A&P Cardiovascular chpt 20
Heart Chambers and valves
*4 Chambers* = right & left atria superiorly; right & left ventricles inferiorly.
Differentiate a stenotic valve from an incompetent valve.
*Stenotic* = narrowed opening due to fusion/stiffening of cusps. doesn't open properly *Incompetent* = leaky; doesn't close completely. *Both disorders reduce effeciency of the heart
Circulatory Functions of the Heart:
*Transport* -respiratory gases, nutrients, wastes, hormones *Protection* -blood clotting, immunity
Layers of the heart wall
*epicardium* -visceral layer of serous pericardium. often infiltrated w/ fat in old people. *myocardium* - forms bulk of heart; cardiac muscle tissue and is the layer that contracts. *endocardium*- sheet of simple squamous epithelium resting on thin layer of CT. lines heart chambers and covers heart valves.
What is the hearts largest organ?
*mediastinum* - region between the 2 lungs (and pleural cavities)
The brachiocephalic trunk (which branches off the arch of aorta) branches into:
- Right common carotid artery which supplies the right side of the head & neck - Right subclavian artery which supplies the right arm
Valves closing at different times giving them different sounds through a stethoscope
-*Aortic valve* at 2nd intercostal space at right sternal margin -*Pulmonary valve* in 2nd intercostal at left sternal margin -*Mitral valve* heard over heart apex, in 5th intercostal in line with middle of clavicle -*Tricuspid valve* right sternal margin of 5th intercostal space
What is the pacemaker of the heart? Where is it located? What type of tissue forms the structures of the conducting system of the heart?
-Pacemaker = *sinoatrial (SA) node* -in right atrium -specialized cardiac muscle cells that initiate electrical signal for heart rate -all other conducting system structures are composed of specialized cardiac muscle cells.
Left Ventricle"
-forms apex; dominates heart's inferior surface -pumps blood into systemic circuit -like right ventricle, contains trabeculae carnae, papillary muscles, chordae tendinae, and mitral valve. -superiorly, opens into stem artery of systemic circulation (aorta) through *aortic semilunar valve*
Systemic circuit:
-left side receives oxygenated blood from lungs -pumps this blood through body to supply oxygen and nutrients to tissues -vessels that transport blood to and from tissues and back to heart = *systemic circuit*
Right Ventricle:
-receives blood from right atrium and pumps it into pulmonary circuit via an artery called *pulmonary trunk* -walls with ridges of muscle called *trabeculae carnae* -*papillary muscles* -*chordae tendinae* - "heart strings"
Right Atrium:
-receives oxygen-poor blood from systemic circuit -receives blood through superior vena cava, inferior vena cava, and coronary sinus
Left Atrium:
-receives oxygen-rich blood from lungs trough two right and two left *pulmonary veins* -opens into left ventricle through *mitral valve*
Vessels carrying oxygenated blood?
-right & left pulmonary veins -aorta
Pulmonary circuit:
-right side receives oxygen-poor blood from the body tissues -pumps this to lungs -picks up oxygen and CO2 -blood vessels that carry blood to and from lungs = *pulmonary circuit*
Vessels carrying deoxygenated blood?
-superior vena cava -left & right pulmonary artery -pulmonary trunk -inferior vena cava
How do the autonomic nerves that innervate the heart influence heart function?
-sympathetic innervation increases heart rate and contraction strength -parasympathetic only influences heart rate; it decreases it
The pericardium has *3* layers:
1 layer - *Fibrous pericardium* (outer dense CT. holds heart in place & keeps it from overfilling w/ blood) 2 layers - *serous pericardium* -parietal (inner) -visceral (on surface of heart; part of heart wall)
The *Cardiac Skeleton* lies between the atria and ventricles and surrounds all four heart valves like handcuffs. Composed of dense connective tissues, it has four functions:
1. anchors valve cusps 2. prevents overdilation of the valve openings as blood flows through 3. point of attachment for bundles of cardiac muscle 4. blocks direct spread of electrical impulses from atria to ventricles. critical for proper contractions.
AV valves open; atrial pressure greater than ventricular pressure
1. blood returning to heart fills atria, pressing against AV valves 2. as ventricles fill, AV valve flaps hang limply into ventricles 3. atria contract, forcing additional blood into ventricle
Four corners of the heart
1. superior right - costal cartilage of 3rd rib joins sternum 2. superior left - costal cartilage of 2nd rib 3. inferior right 4. inferior left
AV valves closed; atrial pressure less than ventricular pressure.
1. ventricles contract, forcing blood against AV valve cusps. 2. AV valves close 3. papillary muscles contract and chordae tendineae tighten, preventing valve flaps from everting into atria.
During ventricular systole, are the AV valves open or closed? Are the semilunar valves open or closed during this period?
AV valves closed during ventricular systole. Semilunar valves open.
_______ muscle makes up the myocardium.
Cardiac
Name all the layers from superior to deep of the pericardium to the heart.
Fibrous pericardium, parietal layer of serous pericardium, pericardial cavity, epicardium the visceral layer of serous pericardium, myocardium, endocardium and heart chamber.
Assume blood is flowing from the coronary sinus to the lung capillaries. Place the anatomical items in order of flow.
From the coronary sinus, right atrium, tricuspid valve, right ventricle, pulmonary semilunar valve, pulmonary trunk, pulmonary arteries.
Surface and External features
Great Cardiac Vein: Coronary Sinus:
What is the primary importance of the ductus venosus in the fetus?
It is a shunt that re-routes blood away from the portal system directly to the inferior vena cava.
Starting with the lung capillaries put in order of blood flow of oxygen-rich blood into the heart.
Lung capillaries, pulmonary veins, left atrium, mitral bicuspid valve.
What are the heart valves?
Paired atrioventricular (AV) and Semilunar vales
Which heart chamber sends deoxygenated blood to the lungs?
Right ventricle
Name three vessels that empty into the right atrium. Are these vessels arteries or veins?
Superior vena cava, inferior vena cava, and coronary sinus are 3 major veins that empty into right atrium.
Is the aorta oxygen rich or oxygen poor?
The aorta is oxygen rich.
The vessel that carries oxygen rich blood to tissues is what?
The aorta is the vessel that carries oxygen rich blood to tissues.
The structure that is located anatomically between the aorta and the left ventricle is what?
The aortic semilunar valve is the structure that is located anatomically between the aorta and the left ventricle.
Which vessel or vessels are the first to branch off the aorta?
The coronary arteries branch off the aorta just superior to the aortic vavle
The what carries oxygen poor venous blood of the coronary circulation into the right atrium
The coronary sinus carries oxygen poor venous blood of the coronary circulation into the right atrium
What is the outermost covering of the heart?
The fibrous pericardium is the outermost covering of the heart.
The what carries oxygen poor venous blood from below the diaphragm from areas of the lower body and extremities into the right atrium?
The inferior vena cava carries oxygen poor venous blood from below the diaphragm from areas of the lower body and extremities into the right atrium.
From what vessel do the left and right coronary arteries arise?
The left and right coronary arteries arise from the aorta.
Is the left atrium oxygen rich or oxygen poor?
The left atrium is oxygen rich.
Which heart chamber receives blood from the pulmonary veins?
The left atrium receives oxygenated blood from the pulmonary veins
Is the left ventricle oxygen rich or oxygen poor?
The left ventricle is oxygen rich.
Which chamber pumps oxygenated blood out the aorta to the systemic circuit?
The left ventricle pumps oxygenated blood out the aorta to the entire body (systemic circuit).
The structure that prevents backflow of blood into the left atrium is what.
The mitral or bicuspid valve is the structure that prevents backflow of blood into the left atrium.
Are the pulmonary arteries oxygen rich or oxygen poor?
The pulmonary arteries are oxygen poor.
Are the pulmonary veins oxygen rich or oxygen poor?
The pulmonary veins are oxygen rich.
Is the right atrium oxygen rich or oxygen poor?
The right atrium is oxygen poor.
Is the right ventricle oxygen rich or oxygen poor?
The right ventricle is oxygen poor.
Which heart chamber pumps unoxygenated blood out the pulmonary trunk?
The right ventricle pumps unoxygenated blood out of the pulmonary trunk to the lungs
When compared to skeletal muscle, what differences are observed in cardiac muscle?
The sarcoplasmic reticulum is less complex, cells are branched, and there is a greater abundance of mitochondria.
The what carries oxygen poor venous blood from above the diaphragm from areas of the upper body and extremities into the right atrium?
The superior vena cava carries oxygen poor venous blood from above the diaphragm from areas of the upper body and extremities into the right atrium.
Is the superior vena cava oxygen rich or oxygen poor?
The superior vena cava is oxygen poor.
The capillaries receiving blood flow from the left side of the heart are what?
The systemic capillaries are the capillaries that receive blood flow from the left side of the heart.
the blood vessel layer that is comprised of circular and longitudinal smooth muscle.
Tunica Media
The heart is actually how many pumps?
Two pumps. The right side of the heart pumps to/from the lungs (pulmonary circuit) and the left side of the heart pumps to/from the rest of the body (the systemic circuit)
Heart valves open to _______ and close to _____.
allow blood flow; block blood flow
Heart assumes oblique position in the thorax, with its pointed _______ lying to the left of the midline and anterior to the rest of the heart.
apex
The left common cartoid artery which supplies the left side of the head & neck and the left subclavian artery which supplies the left arm both branch directly out of the
arch of the aorta
Semilunar valves open
as ventricles contract and intraventricular pressure rises, blood is pushed up against semilunar valves, forcing them open
Semilunar valves closed
as ventricles relax and intraventricular pressure falls, blood flows back from arteries, filling the cusps of semilunar valves and forcing them to close.
Which vessels supply blood to the brain?
common carotid arteries and subclavian arteries
Each heart valve consists of 2 or 3 _________, which are flaps of endocardium reinforced by cores of dense connective tissue.
cusps
The heart acts as a _____ ______, sending out blood to both circuits at once.
double pump
What are the function of the valves?
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.
What is another name for epicardium?
epicardium is the visceral layer of the serous pericardium
What heart chamber contains the fossa ovalis?
fossa ovalis in right atrium
Where does blood travel after passing through the aortic semilunar valve? Is this blood oxygenated or deoxygenated?
from aortic semilunar valve, blood enters aorta (the great artery that carries oxygenated blood to systemic circuit.)
What is the significance of gap junctions in the intercalated discs?
gap junctions allow stimulus to contract to be passed from one muscle cell to an adjacent cell. This linkage allows all muscle cells in a heart chamber to contract at the same time.
Internally, the heart is divided longitudinally by a partition called the ____ _____ between the atria, and the ____ ______ between the ventricles.
interatrial septum; interventricular septum.
Where is the apex of the heart located in reference to the anterior thoracic wall?
left midclavicular line at intercostal 5 (ICS 5)
What heart chamber contains the pectinate muscles?
located in both atria
Circular and spiral arrangement of cardiac muscle bundles in the _________ of the heart.
myocardium
What heart chamber contains the papillary muscles?
papillary muscles in both ventricles
Location of the heart in the thorax
posterior to the sternum and costal cartilages & rests on the superior surface of the diaphragm.
Semilunar valves
prevent backflow from the great arteries into the ventricles
The two atrioventricular (AV) valves
prevent backflow of blood into atria during contraction of ventricles.
what are the two circuits?
pulmonary circuit and systemic circuit
Which chamber of the heart receives blood from the superior and inferior vena cavas?
right atrium receives unoxygenated blood from the systemic circuit.
The role of the coronary arteries is to
supply blood to the heart tissue
Blood supply to the walls and tissues of the heart is delivered by
the right and left coronary arteries
Which body regions are supplied by the brachiocephalic artery?
the right side of the head and thorax and the right upper limb
Which side of the heart receives and pumps deoxygenated blood?
the right side of the heart receives and pumps deoxygenated blood
The vessel that arises from the union of the left and right brachiocephalic veins.
the superior vena cava
What heart chamber contains trabeculae carnae?
trabeculae carnae are muscle ridges in both ventricles
