Exam 2 – Cardio Ch 21 Flashcards
What can happen to muscle blood flow during exercise?
Can increase 20 fold during exercise
What makes up a large portion of body mass? What does this have a great effect on?
Muscle
Cardiac output
What is the resting blood flow?
to 4 ml/min/100 gm muscle
What can happen to the resting blood flow during exercise?
It can increase 15-25X
What happens to capillary density during exercise?
It increases markedly
When does most blood flow occur during exercise?
Between contractions
Look at the changes in capillary density during exercise
Look at the changes in capillary density during exercise
Look at the exercise and muscle blood flow chart
Look at the exercise and muscle blood flow chart
What happens to heart rate during exercise?
Increase, up to as much as 180 bpm
What happens to stroke volume during exercise?
It slightly increases, then decreases
What happens to cardiac output during exercise?
Increases, up to as much as 15 L/min
Which increases more during exercise, systolic, mean, or diastolic arterial pressure
They all increase, but systolic increases the most.
Mean is second and then diastolic, which barely increases
What happens to total peripheral resistance during exercise?
Decreases
What happens to oxygen consumption during exercise?
Increases
What happens to arteriovenous oxygen difference during exercise?
It increases
What happens to blood flow to the heart during exercise?
Increases
What happens to blood flow to the brain during exercise?
Stays the same
What happens to blood flow to the active skeletal muscle during exercise?
Increases
What happens to blood flow to the inactive skeletal muscle during exercise?
Decreases
What happens to blood flow to the skin during exercise?
Goes down when you start to exercise, but will go back up once you get hot and it dilates
What happens to blood flow to the kidney, liver, gastrointestinal tract, etc during exercise?
Decreases
What does decreased oxygen during exercise affect?
Vascular smooth muscle directly, which causes vasodilation
What are examples of vasodilators?
K+
Adenosine
Osmolality
Endothelium derived relaxing factor (nitric oxide)
What happens during nervous regulation?
Sympathetic release of norepinephrine locally (mainly α)
Adrenals release epinephrine (β and α) and norepinephrine (α and a little β)
Look at sympathetic regulation of the circulation
Look at sympathetic regulation of the circulation
How much does mean arterial pressure increase during exercise?
20-80 mmHg
What does increased blood pressure cause in muscle?
Increased flow
What will mean arterial pressure do to blood vessels?
Stretch them causing vasodilation
What are the hemodynamic and humoral changes in exercise?
Mass sympathetic discharge Decrease parasympathetic impulses HR increases Mean arterial pressure increases Heart strength increased Local vasodilation Global venoconstriction (net effect is increased venous return) Venous return and cardiac output increased
What does exercise do to circulation?
Redistributes to essential vs non-essential depending on what your body is doing
What is the rate of coronary flow?
225 ml/min
What vessels are involved in coronary flow?
Epicardial Subendocardial (large plexus, least amount of pressure)
What percentage of the blood comes back through the coronary sinus to the right atrium?
90-95%
Look at epicardial and subendocardial vasculature
Look at epicardial and subendocardial vasculature
Where are thebesian veins located?
Internally
Where do thebesian veins go?
Into the heart
How much blood goes through the thebesian veins?
10% or less
Look at changes in coronary flow during the cardiac cycle
Look at changes in coronary flow during the cardiac cycle
What are the controllers of coronary flow?
Myocardial O2 consumption (pump work)
Adenosine – related to decrease O2
Nervous stimuli
Others (K+, CO2, Kinins, Prostaglandins, Nitric oxide)
Where do nervous stimuli mostly go to?
Sympathetic
Where are the nervous stimuli?
Mainly affects epicardial flow (α)
Little effect of parasympathetics
β sympathetic subendocardial flow
What is energy supply for the heart?
Fat metabolism (70% fatty acids) Glycolysis (anaerobic)
How does venous drainage from the heart occur?
Coronary sinus
Anterior cardiac veins to right atrium
Thebesian veins
How does the coronary sinus flow?
Into the right atrium from the left ventricle
Where is tissue mass the biggest? Why?
Around the left ventricle
Because of the amount of blood flow
What happens as total peripheral resistance increases?
Venous return and cardiac output falls
What happens as total peripheral resistance increases and less blood goes to the tissues?
More blood goes to reservoirs and venous return stays the same, which causes higher aortic pressure. Then, there is feedback to decrease sympathetic tone and increase parasympathetic. The slower heart rate and lower force of contraction causes cardiac output to fall
What happens as total peripheral resistance decreases?
Venous return and cardiac output increases
What happens as total peripheral resistance decreases and more blood goes to tissues?
Causes lower aortic pressure, which leads to less blood staying in the reservoirs and increased venous return because of feedback to increase sympathetic tone and decreases parasympathetic. This leads to higher venous return and higher heart rate and force of contractions, which increases cardiac output
