Cardiac histology Flashcards by Jordan Allen

What are the receiving chambers of the heart?

The two atria

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The pumps or discharging chambers are what?

Ventricles

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What side of the heart pumps blood out to the body? (systemic circuit)

The left side

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Which atrium receives oxygenated blood?

The left atrium

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Which side of the heart is for the pulmonary circuit?

The right side

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Which atrium receives deoxygenated blood?

The right atrium

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The heart has a fibrous skeleton- what surrounds the valves and what connects the rings?

Four fibrous rings surround the valve orifices

Two fibrous trigones connect the rings

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What is the epicardium?

The outer; visceral layer of the serous pericardium

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What is the myocardium?

The middle layer, primarily composed of cardiac muscle

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Which layer of the heart wall contains the fibrous skeleton of the heart?

The mycardium

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What is the endocardium and how many components are in it?

It is the inner layer with three components

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What are the three components of the endocardium and what are they made up of?

Endothelial cell layer- inner layer
Subendothelial layer-Underlying layer of dense CT
Subendocardial layer- CT layer

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Why are the walls of the left ventricle thicker than those of the right ventricle?

Because the left ventricle sends blood to the systemic circuit (the entire body) and has to overcome much more friction than the pulmonary circuit of the right side

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Is the heart sitting in a sac?

Yes

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What is the purpose of the atrioventricular valves?

Prevent backflow into the atria

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What are the two atrioventricular valves?

Tricuspid and bicuspid (mitrial) valves

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What are the two semilunar valves?

Aortic semilunar and pulmonary semilunar valves

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What is the purpose of the two semilunar valves?

To prevent backflow into the ventricles.

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T/F both ventricles have the same amount of blood being push out of the ventricles?

Truth

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Are there valves associated with entrances of venae cavae, coronary sinus, and pulmonary veins into the heart?

Nope

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T/F Heart valves enforce one way blood flow through the heart and open/close in response to pressure changes.

True

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What is the composition of heart valves?

connective tissue overlying endocardium

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What are the three layers of the heart valves?

Spongiosa
Fibrosa
Ventricularis

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The tricuspid valve is in on what side of the heart?

The right side

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The bicuspid/mitral valve is on which side of the heart?

The left!

What is the spongiosa layer of the heart valve responsible for?

Shock absorber

What is the fibrosa layer of the heart valve for?

It is the core of the valve that contains fibrous extensions from the dense CT of the skeletal rings of the heart

What is the ventricular layer of the heart valve made of and where is it at?

Well, it's dense CT with layers of elastic fibers- adjacent to the ventricular side of the valve

Which layer of the heart valve is thickest?

The fibrosa layer

What allows the cardiac muscle of the heart to depolarize and contract without impulses from the nervous system?

The intrinsic cardiac conduction system

Which node is the pacemaker of the heart?

The sinoatrial (SA) node

An impulse travels from the SA node to the AV node via what?

Internodal tracts/pathways

How long is the impulse delayed between SA and VA nodes and why?

0.1 seconds to allow the atria to contract so the heart doesn't explode like a balloon as everything contracts at once

What is the only electrical connection between the atria and ventricles?

The atrioventricular bundle or bundle of His

Where are the right and left bundle branches of the atrioventricular bundle headed?

toward the apex of the heart through the interventricular septum

Where are the purkinje fibers headed?

They finish the pathway and head from the apex back up towards the atria

Describe the nodal cardiac cells.

Found in SA and AV nodes They are modified cardiac muscle cells Smaller than surrounding atrial contractile cardiac cells Contain fewer myofibrils and lack intercalated disks

Describe purkinje fibers

Found in AV bundle, bundle branches, and subendothelial branches Also are modified cardiac cells Larger than surrounding ventricular contractile cardiac cells Contain myofibrils at periphery of cell Nuclei are round and larger than nuclei of regular cardiac fibers Have associated intercalated discs

What are the three types of blood vessels?

Arteries Capillaries Veins

What do arteries do?

Carry blood away from the heart- oxygenated in systemic circuit, deoxygenated in pulmonary circuit

What is the smallest artery called?

Arteriole

What do capillaries do?

smallest of the blood vessels, thin wall- they all the exchange of materials between the blood and body tissues

What do veins do?

Carry blood towards the heart- oxygen poor blood in systemic circuit and oxygen rich blood in pulmonary circuit

What is the smallest vein called?

Venule

The walls of blood vessels, except the smallest, have three layers. What are they?

Tunica intima Tunica media Tunica externa

Tell me about the tunica externa.

In larger vessels this tunic contains a vasa vasorum and a nervi vascularis

Tell me about tunica media.

Contains rings of smooth muscle cells responsible for vasoconstriction and vasodilation- can contain elastin!

Tell me about tunica intima.

Has three parts- endothelium, basal lamina, subendothelial layer

In cross section ____ will appear more open while _____ will appear more flat.

Arteries | Veins

What is the thickest layer of arteries?

The tunica media

What is the thickest layer of veins?

Tunica externa

What do elastic/conducting arteries do?

These are the largest diameter arteries, they are elastic and are important in helping to propel blood onward while ventricles are relaxing- the elastic fibers function as a pressure reserve

What are muscular/distributing arteries?

Medium sized arteries- contain lots of smooth muscle- regulate blood flow to specific body regions- smooth muscle cells responsible for vasodilation/constriction

How big are elastic/conducting and muscular/distributing arteries?

Greater than 10mm | 2-10 mm

Describe small arteries.

0.1mm-2mm in diameter and as many as 8 layers of smooth muscle in the tunic amedia

Describe arterioles.

Smallest artery diameter- 10-100 micrometers- only one or two layers of smooth muscle in the tunica media

Describe capillaries.

Smallest diameter of blood vessels. Thin wall Allows for exchange of materials

What are the three types of capillaries?

Continuous Fenestrated Discontinuous (sinusoidal)

Where are continuous capillaries found?

In muscles Lungs CNS

Do continuous capillaries have holes in their walls?

No- they have tight junctions

Are pinocytotic vessels or pericytes seen in continuous capillaries?

Yep

Where are fenestrated capillaries found?

In endocrine glands and at sites of fluid and metabolite absorption

Will you see pinocytotic vessels or pericytes in fenestrated capillaries?

Just pinocytotic vessels

Where are discontinuous (sinusoidal) capillaries found?

Liver, spleen and bone marrow

Which capillaries have the biggest holes in them?

Sinusoidal capillaries

The flow of blood from an arteriole through a capillary network to a postcapillary venule is called what? What is the functional unit called?

Microcirculation | Microcirculatory bed/microvascular bed

What are the two types of vessels in the capillary network?

True capillaries | Ateriorvenous anastomoses/shunts

What type of capillary has oval windows? Which type has irregular holes?

Fenestrated- ovals | Sinusoidal- irregular

If precapillary sphincters relax, more blood flows through which capillaries?

True capillaries

If precapillary sphincters constrict, where does more blood go?

The arteriovenous anastomoses to bypass the true capillaries

What are the four types of veins?

Venule Small veins Medium veins Large veins

Venules receive blood from what? | What are the two types of venules?

Capillaries Postcapillary venule Muscular venule

Small veins receive blood from what?

Muscular venules

In which veins are all three layers present?

Medium and large veins

Most veins in the limbs have ___.

Valves

Valves in veins are really what?

Folds in the tunica intima

What do valves in veins do? What is their purpose?

Prevent backflow