Cardiovascular System Chaper 14 & 16 Flashcards
What are the primary function of the cardiovascular system?
Delivers material throughout the body
Capability of protecting the body from blood loss and invaders
Involved in homeostatic function
What are three major components that accomplish this job
Medium: blood
Pump: Heart
Plumbing: The blood vessels/ vasculature
What are the two separate circuits joined in series of the cardiovascular system?
Systemic circulation
Pulmonary circulation
What does the systemic circulation do?
Delivers O2, glucose, hormones, and other matter to the tissues
Removes CO2, wastes, sometimes excess heat form the tissues
What is the function of the Pulmonary circulation?
Delivers O2-deficient, CO2-rich blood to the lungs
Allows gas exchange between the respiratory system and blood
What are the components of the blood after centrifugation?
Top to bottom
Blood plasma
Buffy coat
Formed elements (RBC’s) Hematocrit
What are the cells of the Buffy coat?
Clotting factors (platelets) and leukocytes (WBC’s)
The formed elements are what?
Hematocrit and the buffy coat
What is the plasma
Watery cell free component
On average how much blood is in the body?
~5 liters
The plasma proteins are a small percentage of the plasma what are the three major plasma proteins?
Albumin
Globulin
Fibrinogen
What is the function of Albumin and where is it made?
Synthesized in the liver, and its the most abundant. Contributes the osmotic pressure
What are the two functions of Globulin?
Liver transport globulins (alpha and beta globulins) that carry small molecules, ions
Immunoglobulins (gamma-globulins) involved in acquired immune response
What is the function of Fibrinogen?
Least abundant
Clotting function
What are the formed elements?
Erythrocytes RBC’s, leukocytes, and platelets
What of the formed elements are not true cells and why?
RBC’s
No nucleus and no organelles
What is the function of RBC’s and describe them?
Each RBC contains 250 million hemoglobin molecules, which can reversible bind O2, CO2 and protons.
They are small biconcave discs, ~ 7 microns in diameter
They last ~ 120 days
What are the Leukocytes?
They are the WBC’s and are true cells because they have a nucleus and organelles
What are the two primary classifications of the leukocytes?
Granulocytes
Agranulocytes
They make up 1% of the WBC’s
What are the granulocytes?
Neutrophils
Eosinophils
Basophils
What are the Agranulocytes?
Lymphocytes, Monocytes
What is the function of the Leukocytes?
How is this done?
Fight pathogens (foreign invaders) throughout the body, not just within the blood
Use phagocytosis or may release chemicals to mark, disable or destroy the targets.
What are the chemicals or released factors that destroy, or disable their targets?
Lysozyme, oxidants, antibodies
How doe WBC’s get to the foreign invaders?
Once they do their job what do they do?
Many of them leave the blood and invade the interstitial tissue.
Injured tissue release factors to attract WBC’s
Once they leave the blood, they typically do not return
What are the most abundant Granulocyte/Leukocyte?
What is their function?
Neutrophils
Phagocytic, also releases chemicals to kill bacteria
Called polymorphonuclear Leukocytes
What is the function and description of Eosinophils?
Phagocytic, can kill worms
They release histamine
Stain Red with Eosin
What are the characteristics and functions of Basophils?
Least abundant WBC. Similar to mast cells in connective tissue.
Release serotonin and histamine, which attracts other WBC’s to the site of infection/injury
Stain blue, purplish with basic dyes like methylene blue
What are the functions of Lymphocytes?
Involved in the adaptive immune system response
Lymphocytes can last for many, many months. They typically don’t leave the blood.
What are the major cells of the lymphocytes and their function?
B-cells: release antibodies
T-cells: attack invaders, mediate the immune response
Natural Killer cells: destroy many different invaders and tumor cells. They release perforin protein that creates hole in invaders
What is the function and characteristics of Monocytes?
Large leukocytes that are capable of phagocytosis
Once they cross the tissues, they differentiate into wandering macrophages that clean up debris and bacteria in the infection site.
What are platelets?
What are their characteristics?
Split off from the large cells called Megakaryocytes
They lack a nucleus and cytoplasm
They are simply cell fragments
What is the function of the platelets?
Are involved in clotting
When does clotting happen?
Damage to blood vessel walls
Sticks to collagen in the damaged area
Swell, then form a plug in the vessel wall
What helps the newly formed clot?
Plasma protein fibrin infiltrates and strengthens the newly formed clot
Once the clot forms, what takes place?
The platelets shrink and draw the vessel walls together, which aids in wall repair.
What are the two pathways that form clots from fibrin and formed elements?
Intrinsic
Extrinsic : the injury pathway
What are the critical end reactions that take place to form a clot?
Formation of the prothrombinase enzyme complex (Factor X and V)
Conversion of Prothrombin into Thrombin by that enzyme
Catalysis of plasma fibrinogen in to fibrin by thrombin
Crosslinkage of fibrin into a cross-linked network in a clot
What type of feedback are these two pathways of forming a clot?
Both are positive feedback
What type of pump is the heart?
The heart is a dual pump
The atria does what?
The ventricles do what?
The atria receive blood from veins
The ventricles pump blood into arteries
What is the function of the fibrous skeleton of the heart?
It’s non muscular and it exists between the atria and ventricles
Electrically separates the two chambers
Serves as an anchor point for the two during contraction
Location of the heart valves
What are the types of heart valves and their function?
They prevent backwards blood flow
Atrioventricular valves
Semilunar valves
Where are the AV valves located?
Found between atria and ventricles
Where are the semilunar valves located?
Located between the ventricles and arteries
What is the major thing about the veins and the atria?
NO valves exist between veins and atria
What causes the valves to open and close in the heart?
Valve open and close in response to pressure differences across the valve
What are the two circuits that blood flows in?
Systemic and pulmonary circulation
what takes place with in the systemic circulation?
Deoxygenated systemic blood arrives via the vena cava and enter the right atrium and ventricles
What is the purpose of contraction of the right atrium?
To top off the right ventricle
What takes place when the right ventricle contracts?
The right ventricle contracts, driving blood into the pulmonary trunk (artery)
Once the blood reaches the lungs what takes place?
The blood gains O2 and releases CO2 in the pulmonary capillaries
During pulmonary circulation what is the first thing that takes place?
Blood returning via the pulmonary veins enters the left atrium and ventricles
What is the purpose of the left atria contraction?
To top off the left ventricle
When the left ventricle contracts, what is taking place?
Drives blood into the systemic arteries
What do each part of the heart contract? What is the timing that this takes place?
Efficient output of the heart requires coordination between the atria and ventricles
Both atria must contract simultaneously, then the ventricles contract about 200 milliseconds later
Where does contractile Activity come from and how is it initiated and coordinated?
Contractile activity arises from cardiac myocytes
Their activity is initiated and coordinated by autorhythmic cells
What are the significant characteristics of cardiac Myocytes?
Striated appearance
Significant branching- adjacent cells are connected by gap junctions and desmosomes, which form intercalated disks
Contraction is involuntary controlled
There are two major types of Autorhythmic/Pacemaker cells what are they?
Pacemaker cells
Conductive cells
What is the function of the pacemaker cells?
Generate action potentials that spread across the Cardiac muscle
What is the primary pacemaker of the heart and where is it located?
What is their function?
located in the Sinoartial node of the right atria
The pacemaker cells depolarize spontaneously to threshold
This electrical Activity is called what?
The pacemaker potential
What are the major ions of the cardiac AP
Na+, Ca2+, K+
What are the phases of the AP of cardiac pacemakers
Phase 4- slow depolarization
Phase 0- fast depolarization
Phase 3- repolarization
What takes place during phase 4 of the cardiac pacemaker AP
Initial slow influx of Na+ and just before reaching threshold late Ca2+ influx to depolarize past threshold.
What takes place during Phase 0, what is this referred to as?
Fast depolarization
Lots of Ca2+ channels open and the Na+ channels close
What takes place during phase 3 repolarization?
Ca2+ channels close and K+ channels open causing repolarization
What is the membrane potential voltages?
- 60 mV to threshold of -40 is the Pacemaker potential
- 40 to 20mV then back to -60 mV is the AP
How does the Pacemaking AP spread throughout the Myocardium
Moves from the site of origin (SA node) via gap junctions into atrial myocytes and spreads to the left atrium via conductive cells in the interatrial pathways
This is what causes the atrial muscle to contract simultaneously
What takes place when the AP moves from the SA node to the AV node?
The AP moves via conductive pathways to the AV node
There is a delay between the AV node into the ventricles. This allows for the ventricles to almost completely fill then the atria contact topping off the ventricles.
What is the path of the Cardiac AP?
SA node to the AV node pause then through the bundle of His then through the Purkinje fibers
What takes place with the AP propagates through the conductive cells in the bundle of His?
The bundle spits into the right and left bundle branches which supply the two ventricles
At the apex then it moves into the Purkinje fibers which then spreads the AP into the myocytes causing contraction from the apex upward
Describe the phases of the Cardiac AP when the myocytes fire off?
Phase 0- Na+ influx during the upswing via V-gated Na+ channels, which is called rapid depolarization
Phase 1- the v-gated channels inactivate, then transient K+ flux via a v-gated channel and this causes brief repolarization
What takes place during phase 2 and what is it referred to?
Called the Plateau of the cardiac AP
Lasts about 200 mSec
Slow influx of Ca2+ via L-type channels and slow efflux of K+ via the delayed rectifier K+ channel
What are the events of phase 3?
Repolarization
the L-type channels close and a slowly activating K+ channel allow K+ to efflux
What takes place in phase 4 of the cardiac AP
Returns to RMP
K+ continues effluxing and the Ca2+ channels completely close
What is the process for EC coupling of cardiac muscle conctraction?
Depolarization activates V-gated L type Ca2+ channels in the PM this allows Ca+ to enter down its electrochemical gradient and this influx will cause the RYR receptor to release Ca2+ in abundance from the SR
This is where the plateau phase takes place and allows tension development for ~ 200mSec
What takes place during the falling phase of the AP?
The Ca2+ channels inactivate and Ca2+ is removed from the cytoplasm by the CaATPase back into the SR.
Also the Na+/Ca2+ exchanger (NCX) removes Ca2+ from cardiac muscle as well this causes relaxation
