Chapter 17: The Heart Flashcards
Parts of the cardiovascular system
- Heart
- Blood vessels
- Blood
Function of cardiovascular system
- Pump blood into blood vessels and distribute oxygen throughout the body
Heart
A pump that contracts rhythmically to deliver blood to the body
Mediastinum
Subdivision of the thoracic cavity which houses the heart, great blood vessels, trachea, and esophagus
Pericardial cavity
Subcavity of the mediastinum
Orientation of the heart
- Apex points toward the left hip
- Flattened base on the posterior side
Chambers of the heart
- Atrium (R & L)
- Ventricle (R & L)
Atrioventricular sulcus
An external indentation found at the boundary between the atria and ventricles
Interventricular sulcus
- An external indentation found at the boundary between the ventricles
- AKA interventricular groove
Veins
Blood vessels that bring blood to the heart
Veins that directly feed the heart
- Superior/inferior vena cava
- Pulmonary veins
Arteries
Blood vessels that carry blood away from the heart
Arteries that connect directly to the heart
- Pulmonary trunk
- Aorta
Great vessels
The main veins and arteries that transport blood toward and away from the heart
Circuits of the cardiovascular system
- Pulmonary circuit
- Systemic circuit
Pulmonary circuit
Series of blood vessels which direct blood from the heart to the lungs to receive oxygen
Systemic circuit
Series of blood vessels which direct blood from the heart to the body to deliver oxygen
Where does gas exchange take place?
In the alveoli
Alveoli
- Tiny air sacs in the lungs
- Smallest vessels of the pulmonary circuit
Low-pressure circuit
Pulmonary circuit
High-pressure circuit
Systemic circuit
Functions of the heart
- Pump blood
- Maintain BP homeostasis
- Atria acts as as an endocrine organ
What hormone do the atria produce?
Atrial natriuretic peptide (ANP)
Function of ANP
Lowers BP by decreasing sodium ion retention in the kidneys
Pericardium
The membranous structure surrounding the heart
Components of the pericardium
- Fibrous pericardium
- Serous pericardium
Fibrous pericardium
A tough outer layer that attaches the heart to surrounding structures
Serous pericardium
A thin inner serous membrane that produces serous fluid
What result do the collagen bundles in fibrous pericardium have?
- Make it tough
- Anchor the heart to surrounding structures
- Low distensibility (doesn’t change shape when forces are applied)
Layers of the serous pericardium
- Parietal pericardium
- Visceral pericardium
Parietal pericardium
Encases the heart like a sac
What happens when the parietal pericardium reaches the great vessles
Folds under itself and attaches itself directly to the heart
Visceral pericardium
- AKA epicardium
- Considered the most superficial layer of the heart wall
Important consideration about pericardium
Parietal and visceral pericardium are actually one continuous structure
Pericardial cavity
Space between parietal and visceral pericardia filled with pericardial fluid
Pericardial fluid
Serous fluid which fills the space between parietal and visceral pericardia
Function of pericardial fluid
Acts as a lubricant, decreasing friction as the heart moves
Layers of heart wall
- Epicardium (visceral pericardium)
- Myocardium
- Endocardium
Myocardium
Thickest heart wall layer
Components of myocardium
- Cardiac muscle tissue
- Fibrous skeleton
Cardiac muscle cells
Myocytes
Fibrous skeleton of myocardium composition
- Irregular collagenous connective tissue
- Located in regions that need additional support
Fibrous skeleton of myocardium function
- Giving cardiac myocytes something to pull on when they contract
- Provide structural support
- Act as an insulator for the heart’s electric activity
Endocardium
Composed of endothelium and several layers of connective tissue with elastic and collagen fibers
Endothelium
A special type of simple squamous epithelium
Function of endothelium
Regulate the concentration of electrolytes and other chemicals in the extracellular fluid of the myocardium
Superior vena cava
Drains deoxygenated blood from most veins superior to the diaphragm
Inferior vena cava
Drains deoxygenated blood from most veins inferior to the diaphragm
Pulmonary trunk
Receives deoxygenated blood pumped from the right ventricle
Pulmonary veins
Returns oxygenated blood from the lungs to the heart
Aorta
- Supplies the entire systemic circuit with oxygenated blood
- Ascending aorta –> aortic arch
Structural differences between atria and ventricles
- Ventricles have thicker walls and are larger
- Thicker walls make them stronger pumps
Differences between atria
- Right atrium is large, thin-walled, and anterior
- Right atrium has a larger auricle
Auricle
A muscular pouch found in each atrium
Function of auricle
Expand to give the atria more space to hold blood
Pectinate muscles
Muscular ridges on the internal surface of the right atrium
Interatrial septum
Thin wall which separates the atria
Fossa ovalis
- Small indentation in the interatrial septum
- Remnant of a hold in the fetal heart called the foramen ovale
Function of foramen ovale
Direct blood from the right atrium directly to the left atrium
Differences between right and left ventricles
Right ventricle - Thin wall - Crescent-shaped Left ventricle - Thick wall - Circular
Trabeculae carneae
Ridged surface in each ventricle created by irregular protrusions of cardiac muscle
Papillary muscles
Finger-like projections which attach by the chordae tendineae to the atrioventricular valves
Chordae tendineae
Tendon-like cords which connect the papillary muscles to the atrioventricular valves
Interventricular septum
A thick, muscular wall separating the right and left ventricles
Atrioventricular valves
The valves between the atria and ventricles
Right AV valve
Tricuspid valve
Left AV valve
- Bicuspid valve
- AKA mitral valve
Semilunar valves
- Prevent backflow into the ventricles
- Pulmonary valve
- Aortic valve
Coronary Circulation
- Blood vessels that supply oxygen and nutrients to the heart
- Part of systemic circulation
Coronary arteries
- Right and left
- Immediate branches after the ascending aorta
Marginal artery
- The largest branch of the right coronary artery
- On the inferior margin of the heart
Posterior interventricular artery
- After marginal artery
- Curls around to the posterior side
- Travels in the posterior interventricular sulcus
Anterior interventricular artery
- AKA leeft anterior descending artery (LAD)
- Travels along the anterior interventricular sulcus
Circumflex artery
- Curves along the left AV sulcus and flexes around the heart
- Supplies the left atrium and parts of the left ventricle
Coronary sinus
A large venous structure on the posterior heart into which the majority of the heart’s veins empty
Major veins supplying the coronary sinus
- Great cardiac vein
- Small cardiac vein
- Middle cardiac vein
Great cardiac vein
- Ascends along the anterior interventricular sulcus
- Then travels to the posterior side of the heart along the left AV sulcus
- Drains the left atrium and much of both ventricles
Small cardiac vein
- Travels along the right AV sulcus
- Drains the right atrium and parts of the right ventricle
Middle cardiac vein
- Travels along the posterior interventricular sulcus
- Drains mostly the posterior left ventricle
Plaques
Buildup of fatty material in the arteries
Coronary Artery Disease
- CAD
- Buildup of fatty material in the coronary arteries
- Decreases blood flow to the myocardium, decreasing its oxygenation
Myocardial ischemia
Decreased oxygenation due to decreased blood flow
Angina pectoris
Chest pain
Myocardial infarction
- Heart attack
- Occurs when plaques in the coronary arteries rupture
- Clot forms that obstructs blood flow to the myocardium
Coronary angioplasty
- An invasive procedure during which a ballon is inflated in the blocked artery
- A wire-mesh tubing (stent) is inserted to keep it open
Action potential
Electrical excitation
Pacemaker cells
Modified cardiac muscle cells which rhythmically and spontaneously generate action potentials
Autorhthymicity
Sets its own rhythm without need for input from the nervous system
Intercalated discs
Join adjacent cardiac muscle cells
Selective gated ion channels
- Voltage-gated sodium ion channels
- Calcium ion channels
- Potassium ion channels
- Nonselective cation channels
Voltage-gated sodium ion channels
Found in call cardiac muscle cells except certain pacemaker cells
Calcium ion channels
- Present in all cardiac muscle cells
- Voltage-gated opening
- Time-gated closing
Potassium ion channels
Present in all cardiac muscle cells
Nonselective cation channels
- Unique to certain pacemaker cells
- Activated by hyperpolarization
- Allow sodium ions to enter the cell while potassium ions exit
