Choose the appropriate letter below to make the statements true. (a) stimulates
ID: 3516670 • Letter: C
Question
Choose the appropriate letter below to make the statements true.
(a) stimulates or increase
(b) decreases or inhibits
(c) has no effect on
- Decreased cardiac output ___ the mean systemic arterial blood pressure.
- Decreased venous radius ___ the venous return.
- Increased arteriolar radius ___ the total peripheral resistace.
- Decreased O2, increased CO2, increased acid, and increased K+ concentrations in the skeletal muscle ___ the radius of the arterioles supplying this skeletal muscle.
- Increased total peripheral resistance ___ the mean systematic arterial blood pressure.
- Increased parasympathetic nerve activity ___ the heart rate.
- Decreased blood pressure ___ the rate of firing in afferent nerves arising from the baroreceptors.
-Increased venous return ____ the end-diastolic volume.
Explain reasoning for each
Explanation / Answer
-- Decreased cardiac output (b) decreases the mean systemic arterial blood pressure.
Cardiac output is the measure of amount of blood that is being pumped out of the heart in one minute and Mean arterial blood pressure is the average arterial pressure of blood that is pumped out of the left ventricle into the aorta during cardiac cycle. it is a measure of Cardiac output (CO) and Total peripheral resistance. hence if cardiac output is decreased the heart rate and stroke volume will decrease resulting into decrease of Pressure of blood on arterial walls.
---Decreased venous radius will (b) decrease the venous return.
Venous return is the cardiac inflow or flow of blood back to the heart
----Increased arteriolar radius (b) decreases the total peripheral resistance.
total peripheral resistance is the resistance of flow of blood in systemic circulation. with increased arteriolar radius there occurs vasodilation of artery walls which results in less resistance of blood to the walls and so there is decreased total peripheral resistance.
----Decreased O2, increased co2 , increased acid and increased K+ concentrations in skeletal muscle (a) increases (vasodilation) the radius of arterioles supplying skeletal muscle. With decreased oxygen means there is increased demand for oxygen by tissues and potassium ion is released from cardiac and skeletal muscle cells to increase its concentration and decrease carbon dioxide , this results into increased oxidative metabolism and so blood vessel or arteriole of skeletal muscle need to dilate for proper blood flow.
----Increased total peripheral resistance (a) increase the mean systemic arterial blood pressure. It is the resistance of arteries to blood flow and blood pressure is pressure exerted on walls of arteries hence with increasing resistance pressure will increase as they are directly related alongwith cardiac output.
----Increased parasympathetic nerve activity (b) decreases heart rate . parasympathetic activity is related to slowing down heart rate via vagus nerve and so with its increase heart rate decrease as parasympathetic activity will depress the neurons.
---Decreased blood pressure (b) decreases the rate of firing in afferent nerves arising from the baroreceptors. baroreceptors are neurons situated in carotid sinus and they help in sensing and regulating blood pressure through baroreflex. with decreased blood pressure there occurs decreases activation of baroreflex and so dcereased heart rate causing blood pressure to restore levels.
-----Increased venous return(a) increases end diastolic volume . End diastolic volume is the filled volume of ventricle just before the systole occurs. increase in venous return increases preload to the fibers thereby increasing the end diastolic volume.