The Heart: Gross Anatomy Flashcards
1
Q
Layers of the heart
A
- Endocardium:
- simple squamous epithelium(endothelium) that lines all heart chambers and valves
- function: reduces trauma to blood cells against heart walls - Myocardium:
- cardiac muscle thicker on left side
- function: pumps blood within/from heart - Pericardium:
- external serous membrane
- parietal pericardium
- visceral pericardium or “epicardium”
function: isolates/lubricates heart
2
Q
Chambers
A
- Atria (L and R):
- receiving chambers for incoming venous blood.
- prenatal connection= foramen ovale (allows blood to bypass the lungs) - Ventricles (L and R): pumping chambers of outgoing arterial blood
3
Q
Major Associated Vessels
A
- Inferior Vena Cava:
- vein entering lower right atrium that receives blood from lower extremities and abdomen - Superior Vena Cava:
- vein entering upper right atrium that receives blood from head and upper exttemities - Pulmonary Artery:
- from right ventricle branching to lungs
- fetal connection with aorta = ductus arteriosus (changes to ligamentum arteriosus after birth) - Pulmonary veins (4): from lungs to left atrium
4
Q
Aorta:
A
-leaves left ventricle
- coronary vessels:
- R and L coronary arteries are first branches of aorta, which supply oxygen to myocardium.
- cardiac veins—->coronary sinus; return blood from myocardium to R atrium - aortic arch:
aortica arch—->thoracic aorta
-possesses 3 major branches: brachiocephalic, L common carotid, L subclavian
5
Q
Heart Valves
A
- prevent backflow(“regurgitation”)
- Atrioventricular:
- R=tricuspid L=mitral
- flaps restrained by chordae tendinae, connected to papillary muscles - Semilunar:
- R=pulmonary L=aortic
- valves sealed by overlap of three cusps
6
Q
Cardiac cycle
A
- atrial relaxation (blood enters both atria)
ventricular contraction(systole) blood leaves ventricles
-AV valves closing “Lub” sound
- semilunar valves open - atrial contraction (blood leaves both atria)
ventricular relaxation (diastole) blood fills ventricles
-AV valves open
- semilunar valves closing “Dub” sound
7
Q
Coordination and control of the heart:
A
- Pacemaker= sinoatrial (SA) node
- Superior/posterior portion of right atrium that sets contractile rate for both atria - Receiver= atrioventricular (AV) node
- on lower interatrial septum
- accepts electrical excitation from atria - Transmitter=atrioventricular bundle
- connected to AV node
- spreads excitation through ventricular walls via the conduction myofibers(Purkinje fibers) - heart rate
- suppressed by parasympathetic nerves (vagus)
- accelerated by sympathetic nerves (T-1 through T-5)
8
Q
Arteries
A
Three tissue layers:
- tunica interna (intima):
- simple squamous epithelium over thin layer of elastic connective tissue - tunica media:
- elastic fibers and circular smooth muscle - tunica externa:
- elastic and collagenous fibers
9
Q
veins
A
Three tissue layers:
- tunica interna:
- less connective tissue than arteries of similar size - tunica media:
- less smooth muscle than arteries - tunica externa:
- slightly thicker than arteries
~veins carry blood at lower pressures than arteries;collapsible
~venous valves: two endothelial flaps prevent back flow, especially in veins below heart
10
Q
capillaries
A
- microscopic vessels carrying blood between arterioles and venules
- One cell layer (tunica interna):
- simple squamous epithelium permits diffusion of O2/ CO2, nutrients, and wastes to/from adjacent tissue cells.
11
Q
pulmonary circulation
A
- circuit through the lungs for reoxygination of the blood and elimination of CO2
1. capillary network surround alveoli pick up O2 and release CO2
2. pulmonary veins: - two from both lungs
- return oxygenated blood to left atrium
12
Q
systemic circulation
A
-circuit to deliver oxygen/nutrients to all organs and return CO2 and waste products to the heart.
13
Q
hepatic portal circulation
A
- portal vein:
- receives venous blood from splenic vein, gastric vein, inferior mesenteric vein, superior mesenteric vein
- circuit from organs of the digestive tract to the liver
- stores, modifies, or detoxifies substances from g.i. tract and adds plasma proteins and glucose to blood
- returns blood systemic circulation vie hepatic veins
14
Q
plasma
A
-90% water
-cell nutrients, wastes, hormones, blood gases
-plasma proteins: confined to the bloodstream; produced in liver
~albumin
~globulins(alpha/beta/gamma)
~fibrinogen and prothrombin (coagulation)
15
Q
RBC production (erythropoiesis)
A
- develop in red bone marrow
hemocytoblast(stem cell)—>erythroblast(hemoglobin forming)—>reticulocyte(nucleus expelled)—>erythrocyte(mature RBC) - RBC contain “hemoglobin”:
- heme=red, iron containing pigment that carries O2
- globin=protein portion that carries CO2 - RBC production stimulated by “erythropoietin”, a hormone from the kidney
- RBC destruction in liver or spleen:
- macrophages phagocytize worn or damaged cells
- globin returned to circulation
- heme—> iron(recycled of restored) bilirubin (excreted in bile)
