Blood flow alternates between two circuits. What are they?
Pulmonary and Systemic
Pulmonary Circuit
Carries blood to and from gas exchange surfaces of lungs
Systemic Circuit
Carries blood to and from the body
What are 3 types of blood vessels
Arteries, Veins, and Capillaries
Arteries
carry oxygen away from heart, blood is usually oxygenated, but not always
Veins
carry blood toward the heart, blood is usually deoxygenated, but not always
Capillaries
-networks between arteries and veins, allow transport in and out of blood
-exchange materials between blood and tissues -exchange only occurs in capillaries materials include dissolved gases, nutrients, and wastes
-also called exchange vessels
What are the four chambers of the heart?
Right Atrium, Right Ventricle, Left Atrium, Left Ventricle
Right Atrium
Receives blood
Right Ventricle
Pumps blood
Left Atrium
Receives blood
Left Ventricle
Pumps blood
Pulmonary Circuit is supplied by which side of the heart?
-the right side
-right atrium collects blood from systemic
-right ventricle pumps blood into systemic
Systemic Circuit is supplied by which side of the heart?
-the left side
-left atrium collects blood from pulmonary
-left ventricle pumps blood into systemic
Where is heart located?
-directly behind sternum
-base is at level of 3rd rib (large vessels at base)
-Apex is at 5th intercostal space (pointed tip faces left)
What is the heart surrounded by?
-the heart is surrounded by the pericardial sac
(which is formed by 2 pericardial membranes)
-between 2 pleural cavities
-in the mediastinum
Where and what is in the mediastinum?
-cavity in center of thoracic cavity
-contains esophagus, large vessels, trachea and thymus
Pericardium
-double lining of the pericardial cavity
(serous membrane)
-protects heart from friction
What are the two layers of the pericardium?
-parietal pericardium
-visceral pericardium
Parietal pericardium
-outer layer
-forms inner layer of pericardial sac
Visceral pericardium
-inner layer of pericardium
-found on surface of the heart (aka epicardium)
What are the structures of the pericardium?
-pericardial cavity
-pericardial sac
Pericardial cavity
-between parietal and visceral layers
-contains pericardial fluid
Pericardial sac
-fibrous tissue
-surrounds and stabilizes
-smooth lining prevents friction
Atria (atrium)
-thin walled receiving chambers
(require very little muscle in wall)
-have expandable outer auricle
(auricle is visible externally)
-function is to receive blood and push it into ventricles
Ventricles
-thick walled pumping chambers
-have thick layer of cardiac muscle
(generates force to pump blood)
-right and left differ in chamber size and wall thickness
(right has thinner wall and larger chamber)
(left has thicker wall and smaller chamber)
Coronary sulcus
-divides atria and ventricles
-contains coronary vessels
Anterior and posterior interventricular sulci
-separate left and right ventricles
-contain coronary vessels
What are the 3 layers of the heart wall?
-epicardium
-myocardium
-endocardium
Epicardium
-thin outer layer
-forms visceral pericardium
Myocardium
-thick middle layer
-contains cardiac muscle in concentric layers
Endocardium
-thin inner layer
-endothelial cells form smooth lining
Cardiac muscle contain what two important things?
-intercalated discs
-gap junctions
Intercalated discs
-interconnect cardiac muscle cells
-secured by desmosomes
(which tightly fasten cells together and convey force of contraction)
Gap Junctions
-allow direct communication between cells
-propagate action potentials
Veins bring blood to what part of the heart?
-the atria
the superior and inferior vena cavae carry blood from....
systemic circuit to right atrium
right and left pulmonary veins carry blood from....
pulmonary circuit to left atrium
Arteries carry blood away from what part of the heart?
-the ventricles
Pulmonary trunk receives blood from the....
right ventricle (carries blood into pulmonary circuit)
Aorta receives blood from the....
left ventricle (carries blood into systemic circuit)
Blood flow through the heart
-superior and inferior vena cava
-right atrium
-tricuspid valve (right AV valve)
-right ventricle
-pulmonary semilunar valve
-through pulmonary circuit
-right and left pulmonary veins
-left atrium
-bicuspid valve (left AV valve)
-left ventricle
-aortic se
What do the heart valves do?
prevent blood from flowing in wrong direction
(back flow)
What are the two sets of heart valves that prevent back flow?
-atrioventricular valves (AV)
-semilunar valves (SL)
Atrioventricular Valves (AV)
-between atria and ventricles
-permit blood flow in one direction
-pressure from ventricular contractions closes valves
-prevent back flow from ventricles to atria
-each AV valve has three parts
-right AV is aka tricuspid valve
-left AV is aka bicuspid or
Semilunar Valves (SL)
-between ventricles and large arteries
-prevent back flow from arteries to ventricles
-cusps of fibrous connective tissue
(extend from the wall at the beginning of lrg arteries)
-each valve has 3 cusps
-cusps fill with blood when ventricles relax
(closing
What are the three parts of the AV Valve?
-cusp
-chordae tendinae
-papillary muscle
Cusp
-blocks blood flow
Chordae tendinae
-fibrous strands that connect cusps to myocardium
Papillary muscle
extensions of myocardium that attach to chordae tendinae
Function of AV valves
-close during ventricular contraction
-blood pushed upwards fills cusps
-chordae tendinae are pulled tight when myocardium contracts. (causes contraction of papillary muscle)
-tight chordae tendinae prevent cusps from inverting
-cusps close with enough fo
Regurgitation
failure of valves causing some back flow
Structural differences between left and right ventricle: LEFT VENTRICLE
-left has larger, thicker muscle than right
(contract with force)
-Left chamber is more round which allows more pressure to be generated during ventricular contraction
structural differences between left and right ventricle: RIGHT VENTRICLE
-right wall is thinner, develops less pressure than left ventricle
-is pouch shaped
Similarities of right and left ventricles
both hold same volume of blood
What do connective tissue fibers of the heart do
-physically support cardiac muscle fibers
-distribute forces of contraction
-add strength and prevent over expansion of heart
-elastic fibers return heart to original shape after contraction
Fibrous skeleton
-4 bands around heart valves and bases of pulmonary trunk and aorta
-stabilize valves
-electrically insulate ventricular cells from arterial cel
(allow atria and ventricles to contract independently)