Chapter 4 Flashcards
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
- fluid and electrolyte balance targeting the kidney
2. decrease blood pressure targeting small arteries and arterioles
what is the pericardium (serous pericardium) composed of
- ) 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 - ) parietal pericardium
a. mesothelium - secretes serous fluid
b. layer of fibroelastic CT
What does the pericardial sac consist of
- 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
angina
what are abnormal heart rhythms caused by damaged or dead purkinje fibers and other conducting tissues
dysrhythmia
infection in pericardial cavity and therefore inflammation of the serous pericardium (visceral and parietal)
pericarditis
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
- tunica intima - no internal elastic lamina
- tunica media - no external elastic lamina, most dominant
- 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
- metarterioles
- AVA’s
- lumen size of terminal arteriole
- precapillary sphincters
what is the general capillary structure
- cells - single layer of flattened endothelial cells
- pinocytotic vesicles - form tiny transient channel pockets thru cytoplasm. fxn - movement of large molecules
- cell junctions - fasciae occludens bet endothelial cells
fxns - a. move macromolecules b. allows cell movement
what are the types of capillaries
- continous capillaries - most common
- fenestrated capillaries
- 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
- post capillary venules
- collecting venules
- 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
- drain excess interstitial fluid
- transmit lymph to lymph nodes (foreign antigen detection in lymph nodes)
- transport lymph to the blood stream
desribe lymphatic capillaries
structurally resemble blood capillaries
differentiate lymphatics from continous blood capillaries
- blind ended - suddenly begin
- no pericytes
- endothelial cells can overlap but creat clefts between cells which allows for easy movement into and out of vessels
- no fenestrae and no tight junctions between endothelial cells
- 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
