Lecture 10, 11 & 13 Cardiovascular System Flashcards
What are the functions of Blood?
- Transportation
- Regulation
- Protection
Explain the regulation function of blood.
The blood regulates:
- Body Temperature: blood absorbs heat from body cells and releases it at the skin
- Body pH: blood absorbs acid and base from body cells to maintain a healthy pH
- Fluid Balance: water is added to blood from the GI tract and is lost in numerous ways
What are the components of whole blood?
- Erythrocytes (red blood cells)
- Buffy coat
- Plasma
What is the Hematocrit?
The percentage of all formed components in blood.
- Males have 42-56%
- Females have 38-46%
What are the components of plasma?
- Water 91%
- Plasma proteins 7%
- Other solutes 2%: electrolytes, nutrients, respiratory gases, waste products
Pasma proteins are produced where? What do they include?
Most plasma proteins are made in the liver and
include:
– Albumin
– Globulins
– Fibrinogen (and other clotting proteins)
– Regulatory enzymes, like hormones
What is colloid osmotic pressure?
This pressure is responsible for pulling fluids into the blood and preventing excess fluid loss from the blood into the interstitial fluid
* Ultimately helps to maintain blood volume (and thereby blood pressure)
What are Albumins Proteins?
- 58% of all the plasma proteins
- Roles are primarily to maintain blood volume and blood pressure
- Secondary role is to act as a transport protein to carry ions, hormones, and some lipids in the blood
What are Globulins Proteins?
– 36% of all the plasma proteins
– Bind to and transport some water-insoluble molecules and hormones (doesn’t dissolve)
– Antibodies are also from this category
What are Fibrinogen Proteins?
– 4% of all plasma proteins
– Is converted into a long, insoluble form called fibrin which helps form blood clots
What are Regulatory Proteins?
– <1% of plasma proteins
– Include hormones being transported through the blood and enzymes
What is hemopoiesis?
A process in which the body continuously makes new blood cells to replace old ones.
– This occurs in the red bone marrow of the bones of the axial skeleton
- Hemopoiesis starts with stem cells called hemocytoblasts
What are hemocytoblasts?
Stem cells that start the hemopoiesis process.
- They are multipotent because they have the potential to develop into many different types of cells.
They produce two different lines for blood
cell development
- Myeloid line
- Lymphoid line
What types of cells do Myeloid and Lymphoid lines produce?
Myeloid: forms erythrocytes and leukocytes (except
lymphocytes) and megakaryocytes
Lymphoid: forms lymphocytes
What are the different types of formed elements?
- Erythrocytes (Red blood cells)
– Account for about 99% of the formed elements. - Leukocytes (White blood cells)
– Less than 0.01% of formed elements - Thrombocytes (Platelets)
– Less than 1% of formed elements.
Explain what Erythrocytes are.
(Red blood cells)
Small, flexible cells that lack a nucleus and cellular organelles
- The plasma membrane houses about 280 million hemoglobin molecules.
- Function is to transport oxygen and carbon dioxide between the tissues and lungs.
Explain the composition of Hemoglobin molecules.
Contains:
- Four globin molecules: transports carbon dioxide
- Four heme molecules: transports oxygen (each containing one iron atom)
Iron is required for oxygen transport.
What is Erythropoiesis?
The process of erythrocyte production
- Produce about 3 million erythrocytes per second
What is Erythropoietin (EPO)?
It’s a hormone produced by the kidneys in response to low blood O2 levels.
- Decreased red blood cells
- Decreased hemoglobin
- Diseases of the lungs
- Increased demand for oxygen
Explain what Leukocytes are.
(White blood cells)
- Protect the body against pathogens
- There are 5 types of leukocytes split into 2 groups: Granulocytes & Agranulocytes
What are Granulocytes & Agranulocytes?
The 2 groups in which Leukocytes (white blood cells) are divided into.
Granulocytes:
* Cytoplasm contains large granules; have multi-lobed nuclei.
* Three distinctive types: neutrophils, eosinophils, basophils
Agranulocytes:
* Cytoplasm contains small granules and nuclei that are not lobed.
* Two distinctive types: lymphocytes and monocytes
What is Diapedesis?
A process in which leukocytes enter the tissues from the blood, where they squeeze between the capillary endothelial cells.
What are Neutrophils?
Type of Granulocyte white blood cell
- Remain in circulation for 10-12 hours before leaving the blood and entering tissue where they phagocytize infectious pathogens, especially bacteria.
- Account for 50-70% of the WBC
What are Eosinophils?
Type of Granulocyte white blood cell
- Phagocytize antibody-antigen complexes or allergens
- Release chemicals that attack parasitic
worms
- Account for 1-4% of the WBC
What are Basophils?
Type of Granulocyte white blood cell
- Produces histamine which causes vasodilation
- Produces heparin which inhibits blood clotting
- Account for less than 1% of the WBC
What are Lymphocytes?
Type of Agranulocyte white blood cell
Reside in the lymphatic organs and structures
*T lymphocytes: Attack viruses and foreign cells
*B lymphocytes: Produces antibodies
*Account for 20-40% of the WBC
What are Monocytes?
Type of Agranulocyte white blood cell
*Remain in circulation for 3 days, leave circulation
and become macrophages
* Macrophages are large cells that phagocytize bacteria, viruses, cell fragments, dead cells and debris in the tissues.
*Account for 2-8% of the WBC
What are Thrombocytes (platelets)?
- Cell fragments pinched off from megakaryocytes in red bone marrow
- Circulate for 8-10 days if not used and then broken down and recycled
- Allows adhesion to other molecules
- Important in preventing blood loss
Explain Platelet plug formation.
Seal up small breaks in blood vessels
Damaged blood vessels have exposed collagen fibers to which platelets will stick too and adhere in order to block the damaged area of the blood vessels. Platelets will not adhere to healthy blood vessels because collagen is not exposed. 3 steps.
- Platelet adhesion: platelets bind to collagen of damaged blood vessels, mediated through a protein called von Willebrand factor.
- Activation of platelets: activated platelets release chemicals that activate further platelets.
- Platelet Aggregation: as platelets become activated they change shape and can bind fibrinogen, a plasma membrane protein. This forms the platelet plug.
Explain what Extrinsic Pathways are.
Activation of clotting factors begins with the intrinsic
and/or extrinsic pathways
- Begins with chemicals that are outside of the blood vessel
- Damage tissue releases a mixture of lipoproteins and phospholipids called thromboplastin (tissue factor 3)
- Thromboplastin, in the presence of Ca2+ forms a complex with factor 7 that activates factor 10.
Both pathways converge on the common pathway by activating factor 10!
Explain what Intrinsic Pathways are.
Activation of clotting factors begins with the intrinsic and/or extrinsic pathways
- Begins with chemicals that are inside of the blood vessel wall and are initiated by platelets.
- Damage to blood vessels can expose collagen in the connective tissue, in the lining of the blood vessel
- This sets off a series of reactions resulting in activation of factor 10. (Clotting factors 12,11,9,8 and Calcium are all involved in the pathway)
Both pathways converge on the common pathway by activating factor 10!
Explain what the Common Pathway is.
- Activated factor 10, factors 2 and 5, Ca2+, and platelet factor 3 combine to form prothrombinase.
- Prothrombinase converts the plasma protein prothrombin into thrombin.
- Thrombin converts the plasma protein fibrinogen into fibrin.
– An insoluble protein that forms the fibrous network of the clot. - Thrombin also activates factor 13 which is necessary to stabilize the clot.
Explain Type A blood.
Has red blood cells with type A surface antigens and plasma with type B antibodies
Explain Type B blood.
Has red blood cells with type B surface antigens and plasma with type A antibodies
Explain Type AB blood.
Has red blood cells with both type A and type B surface antigens and plasma with neither type A nor type B antibodies
Explain Type O blood.
Has red blood cells with neither type A nor type B surface antigens and plasma with both type A and type B antibodies
Explain Cardiac Muscle cells.
They are elongated, branching cells containing 1-2 centrally located nuclei
* Contains actin and myosin myofilaments which are organized into sarcomeres
Muscle cells are joined by intercalated disks which allow action potentials to pass easily from one cell to the next.
* Organelles in cardiac muscle aren’t as efficient as they are in skeletal muscle
What is the Cardiac Conduction System?
It’s the electrical system of the heart, it generates and relays action potentials through the heart
* System consists of modified cardiac muscle cells that form:
- 2 nodes
- 1 conducting bundle and its branches
What is the Sinoatrial (SA) Node?
Located medial to the opening of the superior vena cava in the right atrium.
- Has specialized cardiac muscle cells that generate spontaneous action potentials. This initiates the heartbeat
- From the SA node action potentials will pass to atrial muscle cells and to the AV node.
What is the Atrioventricular (AV) Node?
Located medial to the right atrioventricular valve in the right atrium.
- Action potentials are conducted more slowly here than in any other part. This ensures ventricles receive signals to contract after the atria have contracted.
What is the Atrioventricular Bundle?
Also known as the “Bundle of His”
passes through a hole in the cardiac skeleton to reach the interventricular septum where it divides to form:
- Right and left bundle branches extend beneath the endocardium to apices of right and left ventricles and terminate as the:
- Purkinje Fibers: Large diameter cardiac muscle cells with few myofibrils. Many gap junctions. Conduct action potential to ventricular muscle cells.
What does it mean that the heart is autorhythmic? How does this occur?
The heart stimulates itself to contract at regular intervals
What is the P wave in an Electrocardiogram?
- Represents depolarization of the atrial muscle cells and signals the onset of atrial contraction.
What is the QRS complex in an Electrocardiogram?
- Represents the initiation of ventricular depolarization and signals the onset of ventricular contraction.
What is the T wave in an Electrocardiogram?
- Repolarization of ventricles, relaxsation
What happens in the 1st step of the Cardiac Cycle?
At the beginning of the cardiac cycle:
* the atria and ventricles are relaxed
* AV valves are open, and SL valves are closed
Blood is moving passively from veins into the atria and into ventricles (bc AV valves are open) due to pressure differences, this is called Passive Ventricular Filling
Then the SA node will generate an action potential that stimulates the atria to contract, forcing more blood into the ventricles, this is called Active Ventricular Filling
* The ventricles are holding the maximal amount of blood volume at this point
What happens in the 2nd step of the Cardiac Cycle?
After the 1st step, the action potentials will pass to the AV node, AV bundle, L/R bundle branches, and the Purkinje fibers and cause ventricular systole (contraction)
* This contraction causes an increase in pressure in the ventricles, movement of blood toward the atria, and closure of AV valves. (so blood won’t backflow)
At this time all valves (AV and SL) are closed and no blood movement occurs. This is called the Period of Isovolumetric Contraction.
What happens in the 3rd step of the Cardiac Cycle?
After the 2nd step, ventricular systole (contraction) continues and the pressure eventually increases higher than that of the aorta and pulmonary trunk.
This rise in pressure causes the AoSL and PSL valves to be forced open and blood flows to the arterial trunks. This is called the Period of Ejection
* Not all blood is pumped out, there is some remaining in the ventricles after contraction. This is called the End Systolic Volume.
What happens in the 4th step of the Cardiac Cycle?
After the 3rd step, ventricular diastole (relaxation) begins and ventricular pressure decreases below that of the aorta and pulmonary trunk.
As a result, blood flows back towards the ventricles causing the AoSL and PSL valves to close.
* All valves are now closed and no blood can enter the relaxing ventricle. This is called the Period of Isovolumetric Relaxation
What happens in the 5th step of the Cardiac Cycle?
As ventricular relaxation continues, the AV valves open and blood flows from the atria into the relaxing ventricles and the cycle repeats.
