Blood & the Heart Flashcards
Define hematocrit.
The percentage of blood occupied by cells.
What is the normal range & average hematocrit for females?
Normal range: 38-46%.
Average: 42%.
What is the normal range & average hematocrit for males?
Normal range: 40-54%.
Average: 45%.
Why do males tend to have a higher hematocrit level?
Testosterone stimulates RBC production.
Anemia is a condition where patients:
don’t have enough RBCs or hemoglobin.
Polycythemia is a condition where patients:
have too many RBCs (over ~65%).
What are 3 common causes of polycythemia? Why do they cause polycythemia?
Dehydration: causes low plasma levels = higher ratio of plasma:cells. Tissue hypoxia (not enough O2): stimulates production of hormones to create RBCs. Blood doping (athletes): transfusing hematocrit before performance.
Why is polycethemia dangerous?
Causes strain in the heart.
How are RBCs unique compared to other cells?
They have no nucleus, organelles or ribosomes because they are shed during differentiation.
Unique shape: biconcave discs.
Why is the shape and flexibility of a RBC advantageous (3)?
Larger surface area for O2 diffusion across membrane.
Thinness allows O2 to diffuse rapidly.
Can stack to go through a smaller vessel.
What is the primary role of hemoglobin?
Carrying O2.
What are 4 other molecules that hemoglobin can combine with?
CO2.
H+ from carbonic acid.
CO.
NO.
Describe the two parts of hemoglobin.
Globin portion: protein composed of 4 highly folded polypeptide chains.
Heme groups: 4 iron-containing nonprotein groups, each bound to one globin polypeptide.
What are the normal RBC counts (per drop) for males and females?
Males: 5.4 million/drop.
Females: 4.8million/drop.
Describe the 2 important erythrocyte enzymes.
Glycolytic enzymes: ATP formation.
Carbonic anhydrase: CO2 transport.
Where are erythrocytes developed?
Prenatally: prenatal yolk sac, liver, spleen.
Later: bone marrow.
Which hormone is important in erythropoiesis?
Erythropoietin.
Approximately how long is an RBC’s lifespan?
120 days.
How do we classify leukocytes?
Granular or agranular, based on presence of cytoplasmic granules (seen through staining).
Which 3 leukocytes are granulocytes?
Neutrophils, eosinophils & basophils.
Describe the role of neutrophils.
Bacteria-destroying, phagocytic specialists.
1st defenders on scene of infection.
Important to inflammatory response.
Call other WBCs to assist in response.
Eosinophils are mostly associated with (2):
allergic conditions & parasitic infestations.
Basophils are similar to ____ _____ & secrete/store _________.
mast cells; histamine.
Which 2 leukocytes are classified as agranulocytes?
Monocytes & lymphocytes.
Differentiate between monocytes & macrophages.
Monocytes: immature, circulate for 1-2 days.
Macrophages: mature & enlarged after settling in tissue.
What are the 2 types of lymphocytes?
B lymphocytes & T lymphocytes.
What is the primary role of B lymphocytes?
Produce antibodies & are responsible for antibody/humoral immunity.
What is the primary role of T lymphocytes?
Directly destroy target cells by releasing chemicals (cell-mediated immunity).
Target cells may include viral host cells & cancer cells.
Granulocytes & monocytes are produced in the:
bone marrow.
New lymphocytes are usually produced by:
existing lymphocytes in lymphoid tissue (ex: lymph nodes, tonsils).
What is a differential WBC count and why is it clinically significant?
Tells us the number of different types of WBCs out of 100.
We can assess what is happening in the blood/body and determine if there are any types of WBCs that are too abundant or deficient.
How are platelets structurally unique?
Disc-shaped cell fragments - not complete cells.
No nucleus, but contains smooth ER.
Where are platelets formed?
Bone marrow.
Which hormone stimulates platelet production & where is it produced?
Thrombopoietin, produced in the liver.
What are the 3 named phases of blood clotting?
- Vascular phase (vascular spasm).
- Platelet phase (platelet aggregation).
- Coagulation phase.
What happens during the platelet phase of blood clotting?
Release of chemicals (ex: ADP, platelet activating factor), von Willebrand factor).
What is the ultimate outcome of the coagulation cascade?
Conversion of fibrinogen → stabilized fibrin mesh.
Differentiate between the extrinsic & intrinsic pathway in the coagulation cascade.
Extrinsic: requires contact with tissue factors external to the blood.
Intrinsic: activated by factor XII contact with exposed collagen or a foreign surface.
Describe the common pathway in the coagulation cascade.
- Factor X becomes prothrombin activator.
- Prothrombin activator causes prothrombin to convert to thrombin in the presence of Ca2+.
- Thrombin causes fibrinogen to convert to fibrin.
What is thrombocytopenia and some common causes of it?
Too few platelets.
May be due to viral infections, chemo/treatments, etc.
What is von Willebrand’s disease and common symptoms?
Defect of vWF causing improper clotting.
Possible symptoms: frequent spontaneous nosebleeds, heavier menstrual cycles, etc.
What is hemophilia and what is it usually due to?
Severely reduced blood clotting ability.
Usually due to hereditary deficiencies of clotting factors (especially VIII).
Liver diseases tend to cause impaired production of:
blood clotting factors.
What is a thrombus?
Abnormal intravascular clot attached to a vessel wall.
Can eventually completely occlude the vessel.
What are emboli?
Freely floating clots that can suddenly block blood flow.
What are 4 factors causing thromboembolism?
- Roughed vessel surfaces due to atherosclerosis (hardening & narrowing of arteries).
- Imbalances in clotting-anticlotting systems.
- Slow-moving blood.
- Release of tissue thromboplastin into blood from large amounts of traumatized tissue (factor X).
Patients with Type A blood will have _ antigens and _ antibodies.
A; B.
Patients with Type B blood will have _ antigens and _ antibodies.
B; A.
Patients with Type O blood will have _ antigens and _ antibodies.
no; A and B.
Patients with Type AB blood will have _ antigens and _ antibodies.
both A and B; no.
Which blood type is considered the universal donor and why?
O-
Doesn’t have any antigens, so no antibodies will react to it and it can be given to anybody.
Which blood type is considered the universal recipient and why?
AB+
Type AB+ patients have all the antigens on their cells and therefore no antibodies, so they can receive any kind of blood.
Do Rh- patients naturally contain any Rh- antibodies?
No: they only develop with exposure to the Rh antigen so they wouldn’t have a reaction to Rh+ blood until their second encounter with it.
Describe hemolytic disease of the newborn.
An Rh- mother carries her first Rh+ child, causing her to develop Rh antibodies once she comes into contact with the fetus’ placenta.
If she carries a second Rh+ child, it her Rh antibodies will attach the fetus’ RBCs.
What is done to prevent hemolytic disease of the newborn?
Mother can receive a RhoGam shot shortly after first Rh+ deliver, miscarriage or abortion.
The circulatory system contains 2 circuits:
- Pulmonary circuit to the lungs.
2. Systemic circuit to the rest of the body.
The heart sits at an _______ angle & is slightly rotated to the ____.
oblique; left.
Where is the heart located in the thoracic cavity relative to other structures?
Between the 2 lungs, slightly to the left of the midline.
Which part of the heart forms the superior border?
The base.
Which part of the heart is considered its base?
Superior part of the heart where all the vessels are attached.
Which chamber of the heart forms its right border?
Right atrium.
Which chambers of the heart form its left border?
Left atrium & left ventricle.
Which chamber of the heart forms its inferior border?
Right ventricle.
Where is the apex of the heart?
Tip of the heart forming the corner between the inferior & left borders of the heart.
In which intercostal space is the apex of the heart usually located?
5th intercostal space, in the mid-clavicular line.
What is the pericardium?
Membranes surrounding the heart.
The heart is contained within the ___________ cavity, which is formed by the ___________ ___.
pericardial; pericardial sac.
Describe the 2 layers of the pericardium.
Fibrous pericardium: outermost containing tough, fibrous connective tissue.
Serous: thin membrane with 2 parts.
Describe the 2 parts of the serous pericardium.
Parietal: lines the inside of the fibrous pericardium.
Visceral: lines the outside of the heart, making up the external cardiac surface (epicardium).
What is the function of pericardial fluid and where is it found?
Between the parietal & visceral membranes for lubrication.
What are the 3 layers of the heart wall, from outermost to innermost?
Epicardium.
Myocardium.
Endocardium.
What does the myocardium contain?
Cardiac muscle, connective tissue, nerves.
What is the endocardium?
Epithelium lining the inner surfaces of the heart, including the valves.
What is the function of the right atrium?
Receives deoxygenated blood from systemic circulation (vena cava) & coronary vessels.
What separates the RA from the LA?
Interatrial septum.
What does the blood pass through to get from the RA to RV?
Tricuspid valve (right AV valve).
How is the tricuspid valve attached to the chambers of the heart?
3 cusps are attached to chordae tendinae, which arise from the papillary muscles in the RV.
What are chordae tendinae?
Collagen fibre branches.
What is the function of the right ventricle?
Receives deoxygenated blood from RA and pumps blood into the pulmonary valve → arteries.
What separates the RV from the LV?
Interventricular septum.
What is the function of the left atrium?
Receives oxygenated blood from pulmonary veins.
What does blood pass through to get from the LA to the LV?
Mitral/bicuspid/left atrioventricular valve.
What is the function of the left ventricle?
Receives oxygenated blood from the LA & pumps it across aortic (semilunar) valve into the aorta & into the coronary arteries via the coronary sinuses.
Which chamber of the heart has the thickest muscular wall and why?
Left ventricle: muscle wall needs to be thick & strong enough to pump blood throughout the entire body.
Describe the structures of the heart that blood passes through in order, beginning with deoxygenated blood from the body (systemic).
- Inferior/superior vena cava.
- RA.
- Right AV (tricuspid) valve.
- RV.
- Pulmonary semilunar valve.
- Pulmonary arteries.
- Pulmonary veins.
- LA.
- Left AV/mitral/bicuspid valv.
- LV.
- Aortic semilunar valves.
- Aorta.
Where are the coronary arteries?
Originate in the aortic sinus at the base of the ascending aorta.
Describe the 2 major coronary arteries.
Right coronary artery: supplies oxygenated blood to RA, RV, part of LA, part of LV, interatrial septum, part of interventricular septum & part of conduction system.
Left coronary artery: supplies oxygenated blood to LA, LV, parts of RV & parts of interventricular septum.
Where does the impulse initiated by the SA node travel to?
AV node
What is arrhythmia?
Variation from normal rhythm and sequence of excitation of the heart
What are 3 examples of arrhythmia?
Atrial fibrillation, ventricular fibrillation & heart block
What are the 2 abnormalities in heart rate?
Tachycardia & bradycardia
What is the difference between tachycardia and bradycardia?
Tachycardia: rapid, >100 bpm
Bradycardia: slow, <60 bpm
What event produces the P wave?
Atrial depolarization
What event produces the PR segment?
AV nodal delay
What event produces the QRS complex?
Ventricular depolarization & simultaneous atria repolarization
What event produces the ST segment?
Ventricles contract and empty
What event produces the T wave?
Ventricular repolarization
What event produces the TP interval?
Ventricles relax and fill
Why is summation and tetanus of cardiac muscle impossible?
Long refractory period occurs in conjunction with prolonged plateau phase
The ability to generate + conduct its own impulses is called ____ or ____
autorhythmicity, automaticity
What structure is the pacemaker of the heart?
SA node
What is the function of the SA node?
Originate electrical impulse
Where does the impulse initiated by the SA node travel to?
AV node
Describe the events of action potentials in the heart.
Resting potential: -90mV.
- Massive Na+ influx (depolarization).
- Slow Ca2+ influx (plateau): lengthens action potential.
- Quick K+ efflux causing rapid repolarization.
Describe the events of pacemaker potentials in the heart.
Threshold: -40mV.
No steady rising potential.
1. Ca2+ influx for depolarization.
2. K+ efflux for repolarization.
As the impulse travels down the internodal pathways, it also travels through cardiac muscle, starting ____ contraction
atrial
Where does the impulse travels to from the AV node?
AV bundle (Bundle of His)
Where does the impulse travels to from the AV bundle?
Down the interventricular septum, then dividing into the right bundle branch (RBB) and left bundle branch (LBB), then the apex of the heart
What do the bundle branches branch further into?
Purkinje fibers
As the impulse travels down the conducting fibers, it also travels through ventricular myocardium, starting ____ contraction.
ventricular
What is isometric ventricular relaxation?
Where the ventricles relax without any change in blood volume since the AV valves are not yet open.
What 4 events occur during late ventricular diastole?
- SA node reaches the threshold, so it fires.
- AV valves open.
- Atrial systole.
- Blood flows from atrium to ventricle due to atrial pressure exceeding ventricular pressure.
What is EDV and what is the average EDV value?
End diastolic volume: amount of blood in ventricles after ventricular diastole.
Average: 135 mL.
What causes the beginning of ventricular systole?
The impulse reaches the AV node.
When does isometric ventricular relaxation occur?
Between mid & late ventricular diastole.
What is isometric ventricular contraction?
When the ventricles contract without any change in blood volume because of the brief period before semilunar valves open.
What is ESV and what is the average ESV value?
End systolic volume: amount of blood in ventricles after ventricular systole.
Average: 65 mL.
How do we calculate stroke volume?
EDV - ESV.
What is the average stroke volume?
70 mL.
What is stroke volume?
Amount of blood pumped out of each ventricle into major vessels with each contraction.
What is the first heart sound caused by?
Closing of AV valves (contraction).
What is the second heart sound created by?
Closing of semilunar valves (relaxation).
Describe the 2 controls affecting stroke volume.
Intrinsic control: EDV & venous return.
Extrinsic control: sympathetic activity.
Parasympathetic stimulation _____ heart rate.
slows.
Sympathetic stimulation ______ heart rate.
quickens.
What is the Frank Starling Law of the Heart?
The greater the heart muscle is stretched during filling, the greater the force of contraction & the greater the quantity of blood pumped into the aorta.
What does preload refer to in the Frank Starling Law of the Heart?
The extent of stretching during filling.
What does afterload refer to in the Frank Starling Law of the Heart?
Pressure required in ventricles for blood to push open the semilunar valves.
High blood pressure or resistance will ________ afterload, therefore _________ stroke volume.
increase; decrease.
What is decompensated heart failure?
The point at which the heart can no longer pump out a normal stroke volume despite compensatory measures.
Left-sided heart failure will affect the _____.
lungs.
Right-sided heart failure causes congestion in the _______ circuit.
systemic.
