Course Hero Logo

Heart- histology and physiology .pdf - ONLINE LECTURE...

Course Hero uses AI to attempt to automatically extract content from documents to surface to you and others so you can study better, e.g., in search results, to enrich docs, and more. This preview shows page 1 - 4 out of 11 pages.

ONLINE LECTUREChapter 20heart: histology and physiologyCardiac muscle*nuclei are centrallylocated*fewer nuclei than theskeletal muscle*located in the verycenter of the cellb/cnot as many myofibrilscompared to skeletal*number of mitochondriahas a lot of it comparedto skeletal muscle b/cheart has to work over our life-span (so ATP is required)elongated, branching cells containing 1-2 centrally located nuclei and do not run theentire length of the cell, they are short and connect in seriescontains actin and myosin myofilamentsintercalated disks: specialized cell-cell contacts.regions of plasma membrane thathave specialized cell-cell contacto[in the region of the intercalated disk] desmosomes: plasma membranestructures that are used to hold the cells togetheract like staples to keep themuscle fiber together while it is contractingessentially it will pull the neighboring cells that it is attached toogap junctions [where we had electrical synapses/ direct movement of ions fromone cell to another cell]allowed us to have a direct change in membranepotentialfrom one cell affecting a neighboring cellElectrically, cardiac muscle of the atria and of the ventricles behaves as single unit
Components of cardiac muscle fibersDifferences b/w skeletal and cardiac muscles:Transverse tubules are quite a bit larger [however less frequent along the length of thefibrepresent where the Z-disk is located]oIn skeletal muscle: Action potential is moving along the sarcolemmadrops downto the T-tubles, that signlas the SR to relase Ca+, whichCa+ binds onto thetroponin found over top of the actin, move the tropomyosin over the bindingsite and allow cross bridge cycling to occurHowever in cardiac since the T-tubles are not located all the actin andmyosin is, but in between them, where the Z-disk are. This makes thecontraction a little slower, due to the regulated heartbeat .oDon’t have enlarged regions, instead the sarcoplasmic reticulum is not as highlyorganized, and does not come in contact with the transverse tubules as great asextentConducting system of heart*how action potentials move through the heart. Need an action potential to move along thesarcolemma in order to stimulate the Ca+ to bind onto the troponin, to cause the musclecontraction.
Conducting system of heartSA node: sinoatrial node. Generate spontaneous action potentials. Action potentials

Upload your study docs or become a

Course Hero member to access this document

Upload your study docs or become a

Course Hero member to access this document

End of preview. Want to read all 11 pages?

Upload your study docs or become a

Course Hero member to access this document

Term
Winter
Professor
Dr. Howard

Newly uploaded documents

Show More

Newly uploaded documents

Show More

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture