The Heart Flashcards
What are the different pleural structures in the thoracic cavity?
Mediastinal parietal pleura: the serosa on the mediastinum
Pericardial pleura: part of the mediastinal pleura
Costal parietal pleura: the serosa lining the thoracic wall
Diaphragmatic parietal pleura: the serosa lining the diaphragm’s thoracic side
Which structures are contained within the mediastinum?
Heart, thymus, esophagus, trachea, vessels, nerves.
Which animals have an incomplete mediastinum?
Dogs, sheep, horses.
What is the apex of the heart?
pointed, free-end, directed caudally and ventrally
What is the base of the heart?
directed cranially and dorsally, continuous with the large arteries and veins.
What structure forms the apex of the heart?
Left ventricle forms the apex of the heart.
Where is the heart located within the thoracic cavity?
Located between the 2nd and 6th intercostal spaces.
What is the structure of the pericardium?
Structure is divided into the fibrous and serous pericardium.
Fibrous pericardium is the strong outer covering.
Serous pericardium lines the pericardial cavity.
What are the three layers of the heart wall?
- Epicardium
- Myocardium
- Endocardium
What are the names of the right/left A-V (atrioventricular) valves?
Left A-V: “Mitral” valve
Right A-V: “Tricuspid” valve
What are the names of the semilunar valves?
Left semilunar valve: Aortic valve
Right semilunar valve: Pulmonic valve
Pericardium
fibrous sac that the heart is pushed into during development
Fibrous pericardium
strong outer covering, made of thick connective tissue
Visceral pericardium
fused to the muscle of the heart
Parietal pericardium
outer layer of the pericardium, fused to the fibrous pericardium
Pericardial space
potential space between the visceral and parietal pericardium, contains a small amount of fluid to provide lubrication.
Coronary groove
separates the atria from the ventricles, contains the left circumflex and right coronary arteries/veins.
Interventricular groove
descend from the coronary groove and divide the left and right ventricles.
Chordae tendinae
tough fibrous cords that are extensions of the valve leaflets
Moderator band
thin muscular strand that runs from the interventricular septum to the free wall of the right ventricle.
Interventricular septum
separates the left ventricle and the right ventricle
Auricles
ear-shaped structures attached to each atria
Papillary muscles
The papillary muscles project like nipples into the cavities of the ventricles.
They are attached by fine strands of tendon to the valves between the atria and ventricles and prevent the valves from opening when the ventricles contract.
Found in A-V and L/R ventricles
Trabeculae carnae
Rounded or irregular muscular columns which project from the whole of the inner surface of the ventricle.
Serve a similar function to papillary muscles in that their contraction pulls on the chordae tendinae, preventing inversion of the mitral (bicuspid) and tricuspid valves.
Fossa ovale
Remnant depression of varying shapes, located in the inferior aspect of the right interatrial septum.
Ligamentum arteriosum
connects the descending aorta with the left pulmonary artery
Which side of the heart has thicker walls? Right or left?
Left ventricle has thicker walls.
What are the three segments of the aorta?
- Ascending aorta
- Transverse arch
- Descending aorta
What structures emerge from the transverse arch of the aorta?
- Brachiocephalic trunk
- Left subclavian artery
Describe the coronary vasculature of the dog.
Right and left main coronary arteries arise from the root of the aorta.
Left main coronary artery is short, divides almost at once. Branches into the circumflex branch and the paraconal interventricular branch.
Right main coronary artery lies in the right atrioventricular groove. Supplies about ⅔ of the right ventricular free wall and the right atrium with blood via ventricular branches.
What are the three layers of arterial walls?
- Tunica interna
- Tunica media
- Tunica adventitia
Arterioles
smallest arteries, muscle is reduced to just a few layers.
Capillaries
Narrow tubes lined by endothelial cells.
Wider, less regular, and more commonly fenestrated.
Fluid passes through them from the blood into the interstitial tissue.
Sinusoids are special capillaries found in certain organs.
Veins
thinner-walled than arteries.
A type of blood vessel that return deoxygenated blood from your organs back to your heart
Venules
smallest veins and receive blood from capillaries
Red blood cells (RBC)
-contain hemoglobin
-biconcave disc
-increased surface area to volume ratio
-efficient for diffusion of gasses
-formed in bone marrow
-no nucleus (mammals)
-life span: 120 days
Neutrophils
-granules stain neither red or purple
-can phagocytize material
-main targets are bacteria and fungi
-granules contain hydrogen peroxide, collagenase, lactoferrin
-multilobed nucleus
-short life span: hours to few days
~60-70% of white blood cells
Eosinophils
-have pink granules
-bilobed nucleus
-participate in parasitic and allergic reactions
-granules contain histamine, peroxidase, ribonuclease, deoxyribonuclease
-Life span: 8-12 days
Basophils
-granules stain purple
-not phagocytic
-similar to mast cells found in tissues
-plays a role in allergic responses
-granules contain histamine, bradykinin, serotonin, and lysosomal enzymes
-life span: few hours to days
-bilobed/trilobed nucleus
Lymphocytes
-round nucleus
-small amount of blue cytoplasm
-participate in immune response (NK cells, T-cells, B-cells)
Natural Killer Lymphocytes
-part of the innate immune system
-destroys tumor cells and virally infected cells
T-Lymphocytes
-formed in bone marrow
-mature in thymus
-participate in cell-mediated immunity
-two major subtypes: helper T cells and cytotoxic T cells
B-Lymphocytes
-mature in bone marrow
-participates in the humoral response (secretes antibodies)
Monocytes
-blue cytoplasm
-nucleus that is no round; bean shaped, horseshoe-shaped
-produced in bone marrow
-circulate briefly in blood, then migrate to tissues
-mature into macrophages
Platelets
-small and has NO nucleus
-plays role in clotting blood
-have small pink granules
-formed by megakaryocytes in the bone marrow
What structures are connected by the ductus arteriosus and what is it analogous to?
Ductus arteriosus connects the aorta and the pulmonary artery.
Function to shunt blood from the pulmonary trunk into the aorta.
Enters the aorta distal to the origin of the brachiocephalic trunk, therefore supplying the caudal body without diluting the blood going to the brain via common carotid arteries.
Analogous to ligamentum arteriosum.
What structures are connected by the ductus venosus and what is it analogous to?
Ductus venosus connects the umbilical vein with the caudal vena cava.
Allows some of the umbilical blood to bypass the liver and empty directly into the caudal vena cava.
Analogous to ligamentum venosum (forms into this structure)
What structures are connected by the foramen ovale and what is it analogous to?
Foramen ovale is an aperture in the muscular tissue between the left and right atrium that allows blood to cross the atria and bypass pulmonary circulation during fetal development.
Analogous: Closes at birth, eventually forms the fossa ovalis.
