Hemodynamics and the Circulatory System Flashcards
What are the three functions of blood?
Transportation, regulation, protection
What does blood regulate?
- PH
- Water in plasma has heat absorbing and coolant properties which help maintain and adjust body temperature
What does blood protect against?
- Clotting of blood protects against excessive blood loss
- WBCs protect against disease through phagocytosis and production of antibodies
What does blood transport?
- Transports O2 from lungs to cell
- Carries CO2 from body cells to lungs
- Transports nutrients from GI tract to body cells
- Carries heat and waste products away from cells
- Transports hormones from endocrine glands to other body cells
What are five characteristics of blood?
- Blood is more dense and more viscous than water and flows more slowly
- Temperature of blood is 38oC (100.4oF)
- Blood has slightly alkaline PH
- Blood makes up about 8% of body weight
- Blood volume is 4-5 liters (1.2 gal) in an average adult female and 5-6 (1.5 gal) in an average adult male
Whole blood is composed of what two components?
- Blood plasma
- Formed elements
- ____ is a watery liquid that contains dissolved substances
- ____ is usually about 55% plasma
Blood plasma
- ____ are cells and cell fragments
- ____ are usually about 45% blood
- ____ are usually more than 99% RBCs of total blood volume
- ____ are usually less than 1% WBCs of total blood volume
Formed Elements
When formed elements are removed from blood, the remaining straw-colored liquid is called ____
Blood plasma
____ is about 91.5% water and 8.5% solutes
Plasma
What are the three types and percentages of plasma proteins that make up the 7% of solutes that are synthesized by the liver?
What is included in the remaining 1.5% of solutes in plasma?
- Electrolytes
- Nutrients
- Regulatory substances such as enzymes and hormones
- Gases and waste products such as urea, Uris acid, creatinine, ammonia and bilirubin
The three components of formed elements of blood include?
____ contain oxygen carrying protein called hemoglobin and do not contain a nucleus
RBCs (erythrocytes)
The percentage of total blood volume occupied by RBCs is called the ____?
Hematocrit
____ are nucleated and do not contain hemoglobin
WBCs (leukocytes)
____ leukocytes include eosinophils, basophils and neutrophils
Granular
____ leukocytes include lymphocytes and monocytes
Agranular
____ function to protect the body against foreign substances, accumulation of damaged cells, and infectious organisms
WBCs
____ are actually cell fragments with pieces of cell membrane that originate from large cells called megakaryocytes that splinter into 2000-3000 fragments
Platelets (thrombocytes)
____ are disc shaped and are not nucleated; help stop blood loss from damaged vessels by forming a platelet plug; release chemicals that promote blood clotting
Platelets
____ form a closed system that carries blood away from the heart to the body tissues and then returns blood from the tissues to the heart
Blood vessels
- Large elastic arteries leave the heart and divide into medium sized muscular arteries that branch to various regions of the body
- Medium sized arteries branch into smaller vessels called ____
Arterioles
When Arterioles enter tissues, they branch into microscopic vessels called ____
Capillaries
- Substances are exchanged between blood and body tissue through the thin capillary walls
- Before leaving tissues, capillaries unite to form very small veins called ____
Venules
- Venules merge to form veins
- Veins carry blood from tissues back to the heart
- Large vessels are nourished from their own blood vessel supply called the ____
Vasa Vasorum
What are the three tunics or coats that Arterial walls have?
- Tunica interna (intima)
- Middle tunica (tunica media)
- Outer coat (tunica externa)
Intima is composed of a thin lining of simple squamous epithelium called ____, a basement membrane and a layer of elastic tissue called the internal elastic lamina
Endothelium
____ is a continuous layer of cells that lines the entire cardiovascular system
Endothelium
____ is the thickest tunic layer
Tunic media
____ Consists of elastic and smooth muscle fibers arranged in rings around the lumen
Tunica media
____ consists of mostly elastic and collagen fibers
Outer coat (tunica externa)
An increase in sympathetic stimulation causes muscle contraction that
reduces the size of the vessel lumen (vasoconstriction)
An decrease in sympathetic stimulation causes muscle relaxation that
widens the size of the vessel lumen (vasodilation)
If an artery is damaged muscles will ____ producing a ____ that limits blood flow and ____ blood loss
contract; vascular spasm; reduces
Largest diameter arteries are called
elastic arteries
Elastic arteries help propel blood while ventricles are ____
Relaxed
(during diastole)
When ventricles of the heart ____, blood is ejected into elastic arteries and Arterioles walls stretch.
Contract
The stretched arterial walls store mechanical energy and function as ____
Pressure Reservoir
When the ventricles are relaxed the vessel walls recoil and transfer ____ energy in the walls to ____energy in the blood
mechanical; kinetic
The aorta, brachialcephalic, common carotid, subclavian, vertebral, pulmonary and common iliac arteries are ____ arteries
elastic
Muscular arteries (such as brachial artery in the arm and radial artery in the forearm) are called ____ arteries
distributing
Walls of ____ arteries are relatively thick in proportion to diameter of lumen
muscular arteries
____ are small arteries that are important in regulating blood flow from arteries to capillaries
Arteriols
A change in ____ of Arterioles can significantly change ____
____ are microscopic vessels that usually connect arterioles and venules
capillaries
Flow in these vessels is called
microcirculation
____ represent the greatest cross-section area of the circulatory system
capillaries
Blood flows the slowest in ____
capillaries
When several capillaries unite, small veins are formed called ____
venules
Venules collect blood from capillaries and drain into ____
Viens
____ frequently appear collapsed or flattened when sectioned and contain numerous valves
viens
- ____ are thin folds of tunica interna that form flap like cusps that project into the vessel lumen
- ____ project one way toward the heart
- ____ aid in returning venous blood by preventing back flow of blood
Valves
____ is a vein with a thin endothelial wall and contains no smooth muscle to alter diameter
vascular (venous sinus)
The union of the branches of two or more arteries feeding the same region is called ____
Anastomoses
____ provide an alternate route for blood to reach a tissue or organ
Anastomoses
The alternate route of blood flow to a tissue or organ (in the presence of disease, injury, etc.) through an anastomosis is called ____
collateral circulation
Arteries that do not anastamose are known as ____
end arteries
The largest portion of blood volume at rest (60%) is found in
systemic veins and venules
Systemic capillaries hold about ____ of blood volume; Arteries and arterioles hold about ____
5%; 15%
Because they hold a large volume of blood, veins and venules function as ____
blood reservoirs
The volume of blood that flows through any tissue at a given period of time is called ____ and is measured in ml/min
blood flow
The ____ of blood flow is inversely related to total cross-sectional area
velocity
As arteries branch, cross-sectional area ____ and velocity of blood flow ____
increases; decreases
When branches combine, cross-sectional area ____ and velocity of flow increases
decreases; increases
____ is the time it takes for blood to pass from the RA, through the pulmonary circulation to the LA, through the systemic circulation down to the foot and back to the RA; is usually one minute when resting
Circulation time
____ is the volume of blood that is ejected into the systemic (or pulmonary) system each minute (at rest is about 5.25 l/min)
Cardiac output (CO)
SV (Stroke volume) x HR (heart rate) =
(CO) Cardiac output
end diastolic volume – end systolic volume of the LV =
(SV) Stroke volume
At rest SV is about ____ ml
70ml
Due to friction between blood and vessel walls, what two other factors affect cardiac output
blood pressure and resistance
Blood flows from regions of ____ pressure to ____ pressure
higher; lower
The greater the pressure difference, the ____ the flow; higher resistance ____ blood flow
greater; lowers
Blood pressure is the ____ exerted on vessel walls by the blood
hydrostatic pressure
____ is generated by contraction of the ventricles and is highest in the aorta and large systemic arteries
BP (Blood Pressure)
Resting BP in an adult rises to about 120 mm/hg during ____ and falls to about 80 mm/hg during ____
systole; diastole
Diastolic BP + 1/3 (Systolic BP – Diastolic BP) =
MABP (Mean arterial BP)
MABP / R (resistance) =
CO
BP ____ progressively as the distance of blood from the LV ____
decreases; increases
If ____ decreases an amount greater than 10% of total blood volume then BP drops
blood volume
Normal volume of blood in an adult is about ____ liters
5 liters
An increase in blood volume (such as water retention) will ____ BP
increase
____ refers to the apposition of blood flow as a result of friction between the blood and vessel walls
Resistance
Resistance depends upon the average ____, ____, and _____
- blood vessel radius
- blood viscosity
- total vessel length
The smaller the radius of the vessel the ____ the resistance it offers to blood flow (inversely proportional)
greater
Blood thickness (viscosity) depends mostly on the ratio of RBCs to ____. The thicker the blood the higher the resistance (directly proportional) anemia or hemorrhage will deplete RBCs and proteins and cause a decrease in resistance and BP
plasma volume
____ refers to all the vascular resistances offered by the systemic vessels, Arterioles function to control SVR
Systemic vascular resistance (SVR)
Blood return to the heart from systemic veins depends upon the pressure difference between ____ (16mmHg) and the ____ (5mmHg)
venules; RA
Although this pressure difference is small, ____ is adequate because resistance in veins is very low
venous return
If pressure increases in the ____, then venous flow will back up (may be seen in the case of a regurgitant tricuspid valve)
RA
The skeletal muscle pump propels venous blood by contraction and relaxation of muscles
