[2] Lecture 17: Smooth And Cardiac Muscle Flashcards
(19 cards)
Not as extensive in skeletal muscle
T tubules in cardiac muscle
Single mononucleated cells Centrally positioned nuclei Sarcomeric arrangement Communicate via gap junctions Cells not directly innervatd
Cardiac muscle tissue
Cardiac muscle tissue-cells communicate via gap junction. What’re they called?
Intercalated discs
Cardiac t tubule:
Loacated along z line and diad-interacts w/ one cisterna [as opposed to skeletal triad]
Cardiac muscle composed of 3 types of junctions:
Macula adherentes (desmosomes)
Fascia adherentes
Gap junctions
Part of longitudinal component
Gap junctions
Link intermediate filaments [desmin] of adjoining cardiac muscle cells - part of transverse component
Macula adherentes
Anchor actin filaments of sarcomeres—-transverse component
Fascia adherentes
Secreted by cardiac muscle cells in atria
Regulate electrolyte imbalance
Relaxes vascular smooth muscle
Stored as prohormone in secretory vesicles
Release stimulated by atrial stretch
ANP- atrial natriuretic peptide
ANP relaxing vessels causes:
Reduces blood volume and pressure
How atrial stretch causes ANP release
Causes cleavage of pro hormone
Involuntary and visceral muscle tissue:
Smooth muscle tissue
Single mononucleated cells w/ central nuclei
No sarcomeric arrangement
Don’t respond “all or none”
Cells innervated via ANS or enteric system
Communicate via gap junctions
Smooth muscle cells
Where are the actin and myosin bundles which are in mesh work arrangement in smooth cells where are they found?
Cytoplasm except in nuclear area
Anchor actin filaments to each other and to cell membrane
Contains alpha actinin
Inteconnected by a specific type of desmin
Communicate force of contraction to cytoskeleton and cell membrane
Found in cytoplasm and in cell membrane
Dense bodies
Permanent depressions of the cell membrane thatre involved in fluid and electrolyte transport
Preceded by membrane lipid rafts composed of cholesterol and sphingolipids
Caveolin binds to the cholesterol in the lipid rafts and initiates the formation of caveolae
Vesicles are formed detach and participate in vesicular trafficking
Cavolae and lipid rafts
Recptors in smooth muscle cells
Adrenergic and muscuranic —- g-proteins
Nicotinic cholinergic receptor—cation channel
Smooth muscle sheets of most major organs are poorly innervated by what type junctions:
Gap junctions
Don’t have t tubule system or extensive SR;
Dependent on ECM Ca+ for contraction
Pinocytotic vesicles: may transport Ca++ ions from ECF to SR
Smooth muscle cells
