Cardiovascular System Lecture 1 Flashcards
What Components make up the Cardiovascular system? (3)
- Heart - pump, driving force
- Blood Vessels (Vascular System)
- Passageways, circulation - Blood - Fluid Connective Tissue, medium
How much blood is in the human body?
- 8% of Body Weight
- 5 L of Blood Volume
What 2 Components make up blood?
- Plasma
- Cellular Elements
- Erythrocytes - RBC’s
- Leukocytes - WBC’s
- Thrombocytes - Platelets
What does plasma consist of? (3)
- 92% Water - fluid portion
- 7% Plasma Proteins
- produced in Liver & circulating in plasma - 1% other solutes
What “other” solutes are found in plasma?
(5)
- Electrolytes (sodium, potassium, chloride..)
- Nutrients (carbs, fats, proteins, vitamins, minerals)
- Wastes (urea, creatinine, bilirubin)
- Gases (oxygen, carbon dioxide)
- Regulatory Substances (hormones, enzymes)
What fluids are found outside the cell?
(3)
- Extracellular Fluid (outside cells)
- Plasma (outside cells in blood)
- Interstitial Fluid (outside cells in tissue)
What are Compartment Shifts?
Under certain conditions get exchange between compartments.
- Plasma <–> Interstitial
- Intracellular <–> Extracellular
Where are Cellular Elements developed?
(erythrocytes. leukocytes, thrombocytes)
All initially formed in red bone marrow
- 100 billion new cells/day
What specific type of stem cell can form all mature blood cells?
Pluripotent hematopoietic stem cells
What are Myeloid Stem Cells?
Myeloid Stem Cells can form all mature blood cell lines except lymphocytes
What are Lymphoid Stem Cells?
Lymphoid Stem Cells mature to form Lymphocytes
What are Precursor Cells? (Blast Cells)
Precursor cells (blast cells)
– committed to forming a particular mature blood cell line.
What 2 Cellular Elements are found in the Cardiovascular System?
- erythrocytes
- thrombocytes
How are Thrombocytes (platelets) Formed?
(5)
- Originate from a Myeloid Stem Cell
- Leads to a Megakaryoblast
- Forms a large Megakaryocyte
- Megakaryocyte breaks into Cell Fragments
- These fragments are Platelets
What is the lifespan of a Platelet?
5-9 days
(have no nucleus)
What is the role of the Thrombocytes in Hemostasis? (3 Steps)
Step 1 - Platelet Adhesion
Step 2 - Platelet Activation
Step 3 - Platelet Aggregation
What is Platelet Adhesion?
(Step 1)
Platelets stick to exposed collagen fibers at a damage site using the von Willebrand factor secreted by damaged endothelium and platelets (forms bridge).
What is Platelet Activation?
(Step 2) (3)
- Adhesion triggers platelets to release vesicle contents into blood including:
Adenosine Diphosphate (ADP), Serotonin - This triggers the activation of local platelets
(changes in shape, metabolism & Surface Proteins) - Synthesis and release of THROMBOXANE A2 triggers activation and attraction of circulating platelets to damage site
What is Platelet Aggregation? (3)
- Platelet Activation causes platelets to stick to one another and form an accumulating mass called a PLATELET PLUG
- Prostacyclin (PGI2) and nitric oxide (NO) release from healthy endothelium to prevent platelet steps
- Platelet Plug size and spread is kept in check
What is the role of Aspirin in Platelet Aggregation?
blocks steps in platelet plug formation.
What is Blood Coagulation or Clotting?
Where does it form?
Conversion of blood to solid state; forms around initial platelet plug location.
What 2 Forces promote and oppose Blood Coagulation?
Procoagulant – promotes clotting
Anticoagulant – opposes clotting
What is Procoagulant?
(Promotes Clotting) (3)
- Damage site starts a clotting cascade
- Calcium release leads to circulating fibrinogen (inactive) being converted into fibrin (active) which forms a mesh network at the damage site.
- Material (blood cells, platelets, proteins) becomes trapped in mesh and forms a clot
What is Anticoagulant?
(Opposes Clotting)
- Secretion:
tissue factor pathway inhibitor, antithrombin III - Activation:
protein C / drugs: heparin, warfarin - These inactivate clotting factors and block steps in the clotting cascade
When do Clots dissolve?
Once repair is done or if clot forms at inappropriate location
What is fibrinolysis?
clot-dissolving
How are Clots Dissolved?
Plasminogen (inactive) is incorporated into clot as it is formed.
The release of a plasminogen activator by endothelial cells converts plasminogen (inactive) to plasmin (active) to dissolve clot
Active vs Inactive
Fibrinogen (inactive)
Fibrin (active)
Plasminogen (inactive)
Plasmin (active)
What are the two main Intravascular Clots?
Thrombos and Embolus
What is a Thrombus?
blood clot attached to the inner vessel wall.
What is an Embolus?
free floating clot; often a small piece of a thrombus that has broken free
What are the risks involved with Intravascular Clots?
Occlusion – blockage of blood vessel
(local or distant site; partial or complete)
What medical problems can arise from Intravascular Clots in Specific Blood Vessels?
- Coronary blood vessels –
myocardial infarction (heart attack). - Cerebral or cerebellar blood vessels – stroke.
- Deep vein thrombosis (DVT) – especially legs
(long periods of sitting, air travel concern)
What is Atherosclerosis?
Plaque (fatty substances, cholesterol, cellular waste, etc.) forms on an inner artery wall.
Occlusion risk – plaques often rupture triggering a thrombus to form at the site or can lead to a piece breaking away as an embolus/cycle of repeated plaque rupture – clot growth can be rapid.
Are Platelets Cells?
- Platelets are NOT cells,
- They are cell fragments
- Have no Nucleus
What is the Von Willebrand Factor?
Von Willebrand factor is a blood protein that plays a key role in blood clotting by helping platelets adhere to blood vessel walls.
Platelet Steps Summary
- Adhesion: When a blood vessel is injured, platelets stick to the exposed area.
- Activation: These adhered platelets change shape and release chemical signals.
- Aggregation: Activated platelets attract and stimulate other platelets to form a plug at the injury site.
- Clot Formation: This plug, reinforced by threads of fibrin, creates a stable blood clot, stopping the bleeding.
