Block 2 Histo

Question 1

Smooth Muscle (involuntary muscle)

Answer 1

Spindle shaped soma and single fusiform nucleus

Eosinophilic cytoplasm because of contractile proteins

Locations: tunica media of non-capillary vasculature, deep to mucosa in respiratory and digestive systems

Question 2

Skeletal Muscle (striated muscle)

Answer 2

Always under volitional control

Banded, striated, striped appearance

Nuclei are displaced to periphery of cell, and many nuclei per cell

Nuclei are rod-shaped

Cells attached in segmental fashion so contractile force is uni-directional

Question 3

Cardiac Muscle

Answer 3

Majority of heart muscle

Similar to skeletal (striated), with a few exceptions

Intercalated discs separating cells

Cells have short branches that connect then to adjacent cells, so direction of contractile force is distributed instead of uni-directional

Can be single or multi-nucleated

Nuclei are rounded and in the center of the cell

Question 4

Heart wall

Answer 4

Epicardium

Myocardium

Endocardium

Question 5

Endocardium

Answer 5

Simple squamous endothelium

Subendothelial layer

Question 6

Myocardium

Answer 6

Subendocardial layer (between subendothelial of endocardium and rest of myocardium)

Myocardium (richly vascularized layer of myocytes)

Question 7

Subendocardial layer

Answer 7

Matrix of fibrous connective tissue

Contains nerves, blood vessels, Purkinje fibers/other components of impulse-conducting system

We will consider it part of the myocardium

Question 8

Myocyte

Answer 8

Cardiac muscle cells

Multiple short bands extending from central area where nucleus is

Separated by intercalated discs

Plasma membrane called sarcolemma

Contain mitochondria, glycogen granules

Question 9

Intercalated disc

Answer 9

Transverse portions have desmosomes and fascia adherens (similar to zona adherens)

Longitudinal portions have gap junctions

Question 10

Epicardium

Answer 10

Epithelium called mesothelium

Subepicardial layer contains blood vessels, nerves, adipocytes

Question 11

Heart valves

Answer 11

Dense fibrous connective tissue surrounded by epithelium

Question 12

3 layers of blood vessels

Answer 12

Tunica media (myocardium)

(Outermost) Tunica externa or adventitia (epicardium)

(Innermost) Tunica intima (endocardium)

Question 13

Tunica intima

Answer 13

Simple squamous epithelium on basement membrane

Subendothelial layer of loose connective tissue with occasional smooth muscle cells

In veins, folds to form a valve

Question 14

Tunica media

Answer 14

Unlike myocardium, has smooth muscle instead of cardiac muscle

Elastic fibers and reticular fibers of Type III collagen

Thickest layer in aorta, muscular arteries, arterioles

Question 15

Tunica externa or adventitia

Answer 15

Contains Type I collagen and elastic fibers, blood vessels, and nerves

Thickest layer in vena cava, medium-size veins, and venules

Question 16

Internal elastic lamina

Answer 16

Elastic fiber ring located in tunica intima

Aorta and muscular arteries have one

Vena cava has interrupted one

Question 17

External elastic lamina

Answer 17

Elastic fiber ring located in tunica media

ONLY muscular arteries have this

Question 18

Vasa vasorum

Answer 18

Microvasculature that supplies vessels

Aorta, vena cava, muscular arteries, medium-size veins have vasa vasorum

(Arterioles and venules do NOT)

Question 19

Nervi vasorum (nerves)

Answer 19

In aorta and muscular arteries, and very thin in arterioles

Fewer in vena cava and medium-size veins, and none in venules

Question 20

Capillary

Answer 20

Wall is 1 endothelial cell layer thick = tunica intima

No tunica media

Basement membrane is tunica externa or adventitia

3 types: continuous, fenestrated, sinusoidal

Pericytes on continuous capillaries are contractile

Histologically hard to distinguish from postcapillary venule

Have micropinocytotic vesicles to transport materials

Question 21

Lymph capillary

Answer 21

Wall is 1 endothelial cell layer thin = tunica intima

No tunica media

Incomplete basement membrane = tunica externa or adventitia

Irregular lumen containing lymph, no RBCs

Anchored to surrounding tissue by elastic filaments

Question 22

What happens to smaller muscular arteries in hypertension?

Answer 22

Hypertrophy of tunica media

Duplication of internal elastic lamina

Fibrotic thickening of tunica externa or adventitia

Question 23

Where does edema from inflammation come from?

Answer 23

Venules, because they have the loosest endothelial connections

Question 24

Precapillary sphincter

Answer 24

Rings of smooth muscle where arterioles are about to become capillaries (on precapillary arterioles)

Regulate blood flow to capillary bed

Question 25

Compare endocardium to epicardium

Answer 25

Endocardium: has single layer epithelium, subendothelial layer is thin and has no adipose tissue

Epicardium: has single layer epithelium, but subepicardial layer is thicker and has adipose tissue, nerves, and blood vessels

Question 26

Concentric hypertrophy

Answer 26

Due to increased pressure work (aortic stenosis, or increaced BP)

Very thick looking walls, making ventricle hold smaller volume

Question 27

Eccentric hypertrophy

Answer 27

Due to ventricle being overloaded with fluid

Wall does not become thicker, just creates larger lumen, larger diameter

AKA dilated cardiomyopathy