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What are the layers of the heart wall

A. Endocardium
B. Myocardium
C. Pericardium
D. Pericardial Sac
E. Pericardial Cavity


What does the endocardium consist of

a. endothelium - simple squamous
b. looser CT layer: fibroelastic CT
c. more dense irregular CT layer
d. subendochondral layer - looser CT


what makes the subendothelium of the endocardium

a. looser CT layer
b. more dense irregular CT layer


what makes the subendochondral layer of the endocardium

a. looser CT with blood vessels
b. nerves
c. purkinje fibers


what are purkinje fibers

modified cardiac myocytes
fewer myofibrils peripherally placed
contain stored glycogen
attached using gap junctions and macula adherens
fxn to conduct contraction response rapidly


what is the difference between atria and ventricles

atria - less muscle, more elastic fibers
ventricles - well developed muscle layer


what does the intercalated disc consist of

transverse (risers) and longitudinal (steps)
transverse - macula adherens, fascia adherens
longitudinal - gap junctions


what are the functions of intercalated discs

- attach cardiac myocytes in a row using macula adherens
- attach and stabilize myofibrils using fascia adherens
- cell to cell comm. using large gap junctions


what is the relationship of autonomic nervous system to the heartbeat

SNS increase HR and contraction force
PSNS decrease HR and contraction force


what are myoendocrine cells

specialized cardiac muscle cells that secrete hormones in the atria and interventricular system, releasing hormones to the surrounding cells


what do hormones function in

1. fluid and electrolyte balance targeting the kidney
2. decrease blood pressure targeting small arteries and arterioles


what is the pericardium (serous pericardium) composed of

1.) epicardium - visceral pericardium
a. subepicardial layer of fibroelastic CT containing:
1. coronary vessels
2. nerves
3. sometimes much adipose
b. mesothelium - secretes a serous lubricating fluid
2.) parietal pericardium
a. mesothelium - secretes serous fluid
b. layer of fibroelastic CT


What does the pericardial sac consist of

1. parietal pericardium
2. fibrous pericardium


what is the pericardial cavity

it holds ~15-20 ml of fluid and is between:
- parietal pericardium
- visceral pericardium


What is the general valve histology

endothelium with dense irregular CT tissue below dense irregular CT has many collagen I and elastic fibers and is almost avascular


what is the cardiac skeleten made of

dense irregular CT


what are the 3 main components of the cardiac skeleton

A. annuli fibrosi - around base of aorta, pulmonary artery and the openings of the chambers
B. trigonum fibrosum - by cusps of aortic valve
C. septum membranaceum - upper portion of the ventricular septum
function to provide an origin and insertion for cardiac myocytes
D. other chorae tendinae - tendonlike therefore CT type is dense regular


what is the function of cardiac skeleton

isolates atrial and ventricular myocardia to insure individual chamber rhythmic contraction


What chest pain is usually brought on by exertion and is caused by slow progressive narrowing of coronary vessels resulting in decreased oxygen



what are abnormal heart rhythms caused by damaged or dead purkinje fibers and other conducting tissues



infection in pericardial cavity and therefore inflammation of the serous pericardium (visceral and parietal)



composition of blood vessels

tunica intima - continuation of endocardium
tunica media - continuation of mycardium
tunica adventitia - continuation of epicardium


what are elastic arteries

conducting arteries - ex. aorta, common iliac, carotid, brachiocephalic, subclavian


what is the structure of the tunica intima of elastic arteries

-attenuated endothelium
-thin/incomplete internal elastic lamina
-thicker CT with elastic fibers, collagen I, fibroblasts and smooth muscle


what is the structure of the tunica media of elastic arteries

Most dominant layer
- primarily fenestrated elastic lamina with some collagen I and smooth muscle
- thin external elastic lamina possible
- outer portion contains vasa vasorum


what is the structure of the tunica adventitia of elastic arteries

- loose fibroelastic CT
- numerous vasa vasorum


what are muscular arteries

distributing arteries, ex, brachial, radial, renal, femoral


what is the structure of the tunica intima of muscular arteries

- endothelium
- some CT - few smooth muscles possible
-well developed internal elastic lamina


what is the structure of the tunica media of muscular arteries

Thickest and most abundant
- primarily circular smooth muscle
- gap junctions bet smooth muscle cells
- external lamina possible
- richly enervated with sympathetics so can have strong contraction over a small area


arterioles: lumen size is ~= width of vessel wall

1. tunica intima - no internal elastic lamina
2. tunica media - no external elastic lamina, most dominant
3. tunica adventitia - overall structure is similar to muscular arteries CT


what is the relationship of arteries and aging

elastic arteries width increase into your 20's. number of elastic laminae increase in tunica media


what is hypertension

increase in systolic blood pressure around 50 y/o due to a decrease in elastic fibers and increase in collagen I


what is arteriosclerosis/atherosclerosis

hardending primarily in the largest of arteries, tunica intima becomes infiltrated with soft lipids causing lumen diameter to decrease


what are metarterioles

- short teminal arteriole branches that lack a true tunica media
- lead to capillaries and a thoroughfare channel that leads to venules
- precapillary sphincters control blood flow into true capillaries
- allows blood to pulse thru true capillaries - found in all capillary beds


What is AVA and its function

arteriovenous anastomosis - av shunt - thicker tunica media and adventitia, many nerves (SNS and PSNS) functions to control lumen size and therefore the amount of blood into capillaries


what controls blood flow in the capillaries

1. metarterioles
2. AVA's
3. lumen size of terminal arteriole
4. precapillary sphincters


what is the general capillary structure

1. cells - single layer of flattened endothelial cells
2. pinocytotic vesicles - form tiny transient channel pockets thru cytoplasm. fxn - movement of large molecules
3. cell junctions - fasciae occludens bet endothelial cells
fxns - a. move macromolecules b. allows cell movement


what are the types of capillaries

1. continous capillaries - most common
2. fenestrated capillaries
3. sinusoidal capillaries


describe continous capillaries

located in muscles, CT, many organs
contains pericytes


what are pericytes

considered to be mesenchyme cells
numberous on capillaries and venules
secrete basement membrand and matrix components
functions in healing and regulation of blood flow


what is modified continous capillary in CNS

zonula occludens instead of fascia occludens
barrier regulated by endothelium but influenced by astrocytes


describe fenestrated capillaries

-located in pancreas, intestines, endocrine organs, kidneys
- pores with thin protein diaphragm containing 8 fibrils
- function to allow greater movement of molecules and cells


describe sinusoidal capillaries

- located in bone marrow, liver, spleen, lymphatic organs and certain endocrine organs
-structure - enlarged diameter, many fenestrated with no protein diaphragm
-function to enhance exchange between blood and tissues


compare veins with arteries

- not as uniform in structure
- often larger
- more numerous


describe the structure and function of valves

- 2 flaps of tunica intima and fibroelastic CT
- protection by preventing backflow of blood
- works with skeletal muscle to keep blood moving


what are the types of venules

1. post capillary venules
2. collecting venules
3. muscular venules


describe post capillary venules

- tunica intima - endothelium, small amount of CT and numerous pericytes
-no tunica media
-no tunica adventitia


describe collecting venules

-tunica intima is composed of endothelium and small amounts of CT
-no tunica media
-tunica adventitia - CT, fibroblasts and some pericytes


describe mascular venules

-tunica intima
-tunica media - incomplete smooth muscular layer
-tunica adventitia present with few pericytes


how do leaky venules come about

an incomplete tunica media allows products of inflammation through to loosen endothelial cell junctions


describe small veins

similar to venules except a complete tunica media


describe medium veins

-tunica intima - endothelium, basal lamina, CT with reticular fibers
-tunica media - smooth muscle, collagen, fibroblasts
-tunica adventitia - usually thickest and most abundant- CT with collagen I and elastic fibers and few muscle cells


describe large veins

- tunica intima - endothelium, basal lamina, CT with reticular fibers
-tunica media - complete but thin
-tunica adventitia - usually thickest, a lot of fibroelastic CT and vasa vasorum


What are exceptions to the typical vein structure

-superficial veins of legs - tunica media well developed
-pulmonary veins - well developed tunica media, some cardiac muscle in tunica adventitia close to heart
-vena cava - some cardiac muscle close to heart in Tun Adv
-inferior vena cava - some cardiac ms close to heart and some longitudinal smooth muscle


describe varicose veins

-loss of skeletal muscle tone around vein
-degeneration of vessel wall
-valve incompetence


describe esophageal varices

-varicosities in lower esophagus
-common in alcoholics, caused by portal hypertension


what are hemorrhoids

varicosities at the end of the anal canal


what are the functions of lymphatic vessels

1. drain excess interstitial fluid
2. transmit lymph to lymph nodes (foreign antigen detection in lymph nodes)
3. transport lymph to the blood stream


desribe lymphatic capillaries

structurally resemble blood capillaries


differentiate lymphatics from continous blood capillaries

1. blind ended - suddenly begin
2. no pericytes
3. endothelial cells can overlap but creat clefts between cells which allows for easy movement into and out of vessels
4. no fenestrae and no tight junctions between endothelial cells
5. contain bundles of lymphatic anchoring filametns containing elastic fibers


describe small lymphatic vessels

structurally resemble venules


describe medium and large lymphatic vessels

they have larger lumen and thinner walls, tunics blend together more than veins
-tunica intima - endothelium and thin layer of CT with elastic fibers
-tunica media - thin smooth muscle layer
-tunica adventitia - CT with collagen and elastic fibers
-valves are present and closely spaced


where do lymphatic ducts empty

into venous system at the junction of right internal jugular and subclavian veins, includes the short right lymphatic duct and the thoracic duct


describe the structure of the lymphatic duct

tunica intima - endothelium several layers of collagen and elastic fibers, layer of condensed elastic fibers
tunica media - longitudinal and circular layers of smooth muscle
tunica adventitia - longitudinal smooth muscle cells, collagenous CT, vasa vasorum-like vessels