Chapter 42.2 Flashcards
What does the mammalian cardiovascular system do?
meets the body’s continuous demand for O2
Where does blood begin to flow?
the right ventricle pumping blood into the lungs via the pulmonary arteries
What happens in the lungs?
the blood loads O2 and unloads CO2
What happens to oxygen-rich blood from the lungs?
enters the heart at the left atrium via the pulmonary veins
Where is blood pumped through the aorta to?
the body tissues by the left ventricle
What does the aorta do?
provides blood to the heart through the hcoronary arteries
How does blood return to the heart?
through the superior vena vaca and inferior vena cava
superior vena cava
blood from head, neck, and forelimbs
inferior vena cava
blood from trunk and hind limbs
What do the superior vena cava and inferior vena cava flow into?
the right atrium
What do the two atria have and serve as?
relatively thin walls; collection chambers for blood returning to the heart
What do the ventricles have and do?
thicker walls; contract much more forcefully
The cardiac cycle
the rhythmic cycle where the heart contracts and relaxes
systole
the contraction, or pumping phase, of the heart
Diastole
the relaxation, or filling, phase of the heart
Heart rate (pulse)
the number of beats per minute
Stroke volume
the amount of blood pumped in a single contraction
cardiac output
the volume of blood pumped into the systemic circulation per minute
what does the cardiac output depend on
both the heart rate and the stroke volume
Four valves prevent backflow of blood in the heart
- the atrioventricular (AV) valves
2. semilunar valves
Atrioventricular (AV) valves
separate each atrium and ventricle
Semilunar valves
control blood flow to the aorta and the pulmonary artery
What causes the “lub-dup” sound of a heart beat?
the recoil of blood against the AV valves (lub) then against the semilunar (dup) valves
What causes heart murmur
backflow of blood through a defective valve
some cardiac muscle cells are…
autorhythmic
autorhythmic
they contract without any signal from the nervous system
the sinoatrial (SA) node (pacemaker)
sets the rate and timing at which cardiac muscle cells contract
How can impulses that travel during the cardiac cycle be recorded
as an electrocardiogram (ECG or EKG)
Where do impulses from the SA node travel to?
the atrioventricular (AV) node
What happens at the AV node?
the impulses are delayed and then travel to the Purkinje fibers that make the ventricles contract
the pacemaker is regulated by two portions of the nervous system:
the sympathetic and parasympathetic divisions
what does teh sympathetic division do
speeds up the pacemaker
what does the parasympathetic division do
slows down the pacemaker
what is the pacemaker also regulated by
bormones and temperature
