Midterm Flashcards
external cardiac anatomy right border left border inferior border anterior surface
right border = right ventricle
left border = left atrium and left ventricle
inferior border = right atrium and some left ventricle
anterior surface = mostly the right ventricle
blood flow within cardiac chamber
blood from lower trunk + limbs enters the heart through inferior vena cava
blood from above enters from superior vena cava
both drain into the right atrium
through tricuspid valve into right ventricle
through pulmonary valve into left lung via pulmonary artery
back into left atrium via left pulmonary veins (left lung)
through mitral valve into left ventricle
through aortic valve into aorta
the great arteries
pulmonary artery - anterior to aorta to left shoulder
ascending aorta - posterior to pulmonary artery to right shoulder
the aorta and pulmonary artery are at 60-60 degree angle
coronary arteries
right coronary artery and left coronary artery
first branches to come off aorta
right coronary artery
arises from right sinus of valsalva
courses between right atrium and right ventricle in atrioventricular groove
gives rise to right atrium branch, acute marginals (feed right ventricle) and most of the time the posterior interventricular artery (PDA)
- right dominant circulation in 70% of people
left main coronary artery
arises form the left sinus of valsalva
short segment splits into two: circumflex and the left anterior descending
circumflex
courses into left atrioventricular groove
gives rise to obtuse marginal branches that feed lateral left ventricle wall
left anterior descending (LAD)
feeds septum and left ventricle free wall
gives rise to diagonals and septal branches
coronary dominance
insert picture
venous drainage
cardiac veins are paired with arteries
majority of veins drain into coronary sinus (great cardiac vein) in posterior atrioventricular groove
right ventricle venous branches drain directly into right atrium
sequential segments of the internal cardiac anatomy
atria
atrioventricular valves
semilunar valves
ventricles
right atrium
smooth and trabeculated walls separated by crista terminalis
superior and inferior vena cava drain into smooth walled portion
fossa ovalis (thin wall between right atrium and left atrium, looks like slight depression) is formed from downward migration of septum secundum and upward migration of septum primum
tricuspid valve
allows for unidirectional blood flow from right atrium to right ventricle
three leaflets: septal, anterior, posterior
atrioventricular valves
mitral valve
tricuspid valve
these valves depend on hinge lines, valve tissue, chordae (like parachute strings), papillary, muscles, and ventricular wall function for proper performance
mitral valve
only two leaflet valve: posterior and anterior leaflets
allows unidirectional blood flow from left atrium to left ventricle
leaflets attach to mitral annulus - dense connective tissue of the cardiac skeleton that is the junction between the left atrium and left ventricle
leaflet edges are tethered by chordae tendinae which are attached to the ventricle through papillary muscles
right ventricle
inflow portion is below tricuspid valve
has an apex
outflow of infundibulum
has a pulmonary trunk: trabeculates, L shaped, septum is a smooth membranous portion with conduction tissue adjacent
semilunar valves
do not depend on ventricular function
there are two of them: aortic and pulmonary
three leaflets - suspended from the pulmonary trunk and aortic root
scalloped (commissures/ hinge lines)
competency is dependent on attachments and elastic/collagenous nature of the leaflet tissue as well as the dimensions of the root and trunk
weight of heart
- 45% of mens weight: 325gm +/- 75gm
0. 40% of womens weight 275 gm +/- 75gm
cellular composition of heart
myocytes - 25% of total cell number but 90% of mass
endothelial cells - 70% of total cell number but negligible contribution to heart weight
fibroblasts
immune cells
pericardium
fibrous sac that surrounds the heart - rich in collagen making in distensible
does not have elastic
fibrous component faces away from the heart
serous component faces toward the heart
refections from great vessels and veins
normal = 50cc of straw coloured fluid
sudden increases to 250 cc causes tamponade
fibrous skeleton
base of the heart - gives structure and shape
dense collagenous tissue with elastin - this makes up the rings of the atrioventricular valve and aortic annulus - this extends to the pulmonary trunk via conal ligament
separates the atrial and ventricular chambers
separates the left and right ventricles via a membranous septum
the atrioventricular conduction bundle is embedded in it
cardiac skeleton
fibrous skeleton = dense connective tissue made of thick collagen + some fibrocartilage
provides point of attachment for valve leaflets and myocardium
provides rigidity to prevent the dilation of valves that might cause leaking
electrically isolates the atria from the ventricles
- AV conducting system is the only electrical connection between the atria and ventricles
heart wall layers
epicardium - outer most layer
myocardium - muscle layer
endocardium - inner most layer
epicardium
analogue of vascular adventitia
serous pericardium
contains: coronary arteries and veins, fat, nerves, fibroblasts, macrophages
myocardium
analgogue of vascular media
bundles of cardiac muscle separated by fibrous bands
consists of: myocytes, collagen, blood vessels and elastin
5 components of myocytes
- cell membrane (sacrolemma and T tubules) - responsible for impulse conduction
- form gap junctions
- intercalated disks - join myocytes mechanically/ionically
- functional syncytium - sarcoplasmic reticulum - calcium reservoir
- action potential causes it to release calcium - tells actin and myosin to contract - contractile filaments
- actin, myosin, troponin + tropomyosin
- contraction = net effect of actin and myosin sliding closer to the sacromere - mitchondria - energry generation through aerobic respiration only
- 23% of myocyte volume = mitochondria vs regular cell = 2% - nucleus - very large compared to most cells
myocardial anatomy
intercalated disks provide the transmission of contractile energy from cell to cell
long chains of cells are arranged into myofibrils
cardiac muscle fibers
ventriciular cardiac muscle
atrial cardiac muscle
ventricular cardiac muscle
complex layers of cells wound helically around the ventricular cavity
aids in “wringing out the heart” (like a sponge) during contraction of the heart
atrial cardiac muscle
muscle cells that are in the outer layer of the myocardium- form a complex helical structure around the atrial chamber
atrial cardiac muscle cells compared to ventricular cardiac muscle cells: (list 6 things)
are somewhat smaller
have a less extensive T-tubule system
have more gap junctions
can conduct impulses at a rate 3X higher
contract more rhythmically
have many granules that contain atrial natiuretic factor (ANF)
right atrium
receives blood from superior and inferior vena cava and passes it the to the right ventricle
2mm thick
smooth and trabeculated areas
coronary sinus empties into it
epicardium is rich in ganglia
myocytes are smaller than in ventricles
auricular appendage - looks like snoopys nose
electron dense granules contain atrial natiuretic factor (ANF)
left atrium
receives oxygenated blood from pulmonary veins
delivers to left ventricle across the mitral valve
3mm thick
smooth throughout
auricular appendage - shaped like central America
right ventricle
anterior most structure
3 subportions: inflow portion, apex, outflow portion
C shaped around left ventricle
coarsely trabeculated
papillary muscles support tricuspid valve
myocardium is 5 mm thick
membranous septum contains conduction system
low pressure ( this is why its thinner than left ventricle)
left ventricle
high pressure therefore 15mm thick
bullet shaped
3 subportions: inflow, septum, outflow
conducts blood from left atrium via mitral valve to aorta via aortic valve
ventricular diastole
relaxation
semilunar valves are closed
AV are open
pressure in ventricle goes down bc it is relaxed
pressure in atrium is higher
the pressure differential is what causes the opening and closing of valves
ventricular systole
contraction
pushes open valves to pulmonary artery
tricuspid and mitral valves close
fluid wants to leave therefore semilunar valves will open to allow this
aortic valve anatomy
a semilunar valve
located in aortic root
commisures are high points and cusp nadirs are low points - form a suspension bridge structure - this ring of suspension is called annulus
leaflets are named for aortic sinuses (left, right, non)
aortic valve histology (three layers)
fibrosa
- collagen rich, extends to free edge and coaptin surface
- gives strength to the tissue
spongiosa
- proteoglycan and GAG rich, collagen and fibroblasts (dont really need to know)
ventricularis
- Left ventricle side
- acts as shock absorber
- allows leaflets to stretch and coapt under pressure and spring out of the way during ejection
pulmonic valve
a semilunar valve
in pulmonary trunk
anterior and superior to aortic valve
same histology as aortic valve (3 layers = fibrosa, spongiosa, ventricularis) but it is thinner bc lower pressure
what does the competency of semilunar valves depend on?
their attachment to commissures and hinge lines
their strength, pliability, and elasticity
dimensions of the aortic root or pulmonary trunk
histology of the mitral valve (4 layers)
fibrosa
- collagen rich and extends to chordae and tips of papillary muscles
spongiosa
- atrial side, GAG and proteoglycan rich
ventricularis
- ventricular side
- elastin rich and endothelialized
auricularis
- EC layer on atrial side
what is the mitral valve competency based on?
dimension of annular ring structural integrity of leaflets (pliable, elastic, strength) structural integrity of chordae function and dimensions of ventricles
tricuspid valve histology
compared to mitral valve: lower pressure and thinner chordae, papillary muscles, and leaflets
same 4 layers as mitral valve: fibrosa, spongiosa, ventricularis, auricularis
epicardial coronary arteries
the myocardium is dependent on only oxygenated blood
- therefore the heart extracts oxygen maximally (extracts 60%, leaving the venous saturation at 40% compared to 60% everywhere else in the body)
originate from the sinuses of valslava
they are 2-4mm in diameter and 5-10cm in length
branch into intramural arteries
Tunica adventitia
outermost layer of blood vessels
primarily loose connective tissue
- type 1 collagen and elastin anchor it vessel
in veins this is the thickest layer
contains vassa vasorum - found in large arteries and veins
analogous to epicardium in heart
tunica media
middle layer of blood vessel - most variable in size/structure
contains smooth muscle
collagen fibers, reticular fibers and elastic tissue (more of these in arteries compared to veins)
the media layer tends to be large in most arteries
analogous to myocardium in heart
tunica intima
inner most layer (next to lumen) of blood vessels
single layer of endothelial cells and minimal connective tissue
in larger vessels it is subdivided into 4:
- endothelium
- thin basal lamina
- subendothelium (connective tissue including collagen)
analogous to endocardium in heart
properties of the endothelium
can have different functions based on different blood vessel locations
cells are bound together by junctional complexes
can be activated by cytokines to express cell adhesion molecules which allow WBCs to stick and migrate from the blood vessel into the tissue
under normal circumstances: secrete substances that maintain the tone of vascular smooth muscle and prevent blood clotting
cellular composition of blood vessels
endothelial cells
smooth muscle cells
immune cells and fibroblasts are also there but they are not as important for function
components of extracellular matrix in blood vessels
collagen
elastin
glycosaminoglycans
endothelial function in blood vessels
EC-EC junction = permeability layer - regulate uptake
maintain the delicate balance of pro and anti forces in: clotting fibrinolysis vascular tone inflammation mitogenesis (cell growth)
synthesize matrix molecules: collagen and proteoglycans
what anticoagulant, antithrombotic and fibrinolytic molecules do endothelial cells make?
prostacyclins
thrombomodulin
heparans
plasminogen activator
what pro-thrombotic molecules do endothelial cells make?
von willebrands factor
tissue factor
plasminogen activator inhibitor
how do endothelial cells regulate blood flow?
endothelial cells are responsible for the contraction and relaxation of blood vessels
vasoconstriction is caused by endothelin and angiotensin converting enzyme
vasodilatation is caused by prostacyclin and nitric oxide
how do endothelial cells regulate cell growth?
produce regulator molecules:
molecules that stimulate growth: PDGF, FGF, VEG F
molecules that inhibit growth: heparin, TGF beta
how do endothelial cells regulate inflammation and immunity?
interluekins 1 and 6, chemokines - attract immune cells
adhesion factors cause the immune cells to stick and exit blood vessels to go into tissues
vascular smooth muscle cells
primary element of vascular media
responsible for vasoconstriction and vasorelaxation
secrete and synthesize growth factors and cytokines
synthesize proteoglycans, collagen, elastin
in response to injury they migrate to the intima and proliferate
what happens to smooth muscle cells in response to injury?
migrate to intima and proliferate -this is promoted by edothelin, PDGF, FDF, IFN gamma
the cells synthesize matrix
this can = normal healing or atherosclerosis
two types of arteries
elastic and muscular
which arteries are elastic arteries?
aorta brachiocephalic carotid subclavian iliac pulmonary arteries and larger branches
physical characteristics of elastic arteries?
vessels are thick - too thick for diffusion of oxygen therefore get their own oxygen via the vasa vasorum
tissues and cells organized in lamella
intima has endothelial cells and minimal matrix
adventitia collagen predominant with vasa vasora - this provides strength
elastin dominates in media allowing for expansion in systole
- acts as secondary pump (pressure reservoir)
-
intima, media and adventitia of elastic arteries
intima has endothelial cells and minimal matrix
elastin dominates in media - allows for expansion in systole
- this acts as a secondary pump/pressure reservoir
- VSCM are dominant cell in media
adventitia collagen predominant with vasa vasora- this provides strength
what does the aorta arise from and where do its branches go
arises from left ventricle
root gives rise to coronary arteries
arch to head and upper extremity vessels
descending to paired intercostal arteries
atherosclerotic and hypertensive changes in the elastic arteries
intima thickens and develops plaque
fragmentation of collagen and elastin
media degenerates causing reduced blood supply
results in aortic aneurysm or dissection
muscular arteries: layers (intima, media, adventitia)
intima is thinner than elastic arteries
internal elastic lamina is well defined
media has fewer elastin fibers, lamella are defined but discontinuous in some locations, the VSMC is a major component
external elastic lamina is well defined
adventitial thickness/ strength variable
examples of muscular arteries
coronaries
renal arteris
femorals + distributive arteries of the lower extremities
axillaries and distributive arteries of upper extremity
visceral arteries
visceral arteries supply blood to the visceral organs
examples of visceral arteries
celiac trunk - splenic artery, distal esophagus, pancreas, hepatic arteries
superior mesenteric artery - abdominal extremities
inferior mesenteric artery
marginal artery (Drummond) anastomoses the SMA and IMA
- these are important in atherosclerotic occlusive disease of these vessels
- occlusive disease of visceral vessels can result in intestinal angina or hypertensionn
marginal artery (drummond)
formed by antastomoses of the terminal branches of the inferior mesenteric artery (IMA) and superior mesenteric artery (SMA)
this is critical in atherosclerotic occlusive disease of these vessels
occlusive disease of the visceral vessels can result in intestinal angina and hypertension
muscular arteries of the upper extremity
subclavian > axillary > brachial> branches into radial and ulnar (closest to body)
superficial palmar acrches suply hand and digits
INSERT PICTURE
axillary artery
begins at lateral border of first rib to teres major
multiple branches to chest and shoulder
brachial artery
teres major to antecubital fossa
branches to elbow and adjacent forearm musculature - into radial and arteries
radial and ulnar arteries
supply forearm musculature
iliac artery
common iliac: paired arteries at the terminus of the abdominal aorta -4th lumbar vertebra
external iliac: common iliac branch that courses along psoas muscle anterior and inferior to the inguinal ligament
internal iliac: arises at the sacroiliac joint - courses pestero-inferior to external iliac giving rise to branches that supply the pelvic viscera and medial thigh
infra-inguinal arteries: groin
as external iliac crosses he inguinal ligament it becomes the femoral artery
this occurs midway between pubic tubercle and anterior superior iliac spine
NAVL: lateral to medial = nerve, artery, vein, lymph
branches that supply thigh and and sex organs
gives rises to profunda femoris artery - this supplies muscles of upper extremity + provides collaterals down to knee
gives superficial femoral artery: courses down anteromedial thigh deep to muscles to lower extremities
popliteal artery
when superficial femoral artery emerges into posterior knee, from adductor magnus muscle becomes popliteal artery
gives 5 geniculate branches to the knee
travels in interchondylar fossa
divides at popliteal muscle into anterior and posterior tibial aa
lower leg arteries
anterior tibial artery - goes into dorsalis pedis in foot
posterior tibial artery
peroneal artery
head and neck arteries
common carotid artery and brachiocephalic trunk gives rise to internal carotid artery and external carotid artery
branch point is at the carotid sinus
carotid body - sense oxygen content and regulate breathing
carotid branches
external carotid:
- supplies head and neck external to cranium
- multiple branches, most importantly facial arteries and superficial temporal, maxilaryartery
internal carotid:
supplies brain, eyes, forehead
- enters cranium via cranial canal in temporal bone (skull base)
- vertebral artery branches of the subclavian artery ascend through postiero neck adn enter cranium through foramen magnum also supplying the brain
small arteries
provide distribution form named branches to tissues
less than 2 mm in diameter
small arterioles
20-100 mm in diameter
provide blood flow regulation via medial smooth muscle contraction
regulates relative blood flow to capillary beds
provide the majority of flow resistance
histology of small arteries and arterioles
intima is very thin
media = 1 to 6 layers of vascular smooth muscle cells
adventitia thickness is similar to media, merges with adjacent tissue connective tissue
capillaries
diameter of 8µm (RBC diameter) to 30µm
represent a huge cross sectional area in the body
endothelial cell lining but no media or elastin
pericytes that contain myosin are what provide the support
allow rapid exchange of oxygen ad nutrients via diffusion
flow is very slow
EC lining of capillaries
continuous: complete EC lining
fenestrated: EC gaps allowing macromolecular passage
discontinuous: larger gaps in EC layer (liver)
- larger diameter called sinusoids
veins
intima:
- narrow and IEL is difficult to ID
- sparse elastin with only incomplete elastic lamina
media:
- vascular smooth muscle cells dominate in media (there are fewer compared to arteries + more disorganized)
adventitia:
- only largest veins have appreciable connective tissue
vein valves:
- small and medium veins have valves
- made of two bands of lumenal tissue
- allow skeletal muscles to assist in blood return against gravity
large veins (structure/layers)
no valves (ex=vena cava)
Intima:
- EC with some connective tissue
media:
- multiple layers of vascular smooth muscle cells - much thinner than adjacent artery
adventitia:
- more connective tissue compared to medium veins
- blend with adjacent connective tissue
medium veins
has vein valves
intima:
- very thin
- EC is complete
Media:
- few layers of smooth muscle cells (2-5)
adventitia:
- identifiable and blends into adjacent connective tissue
post capillary venules
very thin walled
intima is very thin, no elastin, has endothelial cells
media = 1 or 2 layers of vascular smooth muscle cells
starling law
more venous return to heart = heart pumps more
an increase in muscular stretch = increased contraction
this operates at the level of the sacromere (actin/myosin)
no change in arterial pressure or heart rate
can over stretch = flat/descending starling curve
cardiac regulation
- autonomic control
- heart has abundant parasympathetic and sympathetic innervation
sympathetic drive of cardiac regulation
increase heart rate (chronotropic)
increase strength of contraction (inotropic)
basasl firing of sympathetic fibres (normal condiiton is baseline sympathetic drive)
mediated by beta adreno receptors
parasympathetic tone in cardiac regulation
bradycardia (major effect) (to 20-40bpm)
decreased force of contraction (minor effect) vagal episode
blood flow regulation at the tissue level
metabolic rate is proportional to blood flow
kidney is the only exception to this
states of low tissue oxygen result in release of vasodilator substances that affect arteriolar tone
difference in flow between skeletal muscles at rest and during exercise = 20 fold
control lies at level of arteriole
blood flow regulation by the endothelium
active role in blood flow control
may be a response to sheer stress form increased local flow downstream
- vasodilators: nitric oxide , prostaglandins
- vasoconstrictors: endothelin, thromboxane
affects diameters of pre-arteriolar vessels (even to muscular arteries)
humoral regulation of blood flow
norepinephinre/epinephrine:
- fight or flight
- results in humoral release (adrenals) and increased sympathetic tone
- humoral release has same effect as local innervation (constricts vascular smooth muscle and increases heart rate + force of contraction)
impact of exercise on blood flow
increased return of blood
local vasodilation of skeletal muscle (arteriolar and EC regulated)
increased CNS activity results in vasoconstriction center activation
baroreceptor reflex
stretch receptors widely distributed in vascular system
especially carotid sinus; aortic arch stimulate CNS (medulla)
increased pressure results in inhibition fo vasoconstrictor center and excitation of vagal centre (when you stand there is the opposite effect)
vasodilation of veins and arterioles
decreased heart rate contractility
conduction system
conducts the impulse with a delay from atrium to ventricle (AV node) - between Av valve and coronary sinus
splits into left bundle and right bundle
