Muscle Module 7 Flashcards
Smooth muscle is _______________
not as specialized as skeletal muscle
3 key feature of smooth muscle cells
- there is a SR Membrane in smooth muscle
- No T tubules
- No neuromuscular junction
Why dont we need T tubules in smooth muscle cells
T tubules conduct depolarization in action potential deep in the cell but smooth muscle cells are small
Without neuromuscular junctions what happens to the path of neurotransmitters in cell
neurotransmitters have a larger distance to travel and thus the smooth muscle has a slower response to stimulus
Where does the sarcoplasmic reticulum lay in smooth muscle
no myofibrils so it lays at the membrane
Skeletal muscle from a teleological perspective.
Designed go produce large force rapidly thus
- contractile units are parallel to each other
- neurtransmitter have a short area of diffusion
____________ explains a phenomena in terms of the purpose it serves
teleology
Smooth muscle from a teleologic al perspective although the contraction relies on CA2+ cross bridges too contract;
however, the physiological design is very varied to acomidate for various functions
Smooth muscle filaments
smooth muscle has thin and thick filaments variable in length
________________ is more varied in smooth muscle than skeletal muscle
length and organization of filaments
sarcoplasmic reticulum lays at the membrane because
smooth muscle has no myofibrils
adjacent demosomes allow the cells to
mechanically connect
____________ are specialized structures at the cell membrane that thin filaments attach to. Their function is to allow thin filaments to attach to cell membrane
demosomes
dense bodies connect __________________
adjacent thin filaments.
dense bodies have a composition similar to _________
Z disks
__________ site where two cells are in chemical continuity with one another so small molecules can pass from one smooth muscle cell to another.
Gap junction
Gap junctions allow smooth muscle cells to be in
electrochemical continuity
Where are smooth muscles typically located
walls of hallow organs, blood vessels, airways, GI system
what is the side of an organ that is lined with hallow muscle called
lumen
What is the connective tissue laying between the lumen and smooth muscle called
endothelium
What are the cl;assifications of smooth muscle based on contraction
- phasic
- tonic
______________ are the relatively break and synchronous contractions including the beginning of esophagus
phasic
__________ are the relatively slow and prolonged contractions
tonic
what are some of the causes for the variability in smooth muscle contraction
- variability in neurotransmitters (stimulatory or inhibitory)
- variability in proximity of neuron
- variability in distribution of receptors for NT
- contractility in endocrine regulated (ex hormones)
- variability in density of voltage gated channels
- variabilty ion cell communications
skeletal muscle only has ______________
excitatory neurotransmitters
what is one way that makes smooth muscle cell communications unique
Gap Junctions which sharer electrochemical information
What is the classification of smooth muscle by organization
- multiunit
2. single unit
______________ is characterized by
- fine control and over contraction
- prolongued contraction
multiunit
_______________ is characterized by
- rythmic contraction
- uniform contraction
single unit
example multiunit smooth muscle
blood vessels, airways
example multiunit smooth muscle
blood vessels, airways
-very fine control of controlling the muscles
example single smooth muscle
uterus, intestine
-0rythmic centurion necessisarry to deliver a baby
Examples of tonic muscles
- esopophagus sphincter, arteries
- maintain finetuning
- 0tend to be multiunit
examples of phasic muscles
- intestine, uterus
- rhythmic, rapid
- teend to be single unit
________ graded response, no action potential
multiunit smooth muscle allows this to happen
why are phasic muscles typically single unit
gap junctions and action potentials
_____________ are receptors for neurotransmitter and are less than in skeletal muscle cells
ligand gated channels
________________ for circular factors. CLosser to blood vessels where blood is released
ligand gated channel for circulating factors
__________ are low in number and some are calcium channels for contraction
voltage gated channels
Why aren’t action potentials produced by multiunit smooth muscle
low number of voltage gated Ca2++ ions
What kind of response are produced by multiunit smooth muscle
a little bit of contraction for a relatively brief period of time in a select # of cells operating independently. Because each cell is independent, we can either get a little contraction or ra lot of contraction
Are action potentials produced by single unit smooth muscle
yes because more voltage gated ion channels
do single unit smooth m muscle cells have gap junctions
yes gap junctions
explain the response of single unit smooth muscle
all or none response. Rapid synchronous, depolarized and contraction
