Flashcards in Lecture 10- Circulatory System Deck (54):
What are the subsystems of the circulatory system?
A person develops a thrombus in their femoral vein. If the clot breaks off, where will it most likely end up?
Where does the blood from the femoral vein enter the heart?
Right atrium then eventually will get stuck in the capillaries of the lung. Pulmonary embolism
What would happen if there was a clot in the left atrium?
- Could go to the brain and cause stroke
- infarction in kidney or liver
The wall of the hear is composed of 3 layers. Which layer will be the thickest?
Myocardium (the muscle)
Which part of the heart will have the thickest myocardium?
What type of tissue lines the endocardium?
simple squamous endothelial layer (loose CT with smooth muscle)
What makes up the sub- endocardium?
connective tissue with arteries, veins, nerves, and Purkinje fibers
What is the role of the endothelial layer lining in the endocardium?
- acts as a barrier between blood and heart
- nonthrombogenic surface (no clots)
- modify cardiac performace
What is the role of collagne in the endocardium and subendocardium?
support and strength
What is the function of Purkinje fibers?
Muscle cells that are specialized for impulse conduction instead of contraction
How do Purkinje fibers differ from myocytes?
- Purkinje fibers are fewer and towards the periphery. Lots of glycogen and mitochondria
- myocytes are dense and full of myofibrils
Describe the conduction system of the heart
1) SA node initiates impulse to atria
2) Atrial contraction
3) AV Node sends impulse to ventricles (through bundle of His)
4) Ventricles contract
A 67-year-old male had a dental procedure which caused a transient bacteremia (bacteria in the blood). This precipitated infective endocarditis (inflammation or infection of the endocardium) because they already had damage to which of the following?
Endothelial layer of the endocardium. There is no barrier for the bacteria.
While infective endocarditis can occur in the heart chambers, it most commonly occurs on the valves of the heart. Why?
- vegetations develop in areas of high pressure through a narrow space to low pressure
- valves are covered by endothelial layer
- turbulent flow--> epithelial damage
What type of tissues make up the valves of the heart?
Dense irregular CT
A person had a myocardial infarction which damaged an area of the ventricles containing purkinje fibers. This most likely caused:
-Purkinje fibers affect the conduction of impulse
What is the epicardium?
The external tissue layer surrounding the pericardium or pericardial sac
Describe the two layers of the epicardium?
- external layer is simple squamous layer of mesothelium
- internal layer is loose CT with adipocytes, coronary arteries, veins, and autonomic nerves.
What makes up the serous pericardium?
- visceral layer
- parietal layer
- external fibrous pericardium
* simple sqaumous epithelial tissue that secretes fluid into space.
What type of tissue makes up the fibrous pericardium?
Dense, fibrous CT
What is the function of the pericardium?
- fixes the heart in the chest cavity
- protection against infection
- provides lubrication for the heart when it beats or moves
A 65-year-old male presents to the emergency department with chest pain and difficulty breathing. Testing reveals that he has a pericardial effusion. This is caused by fluid building up in which location around the heart?
Between the visceral pericardium and the parietal pericardium
What are the walls of the arteries?
- Tunica intima
- Tunica media
- Tunica adventitia or externa
What type of tissue is the endothelium?
Simple squamous epithelium
What is the function of the epithelium?
- selective barrier
- nonthrombogenic barrier
- modulates blood flow
What is the Tunica intima?
- endothelium and underlying basal lamina
- subendothelial layer of CT
- internal elastic lamina
-fenestrations for rapid diffusion
What is the Tunica media?
- circumferentially arranged smooth muscle with variable amounts of elastic fibers, reticular fibers, proteoglycans and glycoproteins
- external elastic lamina
- constrict or dilate corresponding to smooth muscle
What is the Tunica adventitia?
- dense irregular CT (Collagen and elastin)
- larger arteries contain vasa vasorum (blood vessels, nerves to adventia and media)
What is the main type of collagen in tunica adventitia?
How do systemic arteries differ from systemic veins?
Arteries are subjected to a much higher pressure than veins
Are the layers of walls for veins the same as the arteries?
How do the walls of veins differ from the walls of arteries?
- one way valves
- thinner smooth muscle layer
- adventitia is thicks
- more extensive vasa vasorum
What are the conductance vessels?
- large, elastic arteries (aorta)
- muscular arteries (medium sized arteries)
What are the resistance vessels?
Small arteries and arterioles
What is the function of large elastic arteries like the aorta?
- Conduct blood
- Help store energy generated by the heart's contraction
Describe systole of the aorta.
- aorta expands or distends
- facilitated by elastic fibers, limited by collagen fibers
- systolic pressure is not too high
Describe diastole of the aorta.
- elastic recoil
- Diastolic pressure is not too low
If elasticity of the aorta is reduced, what happens to systolic and diastolic pressure?
Systolic pressure is higher and diastolic pressure is lower
What type of cells are the predominate constituent of tunica media in muscular arteries?
Smooth muscle cells
What is the function of muscular arteries?
- Conduct blood
- large elastic and muscle arteries are considered conductance vessels or distributing arteries
What is the function of arterioles?
Control the amount of blood going into the capillary
- arterioles dilate
- more blood
- responsible for relative blood flow to an organ at any given mean arterial pressure
- help determine mean arterial pressure
What happens to resistance to blood flow if an arteriole dilates?
What makes up a capillary? (2)
- endothelial layer
- basal lamina
What is the function of capillaries?
Gas, nutrient, waste product exchange between blood and tissues
What are the three types of capillaries?
- continuous (no holes)
- fenestrated (small holes)
- sinusoid (big holes)
What is the most common type of capillary?
How does material go from the lumen of the capillary to the interstitial space?
Diffusion, paracellular transport, transcytosis (type depends on number of tight junctions)
What is the advantage of the fenestrae?
more rapid, easier exchange of substances
What is unique about a sinusoid capillary?
- much larger than the other capillaries
- both the endothelial layer and basal lamina have large holes
Where are the venules located?
After the capillaries
What is the venule wall like?
Gradually develops a tunica media
What is different between arteries and veins? (4)
1) Small/medium arteries have thicker media
2) Large veins have thicker adventitia
3) Arteries are under higher pressure
4) Veins have valves