CV and Heart Development Flashcards
3 vessels tunics
- tunica intima: thin endothelial lining
- tunica media: middle smooth muscle layer
- tunica adventitia: outer connective tissue coat
Veins, 2 mechanisms
- Skeletal muscle pump
- Venous valves
preventing backflow of blood,
however, they do not eliminate it
Azygous system
venous system drains blood from the thoracic wall and some thoracic viscera into the SVC, it consists of the following unpaired vessels:
1. azygous vein
2. hemizygous vein
3. accessory hemizygous vein
right side of heart
receives oxygen-poor blood from body
tissues and pumps it to the lungs where gas exchange takes place; blood vessels that carry blood to and from the lungs form the pulmonary circuit
left side of heart
receives oxygenated blood and pumps it
throughout the body to supply nutrients to the body tissues; vessels that transport blood to and from all body tissues form the systemic circuit
Heart positioning
- posterior to the sternum and costal cartilages
- superior surface of the diaphragm
- oblique position within the thorax, its apex lies to the left of the midline and anterior to the rest of the heart
Pericardium layers
- fibrous pericardium – the outer layer of the sac, dense CT holds the heart in place, prevents blood overflow
- serous pericardium – deep to the fibrous
pericardium, 2 layers: parietal layer: inner surface of fibrous pericardium, visceral layer: epicardium, outer layer of heart wall
Heart wall layers
- epicardium: superficial, visceral layer of the serous pericardium
- myocardium: bulk of heart, cardiac muscle
- endocardium: deep, lies lines the heart chambers and covers the heart valves
Heart chambers
Internal:
- separate the atria from the ventricles:
interatrial and interventricular septum
External:
- coronary sulcus – divides the atria and ventricles.
- anterior and posterior interventricular sulci, separate the ventricles
Right atrium
Receives oxygen-poor blood from the systemic circuit, SVC, IVC, and coronary sinus
- Crista terminalis – a muscular ridge separating the anterior and posterior parts of the atrium
- Fossa ovalis - a depression in the interatrial septum, opens into RV tricuspid
valve (right atrioventricular valve)
Right ventricle
Gets blood from RA, pumps into the
pulmonary circuit via the pulmonary trunk
- Trabeculae carneae – ventricular muscle ridges.
- Papillary muscles – project from the walls into the cavity.
- Chordae tendineae – strong bands that project superiorly from the PM and anchor the cusps of the tricuspid valve.
- Pulmonary semilunar valve – at the opening between the RV and the PT
Left Atrium
Receives O2 blood from lungs via 4 pulmonary veins, Smooth interior.
- Left auricle (pectinate muscles).
- Pumps blood through the bicuspid valve (mitral, or left atrioventricular valve) to the left ventricle
Pulmonary circuit
SVC and IVC → coronary sinus → right
atrium → right ventricle → pulmonary trunk → lungs
Systemic circuit
lungs → pulmonary veins → left atrium → left ventricle → aorta → body
Atrioventricular (AV) valves
between the atria and ventricles.
- right atrioventricular valve – 3 cusps (tricuspid)
- left atrioventricular valve – 2 cusps (bicuspid, mitral)
prevent blood backflow into atria
Aortic and pulmonary valves
at the junctions of the ventricles and the great arteries (aorta and pulmonary trunk), also called semilunar due to shape of their cusps
Semilunar valves
Prevent backflow from the great arteries into the ventricles
Cardiac muscles
conduct impulses, signal the cardiac muscle cells to contract rhythmically
SA node - sets the inherent rate of contraction (RA), impulses spread to the atria, signaling the atria to contact
Autonomic nerve fibers
- anterior to bifurcation of trachea
- posterior to ascending aorta
SA node
sinoatrial (SA) node (the pacemaker) sets the inherent rate of contraction (in the wall of the right atrium). impulses spread to the atria, signaling the atria to contact, then to ventricles
Arteries: blood carried away from heart
- large elastic (e.g. aorta and its arch
branches): elastic layers allow
expansion when heart contracts. - medium muscular (femoral artery): ability to distribute regulates blood flow to
different parts of the body as required. - small arteries and arterioles: narrow
lumina and thick muscular walls
Veins: blood carried to heart
- have thinner walls compared to companion arteries due to lower BP in VS variable and anastomose.
- Smallest veins and venules form plexuses.
- Medium veins in limbs: valves permit
blood flow toward heart; another
mechanism: musculovenous pump. - Large veins (SVC & IVC): wide bundles of longitudinal smooth muscle
Capilllaries
- Continuous – most common type – formed of tight junctions – small molecules are forced to pass between capillaries at intercellular clefts between membranes
- Sinusoidal – Rarer – wider, leaky capillaries that allow transfer molecules that are larger
Aorta
- Ascending aorta: coronary arteries
- Aortic arch: arteries to head, neck,
upper limbs - Descending thoracic & abdominal aorta: arteries to thorax, abdomen, pelvis, lower limbs
Blood
Erythrocytes: Red blood cells (oxygen
carrying cells)
Leukocytes: White blood cells (defense
cells)
Platelets: Clotting cells
Transverse and Oblique Pericardial Sinuses
- Transverse sinus: space posterior to aorta and pulmonary trunk and anterior to SVC
- Oblique sinus: a wide recess posterior to heart framed by SVC, IVC, and PV
Internal and External divisions
- Internal divisions: separate the atria from the ventricles, interatrial and interventricular septum.
- External divisions, coronary sulcus – divides the atria and ventricles, anterior and posterior interventricular sulci separate the ventricles
