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Arteries
- Carry blood from the heart to the capillaries
- consist of three layers in their walls
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Tunica Media
- Middle layer of arteries
- smooth muscle and elastic tissue
- contributes to maintenance of diastolic blood pressure
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Veins
- Carry blood from the capillaries to the heart
- three layers in walls
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Endothelium
- Inner layer of veins
- folded into valves to prevent backflow of blood
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Norepinephrine
- Stimulates vasoconstriction
- raises blood pressure
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Epinephrine
- Increases cardiac output
- raises blood pressure
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ADH
- Increases water absorption by the kidneys
- increases blood volume and blood pressure
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ANP
- Increases excretion of Na+ ions and water by the kidneys
- decreases blood volume and blood pressure
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Aldosterone
- Increases reabsorption of Na+ ions by the kidneys
- water follows Na+
- increases blood volume and blood pressure
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Pulmonary pathway of circulation
Right ventricle --> pulmonary artery --> pulmonary capillaries (exchange of gas) --> pulmonary veins --> left atrium
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Systemic pathway of circulation
Left ventricle --> aorta --> capillaries in body tissue --> superior and inferior caval veins --> right atrium
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Hepatic portal circulation
Blood from the digestive organs and spleens flow through the portal vein to the liver before returning to the heart
purpose: the liver stores some nutrients or regulates their blood levels and detoxifies potential poisons before blood enters the rest of peripheral circulation
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Anastomoses
Connection between vessels of the same type
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What do anastomoses provide?
A alternate pathway for blood flow if one vessel is blocked
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Arterial anastomoses
Provide for blood flow to the capillaries of an organ
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Venous anastomoses
Provide for return of blood to the heart an are most numerous in veins of the legs
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What is the function of capillaries?
to carry blood from arterioles to venules
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Describe capillary walls
One cell thick to permit exchanges between blood and tissue fluid
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In the capillaries, how are oxygen and carbon dioxide exchanged?
Diffusion
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diffusion
Movement of gases from area of greater concentration to area of less concentration
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What is the function of BP in capillaries?
Brings nutrients to tissues and forms tissue fluid in the process of filtration
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Define venous return
The amount of blood that returns to the heart.
If venous return decreases, heart contracts less forcefully and BP decreases.
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What is the function of the skeletal muscle pump in regards to venous return?
- Contracts skeletal muscles, especially in the legs.
- squeezes the deep veins to return the blood
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What is the function if the respiratory pump in regards to venous return?
The pressure changes of inhalation and exhalation expands and compresses the veins in the chest cavity
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Describe the relationship between heart rate, force, and BP
If heart rate and force increase, BP increases
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When does systolic pressure occur?
During ventricular contraction
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When does diastolic pressure occur?
During ventricular relaxation
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What is a normal BP?
90/60 - 120/80
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What is the site of exchange between fetal blood and maternal blood?
Placenta
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What is the normal pH of blood?
7.35-7.45
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Whats another name for RBCs?
Erythrocytes
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name two immature RBCs
Normoblasts and reticulocytes
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What is another name for WBCs?
Leukocytes
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what is the extrinsic factor needed for DNA synthesis in stem cells in RBM?
Vitamin b12
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ABO blood types
- Hereditary
- indicates antigens on RBCs
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What phagocytize pathogens?
Neutrophils and monocytes
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What becomes macrophages?
Monocytes, they also phagocytize dead tissue
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what do basophils contain and what is its functuon?
- Contain the anticoagulant heparin and histamine
- Contribute to inflammation
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Platelet plugs
Rupture of a capillary creates a rough surface to which platelets stick and form a barrier over the break
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Antithrombin
- Synthesized by the liver
- inactivates excess thrombin
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Heparin
Inhibits the clotting process
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What prevents abnormal clotting?
Very smooth endothelium that lines blood vessels
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Clot retraction
Folding of the fibrin threads to pull the cut edges of the vessel closer together to facilitate repair
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Fibrinolysis
The dissolving of the clot once it has served its purpose
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What does chemical clotting involve?
- Platelet factors
- chemicals from damaged tissues
- prothrombin
- fibrinogen
- and other clotting factors synthesized by the liver
- calcium ions
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what is a chemical clot formed from?
Fibrin threads that form a mesh over the break in the vessel
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When a RBC dies, where does the iron go?
It is returned to the RBM and stored in the liver
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What do RBCs carry?
O2 bonded to the iron in the hemoglobin
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Hypoxia
Stimulates the kidneys to produce the hormone erythropoietin, which increase the rate of RBC production in the RBM
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what percent of the plasma is water?
91%
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What does plasma transport?
Nutrients, wastes, hormones, heat, antibodies, cO2 as hco3
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Plasma proteins
Clotting factors are synthesized by the liver
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Albumin
- Synthesized by the liver
- provides colloid osmotic pressure at pulls tissue fluid into capillaries to maintain normal blood volume and blood pressure
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What are the formed elements in blood cells?
RBCs, WBCs and platelets
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Primary hemopoietic tissue
- After birth it is the red bone marrow
- contains stem cells
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Precapillary sphincters
Smooth muscle cells that regulate blood flow into the capillary network
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