The Heart ppt (ALMO)

Functions

1. Regulates blood supply

2. Generates blood pressure

3. Routes blood

4. Ensures 1 way blood flow

Heart Characteristics

size of a fist and weighs less than— lb.

Location

between lungs in thoracic cavity

Orientation:

apex (bottom) towards left side

double-layered sac that anchors and protects heart

Pericardium

membrane around heart's cavity

Parietal pericardium

membrane on heart's surface

Visceral pericardium

space around heart

Pericardial cavity

surface of heart (outside)

Epicardium

thick, middle layer composed of cardiac muscle

Myocardium

smooth, inner surface

Endocardium

structures that ensure 1 way blood flow

Valves

between atria and ventricles

Atrioventricular valves (AV)

AV valve between RA and RV

Tricuspid valve

3 cusps

Tricuspid valve

AV valve between LA and LV

Bicuspid valve (mitral)

cone-shaped, muscular pillars

Papillary muscles

In simple terms, papillary muscles are small, finger-like muscles located in the walls of the heart's ventricles (the lower chambers). Their main function is to anchor and control the heart's atrioventricular (AV) valves, specifically the mitral valve and the tricuspid valve. These muscles are connected to the valve flaps by thin strands called chordae tendineae.

When the heart contracts, the papillary muscles contract as well, tightening the chordae tendineae and preventing the AV valves from swinging back into the atria. This helps to ensure that blood flows in the right direction—out of the heart's chambers and into the arteries—rather than back into the atria. Essentially, the papillary muscles play a crucial role in maintaining the proper one-way flow of blood through the heart.

- attached to AV valve flaps

- support valves

Chordae tendinee

Think of chordae tendineae as tiny ropes or strings inside your heart. These "ropes" connect the valves (like the mitral valve and tricuspid valve) to small muscles called papillary muscles in the heart's lower chambers.

When the heart squeezes (contracts) to pump blood, the valves need to close properly to prevent blood from flowing backward. The chordae tendineae help with this. As the heart contracts, these strings tighten and pull on the valves, making sure they stay closed and blood goes in the right direction—out to the body or lungs and not back into the heart's upper chambers.

So, in simple terms, chordae tendineae act like puppet strings, making sure the heart valves close tightly and keep the blood moving where it's supposed to go.

Semilunar valves

base of pulmonary trunk

Pulmonary

base of aorta

Aortic

•1 centrally located nucleus

• Branching cells.

• Rich in mitochondria

Cardiac Muscle

Striated (actin and myosin)

Cardiac Muscle

Ca2+ and ATP used for contractions

Cardiac Muscle

Intercalated disks connect cells

Cardiac Muscle

• Lower portion

• Pumping chambers

Ventricles

• Thick, strong walled

• Contract forcefully to propel blood out of heart

Ventricles

• Contract forcefully to propel blood out of heart

Ventricles

separates right and left ventricles

Interventricular septum

• Upper portion

• Holding chambers

Atria

• Small, thin walled

Atria

• Contract minimally to push blood into ventricles

Atria

separates right and left atria

Interatrial septum

• Blood flows from LA into LV.

Bicuspid Valve: Open?

• Aortic semilunar valve is closed.

Bicuspid Valve: Open?

• Tension on chordae tendinee is low.

Bicuspid Valve: Open?

1. Bicuspid Valve: Open

   • This refers to a valve in the heart, specifically between the left atrium (LA) and the left ventricle (LV).

   • "Open" means the valve is allowing blood to flow from the left atrium to the left ventricle.

2. Blood flows from LA into LV

   • This just describes the direction of blood flow. Blood is moving from the left atrium to the left ventricle of the heart.

3. Aortic semilunar valve is closed

   • Another valve, called the aortic semilunar valve, is shut. This valve is situated between the left ventricle and the aorta.

   • "Closed" means that this valve is not allowing blood to move from the left ventricle into the aorta at this moment.

4. Tension on chordae tendineae is low

   • There are tiny string-like structures in the heart called chordae tendineae.

   • "Low tension" means that these structures are not under much stress or tightness at the moment.

In summary, during this specific phase:

• The bicuspid valve is open, letting blood move from the left atrium to the left ventricle.

• The aortic semilunar valve is closed, preventing blood from leaving the left ventricle and entering the aorta.

• The chordae tendineae are not under much tension, meaning they are not tightly stretched.

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Chambers and Blood Vessels • 4 Chambers:

- left atrium (LA)

- right atrium (RA)

- left ventricle (LV)

- right ventricle (RV)

separates atria from ventricles

Coronary sulcus

• plate of connective tissue

• fibrous rings

cardiac skeleton

• surround the atrioventricular and semilunar valves

cardiac skeleton

Right Side of Heart

- carries blood from heart to lungs

- blood is O2 poor, CO, rich

Pulmonary circuit

- receives blood from 3 places: superior and inferior

Right Atrium

drains blood above diaphragm (head, neck, thorax, upper limbs)

Superior vena cava

drains blood below diaphragm (abdominopelvic cavity and lower limbs)

Inferior vena cava:

drains blood from myocardium

coronary sinus

So, your heart has its own blood vessels called coronary arteries that bring this special oxygenated blood to the heart muscle itself. But after the heart muscle uses up the oxygen and other nutrients from the blood, it needs a way to get rid of the "used" blood.

Enter the coronary sinus! It's like a little recycling system inside your heart. The coronary sinus collects the "used" blood from the heart muscle and brings it back to the right side of the heart. From there, the heart pumps it to the lungs, where it gets fresh oxygen again, like taking a big breath of air.

So, in simple terms, the coronary sinus helps your heart get rid of the old, used-up blood and sends it off to get refreshed with oxygen so that your heart can keep pumping and keeping you active and healthy!

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Imagine your heart is like a house, and the rooms inside are the different parts of your heart. Now, every house needs a way to get rid of its dirty water, right? In your heart, the dirty water is actually used blood that needs to go back to the laundry (lungs) to get cleaned up.

Now, the coronary sinus is like the heart's special drain. It's a little pipe that collects all the dirty blood (full of waste and carbon dioxide) from the rooms of the heart, which are like the different parts of the house. The coronary sinus takes this dirty blood and sends it off to the laundry (lungs) where it can get cleaned up and be ready to deliver fresh, clean blood again.

So, the coronary sinus is like the heart's way of keeping things tidy and making sure the blood gets a good cleaning before it goes back to work in the heart again!

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- opens into pulmonary trunk

Right Ventricle

splits into right and left pulmonary arteries

Pulmonary trunk:

carry blood away from heart to lungs

Pulmonary arteries

Blood Flow through Heart

1. RA

2. Tricuspid valve

3. RV

4. Pulmonary semilunar valve

5. Pulmonary trunk

6. Pulmonary arteries

7. Lungs

8. Pulmonary veins

10. Bicuspid valve

11. LV

12. Aortic semilunar valve

13. Aorta

14. Body

4 openings (pulmonary veins) that receive blood from lungs

Left Atrium

- opens into aorta

Left Ventricle

- thicker, contracts more forcefully, higher blood pressure than right ventricle has to get to body

Left Ventricle

carries blood from LV to body

Aorta

- supply blood to heart wall -

originate from base of aorta (above aortic semilunar valve)

Coronary arteries

- has 3 branches

- supply blood to anterior heart wall and left ventricle

Left coronary artery:

Action Potentials in Cardiac Muscle

Changes in membrane channels permeability are responsible for producing action potentials and is called

pacemaker potential.

- Na+ channels open

- Ca2+ channels open

Depolarization phase

- Na+ channels close

- Some K+ channels open

-Ca2+ channels remain open

Plateau phase

- K+ channels are open

-Ca2+ channels close

Repolarization phase

prolongs action potential by keeping Ca2+ channels open.

Plateau phase

take 2 msec, in cardiac muscle they take 200-500 msec.

skeletal muscle action potentials

• contraction of atria and ventricles by cardiac muscle cells

Conduction System of Heart

in RA

where action potential originates - functions

Sinoatrial node (SA node):

functions as pacemaker

- large number of Ca?+ channels

Sinoatrial node (SA node):

Path of Action Potential through Hear

1. SA node

2. AV node (atrioventricular)

3. AV bundle

4. Right and Left Bundle branches

5. Purkinje fiber

produce pressure changes within heart chambers.

Cardiac muscle contractions

re responsible for blood movement.

Pressure changes

Blood moves from areas of high to low" pressure

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contraction of atria

Atrial systole

contraction of ventricle

Ventricular systole

relaxation of atria

Atrial diastole

relaxation of ventricles

Ventricular diastole

Components of ECG/EKG

depolarization of atria

P wave

- depolarization of ventricles

- contains Q, R, S waves

ORS complex

repolarization of ventricles

T wave

First sound (SI)

lubb

second (S2)

dupp

result from opening and closing valves

Sounds

- record of electrical events in heart

Electrocardiogram

- diagnoses cardiac abnormalities

- uses electrodes

Electrocardiogram

- contains P wave, QRS complex, T wave

Electrocardiogram

repetitive pumping action which includes contraction and relaxation

Cardiac Cycle

Cardiac Cycle

• Heart is 2 side by side pumps: right and left

• Atria: primers for pumps

• Ventricles: power pumps

Heart is 2 side by side pumps:

right and left

primers for pumps

Atria

power pumps

Ventricles

repetitive pumping action which includes contraction and relaxation

Cardiac Cycle

• Cardiac muscle contractions produce pressure changes within heart chambers.

• Pressure changes are responsible for blood movement.

• Blood moves from areas of high to low pressure.

true

- volume of blood pumped per ventricle per contraction

- 70 ml/beat

Stroke Volume

heart beats/ min

Heart Rate

volume of blood pumped by a ventricle/ min.

- 5 L/min.

CO = SV x HR

Cardiac Output:

• mechanisms contained within heart

Intrinsic Regulation of Heart

amt. of blood that returns to heart

Venous return

degree ventricular walls are stretched at end of diastole

Preload