BLG111 Quiz 1: Chapters 17 & 18 Flashcards
What are the components of blood?
Blood is a type of connective tissue and a fluid matrix called plasma. It is composed of formed elements suspended in plasma:
- Erythrocytes (red blood cells)
- Leukocytes (white blood cells)
- Platelets
How is bleeding stopped when there is a cut in a blood vessel?
Hemostasis, which requires clotting factors and consists of three steps:
1. Vascular spasm
2. Platelet plug formation
3. Coagulation (blood clotting)
What happens when someone with blood type A+ donates their blood to someone with blood type B-?
Agglutination of the donated blood will occur in the recipient for two reasons:
1. Anti-A antibodies (already present in the recipients blood) will bind to the A antigens of the donor red blood cells and cause agglutination
2. There would also be a delayed production (within 3-5 days) in the recipient of anti-Rh antibodies which will bind to the donor’s Rh antigens (because the donor is Rh+) which will cause more agglutination as well as memory B cell production.
Which of the following blood groups has antibodies that can agglutinate O-blood?
a. Type A+
b. Type B-
c. Type AB+
d. None of the above
None of the above. O blood does not contain A or B antigens and is therefore the universal donor. It also does not contain any Rh.
The universal recipient for blood transfusions is?
AB+. This blood type has both A and B and therefore will not agglutinate. It is also Rh+ and will not attack Rh.
What blood combination would result in hemolytic disease of the newborn?
An Rh- mother with an Rh+ baby
Outline the route blood takes starting at the left atrium and returning to the left atrium.
Oxygen-rich blood is released from the left atrium to the left ventricle, as the mitral valve releases due to pressure. Increased pressure causes the Aortic semilunar valve to open and the blood flows into the body via the systemic circuit. Oxygen-poor blood now returns via the Superior vena cava and Inferior vena cava to the Coronary sinus. It then fills the right atrium. Pressure in the right atrium causes the tricuspid valve to release and blood flows into the right ventricle. Pressure causes the pulmonary semi lunar valve to open and blood flows into the pulmonary trunk where it flows through the pulmonary arteries of the lungs to release CO2 and receive O2. Oxygen rich blood returns to the heart via the four pulmonary veins and is released into the right Atrium. See slide 23 Ch 18.
Explain the conduction system of the heart and the resultant cardiac contraction
- The sinoatrial (SA) node generates impulses (pacemaker)
- The impulses pause (0.1s) at the atrioventricular (AV) node
- The atrioventricular bundle connects the atria to the ventricles
- The bundle branches conduct the impulses through the ventricular septum
- The subendocardial network depolarizes the contractile cells of both ventricles
What is cardiac output?
Stroke volume x Heart rate
The right side of the heart…
a. pumps blood to the lungs
b. pumps blood to the body
c. contains the mitral valve
d. both a and c
a. pumps blood to the lungs
If the bundle branches are surgically removed, what happens?
No more impulses would occur in the Purkinje fibers
“Dup” is?
the second heart sound
What does the P wave show us?
depolarization of the atria
Blood returning to the right side of the heart is?
Deoxygenated
The ECG wave produced during ventricular repolarization is the…?
T wave
What part of the ECG recording occurs at the beginning of ventricular diastole?
T wave
What are the functions of blood?
Transport, regulation, protection
Maintaining normal pH using blood buffers is an example of what function of blood?
Regulation
What is hematocrit?
The percent of blood volume that is RBCs (typically 45%)
What is the Buffy coat?
Consists of white blood cells and platelets (typically 1%)
What is the pH range of the blood?
7.35-7.45
What percentage of body weight does the blood make up?
8%
What is the most abundant plasma protein, making up 60% of plasma? Why is it important?
Albumin is responsible for plasma colloid osmotic pressure - it ensures that fluids stay within the vascular compartment
Which formed element is considered a ‘complete cell’?
White blood cell. RBCs have no nuclei or other organelles, platelets are cell fragments.
What three features make RBCs efficient for gas transport?
- Biconcave shape offers huge surface area relative to volume for gas exchange
- Hemoglobin makes up 97% of cell volume (binds reversibly with oxygen)
- No mitochondria; ATP production is anaerobic - they do not consume oxygen, just transport
What are normal levels of hemoglobin?
14-16g/100mL
The formation of all blood cells is a process called…?
Hematopoiesis
Where does hematopoiesis occur?
Red bone marrow
Where can the red bone marrow for hematopoiesis be found?
Axial skeleton, girdles, proximal epiphyses of humerus and femur
What is the stem cell that gives rise to all formed elements?
Hemocytoblast
What causes hypoxia?
- Decreased RBC numbers possibly due to hemorrhage or increased destruction
- Insufficient hemoglobin per RBC (i.e., iron deficiency)
- Reduced availability of oxygen (i.e., pneumonia)
Describe how the kidneys regulate erythropoiesis
- At low oxygen levels, oxygen-sensitive enzymes in the kidney cells cannot degrade hypoxia-inducible factor (HIF), HIF accumulates
- The kidney releases erythropoietin
- Erythropoietin stimulates red bone marrow
- Enhanced erythropoiesis increases RBC count
- Oxygen carrying ability of blood rises, EPO stimulation is stopped
What is Anemia?
Blood has abnormally low oxygen-carrying capacity that is too low to support normal metabolism, can be the result of blood loss, not enough RBCs produced, too many RBCs being destroyed.
An autoimmune disease the destroys stomach mucosa that produces intrinsic factor which is needed to absorb B12 is known as which type of anemia?
Pernicious
Aplastic anemia results in…?
The destruction of red bone marrow
What is polycythemia?
An abnormal excess of RBCs; increases blood viscosity, causing sluggish blood flow
What are the 5 types of leukocytes?
Neutrophils, Eosinophils, Basophils, Lymphocytes, Monocytes
Which leukocytes are considered ganulocytes?
Neutrophils, Eosinophils, Basophils
What is the role of interleukins?
Proteins that determine a lymphoid or myeloid stem pathway in leukopoiesis. Lymphoid stem cells produce lymphocytes, myeloid stem cells produce all other elements.
What is leukemia?
Cancerous condition involving the overproduction of abnormal WBCs.
Describe coagulation
- Initiated by either intrinsic (internal clotting factors) or extrinsic pathways (exposure to tissue factor)
- Prothrombin activator catalyzes transformation of prothrombin to active enzyme thrombin
- Thrombin converts soluble fibrinogen to fibrin
What factors limit normal clot growth?
- Swift removal and dilution of clotting factors
- Inhibition of activated clotting factors
What factors prevent undesirable clotting?
- Smooth endothelium of blood vessels prevents platelets from clinging
- Endothelial cells secret antithrombic substances such as nitric oxide and prostacyclin
- Vitamin E quinone
What is the difference between a thrombus and an embolus?
Thrombus is a clot that develops and persists in an unbroken blood vessel; an embolus is a thrombus that freely floats in the blood stream
Briefly describe the pulmonary and systemic circuit
The right side receives oxygen-poor blood from tissues, pumps the blood to the lungs to get rid of Carbon dioxide and picks up oxygen via the pulmonary circuit; the left side receives oxygenated blood from the lungs, pumps blood to the body tissues via the systemic circuit
What are the four coverings of the heart?
- Pericardium: double-walled sac that surrounds heart and is made up of two layers:
- Fibrous pericardium: functions to protect, anchor heart to surrounding structures, prevent over-filling
- Serous pericardium: deep, two-layered:
- Parietal and Visceral layers: line the internal surface of fibrous pericardium and external surface of the heart and are separated by a fluid-filled pericardial cavity that acts to decrease friction
What are the three layers of the heart wall?
- Epicardium: visceral layer of serous pericardium
- Myocardium: circular or spiral bundles of contractile cardiac muscle
- Endocardium: innermost layer; is continuous with endothelial linin of blood vessels made up of simple squamous epithelium
What are the heart valves, where are they located, and what are they responsible for?
The heart valves ensure unidirectional blood flow through the heart. They open and close in response to pressure changes. There are two major types: The Atrioventricular valves (tricuspid/right, mitral/left) and the Semilunar valves (pulmonary valve/right, aortic/left)
What is the function of the Chordae tendineae?
They anchor cusps of AV valves to papillary muscles that function to hold valve flaps in a closed position and prevent flaps from everting back into atria
Why are the left ventricle walls thicker than the right ventricle walls?
Left ventricle is involved in the systemic circuit was is a long, high-friction circulation
What is coronary circulation?
Coronary circulation provides the functional blood supply to the heart muscle itself and is delivered when the heart is relaxed
What is Angina pectoris?
Thoracic pain caused by fleeting deficiency in blood delivery to myocardium, cells are weakened
What are intercalated discs?
Connecting junctions between cardiac cells that contain desmosomes (hold cells together, prevent cells from separating during contraction) and gap junctions (allows ions to pass from cell to cell; electrically couple adjacent cells) - this allows the heart to be a function syncytium; a single coordinated unit
What are some similarities between skeletal muscle and cardiac muscle?
- Muscle contraction is preceded by depolarizing action potential
- Depolarization wave travels down T tubules; causes sarcoplasmic reticulum (SR) to release Calcium 2+
- Excitation-contraction coupling, Ca 2+ binds to troponin causing filaments to slide
What are some differences between skeletal muscle and cardiac muscle?
- Some cardiac muscle cells are self-excitable (i.e., pacemaker)
- Influx of Ca 2+ from extracellular fluid triggers Ca 2+ release from SR
- Tetanic contractions cannot occur in cardiac muscle due to longer absolute refractory
Describe the steps in the intrinsic conduction system of the heart
- The sinoatrial node generates an impulse
- The impulses pause (0.1s) at the atrioventricular node
- The atrioventricular bundle connects the atria to the ventricles
- The bundle branches conduct the impulses through the interventricular septum
- The subendocardial conducting network depolarizes the contractile cells of both ventricles
A defective SA node may cause…?
Ectopic focus, an abnormal pacemaker that takes over pacing. If AV node takes over, it sets a junctional rhythm at 40-60 beats per min
Describe the extrinsic innervation of the heart
The heartbeat is modified by ANS via cardiac centers in the medulla olongata. The cardioacceleratory center sends signals through the sympathetic trunk to increase both rate and force; it stimulates SA and AV nodes, heart muscle, and coronary arteries. The cardioinhibitory center sends signals through the parasympathetic system via the vagus nerve to decrease rate, inhibits that SA and AV nodes via the vagus nerves.
What does and electrocardiogram measure?
Composite of all action potentials at a given time
What does an enlarged R wave indicated?
Possibly enlarged ventricles
What does elevated or depressed S-T segment indicate?
Cardiac ischemia
What does a prolonged Q-T interval reveal?
Repolarization abnormality that increases the risk of ventricular arrhythmias
What is isovolumetric contraction?
A split-second period when ventricles are completely closed (all valves closed) and volume remains constant, ventricles continue to contract
What is dicrotic notch?
The closure of aortic valve raises aortic pressure as backflow rebounds off closed valve cusps
How long is the cardiac cycle?
0.8 seconds; atrial systole lasts about 0.1 second and ventricular systole lasts about 0.3 seconds
What is cardiac output?
The amount of blood pumped out by each ventricle in 1 minute and is equal to heart rate times stroke volume
What is stroke volume?
Volume of blood pumped out by one ventricle with each beat and correlates with force of contraction
What three main factors affect SV?
- Preload: degree of stretch of heart muscle
- Contractility: epinephrine and norepinephrine increase contraction strength of the heart. They bind to receptor on hormone and increase cyclic AMP and more calcium is released from protein kinases and we get an increase in cross-bridge formation,
- Afterload: back pressure exerted by arterial blood - pressure that ventricles must overcome to eject blood
How do the sympathetic and parasympathetic nervous system influence heart rate and cardiac output?
The sympathetic nervous system releases norepinephrine that binds to B1 receptors and the pacemaker fires more rapidly; parasympathetic releases acetylcholine that hyperpolarizes and slows heart rate down
