2: Circulatory System Flashcards
What are the layers of the heart from inside out?
endocardium, myocardium, pericardium
What is the endocardium epithelium?
simple squamous
What is the endocardium loose connective tissue?
fibro-elastic ct
What other irregular tissue is in the endocardium?
more collagen I, elastic fibers, some smooth muscle
What is the sub-endocardial layer of endocardium?
loose CT, blood vessels, nerves, most PURKINJE FIBERS
What are purkinje fibers?
modified cardiac myocytes fewer myofibrils, peripherally placed contained stored glycogen attached via: gap junctions & macula adherens (desmosomes) fxn: conduct contraction impulse rapidly
What is the myocardium of the atria like?
less muscle, more elastic fibers
What is the myocardium of the ventricles like?
well developed muscle layer
What is the structure of the intercalated discs of myocardium?
Transverse portion: “risers of stairs”; macula adherens, fascia adherens
Longitudinal portion: “step of the stairs”; LARGE GAP JUNCTIONS (ions & sarcoplasm travel through here
What are the functions of the intercalated discs of myocardium?
1) attach cardiac myocytes in a row using MACULA ADHERENS
2) attach and stabilize myofibrils using FASCIA ADHERENS
3) cell to cell communication using LARGE GAP JUNCTIONS
How does the autonomic nervous system affect the heart beat?
SYMPATHETICS: increase the heart rate, increase contraction force
PARASYMPATHETICS: slow the heart rate, decrease the contraction force
What are the specialized cardiac muscle cells called that secrete hormones?
myoendocrine cells
Where are the hormones secreted by the myoendocrine cells released?
surrounding capillaries
What do the myoendocrine hormones function in?
fluid and electrolyte balance: KIDNEYS
decrease blood pressure: SMALL ARTERIES & ARTERIOLES
What is another name for the pericardium?
serous pericardium
What are the two layers of the pericardium?
epicardium & parietal pericardium
What are the two layers of the epicardium?
sub-epicardium & mesothelium
What is the sub-epicardium made of?
fibro-elastic CT (thin layer) with coronary vessels, nerves, and some adipose
What does the mesothelium of the epicardium do?
secretes a serous lubricating fluid
What is the parietal pericardium made of?
mesothelium: secretes serous fluid
layer of fibro-elastic CT
What makes of the pericardial sac?
parietal and fiberous pericardium
What is the pericardial cavity made of?
parietal and visceral pericardium
How much fluid is held in the pericardial cavity?
15-50 mL
What is the general valve histology?
endothelium w/ dense irregular CT (collagen 1 & elastic fibers); mostly avascular
What is the cardiac skeleton made of ?
dense irregular CT
What is are the three main components of the cardiac skeleton?
annuli fibrosi, trigonum fibrosum, septum membranaceum (also chordae tendinae)
Where are the annuli fibrosum?
around the base of the aorta, pulmonary artery, and chamber openings
Where are the trigonum fibrosum?
by aortic valve cusps
What is the septum mebranaceum?
upper portion of the interventricular
What is the function of the septum mebranaceum?
to produce an origin and insertion for the cardiac myocytes
What is the general function of the cardiac skeleton?
isolates atrial and ventricular myocardia to ensure individual chamber contractions
What is angina?
chest pain usually brought on by exhertion
What is the cause of angina?
slow progressive narrowing of coronary vessels therfore less oxygen
What is dysrythmia?
abnormal heart beat
How can dysrythmia result?
when death or damage occurs to the purkinje fibers and other conducting tissues
What is pericarditis?
often due to an infection on the pericardial cavity and therfore inflammation of the serous pericardium (visceral & parietal layers)
What are the three major luminal wall layers in all but the smallest blood vessels?
tunica intima, tunica media, and tunica adventitia
T/F: The 3 major luminal wall layers are a continuation of the hearts histological layers.
true
The tunica intima is a continuation of…
endocardium
The tunica media is a continuation of…
myocardium
The tunica adventitia is a continuation of…
epicardium
What is another name for elastic arteries?
conducting arteries
What are examples of elastic arteries?
aorta, common iliacs, common coratids, brachiocephalics, subclavians
What is the structure of the tunica intima of elastic arteries?
attenuated endothelium
thin/incomplete internal elastic lamina
thicker CT w/ elastic fibers, collagen 1, fibroblasts & smooth muscle
What is the structure of the tunica media of elastic arteries?
fenestrated sheets of elastic fibers w/ some collagen 1 & smooth muscle
thin external elastic lamina possible
outer portion typically has: VASA VASORUM
What is the vasa vasorum?
small BV’s supplying large BV’s
What is the structure of the tunica adventitia of elastic arteries?
loose fiberelastic CT
vasa vasorum numerous
What is the thin cellular layer covering the inside of large blood vessels?
endothelium
What are muscular arteries also called?
distributing arteries
What is the structure of the tunica intima of muscular arteries?
VERY THIN
endothelium
some CT- few smooth muscle cells possible
internal elastic lamina
What are examples of muscular arteries?
brachial, radial, renal, femoral
What layer of muscular arteries has a wavy appearance?
tunica intima- internal elastic lamina
What is the structure of the tunica media of muscular arteries?
primarily circular smooth muscle
gap junctions btwn smooth muscle cells
elastic & reticular fibers, chondrotin sulfate
external elastic lamina possible
richly innervated w/ sypathetics –> strong contraction over a small area
What is the thickest most dominant layer of muscular arteries?
tunica media
What part of blood vessels blocks products of inflammation?
tunica media
What is the structure of the tunica adventitia of muscular arteries?
fibroelastic CT w/ sulfated GAGs
FIBROBLASTS
vasa vasorum is present
What is the relative size of arterioles?
lumen size is ~ equal to width of the vessel
In arterioles, is the tunica intima present?
maybe
In arterioles, is tunica media present?
no
In arterioles, what is the tunica adventitia structure?
??????????
What happens to elastic arteries as you age?
width increases into your 20's # of elastic laminae increase in the tunica media
What happens to muscular arteries as you age?
collagen & proteoglycans increase after middle age: decreases flexibility
coronary vessels greatly affected
What is hypertension?
an increase in systolic BP, can occur ~50 yrs, due to a decrease in elastic fibers & increase in collagen 1
What is arteriosclerosis?
athrosclerosis “hardening of arteries” - primarily the largest
TUNICA INTIMA: infiltrated w/ soft lipids causing decreased lumen diameter
TUNICA MEDIA: often affected - collagen 1 and sulfated GAGs can accumulate here
What are metarterioles?
short terminal arteriole branches that LACK A TRUE TUNICA MEDIA
lead to capillaries and thoroughfare channels taht lead to venules
What controls metarteriole blood flow?
pre-capillary sphincters: allow blood to pulse through capillaries
Found in all capillary beds
What is an AVA?
arteriovenous anastamosis = AV shunt
thicker tunica media & tunica adventitia
many ANS nerves (sympathetic & parasympathetic)
FXN: control AVA lumen size & therefore the amount of blood into the capillaries
If the AVA is closed…
blood to capillary bed is normal
If the AVA is open…
blood by-passes capillary bed
How is the blood flow into capillaries controlled/influenced?
1) metarterioles
2) AVA (some locations)
3) lumen size of terminal arteriole
4) pre-capillary sphincter
What is the general capillary structure?
Cells: single layer of flattened endothelial cells
Pinocytotic vesicles: form tiny pockets through cytoplasm
FXN: mvmnt of large molecules
Cell junctions: FASCIAE OCCLUDENS-btwn endothelial cells
FXN: move macromolecules, allows cell mvmnt
What are the types of capillaries?
continuous capillaries, fenestrated capillaries, sinusoidal capillaries (sinusoids)
What are continuous capillaries?
most common capillary type
found in: muscle, ct, many organs
What are pericytes?
considered “residual mesenchyme cells”
numerous on capillaries & venules
secrete: basement membrane & matrix components
can divide
What can pericytes change into?
1) smooth muscle cells
2) endothelial cells
3) fibroblasts
What are the functions of pericytes?
1) healing
2) regulate blood flow????
Where are fenestrated capillaries found?
pancreas, intestines, endocrine organs, kidneys
What is the structure of fenestrated capillaries?
pores with thin protein diaphragm containing 8 fibrils “wheel structure”
What is the function of fenestrated capillaries?
allows greater movement of molecules and cells
Where are sinusoidal capillaries (sinusoids) found?
bone marrow, liver, spleen, lymphatic organs, certain endocrine organs
What is the structure of sinusoids?
enlarged diameter
many large fenestrae w/ NO PROTEIN DIAPHRAGM
What is the function of sinusoids?
enhanced exchange btwn blood & tissues
How are veins similar to arteries?
they have 3 tunics (intima, media, externa)
How are veins different from arteries?
1) not as uniform in structure
2) often larger
3) higher number
What are vein valves like?
Structure: 2 flaps of tunica intima and fibroelastic ct
FXN: 1) protection by preventing back flow
2) works with skeletal muscle to keep blood moving
What are venules?
determined by tunics not diameter
What are post capillary venules?
THINNEST
tunica intima: endothelium, small amount of ct & numerous pericytes
tunica media & adventitia: NONE
What are collecting venules?
tunica intima: endothelium & small amounts of ct
tunica media: NONE
tunica advetitia: ct, fibroblasts, some pericytes
What is the set up of muscular venules?
tunica intima: present
tunica media: NONE
tunica adventitia: CT, fibroblasts, some pericytes
What allows products of inflammation through and loosens endothelial call junctions resulting in LEAKY VENULES?
incomplete tunica media
What is the structure of small veins?
similar to venules EXCEPT COMPLETE TUNICA MEDIA
what is the structure of medium veins?
VALVES COMMON
tunica intima: endothelium, BL, CT w/ reticular fibers, sometimes and elastic fiber network
tunica media: smooth muscle, collagen, fibroblasts
tunica adventitia: CT w/ collagen, elastic fibers, few smooth muscle cells, vasa vasorum possible
What is usually the thickest, most dominant layer of medium veins?
tunica adventitia
What is the structure of large veins?
tunica intima: similar to medium veins, thicker CT w/ fibroblasts & elastic fibers
tunica media: complete but thin
tunica adventitia: much fibro-elastic CT w/ vasa vasorum
What is usually the thickest layer of large veins?
tunica adventitia
How are the superficial veins of the legs different from the typical structure?
the tunica media is well developed
How are the pulmonary veins different from the typical structure?
tunica media is well developed
tunica adventitia: some cardiac muscle close to the heart
How is the superior vena cava different from the typical structure?
tunica adventitia: some cardiac muscle close to the heart
How is the inferor vena cava different from the typical structure?
tunica adventitia: some cardiac muscle close to the heart is possible & longitudinal smooth muscle
What are varicose veins?
enlarged and winding SUPERFICIAL veins in the legs
What are 3 possible causes of varicose veins?
1) loss of skeletal muscle tone around the veins
2) degeneration of vessel wall
3) valve incompetence
What are esophageal varices?
varicose veins in lower esophagus
In what population are esophageal varices common?
alcoholics; caused by portal hypertension
What are hemorrhoids?
varicose veins at the end of the anal canal
What are the functions of lymphatic vessels?
1) drains excess interstitial fluid
2) transport lymph to lymph nodes - foreign antigen detection n lymph nodes
3) transport lymph to blood stream
What type of capillaries to lymph capillaries resemble?
continuous blood capillaries
How are lymphatic capillaries different from continuous blood capillaries?
1) blind ended - suddenly begin
2) NO pericytes
3) endothelial cells can overlap, create clefts btwn cells
(easy movement of materials in and out)
4) NO fenestrae & NO tight junctions btwn endothelial cells
5) has bundles of lymphatic anchoring filaments
What does the structure of small lymphatic vessels resemble?
venules (a little thinner)
What is the structure of medium and large lymphatic vessels?
larger lumen and thinner walls, tunics blend together more than in veins
What are the layers of med & lrg lymphatic vessels set up like?
tunica intima: endothelium and thin layer of CT with elastic fibers
tunica media: thin smooth muscle layer
tunica adventitia: CT w/ collagen and elastic fibers
valves: present and closely packed
Where do lymphatic ducts empty?
into the venous system at the junction of R&L internal jugular and subclavian veins
What ducts are included in the lymphatic ducts?
short right lympahtic duct and the thoracic duct
What is the general structure of lymphatic ducts?
tunica intima: endothelium - several layer of collagen and elastic fibers; layer of condensed elastic fibers (similar to internal elastic lamina)
tunica media: longitudinal & circular layers of smooth muscle
tunica adventitia: longitudinal smooth muscle cells; collagenous ct; vasa vasorum-like vessels
