smooth n heart muscle Flashcards
1-muscle types:
* —-
– Most abundant muscle, found
throughout the body
– Connected to bones to facilitate
movement, balance, posture
*—-
– Throughout the body, lining
organs such as blood vessels,
stomach and intestines
– Controls movement of contents
of the organ
* —-
– Found in the heart
– Pumps blood around the body
2- 2 types of classification system :
1- — : staited or unstraited
2- — : voluntary or involuntary
skelteal
smooth
cardiac
appearance
intervention
-Nonstriated, or smooth, muscle cells are a major component of — such as:
- Smooth muscle fibers are — and, unlike — muscle fibers, have a —-
- Contraction of smooth muscle serves to alter the — of the organ, which may result in either — the contents of the organ (as in —- of the intestine)
or increasing the — to flow (as in—- )
- The basic mechanism underlying contraction of smooth muscle involves an interaction of —- (as in striated muscle), although there are some important differences
- —- are not organized as sarcomeres in smooth muscle; rather, actin is anchored to the cell membrane and to dense bodies within the cell
- of hollow organs such
as the alimentary canal, airways, vasculature, and urogenital tract - spindle shaped
- skeletal
- single nucleus
- dimension
- propelling
- peristalsis
- resistance
- vasoconstriction
- myosin w actin
- contractile proteins
types of smooth muscle : single unit (viseral ) and multiunit
1- single unit: the smooth muscle cells
are — coupled such that —- of one cell is followed by — of adjacent smooth muscle cell
2- Multi-unit smooth muscle, the second type of smooth muscle observed, are composed of cells that — possess — , and thus are not —
- electrically
- electrical stimulation
- stimulation
- rarely
gap junctions - not electrically coupled
1- types of visceral ( aka main type) smooth muscle:
2- types of mutliunit smooth muscle ( works by itself )
1-
* Intestine
* Uterus
* Bladder
* Ureters
* Ducts of exocrine glands
* Precapillary sphincters
* Small blood vessels e.g. arterioles
2-
* Cilliary muscle
* Iris
* Piloerector muscles
multiunit:
- is —- aka controlled by —
- — intervention
- — developed neursmucalr junctions
- no —-
- no —-
visceral:
- is — controlled by —-
- — innervention
- — nueromsuclar jucntions
- some —
- — or —
- has — and —
neurogenic
nerves
rich
well
spontaneous activity
electrical coupling between cells
myogenic
local factors stretch hormones
spares
poorly
pacemaker cells
gap junction or next link cells
action potentials and slow waves
excitation-contraction coupling in smooth muscle:
* Smooth muscle has no straitation because actin and myosin are — arranged
* Actin filaments are anchored to — bodies
* There is no — , and no —and usually a poorly developed —
* Most of the Ca++ for contraction comes from the —
less regular
dense
no t system
no troponin
SR
extracellular fluids
excitation-contraction coupling:
* In contrast to skeletal muscle, which contains a — alignment of thick and thin filaments that results in striations, the contractile filaments in smooth muscle are not in —- alignment
* The thin filaments of smooth muscle have an actin and tropomyosin composition and structure similar to that in skeletal muscle
* Cross-bridge formation is not regulated by the troponin -tropmoyosin complex complex but instead by the regulatory protein
—
transverse
not in uniform transverse alignment
calmodulin
E-C coupling in smooth muscle :
* — binds to —
*—- activate — which activates — allowing— formation
* phosphorlated cross-bridges cycle until they are
— by —-.
* Myosin ATPase activity is — and muscle contraction is — and —
ca++
calmodulin
ca++/calmodulin
myosin light chain kinase
myosin
crossbirdge
dephosphorated
by myosin phosphate
slow
slow
sustained
smooth muscle contraction :
* Contraction of smooth muscle is thus said to be — regulated, which contrasts with the — regulation of contraction of striated muscle
* Myosin cross-bridge cycle in smooth muscle is similar to that in
striated muscle in that after attachment to the actin filament
* The kinetics of cross-bridge cycling is much —- for smooth
muscle
* Smooth muscle tension has an — relationship with —-. Stretch causes — as —- but sustained stretch causes —- as: —-
thick filament
thin filement
slower
irregular
length
contraction
autoregualtion of blood flow
relaxation
urinary bladder
( check graph 20 )
heart muscle:
1-the – actin/myosin arrangement giving — appearance
2- Cells joined at — which have —of– electrical resistance
3- Therefore, the muscle is not a — but is a — syncytium
regular
staited
intercalated discs
gap junctions
low
structural
functional
E-C coupling in heart muscle:
* Compared to skeletal and smooth, the S.R. is —– in development
* There is only — terminal cisterna per —- and the tubules occur at the —-
* Ca++ comes from both the —- (during the—- l) and the —-
* Action potentials in cardiac muscle are —, lasting —– msec,
which is substantially—- than the
action potentials in skeletal muscle —
* The— receptor allows —- from the T system into the cell where it activates the —- receptor to
release Ca++ from the —
* Events during crossbridge cycling are similar to skeletal muscle
* Ca++ exits the cell mainly by a —-
intermediate
one
t tubule ( a diad )
z line
extracellular fluids
during action potential
S/R
prolonged
150-300
longer
5 msec ( milliseconds ? )
dihydropyridine
ca++
ryanodine
S.R
Na/Ca exchanger
contraction mechanism :
- same as —-
- As long as cytosolic [Ca ++ ] remains — and hence myosin binding sites are —, myosin will bind to actin, undergo a —- –action, and— the cardiac muscle cell.
- Relaxation by — of ca++ by the –, AND by — in the sarcolemma.
skeletal muscle
elevared
exposed
ratchet action
contraction
re accumulation
SR
proteins
role of extracellular ca++ :
* The skeletal muscle contractile mechanism is — affected by extracellular Ca++ concentrations
* Smooth and cardiac muscle are very sensitive to —- and to agents which affect —- into cells
* Ca++ channel blocking drugs will — the contractility of the heart and dilate blood vessels
not directly
extracellular ca++
ca++ entery
reduce
clinical relevance example:
* Parts of the — complex are unique to heart muscle and is released into the blood following —
* Clinically, this is a useful measure of — and —- is a sensitive marker of myocardial injury
* —- of troponins I and T are particular
to cardiac muscle
troponin
myocardial infraction
heart damage
serum troponin
amino acid sequence
heart muscle mechanics:
* Heart muscle demonstrates the —
relationship and the staircase phenomenon.
* It does not show — or —
* Filling of the ventricle is equivalent to— and aortic pressure is equivalent to —
length-tension
summation or tetanus
preload
afterload
