circulatory system Flashcards
the organ system that bring nutrients, oxygen, hormones and other needed substances to the cells of the body
circulatory system
what are the 2 circulation system
Systemic circulation
- Throughout organs or different cells.
Pulmonary circulation
- Involves the circulation of the heart and lungs.
what fluid does the Lymphatic vascular system carries
the lymph fluid
- Includes different structures such as:
lymph nodes
spleen
thymus
blood vascular system is composed of
○ Heart
○ Arteries
○ Capillaries
○ Veins
function of these organs
- heart
- arteries
- veins
- capillaries
● Heart - function is to pump blood (to distribute in different organs).
● Arteries - function is to carry the oxygenated blood with its nutrients and oxygen, to the tissues.
- Pulmonary artery carries
deoxygenated blood.
● Veins - convey the deoxygenated blood to be pumped again.
- Pulmonary vein carries oxygenated blood.
● Capillaries - smallest blood vessels, interchange between blood and tissues takes place (forms microvasculature)
this is where the oxygen, carbon dioxide, nutrients and other waste products exchange between blood and tissues.
microvasculature
incudes:
- capillaries
- arterioles
- venules
Is a muscular organ that contracts rhythmically, pumping the blood through the circulatory system.
heart
*muscular organ - cardiac muscles.
a double serous membrane that covers the heart.
Pericardium
*FPV - from outer to inner
layers:
■ Adipose tissue
■ Fibrous pericardium
■ Parietal layer of pericardium
■ Pericardial cavity (space in between)
■ Visceral layer of serous pericardium (included in the structure of the pericardium)
*its alr in order from outer to inner
what are the 3 major layers or tunics of the walls of the 4 heart chambers
○ Internal endocardium
- made up of simple squamous epithelium with loose CT.
- purkinje fibers can also be found here.
○ Middle myocardium
- made up of muscle tissue.
◆ Purely cardiac muscle tissue.
○ External epicardium
- made up of simple squamous epithelium (very thin).
branches of the impulse conducting system is specifically the purkinje fibers which is a special type of tissue that can withstand electrical impulses.
Subendocardial layer
what do we use for basis when dissecting certain parts
anatomic position
briefly explain the heart chambers
➔ Atria
◆ Receives blood from veins.
◆ Act as a reservoir.
◆ Its contraction forces blood into the ventricles.
➔ Ventricles
◆ Major pumping chambers.
◆ Ejects blood into the arteries & forces it to flow through the circulatory system → systemic
circulation.
◆ The wall in the left ventricle is
thicker because it generates
greater pressure.
which wall in the ventricle is thicker
left wall
- as it generates greater pressure
what are the 4 valves
Tissue Paper My Ass
○ Tricuspid valve
○ Pulmonary semilunar valve
○ Mitral/ Bicuspid valve
○ Aortic semilunar valve
function of heart valves
To ensure the one - way direction of blood flow through the heart.
- opens easily in the direction of blood flow
- closes when blood pushes to opposite direction
briefly explain the 2 atrioventricular valves and the 2 semilunar valves
2 atrioventricular valves:
● Located between Atrium and ventricle.
- responsible to open the atrium.
○ Tricuspid valve - between right atrium and right ventricle
○ Bicuspid valve - between left atrium and left ventricle
2 semilunar valves:
● Located between Artery and Ventricle
- responsible to open the ventricles.
○ Pulmonary semilunar valve
- between right ventricle and pulmonary artery
○ Aortic semilunar valve - between left ventricle and aorta
operation of the heart valves
transes
what type of CT?
- tricuspid valve
- fibrous skeleton
tricuspid valve
- dense regular CT w elastic and collagen fibers
fibrous skeleton
- dense irregular CT
special tissue that can withstand electrical impulses. impulse conducting system
purkinje fibers
Composed of four fibrous rings of dense irregular connective tissue.
fibrous skeleton in cardiac muscle
- anchors the base of the valves
- site of origin and insertion of the cardiac muscle fibers.
Site of origin and insertion of the cardiac muscle fibers.
Fibrous skeleton
briefly explain the blood flow through the heart
[transes]
● Superior and Inferior Vena Cava
- carry blood from the body to the right atrium.
● Pulmonary Vein
- carry blood from lungs to the
left atrium.
● Pulmonary Trunk & Aorta
- exits the heart.
● Pulmonary arteries
- carries blood to the lungs.
● Aorta
- carries blood from the left ventricle of the body.
*once the blood enters the lungs, it becomes oxygenated blood
it control the rhythmic contractions of the heart are coordinated by electrical signals.
conduction system of the heart
- this conduction system is linked tgt through intercalated disk into single units
- atrial walls contract w one another as do ventricular walls
what connects heart cells and allows the electrical signal to spread
Intercalated discs
– They link cardiac muscle cells so the heart beats as one unit.
Sinoatrial Node aka
“The Pacemaker”
– It sets the rhythm for heart contractions.
function of the Sinoatrial (SA) Node
starts the electrical signal that makes the heart contract and controls the heart’s rhythm.
- when the SA node sends an electrical signal, the atria contract simultaneously, pushing blood into the ventricles
- the atria contracts first as the SA node sends an excitation wave over the atria, causing them to contract before the ventricles.
describe the electrical conduction and blood flow sequence in the heart
Sinoatrial (SA) Node Fires → The SA node (pacemaker) sends an electrical impulse.
Atria Contract → The impulse spreads through the atria, causing them to contract and push blood into the ventricles.
Ventricles Contract → The impulse reaches the ventricles, making them contract and pump blood into circulation.
- Right Ventricle → Sends blood to the lungs for oxygenation (pulmonary circulation).
- Left Ventricle → Sends oxygenated blood to the rest of the body (systemic circulation).
describe the electrical conduction system of the heart, which controls how the heart beats in a coordinated way
- SA Node (Pacemaker) Fires
→ The electrical impulse starts at the sinoatrial (SA) node, spreading across the atria, causing them to contract and push blood into the ventricles. - AV Node Delays the Signal
→ The impulse reaches the atrioventricular (AV) node, which slightly delays it to ensure the atria fully contract before the ventricles. - Impulse Travels Down the AV Bundle
→ The signal moves through the AV bundle (Bundle of His), passing through the interventricular septum. - Branches to Both Ventricles
→ The AV bundle splits into right and left bundle branches, sending the impulse toward the apex (bottom) of the heart. - Purkinje Fibers Spread the Impulse
→ The Purkinje fibers quickly carry the impulse throughout the ventricular walls, causing the ventricles to contract and pump blood to the lungs and the rest of the body.
OR
- Sinoatrial (SA) Node
→ This is the heart’s natural pacemaker, located in the right atrium. It generates electrical impulses at 70-80 beats per minute, causing both atria to contract and push blood into the ventricles. - Atrioventricular (AV) Node
→ This node acts as a relay station, delaying the impulse slightly to ensure the atria fully empty before the ventricles contract. - AV Bundle (Bundle of His)
→ The electrical signal moves down this bundle, which branches into the right and left bundle branches, directing the impulse toward the ventricles. - Purkinje Fibers
→ These fibers quickly distribute the electrical impulse to the ventricles, causing them to contract and pump blood to the lungs and the rest of the body.
The Process:
✔ Action potentials spread through the atria
→ atria contract, moving blood into ventricles.
✔ The impulse moves through the AV node and Purkinje fibers, making the ventricles contract.
✔ Blood is pumped to the lungs (via the pulmonary artery) and the body (via the aorta).
systole vs diastole
● Systole
○ “LUB”
○ When the heart contracts, the blood flow will be released.
○ Blood from ventricles to the systemic circulation.
● Diastole
○ “DUB”
○ Part where the atrium will go to the ventricles.
[Systole (LUB) → Heart contracts, blood pumped out
Diastole (DUB) → Heart relaxes, blood fills the ventricles]
[LUB AND DUB is the sound that occurs when valves closes
- “LUB” sound is made when the AV valves (tricuspid & mitral) close to prevent backflow.
- “DUB” sound occurs when the semilunar valves (aortic & pulmonary) close to prevent backflow into the ventricles.]
this is responsible for maintaing valve closure
Heart string/ chordae tendineae
- pulls the strings to maintain the closing of the valve and ensure blood flow
how do blood nourish
not by the blood passing through its chambers but by a specialized network of blood vessels.
- coronary arteries
- supply blood to the wall of the heart - coronary veins
- carry blood from the wall of the heart to the right atrium
enumerate the largest to smallest in veins and arteries
veins:
large vein
medium-sized veins
venules
arteries:
elastic artery
- example: aorta
muscular artery
arterioles
Macrovasculature vs Microvasculature
● Macrovasculature
- vessels that are more than 0.1mm in diameter
○ Large arterioles
○ Muscular veins
○ Muscular and elastic arteries
● Microvasculature - visible only with a microscope. (smaller than 0.1mm)
● Particularly important functionally, being the site of interchanges between blood and the surrounding tissues.
○ Arterioles
○ Capillaries
○ Postcapillary venules
what are the vessels of the microvasculature and its function
arterioles
small capillaries
venules (V)
*make up the microvasculature where, in almost every organ
- function: exchange takes place between blood and the interstitial fluid of the tissues.
what are the tissues of the vascular wall of larger BV
- Simple squamous endothelium
○ Inner layer - Smooth muscle
○ Middle layer - Connective tissue (elastic and collagen fibers)
○ Outer layer
what are the layers of blood vessel walls
➔ Tunica adventitia/ externa
◆ Connective tissue
➔ Tunica media
◆ Smooth muscle cells
◆ Thickest layer - responsible for vasoconstriction and vasodilation to regulate blood pressure and flow
➔ Tunica intima
◆ endothelium (thin layer of cells)
a special type of epithelium that acts as a semipermeable barrier between two internal compartments
■ Blood plasma
■ Interstitial fluid
endothelium
[has 2 layers - basement membrane and subendothelial layer]
function:
○ Mediate and actively monitor the bidirectional exchange of small molecules
○ Restrict the transport of some macromolecules.
The central space where blood passes through (with plasma)
lumen
Found in endothelial cells (mainly in arteries); they help initiate blood clotting when a vessel is damaged
Weibel-Palade Bodies
- usually at tunica intima
- stores selectin and von Willebrand factor, important for blood clotting (coagulation)
[example:
Blood coagulation: once pricked or cut, there is a butas in blood vessels.
Hence, the selectin and von Willebrand factor will call the platelets in the lumen to form adhesion/aggregate = to cover up the butas - basically its platelet clog]
Found in the walls of all vessels larger than capillaries.
Smooth Muscle Cells or Fibers
- arranged helically in layers (circular arrangement)
it is present in vascular walls in amounts and proportions that vary based on local functional requirements.
Connective Tissue
- located in the outer layer/ tunica adventitia/ externa
what are the roles of these following in the CT
- collagen fibers
- elastic materials
- ground substance
● Collagen Fibers
- found throughout the wall
● Elastic Materials
- provide the resiliency for the vascular wall expanded under pressure.
● Ground Substance
- forms a heterogeneous gel in the extracellular spaces of the wall – contributing to the physical properties and affecting
permeability and diffusion of substances through the wall.
true or false:
capillaries has 3 layers of blood vessel walls
false - they are thin for ez exchange of substances
what are the 3 layers of the blood vessel wall
- Tunica Intima or Interna
● endothelium composed of
- simple squamous epithelial cells
- basement membrane
- a small amt. of CT
● In Arteries, has Internal Elastic Lamina
- separates the intima from the
media
- composed of elastin with holes that allow the diffusion of substances to nourish cells deep in the vessel wall. - Tunica Media or Middle Layer
- smooth muscle cells arranged
circularly around the blood vessel
- also contains variable amounts of
elastic and collagen fibers, depending on the size and type of the vessels. - Tunica Adventitia or Externa
- composed of connective tissue (type I collagen and elastic fibers).
- gradually continuous with the stromal CT of the organ through which the blood vessels run.
what are the differences between blood vessels, histologically
Artery has a rounder shape than vein as the artery has many smooth muscle layers compared to veins.
Capillary has no 3 layers.
Endothelium and lumen lang siya.
Capillary is the smallest BV.
what is the smallest BV
capillaries
Vasa Vasorum
○ meaning: “Vessels of the vessels”
○ Consist of arterioles, capillaries, and venules in the tunica adventitia and outer part of media.
[Function: Provide oxygen and nutrients to the outer layers (tunica adventitia & outer tunica media) of large blood vessels]
briefly explain the type of arteries
- elastic arteries
- Biggest arteries with thick walls
- More elastic fibers, less smooth muscle compares w other arteries
- Function:
Stretch and recoil to maintain blood flow while the ventricles are relaxed.
Elastic recoil prevents BP from failing rapidly and maintains blood flow while the ventricles are relaxed.
- Example: Aorta - muscular arteries
- Medium-sized and small diameter arteries
- More smooth muscle, fewer elastic fibers
- Large amt of smooth muscle makes the walls of muscular arteries relatively thick - 40 layers of more smooth muscle cells
- Function: Control blood flow by constricting or dilating - small arteries
- Same structure but smaller and thinner walls
- Have 3-4 layers of smooth muscle
- Function: adapted for vasoconstriction & vasodilation - arterioles
- Tiny arteries that delivers blood to capillaries
- Smallest arteries where the 3 layers (tunics) are still visible
- The tunica media consists of
only one or 2 layers of circular
smooth muscle cells.
what type of arteries that has the largest-diameter arteries and have the thickest wall
elastic arteries
(thickest wall = aorta)
muscular arteries is also called
Distributing Arteries
Are microscopic vessels that connect arterioles to venules.
Capillaries
- consist of: endothelium which is a layer of simple squamous epithelium surrounded by a delicate loose CT
the flow of blood from arterioles to venules through capillaries.
Microcirculation
true or false:
Capillaries branches while changing
their diameter.
false - it branch without changing
cells located in the endothelium of capillaries which are important for blood vessels formation to maintain the structure.
Pericytes
briefly explain the types of capillaries
(refer to image - take note of the holes in the surface)
Continuous Capillaries:
- Have tight, occluding junctions sealing the intercellular clefts between all the endothelial cells to produce minimal fluid leakage.
- Characterized by the distinct continuity of the endothelial cells in its walls.
Fenestrated Capillaries:
- Characterized by the presence of small circular fenestrae through the very thin squamous endothelial cells.
Sinusoid Capillaries (Discontinuous Capillary):
- Discontinuous capillary
- Permits maximal exchange of macromolecules btwn tissues and blood.
Has the following characteristics:
- Have large fenestrae without diaphragms
- Cells from discontinuous layer and are separated from one another by wide spaces
- Basal lamina is discontinuous
most common type of capillary
Continuous Capillaries
this capillary permits maximal exchange of macromolecules between tissues and blood.
Sinusoid Capillaries (Discontinuous Capillary)
characteristics:
● Have large fenestrae w/o
diaphragms
● Cells form discontinuous layers and are separated from one another by wide spaces.
● Basal lamina is discontinuous.
where can fenestrated capillaries be found
in organs that need rapid transport, like the
- kidneys
- intestines
- choroid plexus
- endocrine glands
briefly explain the anatomy of a venule (small veins)
[refer to transes pic]
A venule is a small blood vessel that carries blood from capillaries back to veins.
Tunica Interna (Inner Layer)
- Endothelium: Thin inner lining that allows smooth blood flow.
- Basement Membrane: Supports the endothelium.
- Valve: Prevents blood from flowing backward.
Tunica Media (Middle Layer)
- Contains a small amount of smooth muscle to help blood move.
Tunica Externa (Outer Layer)
- Protects and supports the vessel with connective tissue.
*Venules help return deoxygenated blood to the heart and prevent backflow using valves.
briefly explain the types of veins
● Venules
- consists of tunica interna and a tunica media that has only a few scattered smooth muscle fibers and fibroblasts.
● Small Veins
- slightly larger in diameter than venules
- all 3 tunics are present in small veins
- contains a continuous layer of smooth muscle cells, and the CT of the tunica adventitia surrounds the tunica media.
● Medium-sized veins
- 3 distinctive tunics make up the wall of the medium-sized and large veins.
- media contains some circular smooth muscle and sparsely scattered elastic fibers.
● Large Veins
- many valves in veins of the LOWER LIMBS than in veins of upper limbs,
= preventing the flow of blood toward the feet in response to the pull of gravity.
Collect blood from capillaries and drain into veins.
venules
- composed of endothelium resting on a delicate CT layer
Collect blood from small veins and deliver it to large veins.
Medium-sized veins
in the large veins, why is there many valves in veins of the lower limbs than in veins of upper limbs
this is to prevent the flow of blood toward the feet in response to the pull of gravity.
Sinusoid capillaries is also called
Discontinuous capillary
it receives blood from the veins and acts as a reservoir
atria
it is the major pumping chambers
ventricle
what makes up the tunica intima
endothelium
basement membrane
subendothelial layer
what are the 2 internal compartments does endothelium acts as a semipermeable barrier
btwn blood plasma and interstitial fluid
Separates the intima from the media and is composed of elastin with holes that allow the diffusion of substances to nourish cells deep in the vessel wall.
in arteries - internal elastic lamina
Separates the media from the tunica adventitia
in arteries - external elastic lamina
“Vessel of the vessels”
vasa vasorum
