Describe extrinsic controls regulating the diameter of smooth
muscle in skeletal muscle arterioles.
Describe extrinsic controls regulating the diameter of smooth
muscle in skeletal muscle arterioles.
Solutions
Expert Solution
Resistance to blood flow through a vascular network is
determined by the size of individual vessels( length and diameter)
, physical characteristics of blood etc..
Of many factors , change in vessel diameter is most important
quantitatively for regulating blood flow within an organ as well as
for regulating arterial pressure.
Change in vessel diameter , particularly in small arteries and
arterioles , will enable organ to adjust their blood accroding
metabolic demand of tissue.
If an organ need to adjust blood flow , cell surrounding blood
vessel release vasoactive substances , which can constrict or
dialate the resistance vessels.
Other than local regulatory mechanisms, there are extrinsic
mechanisms acting on the vasculature to regulate vessel
diameter.
One important extrinsic mechanism regulating vascular diameter
operates through the autonomic innervation of blood vessels. In
general, sympathetic adrenergic influences acting through vascular
alpha-adrenoceptors cause resistance vessels as well as veins to be
partially constricted under basal conditions. This is termed
"sympathetic vascular tone." Therefore, removal of sympathetic
adrenergic influences (for example, by administration of an
alpha-adrenoceptor antagonist or by sympathectomy) leads to
vasodilation and an increase in organ blood flow.
A second type of extrinsic influence on the vasculature is
circulating vasoactive hormones such as angiotensin II, epinephrine
and norepinephrine, vasopressin (antidiuretic hormone, ADH), atrial
natriuretic peptide (ANP), and endothelin.
Hence both neural and hormonal factors primarily function in
regulation of arterial pressure by changing systemic vascular
resistance.
Describe at least FOUR processes in neurons and/or myocytes
(muscle cells: skeletal, smooth, & cardiac) in which Calcium
Ions (Ca++) function as important intracellular secondary
messengers. Diagram how calcium exerts its effect on cells in each
of these cases (what molecules does it act upon, and what is the
result?).
** Integrative Question: Describe at least FIVE processes in
neurons, myocytes (muscle cells skeletal, smooth, & cardiac),
and secretory endocrine glands in which Calcium Ions (Ca++)
function as important intracellular secondary messengers. Draw
simple diagrams showing how calcium exerts its effect on cells in
each of these cases (what cells and molecules does Ca++ act upon,
and what is the result?).
Match the following:
Acetylcholine in smooth muscle
Acetylcholine in skeletal muscle
Acetylcholine in pancreas
Acetylcholine in cardiac muscle
a. Functions via G protein and phospholipase C
b. Opening of chemically gated Na+ channels
c. Functions via G protein, opens up K+ channels
d. Functions via G protein, activates protein kinase G
e. Functions via calcium and activates Protein kinase C
Group of answer choices
42. Acetylcholine in smooth muscle
[ Choose ]
B. Opening of...
1/
Which of the following characteristics is shared between smooth
muscle and skeletal muscle?
Select one: _
a. Striated arrangement of the actin and myosin filaments
_
b. Presence of T tubule network
c. Ability to contract in the absence of an action
potential
d. Dependence of contraction on Ca+2 ions
2/ Which of the following conditions causes bleeding tendency
after prolonged exposure to hazardous irradiation?
Select one: _
a. Vitamin K deficiency _
b. Hemophilia L
c. Chronic liver...
1. What is the function of skeletal muscle?
2. Describe the major components of skeletal muscle cels:
Myofibrils
Sarcomeres
Motor unit
Neuromuscular junction
3. How does skeletal muscle produce movement?
4. How do actin and myosin interact in a sarcomere to bring
about muscle contraction? What roles do ATP and calcium play?
5. What is the functiion of the sarcoplasmic reticulum in muscle
cell contraction?
6. Explain why calcium ions and ACh are vitals for muscle
contraction.
7. What is...
What characteristics define cardiac muscle when compared to
other types of muscle (like smooth and skeletal)? in terms of size,
arrangement, appearance.