cardiovascular system Flashcards
cardiovascular system
heart
BV
lymphatic vessels
what are the 2 circuits that distribute in the body and briefly explain the flow
pulmonary circulations:
right ventricle > pulmonary artery > lungs> pulmonary vein > left atrium
(main idea: heart > lungs > heart)
systematic circulations:
left ventricle > aorta > system > veins > SVC/ IVC > right pulmonary
(heart > system > heart)
where does the heart lie
it lies obliquely
abt 2/3 into the left side of the thoracic cavity
in middle mediastinum
what are the 4 chambers of the heart
right and left atria
right and left ventricle
this guards the exits of the chamber
valves
- maintain the unidirectional flow of the blood
what does the heart contains
cardiac muscle
fibrous skeleton
conducting system
coronary vasculature
what divides the atria and ventricles
atria: interatrial septum
ventricles: intraventricular septum (muscular part)
briefly explain the walls of the heart
- epicardium
outer portion
visceral layer of the pericardium - myocardium
composed of cardiac muscle, thickest
principal component of the heart - endocardium
inner portion
covered by endothelium
consists of:
- inner layer of endothelium and subendothelial CT
- middle layer of CT
- deep layer of CT, the subendocardial layer
it is between the epicardium and pericardium
pericardial cavity
- composed of pericardial fluid
- acts as a shock absorber for certain events
it is the principal component of the heart
myocardium
what do the subendocardial layer consists of
AV, atrioventricular nodes
SA, sinoatrial nodes
this acts the outer framework of the heart which consists 4 fibrous rings surrounding the valve orifices
fibrous skeleton
function:
- surround and anchor the heart valves
- provide firm points for the insertion of cardiac muscles
- coordinate heartbeat by acting as electrical insulators btwn atria and ventricles
this is the portion where the opening of the atrioventricular bundle is located which is part of the conducting system of the heart
fibrous skeleton
[There’s a small opening in this “skeleton” where a special part called the AV bundle (or Bundle of His) goes through
This bundle is part of the heart’s electrical system — it carries the signal that tells the bottom part of the heart when to beat.]
fibrous skeleton part and its respective tissue
fibrous ring - dense irreg CT
membranous part of interventricular septum - dense CT
heart valves are composed of
fibrosa
spongiosa
vermicularis/ atrialis - depends on the surface on where the heart bulb faces
it is situated in the ventricular surface of the AV valves and arterial surface of semilunar valves
fibrosa
what are the atrioventricular and semilunar valves and its functions
AV
tricuspid valve:
- acts as the gate/ valve between the right atrium and ventricle
mitral valve:
- acts as the gate/ valve between the left atrium and ventricle
SV
- valves/ gates between the ventricles and vein/ artery
true or false:
in AV valves, the fibrosa continues into the chordae tendineae
true
[means the strong fibrous layer of the AV valve (fibrosa) extends into the chordae tendineae, helping connect the valve to the heart muscles and maintain structure during heartbeats.-
a chord-like structures that extends from the AV valves that collect or extend a collection at the base of the heart which is bound to a papillary muscle
chordae tendineae
[ Stop the valves from flipping backward when the heart pumps.]
papillary muscle - an extension of the cardiac muscle from the myocardium of ventricles
an extension of the cardiac muscle from the myocardium of ventricles
papillary muscle
[small muscle bumps that stick out from the walls of the ventricles.
part of the heart muscle (myocardium)
heart contracts, the papillary muscles also contract, pulling on the chordae tendineae to keep the valves closed tightly.]
the chordae tendineae extends from the ventricular surfaces of the mitral and tricuspid valves into muscular projections
papillary muscle
[chordae tendineae are the strings holding the doors so they don’t swing the wrong way.
papillary muscles are the hands pulling the strings to keep the doors in the right position.]
type of tissue and its function
- fibrosa
- spongiosa
- venticrularis/ atrialis
FIBROSA: dense irreg CT
- provide stencil stiffness to the leaflet of the valve cusps
[give the valve stiffness and strength, so it can open and close properly without flopping around. like the sturdy frame of a tent that holds everything in shape.]
*Valve cusps are the flap-like parts of the heart valves.
“Fibrosa = Firm Frame”
SPONGIOSA: loosely arranged collagen and elastic fibers w abundant ground subs
- acts as shock absorbers during opening and closing of the valves, vibrations are generated during the closing of the pulse and sponge also acts as shock absorbers to dampen these vibrations
“Spongiosa = Soft Sponge”
VENTRICULAIRS/ ATRALIS: dense CT layer
- facilitates valve movement
“Ventricularis = Valve Mover”
immediately adjacent to the ventricular or atrial surface of each valve
ventricularis/ atrialis
true or false:
valve cusps is usually vascular
false - avascular
they do not contain any vessels or any vascular network within the cusps
however, can maintain their internal structure of the valve due to the presence of the valvular interstitial cells
how can the valve cusps maintain their internal structure of the valve
due to the presence of the valvular interstitial cells
- maintain the structure of the cusps throughout the life
- usually contain vimentin and chondromodulin-1:
usually chemicals/ receptors/ surface markers that inhibit blood cell formation
[repair, maintain, and remodel the structure of the valve cusps, even though there’s no blood flowing directly inside the cusps themselves. ]
it is for initiation and propagation of rhythmic depolarizations
conducting system
- formed by modified cardiac muscle cell (5purkinje fibers) which generate and conduct electrical impulses rapidly through the heart
[starts (initiates) and spreads (propagates) the electrical signals that make the heart beat in rhythm]
what are the intrinsic regulation of heart rate
- SA node
generates electrical impulses located near the junction of the SVC and RA
- dominant pacemaker of the heart
- peacemaker rate 60-100 beats/min - AV node
picks up electrical impulses and is carried across the fibrous skeleton to the ventricles by the AV bundles (of His) which further subdivides into purkinje fibers
- the presence of purkinje fibers across the cardiac muscle/ myocardium rapidly performs the rapid passage of electrical impulses throughout the lower portion of the heart (ventricle)
what dos the node consists of
nodal cardiac muscle cells
- which are modified cardiac muscle fibers that are smaller than the surrounding atrial cardiac muscle cells
what cells is present in the SA node
peacemaker cells (P cells)
- mainly generates impulses
transitional cells (T cells)
- propagation of the impulses throughout the right atrium
what does the terminal ramifications of the conducting system consist of
purkinje fibers
briefly explain the diff btwn nodal cardiac cells compared to other cells or heart of muscle fibers
(pic)
round larger nucleus compared to other cardiac muscles
cardiac muscle constitutes some intercalated disc whereas nodal cardiac muscle cells
- since they are specialized, they are like bundles of cardiac muscle, smaller
- they still contain intercalated disc but not evident in the H&E stains
the spontaneous rhythm of thE heart can be altered by nerve impulse from
both sympathetic and parasymphathetic of the ANS
- stimulation of parasympathetic nerves decreases the heart rate
(release acetylcholine)
- stimulation of sympathetic nerves increases the heart rate nerves decreases the heart rate (release epinephrine)
heart rate and force of contraction can be regulated by
circulating hormones and other subs
what hormones from the adrenal medulla regulate heart rate and force of contraction?
epinephrine and norepinephrine
- they both increase the force of contraction and heart rate
(during sympathetic nerves- during fight or flight)
substances that can affect heart function.
calcium ions
thyroid hormones
caffeine
theophylline
digoxin
*these leads to the increase
what drugs decreases the heart rate and force of contraction
propranolol or calcium-channel blockers
central nervous system function
monitors arterial pressure and heart function through specialized receptors located within the cardiovascular system
- barorecpetors
- volume receptors
- chemoreceptors
sense arterial blood pressure located inn the corticoid sinus and aortic arch
baroreceptors
- aka high pressure receptors
sense central venous pressure and provide the CNS with info abt cardiac distension. located within the walls of the atria nd ventricles
volume receptors
- low pressure receptors
detect alterations in oxygen, carbon dioxide tension and pH. these receptors are the carotid and aortic bodies
chemoreceptors
briefly explain the layers of the vascular wall
walls of arteries and veins are composed of layers called: tunics
- tunica intima
innermost layer
3 components:
-endothelium
- basal lamina
- subendothelial layer (contains internal elastic membrane, a lamella of fenestrated elastic material) - tunica media
middle layer
circumferentially arranged layers of vascular smooth muscle cells
arteries > external elastic membrane - tunica adventitia
outermost CT layer
longitudinal arranges collagenous tissue and few elastic fibers
- contains vasa vasorum and nervi vasorum
it is the network of blood vessels that supplies BV with its own blood
vasa vasorum
it supplies/ innervates the blood vessels
nervi vasorum
what lines the different-sized vessels in the circulatory system
and what are its functions
simple squamous epithellium
- called endothelium
functions:
- selectively permeability of barrier where in some hydrophobic molecules can easily pass through the plasma membrane
however, hydrophilic mol. like water and oxygen cannot diffuse in the endothelium (that is y they exit/ enter BV through the cellular pathway)
mediated by endothelial cell-cell adhesion complexes.
permeable to small hydrophobic molecules, while water and hydrophilic molecules cannot
diffuse.
- maintenance of a nonthrombogenic barrier between blood platelets and subendothelial tissue. (through the secretion of anticoagulants and antithrombogenic substances)
- modulation of blood flow and vascular resistance.
vasoconstrictors (endothelins, ACE, prostaglandin H2, thromboxane A2).
vasodilators (NO, prostacycline).
- regulation and modulation of immune response.
- hormonal synthesis and other metabolic activities.
- modification of the lipoproteins.
(excess lipoproteins that travel in BV that cannot be metabolized by the liver resides in the BV . BV can embed these lipoproteins to the walls of BV = atherosclerotic block)
How does the endothelium
- prevent blood clots from forming?
- help control blood flow?
secretes anticoagulants and antithrombogenic substances to keep blood flowing smoothly
Vasoconstrictors (tighten vessels): Endothelins, ACE, prostaglandin H2, thromboxane A2
Vasodilators (relax vessels): Nitric oxide (NO), prostacyclin
What happens when the body can’t break down excess lipoproteins?
get stuck in the blood vessel walls = atherosclerosis (plaque buildup).
briefly explain the process of vasodilation
- Shear Stress
as blood flows, it rubs against the endothelial cells lining the vessel walls.
= triggers a rise in calcium ion (Ca²⁺) levels inside endothelial cells. - Additional Stimulus: VEGF
Vascular Endothelial Growth Factor (VEGF) is also stimulated by shear stress.
VEGF and Ca²⁺ together activate a special enzyme called eNOS. - Activation of eNOS (Endothelial Nitric Oxide Synthase)
eNOS uses oxygen and L-arginine to produce nitric oxide (NO). - Nitric Oxide Diffusion
The NO leaves the endothelium and moves into the tunica media (middle layer of the vessel)
= enters smooth muscle cells. - Activation of Guanylate Cyclase
NO stimulates an enzyme in smooth muscle cells called guanylate cyclase.
Guanylate cyclase converts GTP (guanosine triphosphate) into cGMP (cyclic guanosine monophosphate). - Activation of Protein Kinase G (PKG)
cGMP activates PKG, which leads to smooth muscle relaxation. - Result: Vasodilation
The relaxed muscle allows the blood vessel to widen (dilate), increasing blood flow.
[Shear stress increases Ca²⁺ and VEGF → activates eNOS → produces NO → activates guanylate cyclase → makes cGMP → activates PKG → relaxes smooth muscle → causes vasodilation.]
briefly explain the other factors that induces vasodilation and vasoconstriction
(pic)
Vasodilation:
1. Binding of ADP & Bradykinin
These cause metabolic stress on endothelial cells.
ADP binds to its receptor → activates Prostaglandin I₂ (PGI₂ / Prostacyclin).
➤ Prostacyclin (PGI₂) Pathway:
PGI₂ travels to the tunica media (smooth muscle layer).
Binds to its own receptor → increases cyclic AMP (cAMP) inside smooth muscle.
cAMP activates Protein Kinase A (PKA) → leads to muscle relaxation → vasodilation.
- Endothelium-Derived Hyperpolarizing Factor (EDHF)
EDHF causes opening of potassium (K⁺) channels in smooth muscle cells.
K⁺ flows out of the cells, causing hyperpolarization (makes the inside more negative).
Hyperpolarization prevents contraction, promoting relaxation and vasodilation.
Vasoconstriction:
1. Endothelins
Stimulated by substances like angiotensin II and thrombin.
These bind to their receptors on smooth muscle cells, leading to:
Increased Ca²⁺ inside the cells → contraction → vasoconstriction.
- Prostaglandin H₂ & Thromboxane A₂
Also bind to specific receptors in smooth muscle.
Trigger calcium influx, leading to muscle contraction and vasoconstriction.
vasodilation vs vasocontraction
vasodilation:
relaxation of smooth muscle cells, increase in the diameter of the BV
= better blood flow by increasing vascular resistance therefore decreasing shear stress
vasocontraction:
binding of thrombin and angiotensin II
happens during severed blood vessels (injury) - to reduce blood loss
contraction of smooth muscle in the tunica media, decrease in diameter of BV
[vasodilation: diameter of the blood vessel increases → more space for blood to flow.
vasoconstriction: diameter of the blood vessel decreases → tighter space for blood flow.
Vasodilation = “Open up” → more blood flow
Vasoconstriction = “Tighten up” → less blood flow]
briefly explain the three types of arteries based on tunica media characteristics
large arteries (elastic arteries):
aorta and pulmonary artery
their main branches:
- brachiocephalic trunk
- common carotid
- subclavian
- common iliac arteries
medium arteries (muscular arteries):
- most of the “named” arteries of the body
small arteries (arterioles):
- distinguished from one another by the number of smooth muscle layers in the tunica media.
briefly explain the relatively thickness and what it consists in each arteries
Large Arteries (Elastic Arteries):
INTIMA
*relatively thick
Endothelial lining
- Cells contain Weibel-Palade bodies
Subendothelial layer (smooth muscle cells)
Internal elastic membrane
MEDIA
*contain external elastic membrane
*multiple layers of vascular smooth muscle cells separated by elastic lamellae
Elastin in the form of fenestrated sheets or lamellae between the muscle cell layers.
Vascular smooth muscle cells, which are arranged in a low-pitch spiral relative to the long axis of the vessel.
Collagen fiber and ground substance
EXTERNA
*relatively thin
Collagen fibers and elastic fibers.
Fibroblasts and macrophages
Vasa vasorum
Nervi vasorum
Medium Arteries (Muscular Arteries):
have more smooth muscle and less elastin in the tunica media than elastic arteries
Small Arteries and Arterioles:
Small arteries and arterioles are distinguished from one another by the number of smooth muscle cell layers in the tunica media.
Arterioles control blood flow to capillary networks by contraction of the smooth muscle cells.
*arterioles consist 1-2 cell layers of smooth muscle cells and endothelium
what layer separated the tunic media of elastic arteries which consists of multiple layers of vascular smooth muscle cells
elastic lamellae
how are the small arteries and arterioles distinguished from one another
by the # of smooth muscle cell layers in the tunica media
this control blood flow to capillary networks by contractions of the smooth muscle cells
arterioles
these are the smallest diameter blood vessels, often smaller than the diameter of an erythrocyte.
capillaries
- Form blood vascular networks that allow fluid-containing gases, metabolites, and waste products to move through their thin walls.
- Each consists of a single layer of endothelial cells and their basal lamina
briefly explain the different types of capillaries
- Continuous capillaries
found in
- CT
- muscle tissue
- skin
- lungs
- CNS in BBB - Fenestrated capillaries
found in
- endocrine glands
- sites of fluid or metabolite absorption - Discontinuous capillaries
found in the
- liver (filter some portion of the blood)
- spleen (splenic sinusoids/ sinus - where erythrocytes and other cells entter through these spaces between the steve cells)
- bone marrow
where can the weibel-palade bodies be found
endothelial linings
endothelium of arteries
destroyed epithelium
what can be found in the weibel-palade bodies
von wilebrand factor
- essential for the primary hemostasis
a two-dimensional exchange of fluid occurs between the blood and the tissues
capillaries
what are the functional aspects of the capillaries
plasma pass through the capillary network from the arterioles into the tissue molecule exchange happens.
approx. 90% of the extravasated fluids are reabsorbed by the venous portion of the capillary network
remaining 10% is returned to the blood vascular system via lymphatic vasculature (they enter the lymphatic capillaries as lymph )
what are the 2 important points to understand capillary network function:
Vasomotion:
represents the phenomenon of intermittent blood flow through the capillary network.
Density of the capillary network:
determines the total surface area available for exchange between the blood and tissue
(the higher SA, the better exchange btwn the blood and tissue)
allow blood to bypass capillaries by providing direct routes between the arteries and the veins.
Arteriovenous shunts
commonly found in:
- skin of the fingertips
- nose
- lips
- erectile tissue of the penis
- clitorisis
briefly explain the 4 types of veins based on size
Venules:
receive blood from capillaries have diameter is 0.1mm.
subclassified as
- postcapillary
(this is whr the blood coming from capillaries are collected
site for action of vasoactive agents such as histamine and serotonin)
- muscular venules
(distinguished from the post capillary venules through the presence of tunica media)
Small veins:
less than 1mm in diameter
all 3 tunics are present in the small veins
Medium veins:
represent most of the named veins in this category
diameter is 10mm.
*major of the medium veins found in the lower limb contains valves (to prevent the movement of blood due to gravity)
Large veins:
usually have a diameter greater than 10mm.
Include
- SVC
- IVC
- hepatic portal vein
briefly explain the tunics in the medium and large veins
medium veins:
Tunica intima
- lining of endothelial
Tunica media
Tunica adventitia (thicker than tunica media)
large veins:
Tunica intima
Tunica media (relatively thin)
Tunica adventitia
- myocardial sleeves are present in the adventitia of both SVC and IVC, as well as the pulmonary trunk.
- myocardial sleeves are actually atrial myocardial extensions = lead to atrial fibrillation/ abnormal heartrhythm
briefly explain the atypical BV
- Coronary arteries
originate from the proximal portion of the ascending aorta and lie on the surface of the heart in the epicardium
- provide blood supply for the heart
- walls of coronary arteries is thicker compared to other arteries of the upper or lower limb - due to fact that coronary arteries contain increased or large amt of smooth muscle layers in the tunica media
2.Dural venous sinuses
represent venous channels in the cranial cavity.
- interspersed in the dura mater
- dural venous sinuses are lined with endothelial cells but are devoid of smooth muscle cells (no smooth muscle cells)
- Great saphenous vein
represents a long subcutaneous vein of the lower limb that originates in the foot and drains into the femoral vein just below the inguinal vein.
- muscular vein due to the increased amt or unusual amts of smooth muscle cells present in the tunica media
- characterized by a thickk circular arrangement of smooth muscle in the tunica media - Central adrenomedullary vein
passess through the adrenal medulla and its tributaries.
contain several longitudinally oriented bundles of smooth muscle cells = appearance of irregularly bundled cells (referred to as muscle cushion - enhances the efflux of hormones from the adrenal medulla to the circulation)
briefly explain the subclassification of venules
- Postcapillary Venules
Where they are: Right after the capillaries.
Function: Collect blood from capillaries.
Main site of action for vasoactive substances like:
Histamine
Serotonin
These cause the vessel to dilate or become more permeable (important in inflammation).
- Muscular Venules
Key difference:
Unlike postcapillary venules, these have a thin tunica media (a layer of smooth muscle).
Function: Begin to control venous tone (how tight or relaxed the vessel is).
[Postcapillary = no muscle, reacts to histamine
Muscular = has smooth muscle in tunica media]
why do the major of the medium veins found in the lower limb contains valves
to prevent the movement of blood due to gravity
originate from the proximal portion of the ascending aorta and lie on the surface of the heart in the epicardium
coronary arteries
- provide blood supply for the heart
- walls of coronary arteries is thicker compared to other arteries of the upper or lower limb - due to fact that coronary arteries contain increased or large amt of smooth muscle layers in the tunica media
it represent venous channels in the cranial cavity
Dural venous sinuses
- interspersed in the dura mater
- dural venous sinuses are lined with endothelial cells but are devoid of smooth muscle cells (no smooth muscle cells)
it represents a long subcutaneous vein of the lower limb that originates in the
foot and drains into the femoral vein just below the inguinal vein.
Great saphenous vein
- muscular vein due to the increased amt or unusual amts of smooth muscle cells present in the tunica media
- characterized by a thickk circular arrangement of smooth muscle in the tunica media
it passess through the adrenal medulla and its tributaries. Contain
several longitudinally oriented bundles of smooth muscle cells
Central adrenomedullary vein
= appearance of irregularly bundled cells (referred to as muscle cushion - enhances the efflux of hormones from the adrenal medulla to the circulation)
