Cardiovascular System Histology Flashcards
What is microcirculation?
Capillaries exchanging nutrients
What can regulate blood flow through capillary beds?
Precapillary sphincters
Difference in tunicas between arteries and veins
Arteries have more smooth muscle and elastic fibers. Veins have thicker adventitia and tend to be larger than arteries
-veins tend to be softer; arteries tend to be stiffer
What surrounds capillaries?
Pericytes
- Blood vessels and nerves supplying the heart course through what layer?
- Electrical conducting system course along which layer?
- Epicardium
2. Endocardium
Function of intercalated discs?
Which part of the heart lacks these disks?
Why?
Separate cardiac muscle cells
Electrical conducting system
To aid in the spread of electrical current (gap junctions also help spread this current)
Similarity between skeletal and cardiac muscle?
Difference?
They are both designed for sudden large contractions
Cells are not fused in cardiac muscle (they have intercalated discs and gap junctions)
Cardiac muscle primarily uses what for energy? What else can they use?
Primarily metabolize fatty acids but can also use glycogen
MI is detectable by what lab test and when is this elevated?
Troponin levels in blood (elevated from 3 hours-2weeks after MI)
When cardiac muscle is damaged, what does it generally get replaced by
Connective tissue
Myocardium is thickest and thinnest where?
Thinner in atria, thickest in left ventricle (because it pumps blood to systemic circulation)
What are valves made of?
DCT and LCT and elastic fibers
Which heart layer contains blood vessels?
Epicardium
Where does chest pain come from?
Pain fibers in the heart itself (there are sensory fibers in the heart)
Sympathetic control of the heart comes from what spinal levels
Parasympathetic?
T1-T4
Vagus nerve
Sympathetic: what neurotransmitter does preganglionic neuron use? Post ganglionic?
Parasympathetic: what neurotransmitter does preganglionic neuron use? Post ganglionic?
Sympathetic: pre= acetylcholine; post= norepinephrine
Para: pre and post= acetylcholine
Sympathetic innervation of coronary arteries causes?
Parasympathetic?
Dilation
Constriction
Sympathetic innervation of the heart uses which receptor?
Parasympathetic?
B-adrenergic (Gs coupled)
Muscarinic (Gi coupled)
Epinephrine and norepinephrine has similar actions on the heart as
Sympathetic innervation
Large arteries are also considered __ arteries. Why?
Elastic; allow for distension and recoil in response to ventricular contraction
Medium arteries are also called __ arteries. Why?
Muscular; thick tunica media (smooth muscle)
Key feature of arterioles
Thin tunica media
LARGE ARTERIES
2 components of tunica intima?
Components of tunica media?
Components of tunica adventitia?
Endothelium and basal lamina
Many layers of smooth muscle and a lot of elastic fibers
Connective tissue containing blood vessels, nerves, fibroblasts, and macrophages
MEDIUM ARTERIES
Components of tunica intima?
Components of tunica media?
Components of tunica adventitia?
Same as large arteries
Many layers of smooth muscle, little elastic fibers
Same as large arteries
ARTERIOLES
Components of tunica intima?
Tunica media?
Tunica adventitia?
Same as previous 2
Fewest layers of smooth muscle (so cannot contract much)
Typical components but this connective tissue is often continuous with connective tissue to surrounding tissue
How does sympathetic innervation of arteries vasoconstrict?
Via NE activation of alpha-1 adrenergic receptors (Gq-coupled)
Parasympathetics typically do not innervate arteries except?
So because of this you would say that vasoconstriction happens because of? And vasodilation happens because of?
Arteries in abdominal viscera vasodilate via muscarinic receptors
Vasoconstriction-sympathetic innervation; vasodilation- termination of sympathetic innervation
Function of pericytes?
Surround capillaries; have some contractile function but work mostly as filters
What can pass through fenestrated capillaries?
(Has pores); lipids and other hydrophobic molecules (or else it needs a carrier)
How do immune cells get into CNS?
They cannot; CNS is immune privileged so they cannot unless brain cells enter BBB to allow entry
Function of precapillary sphincters?
Can constrict and reduce blood flow into capillaries
What are shunts?
When shunt is open, what happens?
When would shunt be open
Direct connections between an arteriole and venule that can be constricted
Less blood flow to capillaries (because it is going through shunt instead)
Would be open when you want to preserve heat
What would failure to form a capillary bed cause?
Arteries would get tangled with veins and then the tissue would never be able to get O2, so tissue would eventually die
What is diapedesis?
Migration of blood cells across endothelium.
Function of neutrophils on endothelial cells?
They can bind to receptors to trigger opening of gaps that will allow them to pass through endothelium
Comparing veins to arteries:
- Muscular venules have similar structure to?
- Large veins?
- Components of medium veins?
- Arterioles
- Muscular arteries
- Endothelium, thin tunica media and tunica adventitia
Does regulating BP have more to do with arteries or veins? Why?
Arteries because of the smooth muscle
