bone) form woven bone on the calcified matrix
        
        Matrix:
        
        the substance between cells or in which structures are embedded. "the lipid matrix of olfactory cells"
        fine material used to bind together the coarser particles of a composite substance. "the matrix of gravel paths is hoed regularly"
        
        Remodeling begins with osteoclasts and osteoblasts facilitating the conversion of woven bone into lamellar bone and eventually recreating the appropriate atomical shape
    - - cortical bone or low porosity's direction is based on: lamellar and osteonal orientation
      - trabecular bone or higher porosity's direction is based on: trabecular orientation
- - - - The resulting redistribution of electric charge may alter the voltage difference across the membrane.
        
        A decrease in the voltage difference is called depolarization. If depolarization exceeds a certain threshold, an impulse (i.e., action potential) will travel along the neuron.
        
        Various mechanisms ensure that the action potential propagates in only one direction, toward the axon tip.
- - - - made of platelets and fibrin polymer
      - involves the vasculature, liver, and bone marrow
- - - - Capillaries have:
        
        a wall made of a single layer of cell
        
        no layer of muscle and elastic fibre,
        
        and a very small lumen and
        
        Capillary walls are only one cell thick, allowing the exchange of gases, nutrients and wastes. This is why veins once the blood has passed through the capillaries is oxygen poor and 'empty'
        
        They are so fine that red blood cells must line up single-file to go through them
      - Arteries have:
        
        a thick outer wall,
        
        a thick layer of muscles and elastic fibres,
        
        and small lumen
      - Veins have:
        
        a fairly thin outer wall,
        
        thin layer of muscles and elastic fibers,
        
        and large lumen
    - - Lack a nucleus
        
        Contain hemoglobin
        
        Disk shaped
      - Produced in red bone marrow from the:/
        
        ribs
        
        humerus
        
        femur
        
        sternum and other long bones
      - Old red blood cells are destroyed in the liver and spleen
    - - Recognise proteins that do not belong to the bodies and kill disease. They can travel through walls of the capillaries to patrol the tissues and reach the lymph system (immune system that keeps body fluid levels in balance) (spleen is part)
        
        three types:
        
        granulocytes (includes neutrophils)
        
        lymphocytes
        
        monocytes
    - - Cell FRAGMENTS used in blood clotting derived from megakaryocites, lack a nucleus and so have a short lifespan of about 10 days
- - - - The gallbladder is a sac located under the liver. It stores and concentrates bile produced in the liver. Bile aids in the digestion of fat and is released from the gallbladder into the upper small intestine in response to food (especially fats)
      - GI tract = mouth, esophagus, stomach, small and large intestine, anus - all hollow
        
        small intestine -
        
        duodenum
        
        jejunum
        
        ileum
        
        large intestine -
        
        appendix
        
        cecum (tech the first part of large intestines)
        
        colon
        
        rectum
      - Your pancreas makes a digestive juice that has enzymes that break down carbohydrates, fats, and proteins. The pancreas delivers the digestive juice to the small intestine through small tubes called ducts.
  - - - Proteins break into amino acids
      - Fats break into fatty acids and glycerol
      - Carbohydrates break into simple sugars