Chapter 18 Flashcards
What is the function of the heart?
Pump blood through the 2 circuits
Which side is the pulmonary circuit on?
Right
Which side is the systemic circuit on?
Left
What is the heart?
Biological pump
What is the pressure of the pulmonary circuit?
Low pressure: 2 - 25 mmHg
Where does the pulmonary circuit deliver blood to?
oxygen-poor blood to lungs and oxygen-rich blood to systemic circuit
What is the pressure of the systemic circuit?
High pressure: 2 - 120 mmHg
Where does the systemic circuit deliver blood to?
oxygen-rich blood to organs and tissues and oxygen-poor blood to pulmonary circuit
How does blood decline as it goes through the heart?
arteries –> capillaries –> veins –> atria
Why is the pulmonary circuit low pressure?
don’t have to do a lot to fight gravity because you aren’t going very far
Where does blood return to?
opposite side of the heart
How does blood flow?
down the concentration gradient
Where is the highest point of pressure?
aorta
Why is the systemic circuit high pressure?
Have to fight gravity to get blood to the brain
Name the 4 valves
- Pulmonary (semi-lunar) valve
- Tricuspid valve
- Aortic valve (semi-lunar)
- Mitral valve (bicuspid)
What 3 things does the atria do?
- Receives blood from veins
- Direct blood towards ventricle
- Contract and add a little bit more blood to the ventricle
What do the 4 valves do?
Control flow of blood into ventricles and atria. pressure controls valves
What is the cardiac skeleton?
made up of connective tissue to help hold valves in place.
dense irregular connective tissue.
separates atria from ventricles and stops action potentials
What is ring body?
dense tissue. everything connects to ring body and it holds everything in place
What are the valves made up of?
connective tissue and dense irregular connective tissue covered in epithelium
What are the AV valves made up of?
Connective tissue
What are chordae tenineae
heart strings, attached to papillary muscles in the ventricles
When do the chordae and papillary muscles work?
when the valves are closed
What does the state of the valve depend on?
pressures in the heart
How does blood returning to the heart open the the AV valves?
- blood returning to the heart fills atria, which puts pressure on the AV valves. AV valves open.
- as ventricles fill, AV valve limply hangs into ventricles.
- atria contract, forcing additional blood into ventricles.
How does blood close the AV valves?
- ventricles contract and force blood against AV valve cusps.
- AV valves close.
- Papillary muscles contract and chordae tendineae tighten, preventing valve flaps from everting into atria
What happens when pressure in atria is greater than pressure in ventricle
valve is open and blood will flow; papillary muscles are relaxed and no tension on chordae tendineae
What happens when pressure in atria is less than pressure in ventricle
valve is close and blood will not flow; papillary muscles are tense and there is tension on chordae tendineae
Where are chordae tendineae and papillary muscles found?
SL valves
How do SL valves close?
As ventricles relax and pressure falls, blood flows back from the arteries, filling the cusps of SL valves and forcing them to close.
What is the normal state of an SL valve
closed because the pressure in the artery is greater than the pressure in the ventricle
How do SL valves open?
As ventricles contract and pressure rises, blood is pushed up against the SL valves, forcing them open
What is an incompetent valve?
Leaky valve, the valve doesn’t work all the way so it doesn’t completely close so blood is able to leak
What is stenosis?
Narrowing of the valve
What are the layers of the heart
Endocardium: thin layer of epithelium that forms a seal to keep blood inside the chambers of the heart.
Myocardium: middle layer made up of myocytes and generates pressure. This is the contractile portion of the heart and is responsible for pushing blood through the system.
Pericardium: outside of the heart; surrounds the heart and separates from neighboring tissues. Has 2 regions:
- fibrous: outermost layer; thick layer of dense irregular connective tissue; protective layer.
- serous: somewhat delicate. proper membrane (2 different primary tissues). epithelial and connective tissue layer.
Between parietal and visceral layer of serous, there is the pericardial cavity that is filled with fluid.
Function of the pericardium?
protects the heart during contraction to protect from friction and allows the heart to expand without harming itself or other tissues
What do bundles of cardiac myocytes wrap around?
heart chambers in a nonlinear fashion, which enhances the hearts’ ability to contract and generate pressure
How many layers are in the left ventricle?
2 layers: superficial and deep; which work together to promote contraction and ejection of blood
What type of muscle cells aid in movement of blood through the heart?
specialized striated muscle cells
Describe the size difference of the ventricles?
Right ventricle attaches to the left ventricle and forms a crescent shape.
Left ventricle is a complete stand-alone structure, but the right ventricle needs the left ventricle
What separates the 2 ventricles?
Muscular interventricular septum
What is the job of the papillary muscles?
hold the valves closed
