A4 E2: The Heart

Between the parietal and visceral layers of the serous pericardium is a slitlike space, called the _________________________.

Pericardial cavity, a division of the embryonic coelom.

Diastolic Blood Pressure

Pressure in arteries when the ventricles are filling with blood -lower pressure

Systolic Blood Pressure

Pressure in the arteries when the ventricles are squeezing out blood under high pressure

When ventricles start to contract what happens to the valve cusps? chordae tendineae and papillary muscles that attach to the valves?

Pressure within ventricles rises and forces blood superiorly against the valve cusps, pushing the edges of the cusps together and closing the AV valves. Chordae tendineae are held taught like a parachute!

Pulmonary valve leads blood into the

Pulmonary artery

Antrioventricular valve pumps into

Pulmonary valve

Lub

S1 - tricuspid and mitrol valve (antrioventicular valves) snapping shut when left and right ventricles contract - contract at same time

_____ node sets the basic heart rate by generating 70-80 electrical impulses per minute

SA

Deoxygenated blood enters through these two spots

Superior vena cava or inferior vena cava in the right atrium

Which system has more vessels, and what does this mean?

Systemic circulation has more vessels which means higher resistance to blood flow, making it a lot harder to pump blood through.

The cardiac cycle refers to

The mechanical events occurring during one heartbeat.

Which of the following valves is most often faulty in the heart?

The mitral valve

Prevents regurgitation back into atrium

The papillary muscle within the antrioventricular valve keeps the chordae tendineae taut

Hearts two main pumping chambers

The right and left ventricle that pump blood around the two circuits

Which side of the heart recieves and pumps deoxygenated blood?

The right side

Difference in structure between antrioventricular valve and pulmonary valve

They both have 3 cusps (to prevent blood from flowing back) but pulmonary doesnt have chordae tendineae

Why can a heart beat even when extrinsic nerve impulses are halted?

They have their own intrinsic ability to generate and conduct electrical impulses that stimulate these cells to contract rhythmically.

Chordae tendineae

Thin strong bands

Why are the walls of the atria (thinner/thicker) than those of the ventricles

Thinner because most ventricular filling is done by gravity

Which of the following factors gives the myocardium its high resistance to fatigue?

Twenty-five to thirty-five percent of the volume of a myocardial cell is composed of large mitochondria, which provide these cells with a great resistance to fatigue.

Parietal and visceral layer of the serous pericardium secrete

a protein rich fluid called serous -lubricant for heart

Parietal layer of the serious pericardium

adheres to the inner surface of the fibrous pericardium and is continuous with the visceral layer of the serous pericardium (epicardium)

Veins that drain the right ventricle and empty into the right atrium

anterior cardiac veins

Carries oxygenated blood to the systemic circuit

aorta

Pulmonary artery leads into

arteriole (smaller)

Carries blood away from heart

artery A "Away"

Trabeculae carneae are located in

both ventricles

Pulmonary circuit

bv that carry blood to and from the lungs

Systemic circuit

bv that transport blood to and from all body tissues and back to the heart

When atrial pressure in less than ventricular pressure valve flaps

close

Carry o2 to the myocardium

coronary arteries

Blood draining from the heart wall itself is collected by ____________ and enters the right atrium

coronary sinus

Tiny third opening in the right atrium

coronary sinus.

Each heart valve consists of two or three ________,

cusps: flaps of endocardium reinforced by cores of dense c tissue

Cardiac skeleton is composed of what kind of tissue?

dense connective tissue

Heart chamber is relaxing and filing with blood

diastole

Right auricle

external - small flap projects anteriorly from the superior corner of the atrium.

As ventricles fill, AV valve flaps

hang limply into ventricles

WATCH BEFORE DOING CARDS

https://www.youtube.com/watch?v=NDk8fmIl9V8

The bundles in the myocardium function to squeeze blood through the heart in the proper directions of....

inferiorly through the atria and superiorly through the ventricles

Internal partition that separates the atria

interatrial septum

Internal partition that separates the ventricles

interventricular septum

Makes up most of the heart's posterior surface, or base

left atrium

__________ recieves o2 rich blood returning from the lungs through two right and two left ____________________.

left atrium; pulmonary veins

Dominates the heart's inferior surface

left ventricle

What part of the heart is considered the systemic circuit pump?

left ventricle

pumps blood into the systemic circuit

left ventricle

Right after "lub" what happens?

lub = tricuspid and mitrol valves shut. The aortic and pulmonic valves open up allowing blood to get pushed out to the body SYSTOLE

When atrial pressure is greater than ventricular pressure valve flaps

open

Semilunar valves

prevent backflow from the great arteries into the ventricles pulmonary semilunar valves and aortic semilunar valves

Carries blood away from heart to left and right lung

pulmonary artery

Venules lead into

pulmonary vein

Right atrium

receiving chamber for o2 poor blood returning from the systemic circuit

Function of serous fluid

reduces friction between the beating heart and the outer wall of the pericardial sac

Heart's two receiving chambers

right and left atrium (atrium = entranceway)

Fossa ovalis is found in the

right atrium

Right ventricle receives blood from ____________ and pumps it into the ________________ via ____________.

right atrium; pulmonary circuit; pulmonary trunk (artery)

Conducting system

series of specialized cardiac muscle cells that carries impulses throughout the heart musculature, signaling heart chambers to contract in the proper sequence.

Endocardium cells

simple squamous epithelium resting on a thin layer of c tissue

heartbeat

single sequence of atrial contraction followed by ventricular contraction

Right atrium receives blood via three veins

superior vena cava, inferior vena cava and coronary sinus

Contraction of a heart chamber

systole

Cardiac output

the amount of blood the each ventricle pumps out in one minute cardiac output = heart rate × stroke volume

Pulmonary veins dump into

the left atrium

heart valves

the paired atrioventricular (AV) and semilunar valves that enforce one-way flow of blood through the heart, from the atria to the ventricles and into the great arteries that leave the superior part of the heart

Ventricular walls are marked by irregular ridges of muscle called

trabeculae carneae

Papillary muscles contract and chordae tendineae tighten preventing

valve flaps from everting into atria

Are the vessels that empty into the right atrium veins or arteries?

veins

Brings blood towards the heart

veins

Papillary muscles project from the walls into the _________________.

ventricular cavity.

When capillaries emit CO2 into alveolus and become enriched with O2 from the alveolus they are called

venules

Cardiac skeleton lies in the plane between the atria and the ventricles and surrounds all four heart valves rather like handcuffs. What are it's four functions?

1.) Anchors the valve cusps 2.) Prevents overdilation of the valve openings as blood pulses through 3.) point of attachment for the bundles of cardiac muscle in the atria and ventricles 4.) blocks direct spread of electrical impulses from the atria to the ventricles (critical for proper coordination of atrial and ventricular contractions

Once O2 rich blood is dumped into organs and tissues via capillaries explain how the CO2 blood gets to the capillaries in the lungs.

1.) Capillaries emit o2 and recieve co2 from tissues and become venules 2.) venules lead into veins 3.) veins emty into the left and right vena cavas which dump into the right atrium 4.) the right atrium dumps into the right ventricle via artioventricular valve 5.) Left ventricle empties into a pulmonary vein which goes to the right or left lung 6.) Pulmonary vein branches into arterioles (smaller) and eventually into capillaries

Starting with the pulmonary vein, full of o2 rich blood, explain how this blood gets to the organs and tissues

1.) Pulmonary vein dumps into left atrium 2.) Antrioventicular valve (mitral valve) pumps it into aortic valve 3.) Aortic valve pumps this into the Aorta 4.) Aorta branches into arterioles (smaller) and then into capillaries (smallest) 5.) Capillaries arrive at organs and tissues.

Two main functions of the heart

1.) right side receives oxygen-poor blood from the body tissues and pumps this to the lungs to pick up o2 and dispel co2 via pulmonary circuit 2.) Left side receives o2 blood returning from the lungs and pumps this throughout the body to supply o2 and nutrients to the body tissues via systemic circuit

Right atrium - internal two parts

1.) smooth-walled posterior part 2.) anterior part lined by horizontal ridges called the pectinate muscles these two are separated by a large, C-shaped ridge called the crista terminalis

hemoglobin can bind to

4 O2

There are _____ heart chambers

4: right and left atria superiorly and the right and left ventricles inferiorly

Average heart beat of a person at rest

70-80 times per minute

Heart anatomy: gap junctions

A gap junction forms channels between adjacent cardiac muscle fibers that allow the depolarizing current produced by cations to flow from one cardiac muscle cell to the next. -allowing the heart muscle cells to contract in unison.

differentiate a stenotic valve from an incompetent valve

A stenotic valve has a narrowed opening due to fusion or stiffening of the cusps and thus doesn't open properly. An incompetent valve is a leaky valve that doesn't close completely. Both valve disorders reduce the efficiency of the heart.

Aortic semilunar Valve pumps into the largest artery in the body called the

Aorta

Blood in left antrioventricular valves (mitral valve) gets pumped out through

Aortic semilunar valve (3 cusps)

Aorta branches into

Arterioles (smaller) ---> capillaries (smallest) ---> organs and tissues

Separates atria from ventricles

Atrioventricular valve

Pectinate muscles are located in __________.

Both atria

Papillary muscles are located in ___________.

Both ventricles

Arteriole leads into

Capillary (smallest)

Initiates contraction sequence, therby setting basic heart rate

Conducting system

Important landmark in locating the sites where veins enter the right atrium

Crista (c-shaped ridge seperating internal parts of right atrium)

Antrioventricular valve that connects the artrium to the ventricle consists of

Cusps (flaps) that latch onto papillary muscle via chordae tendineae

Coronary vessels

Dedicated blood vessels that enter into myocardium. Lay on the outside of the heart and penetrate into myocardium.

Fossa ovalis

Depression in the interatrial septum that marks the spot where an opening existed in the fetal heart (right atrium)

What type of blood pressure would be lower?

Diastolic

Heart wall components (layers)

Epicardium (visceral layer of serous pericardium), myocardium and endocardium

This membrane is often infiltrated with fat, especially in older people

Epicardium (visceral layer of the serous pericardium) and outer layer of heart wall.

What produces a lubricating film of serous fluid into the pericardial cavity?

Epithelial cells of the serous pericardium the line the pericardial cavity

Diastole

- After aortic and pulmonic valves close (s2) shut the tricuspid and mitrol valves open back up

Artery and vein pressure and volume

- artery: low volume, high pressure - vein: high volume, low pressure

Endocardium

- inside of the heart - sheet of simple squamous epithelium resting on a thin layer of c tissue. - lines the heart chambers and covers the heart valves

Papillary muscle function

- keeps chordae tendineae taut when the heart contracts which prevents regurgitation back into atrium

Why is the ______ ventricle stronger?

- left - because the systemic circulation has more vessels which means high resistance to blood, overall making it a lot harder to pump blood through. - left ventricle myocardium is 3x thicker

Vasodilation

- lowers body temp because more heat is lost out skin

Cardiac Skeleton

- made up of connective tissues - reinforces the myocardium internally and anchors the cardiac muscle fibers

Myocardium

- middle layer of heart wall - forms the bulk of the heart - consists of cardiac muscle tissue and is the layer that actually contracts. - surrounding the cardiac muscle cells are c tissues that bind these cells together into bundles - bundles squeeze blood through the heart in proper directions - c tissues form the cardiac skeleton

Bundles

- myocardium - cardiac muscle cells bound together by c tissue. - function to squeeze blood through the heart in the proper directions; inferiorly through the atria and superiorly through the ventricles

Difference between right and left (mitral valve) antrioventricular valves

- right 3 cusps left 2 cusps

Location of heart

- slightly to left -mediastinum : middle of chest cavity (thorax) - on top of diaphragm - behind sternum (breast bone)

Fibrous pericardium

- superiorly fused to the roots of the great vessels that leave and enter the heart. - acts as a tough outer coat that holds the heart in place and keeps it from overfilling with blood

Systole

- time between lub (s1) and dub (s2) - The aortic and pulmonic valves open up allowing blood to get pushed out to the body

Pericardium

- triple-layered sac that encloses the heart outer to inner: fibrous pericardium (A) parietal layer of the serous pericardium (B), visceral layer of the serous pericardium (epicardium D) and pericardial cavity (C)

Dub

-S2 - Aortic and pulmonic valves close shut to keep blood from flowing backwards after it leaves the ventricles (ending systole)

The cells of the myocardium behave as a single, coordinated unit called a __________.

Functional syncytium. Because cardiac cells are electrically coupled by the gap junctions, they behave as a single unit called a functional syncytium.

After entering the left atrium, the blood...

Goes through the atrioventricular valve (mitral valve) into the left ventricle

Capillary leads into

In the lungs the capillary lines up against a small sack in the lungs called the alveolus filled with Co2 and o2 leaves avelous into capillary

Heart anatomy: Intercalated discs

Intercalated discs are part of the cardiac muscle sarcolemma and they contain gap junctions and desmosomes.