HISTO - Circulatory System Flashcards Preview

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Flashcards in HISTO - Circulatory System Deck (51):

What are the major functions of the Circulatory system?

- Nutrient and oxygen
- waste
- Hormones


What are the 4 chambers of the heart and what do they do?

2 atria = receiving chambers
2 Ventricles = discharging chambers


_____ is the pump for the systemic circuit.

Left side of heart


______ is the pump for pulmonary circuit.

Right side of heart


_____ receives oxygenated blood.

Left atrium


_____ Receives deoxygenated blood.

Right atrium


The Heart wall contains what 6 structures/tissues?

1. Cardiac muscle
2. Fibrous skeleton of the heart.
- 4 fibrous rings surrounding valve orifices.
- 2 fibrous trigones connecting rings
- membranous portion of inter ventricular and inreratrial septa.
3. Intrinsic conduction system
4. Coronary vasculature
5. A serous membran
6. Endothelial cells and underlying connective tissue.


What are the 3 layers of the heart?

Epicardium = outer layer, viceral layer of serous pericardium.
Myocardium = middle layer, composed primarily of the cardiac muscle (also contains the fibrous skeleton of the heart.)
Endocardium = inner layer with 3 components.


What are the 3 layers of the Endocardium?

1. endothelial layer - inner layer
2. underlying layer - of dense connective tissue and smooth muscle.
3.Connective tissue (deepest layer) contains the intrinsic conduction system.


There are 4 valves associated with the heart,, what are they and what is their function?

Two Atrioventricular Valves (prevents back flow into atria):
1. Tricuspid Valve
2. Bicuspid or Mitral Valve
Two semilunar Valves (Prevent back flow into ventricles)
1. Aortic Semilunar valve
2. Pulmonary semilunar Valve.


True or false, there are no valves associated with the entrances of venue cavae, coronary sinus and pulmonary veins into the heart.



The Heart valves are composed of ______ with overlying _______.

- Connective tissue
- overlying endocardium


What are the 3 layers of the Heart valves?

1. Spongiosa - loose connective tissue covered in endothelium; located on atrial or blood vessels side of valve; loosely arrange collagen and elastic fibers infiltrated with proteoglycan; shock absorber.
2. Fibrosa - core of valve; contains fibrous extensions from the dense irregular connective tissue of skeletal rings of heart.
3. Ventricularis - dense connective tissue with layers of elastic fibers covered in endothelium; adjacent to ventricular side of the valve.


The cardiac muscle of the heart is able to depolarize and contract without imposes from the Nervous system....What makes this possible?

The Intrinsic cardiac conduction system.


Describe the 4 Fascinating facts about the intrinsic cardiac conduction system...

1. Composed of 1% cardiac conduction cells (auto-rhythmic cells) that are self excitable can can dendrite action potential w/out nervous system input.
2. These cells are organized into nodes and tracts called perkinje fibers.
3. These cells are responsible for the ignition and distribution of impulses throughout the heart.
4. Rate of cardiac muscle contraction is set by these pacemaker cells. Pace can be altered by sympathetic and parasympathetic divisions of autonomic NS. * hormones can also impact intrinsic rate.


Describe the 5 steps of the excitatory sequence of the auto rhythmic cardiac cells....

1. Sinoatrial node = the pacemaker of heart: determines heart rate through its sinus rhythm.
2. Atrioventricular node = impulse travels to AV node via the internodal pathway or tracts; impulse is dealer here for 0.1s to allow for atria to contract.
3. Atrioventricular bundle = impulse travels from AV node to right and left bundles; only electrical connection between atria and ventricles; travels across the fibrous skeleton.
4. Right and left bundle branches = branch of the AV Bundle; course toward apex of heart through interventriuclar septum.
5. Purkinje fibers (subendothelial fibers) = finish pathway in inter ventricular septum, around apex of heart, and head back towards atria.


What are the 2 main cells of the intrinsic conduction system?

Nodal Cardiac cells
Purkinje fibers


Describe the Nodal Cardiac cells... (4)

- Found in SA and AV nodes.
- Modified Cardiac muscle cells.
- smaller than surrounding atrial contractile cardiac cells.
- contain fewer myofibrils and lack intercalated discs.


Describe the Perkinje fibers....(8)

- Found in AV bundle, bundle branches and sub endothelial branches
- modified cardiac cells
- larger that surrounding ventricular contractile cells.
- contain myofibrils at periphery of cell.
- nuclei are round and larger
- Have associated intercalated discs
- Positive for PAS staining because of glycogen.
- with H&E stain glycogen rich center of cell appears homogenous and stains pale.


What are the three major types of blood vessels?

Arteries - carry blood away from heart.
Capillaries - smallest blood vessels; thin wall ; main role is to allow the exchange of materials between the blood and body tissues.
Veins - carry blood towards the heart.


Arteries carry ________ blood in the systemic system.



Arteries carry ____ blood in the pulmonary system.



Veins carry _______ blood in the systemic system.



Veins carry _____ blood in the Pulmonary system.



Arteries to veins what is the pathway?

Arteries, Arterioles, Capillaries, Venules, Veins


The walls of the blood vessels (except the smallest) have 3 layers, or Tunics, what are they?

1. Tunica interna (intima)
-Basal lamina
-Subendothelial layer
2. Tunica media = contains rings of smooth muscle & sheets or lamellae of elastin.
3. Tunica Externa (adventitia) = in larger vessels this tunic contains a vasa vasorum and a nervi vascularis.


In _____ the thickest layer is the Tunica Media.



In ______ the thickest layer is the tunica externa.



There are 4 types of arteries, what are they?

1. Elastic or conducting arteries (large arteries)
2. Muscular or distributing arteries (Medium arteries)
3. Small arteries
4. Arterioles


________ are 10mm or greater, walls contain elastic fibers and are important in propelling blood onward .

Elastic or conducting arteries


_____ are 2-10mm and calling large amounts of smooth muscle important in regulating blood flow to specific body regions.

Muscular or distributing arteries


_____ are 0.1-2mm and have as many as 8 layers of smooth muscle in their tunica media.

Small arteries


______ 10um to 100um with only 1-2 layers of smooth muscle in the tunica media.



In which type of artery is the Tunica adventita "relatively thick?"

Muscular or Distributing arteries....all others have thin tunica adventitia.


_______ may or may not have internal elastic fibers in the the tunica intima.



In _____ & _____ the tunica adventitia is "thin and ill-defined".

small arteries and Arterioles


What are the 3 types of capillaries? (based on morphology)

1. continous capillaries
2. Fenestrated capillaries
3. Discontinuous capillaries (Sinusoidal capillaries or sinusoids)


Where are continuous capillaries found? What defines them?

In muscle, lung and CNS.
- has uninterrupted endothelial lining with tight or occluding junctions.
*Will see pinocytotic vessels with a chance of parasites.


Where are fenestrated capillaries found and what defines them?

Found in glands and at sites of fluid and metabolite absorption.
- have oval pores called fenestrations.
*Will only see pinocytotic vessels


Where are discontinuous capillaries found and what defines them?

Found in the liver, spleen, and bone marrow.
-Large diameter and more irregulars shaped than other capillaries.


The blood flow from an arteriole through a capillary network to a postcapillary venue is called __________.



The ______, _____ & ______ from a functional until called the microcirculatory bed or microvascular bed.

Capillary network
Postcapillary venule


What 2 types of vessels are in the Capillary Network?

1. True capillaries
2. Arteriovenous Anastomoses or shunts.


What happens when the pre capillary sphincters RELAX and smooth muscle of the AV shunt CONTRACT?

More blood will pass through the true capillaries in the capillary beds.


What happens when the pre capillary sphincters CONTRACT and the smooth muscle of the AV shunt RELAX?

More blood will pass through the arteriovenous anastomoses and bypass the true capillaries.


_____ veins are greater than 10 mm and contain all three layers.

Large veins


____ veins are 1-10mm and contain all 3 layers.

Medium veins


______ veins are 0.1-1mm and receive blood from musculature vasculature.

Small veins


_______ veins are 10um-100um and receive blood from capillaries.



What are the 2 types of venules?

1. Postcapillary Venule = endothelial cell with basal lamina and pericytes; no tunica media and no adventitia.
2. Muscular Venule = posses a tunica media with one or 2 layers of smooth muscle and a thin tunica adventitia; typically no pericytes here.


True or false, Most veins in limbs have valves.

True, the valves are thin folds of tunica intimate endothelial cells over a thin layer of connective tissue. They prevent back-flow of blood.