cardiovascular system

Question 1

cardiovascular system

Answer 1

heart
BV
lymphatic vessels

Question 2

what are the 2 circuits that distribute in the body and briefly explain the flow

Answer 2

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)

Question 3

where does the heart lie

Answer 3

it lies obliquely
abt 2/3 into the left side of the thoracic cavity
in middle mediastinum

Question 4

what are the 4 chambers of the heart

Answer 4

right and left atria
right and left ventricle

Question 5

this guards the exits of the chamber

Answer 5

valves
- maintain the unidirectional flow of the blood

Question 6

what does the heart contains

Answer 6

cardiac muscle
fibrous skeleton
conducting system
coronary vasculature

Question 7

what divides the atria and ventricles

Answer 7

atria: interatrial septum
ventricles: intraventricular septum (muscular part)

Question 8

briefly explain the walls of the heart

Answer 8

1. epicardium
   outer portion
   visceral layer of the pericardium
2. myocardium
   composed of cardiac muscle, thickest
   principal component of the heart
3. 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

Question 9

it is between the epicardium and pericardium

Answer 9

pericardial cavity
- composed of pericardial fluid
- acts as a shock absorber for certain events

Question 10

it is the principal component of the heart

Answer 10

myocardium

Question 11

what do the subendocardial layer consists of

Answer 11

AV, atrioventricular nodes
SA, sinoatrial nodes

Question 12

this acts the outer framework of the heart which consists 4 fibrous rings surrounding the valve orifices

Answer 12

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

Question 13

this is the portion where the opening of the atrioventricular bundle is located which is part of the conducting system of the heart

Answer 13

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.]

Question 14

fibrous skeleton part and its respective tissue

Answer 14

fibrous ring - dense irreg CT
membranous part of interventricular septum - dense CT

Question 15

heart valves are composed of

Answer 15

fibrosa
spongiosa
vermicularis/ atrialis - depends on the surface on where the heart bulb faces

Question 16

it is situated in the ventricular surface of the AV valves and arterial surface of semilunar valves

Answer 16

fibrosa

Question 17

what are the atrioventricular and semilunar valves and its functions

Answer 17

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

Question 18

true or false:
in AV valves, the fibrosa continues into the chordae tendineae

Answer 18

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.-

Question 19

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

Answer 19

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

Question 20

an extension of the cardiac muscle from the myocardium of ventricles

Answer 20

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.]

Question 21

the chordae tendineae extends from the ventricular surfaces of the mitral and tricuspid valves into muscular projections

Answer 21

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.]

Question 22

type of tissue and its function
- fibrosa
- spongiosa
- venticrularis/ atrialis

Answer 22

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”

Question 23

immediately adjacent to the ventricular or atrial surface of each valve

Answer 23

ventricularis/ atrialis

Question 24

true or false:
valve cusps is usually vascular

Answer 24

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

Question 25

how can the valve cusps maintain their internal structure of the valve

Answer 25

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. ]

Question 26

it is for initiation and propagation of rhythmic depolarizations

Answer 26

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]

Question 27

what are the intrinsic regulation of heart rate

Answer 27

1. 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 2. 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)

Question 28

what dos the node consists of

Answer 28

nodal cardiac muscle cells - which are modified cardiac muscle fibers that are smaller than the surrounding atrial cardiac muscle cells

Question 29

what cells is present in the SA node

Answer 29

peacemaker cells (P cells) - mainly generates impulses transitional cells (T cells) - propagation of the impulses throughout the right atrium

Question 30

what does the terminal ramifications of the conducting system consist of

Answer 30

purkinje fibers

Question 31

briefly explain the diff btwn nodal cardiac cells compared to other cells or heart of muscle fibers

Answer 31

(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

Question 32

the spontaneous rhythm of thE heart can be altered by nerve impulse from

Answer 32

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)

Question 33

heart rate and force of contraction can be regulated by

Answer 33

circulating hormones and other subs

Question 34

what hormones from the adrenal medulla regulate heart rate and force of contraction?

Answer 34

epinephrine and norepinephrine - they both increase the force of contraction and heart rate (during sympathetic nerves- during fight or flight)

Question 35

substances that can affect heart function.

Answer 35

calcium ions thyroid hormones caffeine theophylline digoxin *these leads to the increase

Question 36

what drugs decreases the heart rate and force of contraction

Answer 36

propranolol or calcium-channel blockers

Question 37

central nervous system function

Answer 37

monitors arterial pressure and heart function through specialized receptors located within the cardiovascular system - barorecpetors - volume receptors - chemoreceptors

Question 38

sense arterial blood pressure located inn the corticoid sinus and aortic arch

Answer 38

baroreceptors - aka high pressure receptors

Question 39

sense central venous pressure and provide the CNS with info abt cardiac distension. located within the walls of the atria nd ventricles

Answer 39

volume receptors - low pressure receptors

Question 40

detect alterations in oxygen, carbon dioxide tension and pH. these receptors are the carotid and aortic bodies

Answer 40

chemoreceptors

Question 41

briefly explain the layers of the vascular wall

Answer 41

walls of arteries and veins are composed of layers called: tunics 1. tunica intima innermost layer 3 components: -endothelium - basal lamina - subendothelial layer (contains internal elastic membrane, a lamella of fenestrated elastic material) 2. tunica media middle layer circumferentially arranged layers of vascular smooth muscle cells arteries > external elastic membrane 3. tunica adventitia outermost CT layer longitudinal arranges collagenous tissue and few elastic fibers - contains vasa vasorum and nervi vasorum

Question 42

it is the network of blood vessels that supplies BV with its own blood

Answer 42

vasa vasorum

Question 43

it supplies/ innervates the blood vessels

Answer 43

nervi vasorum

Question 44

what lines the different-sized vessels in the circulatory system and what are its functions

Answer 44

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)

Question 45

How does the endothelium - prevent blood clots from forming? - help control blood flow?

Answer 45

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

Question 46

What happens when the body can’t break down excess lipoproteins?

Answer 46

get stuck in the blood vessel walls = atherosclerosis (plaque buildup).

Question 47

briefly explain the process of vasodilation

Answer 47

1. 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. 2. Additional Stimulus: VEGF Vascular Endothelial Growth Factor (VEGF) is also stimulated by shear stress. VEGF and Ca²⁺ together activate a special enzyme called eNOS. 3. Activation of eNOS (Endothelial Nitric Oxide Synthase) eNOS uses oxygen and L-arginine to produce nitric oxide (NO). 4. Nitric Oxide Diffusion The NO leaves the endothelium and moves into the tunica media (middle layer of the vessel) = enters smooth muscle cells. 5. 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). 6. Activation of Protein Kinase G (PKG) cGMP activates PKG, which leads to smooth muscle relaxation. 7. 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.]

Question 48

briefly explain the other factors that induces vasodilation and vasoconstriction

Answer 48

(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. 2. 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. 2. Prostaglandin H₂ & Thromboxane A₂ Also bind to specific receptors in smooth muscle. Trigger calcium influx, leading to muscle contraction and vasoconstriction.

Question 49

vasodilation vs vasocontraction

Answer 49

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]

Question 50

briefly explain the three types of arteries based on tunica media characteristics

Answer 50

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.

Question 51

briefly explain the relatively thickness and what it consists in each arteries

Answer 51

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

Question 52

what layer separated the tunic media of elastic arteries which consists of multiple layers of vascular smooth muscle cells

Answer 52

elastic lamellae

Question 53

how are the small arteries and arterioles distinguished from one another

Answer 53

by the # of smooth muscle cell layers in the tunica media

Question 54

this control blood flow to capillary networks by contractions of the smooth muscle cells

Answer 54

arterioles

Question 55

these are the smallest diameter blood vessels, often smaller than the diameter of an erythrocyte.

Answer 55

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

Question 56

briefly explain the different types of capillaries

Answer 56

1. Continuous capillaries found in - CT - muscle tissue - skin - lungs - CNS in BBB 2. Fenestrated capillaries found in - endocrine glands - sites of fluid or metabolite absorption 3. 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

Question 57

where can the weibel-palade bodies be found

Answer 57

endothelial linings endothelium of arteries destroyed epithelium

Question 58

what can be found in the weibel-palade bodies

Answer 58

von wilebrand factor - essential for the primary hemostasis

Question 59

a two-dimensional exchange of fluid occurs between the blood and the tissues

Answer 59

capillaries

Question 60

what are the functional aspects of the capillaries

Answer 60

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 )

Question 61

what are the 2 important points to understand capillary network function:

Answer 61

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)

Question 62

allow blood to bypass capillaries by providing direct routes between the arteries and the veins.

Answer 62

Arteriovenous shunts commonly found in: - skin of the fingertips - nose - lips - erectile tissue of the penis - clitorisis

Question 63

briefly explain the 4 types of veins based on size

Answer 63

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

Question 64

briefly explain the tunics in the medium and large veins

Answer 64

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

Question 65

briefly explain the atypical BV

Answer 65

1. 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) 3. 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 4. 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)

Question 66

briefly explain the subclassification of venules

Answer 66

1. 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). 2. 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]

Question 67

why do the major of the medium veins found in the lower limb contains valves

Answer 67

to prevent the movement of blood due to gravity

Question 68

originate from the proximal portion of the ascending aorta and lie on the surface of the heart in the epicardium

Answer 68

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

Question 69

it represent venous channels in the cranial cavity

Answer 69

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)

Question 70

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.

Answer 70

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

Question 71

it passess through the adrenal medulla and its tributaries. Contain several longitudinally oriented bundles of smooth muscle cells

Answer 71

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)