muscle 8 Flashcards
(27 cards)
why does sympathetic activity increase heart rate and contractibility
sympathetic activity wants a more powerful and frequent pulse
what does below 90 bpm indicate
parasympathetic output
what does above 90 bpm indicate
sympathetic output
what receptors are activated by NE released from sympathetic neurone
beta1 adrenergic receptors
How does smooth muscle layers run
In several directions
Why does smooth muscle use less energy to generate and maintain force than skeletal?
It has a much slower myosin ATP
How is smooth muscle contraction initiated?
Electrically or chemically
What is smooth muscle controlled by?
Autonomic nervous system
Is smooth muscle uninucleated or multinucleated
Uninucleated
What is absent in smooth muscle?
Troponin and T tubules
What are the 6 locations of smooth muscle?
Vascular
Gastrointestinal
Urinary
Respiratory
Reproductive
Ocular
What is smooth muscle categorized by (3)
Location
Contraction pattern
Communication with neighboring cells
Are unitary smooth muscles good at communicating? What is it referred to?
Yes
Referred to as visceral smooth muscle
What makes up the walls of most visceral organs?
Unitary (single unit) smooth muscle
Are multi unit smooth muscle good at communicating? Why or why not?
No they are not because they are not electrically coupled.
Where is multi unit smooth muscle
Iris and eyeball
Male reproductive tract
Uterus (except just prior to labour)
what is smooth muscle usually innervated by
autonomic nervous sytem
where do APs usually occur in smooth muscle
unitary smooth muscle
what propagates action potentials in unitary smooth muscle
Ca instead of Na
why is repolarization slower in cardiac muscle/smooth muscle than skeletal
Ca channels inactivate slowly
are some smooth muscles spontaneously activated
yes
when do slow wave potentials fire action potentials
when they reach threshold
what do pacemaker potentials do
always depolarize thresholds
do action potentials occur in multiunit smooth muscles
no
