What is the major difference between the two types of smooth muscle tissue?
What will be an ideal response
In single-unit smooth muscle tissue, action potentials are initiated in response to neurotransmitters, hormones, or an autorhythmic signal. The action potential spreads throughout the tissue by moving through gap junctions that connect all the muscle cells together within the tissue. It is found in the skin and in tubular arrangements that form part of the walls of small arteries and veins and of hollow organs such as the stomach, intestines, uterus, and urinary bladder. In multiunit smooth muscle tissue, muscle cells have few gap junctions with neighboring cells and thus must be excited by their own motor neuron terminal. It is found in the walls of large arteries, in airways to the lungs, in the arrector pili muscles that attach to hair follicles, in the muscles of the iris that adjust pupil diameter, and in the ciliary body that adjusts focus of the lens in the eye.
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When childbirth labor starts, the presence of the hormone oxytocin causes the contractions to increase in strength, which causes the level of oxytocin to increase, which in turn causes the contractions to further strengthen. This would be an example of a
________ feedback mechanism. A) positive B) neutral C) negative
What is a triad?
A. a protein found along the groove of the F-actin double helix B. a T tubule and two adjacent terminal cisternae C. the combination of myosin heads with active sites on actin molecules D. the movement of myosin head while attached to actin myofilament E. after exercise, the oxygen taken in that exceeds the oxygen required for resting metabolism
The layer of the heart that lines the atria and ventricles and forms the cuspid and semilunar valves is the:
A) myocardium B) fibrous pericardium C) serous pericardium D) endocardium
name the attachments of the orbicularis oculi. select all that apply.
a) maxilla just below infraorbital foramen b) eyelids; skin around margin of orbit c) zygomatic arch; fascia near ear d) lacrimal bone; medial angle of eyelid