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.