heart Flashcards
main features of the conduction system of the heart
Sinoatrial (SA) node - establishes normal cardiac rhythm; myocardial conducting cells located in the superior/ posterior walls of right atrium near superior vena cava. the pacemaker.The impulse spreads from SA node throughout the atria to atrial myocardial contractile cells and atrioventricular node.
The wave of depolarization triggers contraction. right atrium, across the superior portions of atria then down through contractile cells. The contractile cells then begin contraction from the superior
to the inferior portions of the atria, pumping blood into the ventricles.
Atrioventricular (AV) node -
inferior portion of right atrium within atrioventricular septum. a critical pause before the AV node depolarizes and transmits the impulse to the atrioventricular bundle
Atrioventricular bundle, bundle of His: divide into two atrioventricular bundle. supplies l and r ventricles
Both bundle branches descend and reach the apex of the heart where they connect with the Purkinje fibers - myocardial conductive fibers that spread the impulse to the myocardial contractile cells in the
ventricles.
bodily landmarks to locate the heart
Dorsal surface of heart - near the vertebrae
Anterior surface - sternum and costal cartilages
great veins, superior and inferior venae cavae, great arteries, aorta, pulmonary trunk - attached to superior surface of the heart, aka the base.
base of the heart - at level of the third costal cartilage
inferior tip of heart aka apex - left of sternum between junction of the fourth and fifth ribs near their articulation with the costal cartilages. sl medial to the left midclavicular line.
**sl deviation of apex to the left!
depression in medial surface
of the inf. lobe of left lung, called the cardiac notch.
layers of the heart and their main features
- outer sturdy parietal pericardium: dense connective tissue. protects heart and maintains its position in the thoracic cavity
- inner visceral pericardium / epicardium: attached to heart, part of the heart wall.
- pericardial cavity: secretes
serous fluid lubricant to reduce friction - myocardium: cardiac muscle cells. contraction of myocardium pumps blood
- endocardium: innermost layer, joined to myocardium. lines chambers, covers heart valves. simple squamous epithelium aka endothelium, lines blood vessels. regulate contraction of myocardium & growth patterns of cardiac muscle cells, regulates ionic concentrations and contractility.
** left ventricle thicker and better developed for systemic circuit
main anatomical features of the cardiac skeleton and of each valve of the heart
Septa of the Heart– physical extensions of the myocardium lined with endocardium.
Interatrial septum - between the two atria; fossa ovalis, foramen ovale.
Interventricular septum - between two ventricles; intact. thicker than interatrial septum
Atrioventricular septum - between atria and ventricles. four openings that allow blood to move from atria into ventricles. from ventricles into pulmonary trunk and aorta
AV Valves - flaps are connected by chordae tendineae to the papillary muscles, which control opening/ closing of valves.
– Tricuspid valve - right atrioventricular valve
– Mitral valve, bicuspid valve or the left atrioventricular valve;
Semilunar valves - no chordae tendineae or papillary muscles
– Pulmonary valve, pulmonic valve, right semilunar valve -
right ventricle at base of the pulmonary trunk; 3 flaps. ventricle relaxes, & pressure differential causes blood to flow back in from pulmonary trunk.
– Aortic valve - prevents backflow from aorta. 3 flaps.
Cardiac skeleton – heavily reinforced with dense connective tissue. boundary in
the heart electrical conduction system.
which valves are open and closed during systole and diastole
Systole (contraction) - right and left ventricle walls contract to pump blood into pulmonary artery and aorta; tricuspid and mitral valves CLOSE; pulmonary and aortic valves OPEN
“Lubb” - closure of the tricuspid and mitral valve at the beginning of systole; the first heart sound (S1)
Diastole (relaxation) - ventricle walls relax and blood flows into the heart from venae cavae and pulmonary veins; tricuspid and mitral valves OPEN and blood goes from right and left atria into the ventricles; pulmonary and aortic valves CLOSE
“Dubb” - closure of the aortic and pulmonary valves at the end of systole; the second
heart sound (S2)
identify structures of the pulmonary circulation (slide 27 and 28)
see midterm study guide https://docs.google.com/document/d/163aUbEuB12PIDJJLnqJh1dKfUbRA3U4U96tQBO3rj2o/edit?usp=sharing
label the anatomical features/structures of the heart
see study guide https://docs.google.com/document/d/163aUbEuB12PIDJJLnqJh1dKfUbRA3U4U96tQBO3rj2o/edit?usp=sharing
trace a drop of blood through the heart
see study guide
main arteries of the coronary circulation
The left coronary artery distributes blood to left side of the heart, the left atrium and
ventricle, and the interventricular septum.
Circumflex artery arises from left coronary artery and follows coronary sulcus to the left -> all branches of right coronary artery.
larger anterior interventricular artery, or left anterior descending artery (LAD), also arise from left coronary artery. It follows anterior interventricular sulcus around pulmonary trunk, gives rise to smaller branches that interconnect with branches of posterior interventricular artery, forming anastomoses, allow blood to circulate to a region even if there may be partial blockage in another branch.
The right coronary artery proceeds along coronary sulcus and distributes blood to the right atrium, portions of both ventricles, and the heart conduction system.
marginal arteries arise from the right coronary artery inferior to the right atrium. supply blood to superficial portions of right ventricle.
on posterior surface of heart, right coronary artery gives rise to the posterior interventricular artery, also known as the posterior descending artery. along the posterior portion of the interventricular sulcus toward apex of the heart, giving rise to branches that supply the
interventricular septum and portions of both ventricles.
autorhythmicity and differences between myocardial contractile and conductile cells
Autorhythmicity - initiate an electrical potential at a fixed rate that spreads rapidly from cell to cell to trigger the contractile mechanism, but heart rate is also modulated by endocrine and nervous systems.
Myocardial contractile cells - (99 percent) of cells in the atria and
ventricles. conduct impulses and are responsible for contractions that pump blood
Myocardial conducting cells (1 percent of the cells) - conduction system of the heart. Except for Purkinje cells, they are generally much smaller than contractile cells. initiate and propagate the action potential (the electrical impulse) that travels throughout the heart and triggers the contractions
main histological features and characteristics of cardiac muscle
striations, the alternating pattern of dark A bands
and light I bands attributed to the precise arrangement of the myofilaments and fibrils that are organized in sarcomeres along the length of the cell
The sarcoplasmic reticulum stores few calcium ions, so most of the calcium ions must come from outside the cells. The result is a slower onset of contraction.
Mitochondria are plentiful, providing energy for the contractions of the heart.
usually a single, central nucleus,
cells branch freely.
A junction between two adjoining cells – intercalated disc, support the synchronized contraction of the muscle
aerobic respiration patterns, primarily metabolizing lipids and carbohydrates. Myoglobin, lipids, and glycogen are
all stored within the cytoplasm.
twitch-type contractions with long refractory periods
followed by brief relaxation periods. The relaxation is essential so the heart can fill
with blood for the next cycle.
main concepts of membrane potentials in both cardiac conductive cells and contractile cells
Conductive cells
- autorhythmicity: series of sodium ion channels allow a normal and slow influx of sodium ions that causes the membrane potential to rise slowly
- spontaneous depolarization (or prepotential depolarization).
- calcium ion channels open, further depolarizing it at a more rapid rate. calcium ion channels close and K+ channels open, repolarization.
- rapid depolarization, followed by a plateau phase and then repolarization. long refractory periods required for the cardiac muscle cells to pump blood effectively
Contractile cells
- more stable resting phase
- action potential
- voltage-gated sodium channels rapidly open, beginning positive-feedback mechanism of depolarization.
- positively charged ions raises the membrane potential, sodium channels close.
- Depolarization, plateau phase, opening of the slow Ca2+ channels, allowing Ca2+ to enter the cell while few K+ channels are open, allowing K+ to exit the cell
- Once membrane potential reaches approximately zero, the Ca2+ channels close and K+ channels open, allowing K+ to exit the cell.
Refractory period - This extended period is critical, since the heart muscle must
contract to pump blood effectively and the contraction must follow the electrical
events.
Understand the main functions of blood
main functions of blood
Primary fx: deliver oxygen and nutrients to and remove wastes from body cells
Also include defense, distribution of heat, and maintenance of homeostasis.
Transportation
- Nutrients: digestive tract - bloodstream - liver processes and releases back into the bloodstream for delivery to body cells.
- Oxygen: lungs - heart - rest of the body
- Hormones: bloodstream - distant target cells.
- Cellular wastes and byproducts - various organs for removal.
Defense
- WBCs protect the body from disease-causing bacteria, seek out and destroy cells with mutated DNA, body cells infected with viruses.
- repair damage to the vessels
Maintain Homeostasis - negative feedback systems
Body temperature regulation
pH balance - buffers
Regulation of water content of cells
What are the predominant proteins found in blood and their importance?
Plasma proteins:
Albumin
- 54% total protein volume
- Manufactured by liver
- binding proteins
- transport vehicles for fatty acids and steroid hormones.
- holds water inside the blood vessels and draws water from the tissues, across blood vessel walls, and into the bloodstream.
- maintain both blood volume and blood pressure.
Globulins
- 38% of total protein volume
- Alpha, beta globulins transport iron, lipids, and the fat-soluble vitamins A, D, E, and K to the cells. also contribute to osmotic pressure.
- Gamma globulins aka antibodies or immunoglobulins.
Fibrinogen
- least abundant plasma protein (7% of protein volume)
- produced by liver.
- essential for blood clotting.
What are the hematopoietic growth factors and their functions?
hematopoietic stem cell, or hemocytoblast. All of the formed elements of blood originate from this specific type of cell.
- hematopoietic stem cell is exposed to appropriate chemical stimuli collectively called hemopoietic growth factors, which prompt it to divide and differentiate.
- stem cells to precursor cells to mature cells
Erythropoietin (EPO)
- glycoprotein hormone secreted by the interstitial fibroblast cells of the kidneys in response to low oxygen levels.
- prompts the production of erythrocytes.
Thrombopoietin, another glycoprotein hormone, produced by liver and kidneys.
- triggers development of megakaryocytes into platelets.
Cytokines
- glycoproteins stimulating the proliferation of progenitor cells and helping to stimulate both nonspecific and specific resistance to disease.
two types:
- Colony-stimulating factors (CSFs): glycoproteins that act locally, as autocrine or paracrine factors. Some trigger the differentiation of myeloblasts into granular leukocytes CSFs,
- neutrophils,
- eosinophils
- basophils.
A different CSF induces the production of monocytes, called monocyte CSFs.
Interleukins: cytokine signaling molecules, play role in differentiation and maturation of cells, producing immunity and inflammation.
