Heart and Vascular Histology Flashcards by Sarah Gillen

______ muscle cells are single, very long cylindrical, multinucleate cells with obvious striations

Skeletal

How well did you know this?

Not at all

Perfectly

______ muscle cells are single, fusiform, uninucleate with nucleus centrally located, and without striations

Smooth

How well did you know this?

Not at all

Perfectly

______ muscle cells are branching chains of cells that may be uni- or binucleate and they do have striations

Cardiac

How well did you know this?

Not at all

Perfectly

Which of the following describes skeletal muscle cells?

A. Striated and voluntary
B. Striated and involuntary
C. Non-striated and voluntary
D. Non-striated and involuntary

A. Striated and voluntary

How well did you know this?

Not at all

Perfectly

Which of the following describes cardiac muscle cells?

A. Striated and voluntary
B. Striated and involuntary
C. Non-striated and voluntary
D. Non-striated and involuntary

B. Striated and involuntary

How well did you know this?

Not at all

Perfectly

Which of the following describes smooth muscle cells?

A. Striated and voluntary
B. Striated and involuntary
C. Non-striated and voluntary
D. Non-striated and involuntary

D. Non-striated and involuntary

How well did you know this?

Not at all

Perfectly

Describe the type of contractions exhibited by smooth muscle

Produces continuous contractions of low force

Rhythmic contraction that is inherent, but responsive to ANS

How well did you know this?

Not at all

Perfectly

Skeletal and smooth muscle both have actin and myosin involved in their contraction, but what makes smooth muscle different?

They are not arranged in sarcomeres, so they lack longitudinal arrangement of contractile proteins. Instead, actin and myosin bundles criss-cross the cell and are anchored at focal densities

Tension produced is transmitted through the densities to the membrane; cells contract as one unit and assume a globular shape.

The signaling mechanism also differs

How well did you know this?

Not at all

Perfectly

_____ Muscle cells are short, branched, and y-shaped. They are associated with extensive capillaries.

Cardiac

How well did you know this?

Not at all

Perfectly

Cardiac muscle cells are associated with _______ ______ which are transverse junctions at the ends of cells that allow passage of electrical current

Intercalated discs

How well did you know this?

Not at all

Perfectly

_______ cells are modified cardiac muscle cells that act as the pacemaker for the heart

Purkinje

How well did you know this?

Not at all

Perfectly

What are the 2 layers of the pericardium?

Fibrous pericardium

Serous pericardium

How well did you know this?

Not at all

Perfectly

The _______ pericardium is the outer covering of dense connective tissue

Fibrous

How well did you know this?

Not at all

Perfectly

The serous pericardium consists of the following:

_______ layer = lines the inner surface of the fibrous pericardium

_______ layer = covers the outer surface of the heart

_______ ______ = space between the above 2 layers

Parietal

Visceral (epicardium)

Pericardial cavity

How well did you know this?

Not at all

Perfectly

Which of the following is referred to as the epicardium?

A. Fibrous pericardium
B. Parietal layer of serous pericardium
C. Visceral layer of serous pericardium
D. Pericardial cavity

C. Visceral layer of serous pericardium

How well did you know this?

Not at all

Perfectly

What are the 2 major layers of the heart wall?

Epicardium = outermost layer

Myocardium = thickest layer of the heart

Endocardium = inner layer

How well did you know this?

Not at all

Perfectly

Describe the histological composition of the epicardium

Dense fibrocollagenous CT with elastic fibers, lined with mesothelium

Branches of coronary arteries are embedded in adipose tissue

How well did you know this?

Not at all

Perfectly

The myocardium is the thickest layer of the herat. What are the 3 major cell types associated with the myocardium?

Cardiomyocytes (contractile)

Nodal cardiomyocytes (SA and AV nodes)

Myoendocrine cardiomyocytes (contain atrial granules)

How well did you know this?

Not at all

Perfectly

Which layer of heart tissue is lined with mesothelium? What is mesothelium?

Epicardium; mesothelium is simple squamous epithelium that is associated with a serous membrane

How well did you know this?

Not at all

Perfectly

Myocardium is characterized by:

________ due to sarcomere arrangement

________ discs

_______ t-tubule system

Mitochondria

_______ and _______ granules

Striations

Intercalated

Diad

Lipofuscin; atrial

How well did you know this?

Not at all

Perfectly

Compare/contrast the t-tubule systems in cardiac vs. skeletal muscle

Cardiac = diad t-tubule system

Skeletal = triad t-tubule system

How well did you know this?

Not at all

Perfectly

Intercalated discs are specialized interdigitating junctions between cardiomyocytes found at sites where cells meet end-to-end. They always coincide with _______

Z lines

How well did you know this?

Not at all

Perfectly

What is the function of intercalated discs?

Bind cells, transmit forces of contraction, and allow the spread of excitation

How well did you know this?

Not at all

Perfectly

Intercalated discs have varying membrane-membrane contacts based on 2 regions: transverse (perpendicular) and longitudinal (parallel).

What are the 3 types of membrane-to-membrane contacts exhibited by intercalated discs? Which region are these associated with?

2 in transverse region:
Fascia adherens
Desmosomes

1 in longitudinal region:
Gap (nexus) junctions

How well did you know this?

Not at all

Perfectly

Intercalated discs have 3 types of membrane-membrane contacts. 2 in transverse region: fascia adherens and desmosomes; and 1 in longitudinal region: gap (nexus) junctions. Which type of membrane-membrane contact transmits contractile forces between cells and is the most predominate?

Fascia adherens

Intercalated discs have 3 types of membrane-membrane contacts. 2 in transverse region: fascia adherens and desmosomes; and 1 in longitudinal region: gap (nexus) junctions. Which type is found at sites of low electrical resistance and allows excitation to pass between cells?

Gap (nexus) junctions

Intercalated discs have 3 types of membrane-membrane contacts. 2 in transverse region: fascia adherens and desmosomes; and 1 in longitudinal region: gap (nexus) junctions. Which type contains actin filaments at the ends of terminal sarcomeres which insert into junction?

Fascia adherens

Intercalated discs have 3 types of membrane-membrane contacts. 2 in transverse region: fascia adherens and desmosomes; and 1 in longitudinal region: gap (nexus) junctions. Which type provides the anchorage for the intermediate filaments of the cytoskeleton?

Desmosomes

Describe the components of a diad T-tubule system associated with cardiac muscle cells

Diad = 1 T-tubule + 1 SR cisterna

Diad t-tubules are fingerlike invaginations of the ________ and are found at the ___-lines. They permit uniform contraction of _____ within a single cardiomyocyte

Sarcolemma; Z Myofibrils

______ granules are small bodies that accumulate ith age in stable non-dividing cells like cardiomyocytes

Lipofuscin

Lipofuscin granules are small bodies that accumulate ith age in stable non-dividing cells like cardiomyocytes. They contain material derived from what?

Residual bodies after lysosomal digestion

What important biological molecule is contained within atrial granules?

Atrial natriuretic factor - which targets the kidneys to decrease Na+ and H2O retention, thus increasing urine output *Important because it gives your heart some endocrine function!*

About 600 atrial granules are contained within each ________ cell, although smaller quantities are found in the _____ atrium and ventricles

Myoendocrine; left

The endocardium is made up of what 2 major components?

Endothelium Thin layer of loose CT

What type of endothelium is found in the endocardium?

Simple squamous

The thickness of the endocardium differs in ventricles vs. atria. The ventricular endocardium has a ________ layer composed of a thin layer of CT with smooth muscle as well as purkinje fibers

Subendocardial

In the _____ of the heart, Purkinje fibers are often closer to the endothelium and intermixed with the myocardium

Atria

List direction of heart conduction from the SA node (pacemaker) to the purkinje fibers

SA node --> AV node --> AV bundle --> R/L bundle branches --> purkinje fibers

_______ cardiomyocytes are modified cardiomyocytes within the SA/AV nodes that initiate/relay electrical signals

Nodal

_________ _________, also known as right and left bundle branches, transmit signals to ventricular cardiomyocytes (purkinje fibers)

Subendocardial branches

The cardiac skeleton is made up of ____ ____ CT located in the __________. It extends into the valve cusps and _____ ______, acting as the insertion of cardiac muscle as well as the electrical insulator between atria and ventricles.

Dense irregular; endocardium Chordae tendinae

What is the function of the cardiac skeleton?

Anchors valves and surrounds AV canals to maintain shape Contributes to interventricular and interatrial septa Electrical insulator between atria and ventricles Insertion of cardiac muscle

Heart valves have a core of _______ CT, aka lamina fibrosa, and are covered by _________.

Fibroelastic; endothelium

Heart valves are continuous with the _____ ______. Their fibroelastic CT (lamina fibrosa) layer condenses to form a _____ ____, which creates the central portion of the valve.

Cardiac skeleton Valve ring

Structurally, arteries and veins are made up of what 3 histological layers?

Tunica externa/adventitia Tunica media Tunica interna

What are the structural components of the tunica externa/adventitia?

``` Fibroblasts Elastin Collagen Vaso vasorum Nerves ```

The tunica externa/adventitia is associated with vaso vasorum, particularly when it comes to large arteries like the aorta. What is the vaso vasorum?

It means "vessels of vessels", referring to blood supply to these large muscular vessels

What is the overall function of the tunica externa/adventitia?

Anchors blood vessels to an organ

What are the structural components of the tunica media?

Smooth muscle Elastic and reticular fibers Sensory fibers External elastic lamina (arteries)

What are the structural components of the tunica intima?

``` Endothelium Subendothelium (loose CT) Basal lamina (type IV collagen) Internal elastic lamina ```

What is unique about the tunica intima in veins?

Tunica intima contains valves in veins

What type of artery is considered the largest, and contains elastic fibers in all 3 tunics?

Elastic arteries

Elastic arteries have elastic fibers in all 3 tunics which allow for stretching due to the increased pressure generated by blood flow from the heart. What are some examples of elastic arteries?

``` Aorta Brachiocephalic trunk Common carotid a. Subclavian a. Pulmonary arterial vessels ```

What type of arteries do elastic arteries branch into?

Muscular arteries

Muscular arteries possess elastic fibers in the internal and external _______ ________. They have a proportionally thicker tunica _______.

Elastic laminae Media

T/F: most 'named' arteries are elastic arteries

False - most named arteries are considered muscular arteries

What do muscular arteries branch into?

Arterioles

Arterioles are the smallest arteries with less than 6 layers of smooth muscle. What histological layer is lost in arterioles?

Internal elastic lamina

What do arterioles feed into?

Capillaries

Sympathetic innervation to tunica media causes ________ Parasympathetic innervation to the tunica media causes ________

Vasoconstriction (increase in BP) Vasodilation (decrease in BP)

Capillaries are the smalles of all blood vessels that form capillary beds. Their diameter is only slight larger than an erythrocyte, and their wall is thin enough for gas exchange. Which tunics are present in capillaries?

Capillaries only have tunica intima - single layer of endothelium!

_______ are perivascular contractile cells associated with regulating blood flow into the capillary beds

Pericytes

Trace the blood flow into a capillary bed from the arterial end to the venous end

Arteriole --> metarteriole --> true capillaries --> thoroughfare channel --> postcapillary venule

______ capillaries are branches from the metarteriole with rings of smooth muscle in their walls

True

Metarterioles and ______ ______ regulate blood flow through the true capillaries

Precapillary sphincters

_________ ________ = distal end of metarteriole that lacks smooth muscle, leads into postcapillary venule

Thoroughfare channel

What is the smallest type of vein found in the body?

Postcapillary venule

Contracted precapillary sphincters will "shunt" bloodflow, preventing exchange within true capillaries. What effect does this have on venous return?

It forces blood to enter venous return more quickly [Shunting of blood flow will differentially occur based on metabolic demand]

_________ cells are flat, polygonal cells that form the innermost aspect of the tunica intima, which acts as a permeability barrier via cell-cell junctions

Endothelial

Endothelial cells forming the innermost aspect of the tunica intima support the ________ _______ and produce _________.

Basement membrane; collagen

Endothelial cells that form the innermost aspect of the tunica intima are metabolically involved in what processes?

Blood coagulation and thrombosis Local vasodilation/constriction

What are the 3 types of capillaries in order of least leaky to most leaky?

Continuous capillaries (cells meet end-to-end) Fenestrated capillaries (fenestra = window) Sinusoid capillaries (discontinuous)

What is the most common type of capillary?

Continuous

Continuous capillaries have tight, occluding junctions sealing off intercellular clefts. Thus, all molecular exchange must occur via _____ or _______

Diffusion; transcytosis

Compare/contrast the basement membrane associated with the 3 types of capillaries: continuous, fenestrated, and sinusoid

Continuous = continuous basement membrane Fenestrated = continuous basement membrane Sinusoidal = partial discontinuous basement membrane

Where might you find continuous capillaries?

Most common, found throughout the body in muscle, brain, peripheral nerves, exocrine glands, etc.

Where might you find fenestrated capillaries?

Organs where molecular exchange with the blood is important - like kidneys, endocrine organs, intestinal walls, choroid plexus

Describe molecular exchange within fenestrated capillaries

Fenestrated capillaries have tight junctions with fenestrations among endothelial cells This allows greater exchange across the endothelium, but limited to the size of the macromolecule

Where might you find sinusoidal capillaries?

Where exchange of macromolecules and cells (between tissue and blood) must openly occur - like bone marrow, liver, and spleen

Describe molecular exchange within sinusoidal capillaries

Large fenestrations among endothelial cells (larger than in fenestrated capillaries) This allows open exchange to occur, large cell movements are allowed

_________ are vessels tht drain capillaries and return blood to the heart

Venules

T/F: pressure in veins is much lower than in arteries and at rest, the body's veins hold about 60% of the body's blood

True; veins function as blood reservoirs!

Veins usually travel as companions to arteries. They are classified as small, medium, or large based on size/development of ________. They contain _____ which are thin folds of intima projecting into the lumen, preventing the backflow of blood

Tunics Valves

______ veins travel with muscular arteries; both the media and externa/adventitia are better developed, but the wall is often folded around large lumen

Medium

T/F: medium veins contain valves

True

Large veins have a muscular media layer, although it is thin compared to the surrounding adventitia. Walls are often folded with the ______ projecting into the lumen as a valve. Large veins travel with ______ arteries

Intima Elastic

Lymph is a clear, yellowish fluid comprised of interstitial fluid, solutes, and foreign material. It is produced due to pressure differences across ______ ______

True capillaries

Lymphatic vessels collect lymph and return it to the _____ supply

Venous

Lymphatic capillaries are _______-ended tubes found among capillary beds. They are composed of overlapping _______cells that form 1-way valves for collecting lymph; these cells are typically ______ than those of blood capillaries

Closed Endothelial Larger

Openings between endothelial cells of lymphatic capillaries are held in place by _______ filaments which contain _______ and are covered by extensions of endothelial cells. They lack a complete _______ lamina

Anchoring; elastin; basal

What vascular tunics are found in lymphatic vessels?

All 3 in addition to valves

The walls of lymphatic vessels remain extremely _____ Normally they do not contain RBCs _______ lymph vessels carry lymph toward lymph nodes _______ lymph vessels carry "clean" lymph away from lymph nodes, which is able to stay clean due to one-way flow thanks to ______

Thin Afferent Efferent; valves

Trace lymph flow from lymphatic capillaries to its final venous destination

Lymphatic capillaries Lymphatic vessels Lymphatic trunks Right lymphatic duct (lymph from R side of head, neck, upper limb, and thorax) Thoracic duct (from most of the body) Drain into brachiocephalic veins