Cardiovascular System (Heart)

Cardiovascular System

- Cardio = heart

- Vascular = Blood vessels

- Work together to move blood throughout the body

- All parts of the body are linked together by cardiovascular system

Cardiovascular System Functions

- Keep blood circulating

- Provides O2, hormones, + nutrients to tissues

- Removes waste products from all tissues

Cardiovascular System Circuits

- Pulmonary circuit

- Systemic circuit

Pulmonary Circuit

- Blood being pumped goes to the lungs

- Blood gains oxygen + gets rid of CO2

- Much shorter than systemic circuit

Systemic Circuit

Blood being pumped is oxygenated and goes throughout all other systems in the body

Heart

Muscle pump that pumps blood throughout the two circuits

Left Pump of Heart

- Pumps blood to systemic circuit

- Works 6 times harder than the right pump

Right Pump of Heart

Pumps blood to pulmonary circuit

Blood Circulation

- Arteries

- Veins

- Arterioles

- Capillaries

- Venules

- Larger veins

- Arrives back in the heart

Arteries

- Vessel that carries blood away from the heart

- A for away

Veins

Vessel that carries blood towards the heart

Arterioles

Smallest possible arteries

Capillaries

- Vessels that have a very thin wall

- Where exchange of substances happens in the blood + tissue surrounding it

Venules

Small veins

Heart Size

- Basically the size of a clenched fist

- Proportional to the size of our body

- Cardio exercises makes the heart work harder and grow 2-3 times bigger

Heart Location

Located between the second + fifth pair of ribs

Mediastinum

Middle of sternum

Base of Heart

Found at the level of the sternal angle

Sternal Angle

- Junction between manubrium + body of sternum

- Second pair of ribs are attached to it

Apex of Heart

- Pointy end of heart

- Found at the fifth pair of ribs

- Points toward left hip

Heart Position

- Slightly shifted to the left

- Shoved into the left lung ---> why it has one less lobe than the right lung

Pericardium

- Sac carrying the heart

- Peri = around

- Cardium = heart

Pericardium Layers

- Outer fibrous pericardium

- Inner serous pericardium

Fibrous Pericardium

- Outer layer

- Very tough

- Difficult to remove with bare hands

- Prevents overfilling of heart

- Made of dense connective tissue

- Anchors heart to surrounding structures

Fibrous Pericardium Anchoring Function

- Can anchor heart to structures such as diaphragm, sternum, + lungs

- Heart can remain properly positioned in thoracic cavity

Serous Pericardium

- Inner layer

- Made of simple squamous epithelium

- Cells secrete serous fluid to the serous membrane

- Formed by parietal layer and visceral layer

Parietal Layer

Serous membrane + fibrous pericardium

Visceral Layer

Is in contact with heart muscle itself

Pericardial Cavity

- Is between the parietal layer + visceral layer

- Filled with pericardial fluid

Pericardial Fluid

- Slippery fluid secreted from the serous pericardium

- Provides lubrication to prevent friction between pericardial layers since they glide over each other every time the heart beats

Pericarditis

- Inflammation of pericardium

- Leads to a very painful friction every time the heart beats

Structure of Heart Wall

- Epicardium

- Myocardium

- Endocardium

Epicardium

- Most outside layer of heart

- Is the same as the visceral layer of heart

Myocardium

- Muscle layer

- Thickest layer

- Where cardiac muscle cells, blood vessels, and nerves are found

Endocardium

- Inner wall of heart

- Made of simple squamous epithelium

Simple Squamous Epithelium

- Same tissue that forms the inside of the blood vessels

- Provides a smooth surface for blood to flow through

Endocarditis

- When endocardium is inflamed

- Can cause serious complications for the heart

Cardiac Muscle Cells

- Has not so prominent striations

- Bound together by intercalated discs

Intercalated Discs

- Desmosomes

- Gap junctions

Desmosomes

Connects cell membranes of two neighboring cells together

Gap Junctions

- Electrically connects two cardiac muscle cells

- Allows electrical current to flow from one muscle cell to the next one

- Cells contract in order that they receive the signal

> Creates wave-like motion

Heart Chambers

- Atria

- Ventricles

Atria

- Receiving chambers

- Right + left atrium

- Has auricle

Auricle

- A wrinkle-like pouched structure

- Works as an appendage of each atrium

- Increases blood capacity of each atrium

- Has pectinate muscles

Ventricle

- Discharging chambers

- Right ventricle (anterior)

- Left ventricle

Coronary Sulcus

- Aka atrioventricular sulcus

- Goes around entire heart like a crown

- Separates atria from ventricles

- Coronary vessels are found here

Anterior Interventricular Sulcus

Separates right + left ventricles in anterior aspect of heart

Posterior Interventricular Sulcus

Separates right + left ventricles in posterior aspect of heart

Interatrial Groove

Separates atria into right + left sides

Superior + Inferior Vena Cava

- Big veins

- Arrive at right atrium of heart

Superior Vena Cava

Brings deoxygenated blood from upper part of body

Inferior Vena Cava

- Brings deoxygenated blood from lower part of body

- Bigger than superior vena cava

Blood Circulation in Heart

- Deoxygenated blood: right atrium ---> right ventricle ---> pulmonary trunk

- Gas exchange of blood: lungs

- Oxygenated blood: pulmonary vein ---> left atrium ---> left ventricle ---> aorta ---> rest of the body

Pulmonary Trunk

- Bifurcates (divides) into two arteries

- Right + left pulmonary arteries

- Takes blood away from heart into lungs

Pulmonary Vein

- 4 in total

- 2 veins per lung for blood to go back to the heart

Aorta

- Largest artery in the body

- Several arteries branch off it into smaller arteries

- Carries oxygenated blood to all parts of body

- The heart itself is the first organ to get oxygenated blood + nutrients when blood is pumped to aorta

Coronary Blood Vessels

- Found in coronary sulcus

- Several vessels are branching off

> Always stays on the heart itself

Coronary Arteries

- Supplies blood to the heart muscles

- First arteries branching off the aorta

- Paired

- First arteries to receive oxygenated blood in the body

Right Coronary Artery

- Aka posterior interventricular artery

- Ends in posterior aspect of heart

- Goes down in-between right + left ventricles

- Supplies blood to right atrium + ventricle

- Is a conduction system of the heart

Conduction System of Heart

- Specialized heart muscle cells located in specific parts of right atrium (deep)

- NOT from CNS

Left Coronary Artery

- Splits into two as soon as it passes behind pulmonary trunk

- Supplies blood to left atrium + ventricle

- Branches:

> Anterior interventricular artery

> Circumflex artery

Anterior Interventricular Artery

Goes down in-between the ventricles in the anterior aspect of the heart

Circumflex Artery

Goes around towards the left side of heart

Coronary Veins

- Blood flows here after heart muscle cells use the oxygen + nutrients that were present

- Includes:

> Great cardiac vein

> Middle cardiac vein

> Small cardiac vein

- These veins get together and dump blood into the coronary sinus

Great Cardiac Vein

- Anterior aspect of heart

- Is between right + left ventricles

- Goes up + surrounds the heart at the coronary sulcus

- Runs parallel to the anterior interventricular artery + circumflex artery

Middle Cardiac Vein

- Posterior aspect of heart

- Runs parallel to posterior interventricular artery

Small Cardiac Vein

Runs parallel to right coronary artery itself

Coronary Sinus

- Directly connects to right atrium

- Brings deoxygenated blood to the heart muscles itself

Coronary Thrombosis

- An obstruction (blockage) of blood flow through one of the coronary artery branches

- Blood cannot reach a specific area of the heart

- Leads to myocardial infarction (heart attack)

Heart Attack

Its severity depends on how long the pericardium cells were deprived of O2 + how big the affected area is

Arterial Anastomosis

- Anastomosis = interconnecting

- Area that receives blood from two different arteries

- Interconnected network of capillaries

Collateral Arteries

- Arteries that come together

- They work to provide circulation to a specific area

- The more interconnections, the better

Why Is it Important to Have Collateral Arteries?

If one of the arteries gets blocked, the other artery can ensure blood supply to the specific area

Interatrial Septum

Is between the right + left atrium

Interventricular Septum

Is between the right + left ventricle

Interatrial + Interventricular Septum

Ensures blood from right + left sides of the heart don't mix

Blood Circulation: Right Atrium

- Receives deoxygenated blood from superior + inferior vena cava and coronary sinus

- Has pectinate muscles

- Has fossa ovalis

Pectinate Muscles

- Squeezes out the maximum amount of blood into the ventricle when the atrium contracts

- Is also in the auricle

Fossa Ovalis

- A scar located in the interatrial septum

- Results from the closure of the opening that was between right + left atrium during developmental stages

Foramen Ovale

- While inside the mother, the fossa ovalis is the foramen ovale where blood from right atrium goes to left atrium since lungs haven't been developed yet + blood is already oxygenated

- As soon as the umbilical cord is removed, the hole is snapped shut

What Happens if Fossa Ovalis Stays Fully Opened?

There is very low chances of survival

What Happens if Fossa Ovalis is Semi Opened?

Can be fixed through open heart surgery

Heart Valves

- Made up of simple squamous epithelium

- Are held in place by chordae tendineae

Chordae Tendineae

- Tendon like cords made of fibrous connective tissue

- Anchors atrioventricular valve cusps to papillary muscle found in ventricle wall

- Prevents heart cusps from turning inside out when ventricles contract to eject blood

Right Atrioventricular Valve

- Aka tricuspid valve

- Is between right atrium + ventricle

- Has three flaps (cusps)

- Ensures one way flow of blood from atrium to ventricle

Blood Circulation: Right Ventricle

- Has papillary muscle

- Has trabeculae carneae

- Has moderator band

Trabeculae Carneae

- Muscular rides

- Helps to squeeze maximum amount of blood out of the ventricle

Moderator Band

- Extends from the interventricular wall to the side of the right ventricle

- Moderates how much this chamber extends since right ventricle wall is much thinner than left ventricle wall

Pulmonary Semilunar Valve

- Is between right ventricle and pulmonary trunk

- Prevents backflow of blood from the pulmonary trunk back into the right ventricle

Blood Circulation: Left Atrium

- Receives oxygenated blood from the lungs via right + left pulmonary veins

- Pectinate muscles are ONLY in the auricle

Left Atrioventricular Valve

- Aka bicuspid valve

- Aka mitral valve

- Is between left atrium + ventricle

- Has two cusps

Blood Circulation: Left Ventricle

- Has very prominent trabeculae carneae

- Has the thickest wall

- Works six times harder than the right ventricle

Aortic Semilunar Valve

- Is between aorta and left ventricle

- Has two holes which is an entrance for the coronary arteries

Operation of Atria + Ventricles

- Blood fills up both atria at the same time

- Due to pressure differences, 70% of blood from atria flows passively to the ventricles

- When pressure is equal between atria and ventricles, the blood cannot flow passively anymore

- Both atria contract at the same time

- All blood is ejected into the ventricles

Operation of Heart Valves

- Pressure of blood filling up the ventricles forces the flaps of AV valves to close

- Semilunar valve cusps get filled with blood which closes both semilunar valves

Blood in the Heart

- All blood is ejected into either pulmonary trunk or aorta

- Blood is ejected out of the heart at the same time

- Blood with pressure goes up and then goes back

Ausculation

- Action of listening to internal sounds of the body

- Gives a quick assessment of heart valves

Lubb Sound

AV valves close

Dubb Sound

Semilunar valves close

Heart Murmur

At least one of the heart valves is not closing properly