Cardiovascular System and Cardiac Muscle+ MAP

what makes up blood

plasma and formed elements (erythrocytes, leukocytes, platelets)_

how many pumps?

two pumps in series

blood flow valves

right atrium → tricuspid valve → right ventricle → pulmonary semilunar valve → lungs

left atrium → mitral/bicuspid valve → left ventrice → aortic semilunar valve → systemic circulation

right ventricle becomes weak and fails to eject: where will blood back up?

vena cava

Chordinae tendinae function

attaches AV valves to papillary muscles in ventricular wall: prevents valve from prolapsing into atria when valves are closed during ventricular contraction

ventricular wall heart muscle layers

Pericardium?

Coronary artery with branches into where?

endocardium, myocardium, epicardium

sac around heart

Myocardium

striations, intercalated disc, nucleus

What ensures that all myocytes are involved with each contraction and enables cardiac muscle to act as functional syncytium?

electrically coupled via gap junctions in the intercalated discs

MAP =?

CO * TPR

What is TPR?

resistance in all of systemic blood vessels

What is main controller of TPR?

arterioles

(arterioles and capilaries have highest resistance, but capillaries lack smooth muscle, so cant control)

What can affect TPR?

What about CO?

Anything that will cause constriction or dilation of arterioles

Contraction and relaxation of veins (venous return)

Short term control of TPR, for example standing up

baroreceptor reflex:

• Heart control

  • Rest: PS

  • SNS

• Vasomotor tone: just SNS
  

1. standing up → rapid decrease of MAP

2. Baroreceptros in aortic arch and carotid sinus

3. increase SNS, decrease PSNS

Baroreceptor response to decrease in MAP: continued: decrease PSNS, increase SNS

• symp

  • Arterioles constrict

    • Increases TPR

  • Veins constrict

    • Increase venous return → increased CO

  • Increased HR

  • increased forced of contraction: both lead to increase in CO

in people with hypertension, why doesnt baroreceptor response lower BP?

only for short term