Ch. 19-21 Worksheets Flashcards
1
Q
Describe the general composition of blood
A
Whole blood is made up of fluid plasma and formed elements. The plasma is 92% water and the formed elements are 99% RBCs and 1% WBCs and platelets.
2
Q
Describe the composition of blood plasma
A
Plasma is made up of plasma proteins, other solutes (nutrients, electrolytes, wastes), and water
3
Q
What are the 3 types of plasma proteins?
A
Albumins
Globulins
Fibrinogen
4
Q
Function of albumins
A
Contributes to plasma osmolarity and osmotic pressure. Important for transporting fatty acids, thyroid hormones, and steroid hormones
5
Q
Function of globulins
A
Play an important role in liver function, blood clotting, and fighting infection
6
Q
Function of fibrinogen
A
The formation of fibrin that binds together platelets and some plasma proteins in a hemostatic plug
7
Q
Where are the 3 plasma proteins produced?
A
The liver
8
Q
What are the formed elements?
A
RBCs
WBCs
Platelets
9
Q
Structure of a RBC
A
Biconcave disc with a thin central region and a thicker outer margin
10
Q
Structure of a WBC
A
Has a nucleus, which is often large and lobed. Each WBC structure consists of a nucleus, cytoplasm and cell wall
11
Q
Structure of a platelet
A
They contain proteins on their surface that allow them to stick to breaks in the blood vessel wall and also to stick to each other. They contain granules that can secrete other proteins required for creating a firm plug to seal blood vessel breaks. Look like disc-shaped cell fragments in a blood smear.
12
Q
Function of RBCs
A
Bring oxygen to the tissues in your body and release carbon dioxide to your lungs for you to exhale
13
Q
Function of WBCs
A
Responsible for protecting your body from infection. As part of your immune system, white blood cells circulate in your blood and respond to injury or illness.
14
Q
Function of platelets
A
Release chemicals important in the clotting process and forms a temporary patch in the walls of damaged blood vessels
15
Q
Another name for RBCs
A
Erythrocytes
16
Q
Another name for WBCs
A
Leukocytes
17
Q
List the 5 types of leukocytes in order of abundance
A
Neutrophils Lymphocytes Monocytes Eosinophils Basophils
18
Q
Function of neutrophils
A
Specializes in attacking and digesting bacteria that have been marked with antibodies or complement proteins
19
Q
Function of lymphocytes
A
Defend against invading foreign cells; produce antibodies; detect and destroy abnormal cells; help to prevent cancer
20
Q
Function of monocytes
A
Engulf items as large/larger than themselves; release chemicals that attract neutrophils, monocytes, and other phagocytic cells; secrete substances that draw fibroblasts to the region
21
Q
Function of eosinophils
A
Attack objects coated with antibodies; engulf antibody-marked bacteria, protozoa, or cellular debris
22
Q
Function of basophils
A
Migrate to injury sites and cross the capillary endothelium to accumulate in the damaged tissues; they discharge their granules in the interstitial fluids; release chemicals that attract eosinophils and other basophils to the area
23
Q
Describe the structure and function of hemoglobin
A
4 polypeptide subunits (2 alpha and 2 beta chains). Each polypeptide is bound to iron-containing compound called a heme group. Iron in each heme group binds to oxygen in places where oxygen levels are high (lungs) to form oxyhemoglobin.
24
Q
What is hematocrit?
A
The ratio of the volume of RBCs to the total volume of blood
25
Locations of hematopoiesis
Organs and tissues such as the bone marrow, liver, and spleen
26
What is the significance of the hematopoietic stem cell?
In red bone marrow, hematopoietic stem cells divide to produce myeloid stem cells (which provide RBCs and several WBCs) and lymphoid stem cells (which produce lymphocytes)
27
What is erythropoiesis?
The formation of RBCs in red bone marrow
28
What is the process of erythropoiesis?
Erythropoiesis is regulated through a negative feedback loop. Blood oxygen levels may begin to decrease and kidney cells will detect this drop. The kidney cells will signal the kidney to produce more EPO and release into the blood. Production of erythrocytes increases.
29
What is the reticulocyte count used for?
To estimate the degree of effective erythropoiesis and can help in the diagnosis of different types of anemia
30
Describe the vascular phase of hemostasis
The endothelial cells contract and expose the underlying basement membrane to the bloodstream. The endothelial cells begin releasing chemical factors and local hormones. The endothelial plasma membranes become sticky. The stickiness helps platelets to attach.
31
Describe the platelet phase of hemostasis
The process of platelet aggregation forms a platelet plug that may close the break in the vessel wall if the damage is not severe or the vessel is small
32
Describe the steps involved in the formation of a platelet plug
As platelets arrive at the injury site, they become activated and release ADP, thromboxane, and calcium ions to further aggregation, which produces a platelet plug
33
Describe the basic steps of coagulation resulting in the formation of the insoluble fibrin clot.
Circulating fibrinogen is converted into fibrin. As the fibrin network grows, blood cells and additional platelets are trapped in the fibrous tangle, forming a blood clot that seals off the damaged portion of the vessel.
34
The main difference between intrinsic and extrinsic pathways
The intrinsic pathway is activated by a trauma inside the vascular system whereas the extrinsic pathway is activated by external trauma.
35
What does the intrinsic pathway begin with?
The activation of factor XII exposed to collagen fibers at the injury site
36
When does the extrinsic pathway begin?
When damaged endothelial cells or peripheral tissues release factor III
37
When does the common pathway begin?
The common pathway may result after the activation of factor X at the end of the intrinsic OR extrinsic pathway
38
Explain how the positive feedback loops in the platelet and coagulation phases promote hemostasis.
As the platelets continue to amass, more of the chemicals are released and more platelets are attracted to the site of the clot. The positive feedback accelerates the process of clotting until the clot is large enough to stop the bleeding
39
Explain the role of vitamin K in blood clotting.
Vitamin K must be present for the liver to synthesize four of the clotting factors. Vitamin K deficiency can deactivate the entire clotting system
40
Describe the process of fibrinolysis
Fibrinolysis begins when two enzymes activate plasminogen, which produces the enzyme plasmin that begins digesting the fibrin strands and eroding the blood clot.
41
Explain the role of surface antigens on erythrocytes in determining blood groups.
Blood type is determined by the presence or absence of specific surface antigens in RBC plasma membranes. Your immune system ignores surface antigens on your own RBCs. Your plasma contains antibodies that will attack antigens on foreign RBCs.
42
List the type of antigen and the type of antibodies present in type A blood
Anti-B antibodies
| A antigens
43
List the type of antigen and the type of antibodies present in type B blood
Anti-A antibodies
| B antigens
44
List the type of antigen and the type of antibodies present in type AB blood
No antibodies
| A & B antigens
45
List the type of antigen and the type of antibodies present in type O blood
Anti-A & anti-B antibodies
| No antigens
46
Describe how the presence or absence of Rh antigen results in blood being classified as positive or negative.
The Rh blood group is based on the presence or absence of the Rh surface antigen. Rh+ indicates the presence of the Rh surface antigen. Rh- does not have the Rh factor.
47
Describe the development and clinical significance of anti-Rh antibodies.
If an Rh- mother has an Rh+ fetus the first time, it is not a big deal. If this happens during the second pregnancy, the mother’s blood will abort the fetus.
48
Predict which blood types are compatible
A blood is compatible with A and O. B blood is compatible with B and O. AB is compatible with A, B, AB, and O. O blood is compatible with O.
49
What happens when the incorrect ABO or Rh blood type is transfused?
Transfusion with the wrong blood type can cause a severe reaction that may be life-threatening.
50
What is MCV?
Mean cell volume
51
How to calculate MCV
Hematocrit x 10 divided by the RBC count
52
Why is the mean cell volume important?
Describes the average size of RBCs in a blood sample and can help diagnose health conditions and anemia.
53
What is MCHC?
Mean corpuscular hemoglobin concentration
54
Why is the MCHC important?
If MCHC is too low, you’re not carrying the right amount of oxygen and could have anemia. If it’s excessive, you could be hyperchromic
55
List the parts of the electrical conduction system of the heart in the correct sequence for one contraction
The sinoatrial node starts the sequence by causing the atrial muscles to contract. Next, the signal travels to the atrioventrical node, through the bundle of HIS, down the bundle branches, and through the Purkinje fibers, causing the ventricles to contract.
56
Explain how the electrical conduction system functions.
The heart conduction system is the network of nodes, cells and signals that controls your heartbeat. Each time your heart beats, electrical signals travel through your heart. These signals cause different parts of your heart to expand and contract. The expansion and contraction control blood flow through your heart and body.
57
Explain why the SA node normally paces the heart.
Because the SA node reaches threshold first, it establishes the basic heart rhythm. The impulse generated by the SA node brings the AV pacemaker cells to threshold faster than the pacemaker potential of the AV pacemaker cells
58
Explain how the cardiac conduction system produces coordinated heart chamber contractions.
The SA node sends out an electrical impulse. The atria contract. The AV node sends an impulse into the ventricles.
59
Explain what happens during a QRS wave
Impulses travel through ventricles, causing ventricles to contract
60
Explain what happens during a P wave
The depolarization of the atrial contractile cells causes the atria to contract
61
Explain what happens during a QRS wave
1 The depolarization of the ventricular contractile cells causes the ventricles to contract. During this time, atrial repolarization is taking place.
62
Explain what happens during a T wave
Ventricles return to resting state, indicating repolarization of the ventricular contractile cells.
63
Define cardiac cycle
The period between the start of one heartbeat and the beginning of the next is a single cardiac cycle
64
Define systole
AKA Contraction
The chamber contracts and pushes blood into an adjacent chamber or into an arterial trunk
65
Define diastole
AKA relaxation
Follows systole; the chamber fills with blood and prepares for the next cardiac cycle
66
Describe the phases of the cardiac cycle.
- Atrial systole begins. Atrial contraction forces a small amount of additional blood into relaxed ventricles.
- Ventricular systole. Atrial systole ends, atrial diastole begins. Ventricular contraction exerts enough pressure on the blood to close AV valves but not enough to open semilunar valves. As ventricular pressure rises and exceeds pressure in the arteries, the semilunar valves open and blood is ejected.
- Ventricular systole. As ventricles relax, pressure in ventricles drops; blood flows back against cusps of semilunar valves and forces them closed. Blood flows into the relaxed atria. All chambers are relaxed and ventricles fill passively.
67
Relate the electrical events represented on an electrocardiogram to the normal mechanical events of the cardiac cycle.
A typical ECG tracing of the cardiac cycle (heartbeat) consists of a P wave (atrial depolarization), a QRS complex (ventricular depolarization), and a T wave (ventricular repolarization). An additional wave, the U wave (Purkinje repolarization), is often visible, but not always.
68
Explain how atrial systole is related to ventricular filling.
When the action potential triggers the muscles in the atria to contract (atrial systole), the pressure within the atria rises further, pumping blood into the ventricles.
69
Relate the opening and closing of specific heart valves in each phase of the cardiac cycle to pressure changes in the heart chambers and the great vessels
- Atrioventricular valves open; atrial pressure is greater than ventricular pressure
- Atrioventricular valves close; atrial pressure is less than ventricular pressure
- Semilunar valves open; Pulmonary valve pressure is greater than the aorta and the pulmonary trunk
- Semilunar valves close; Pulmonary valve pressure is less than the aorta and the pulmonary trunk.
70
Relate the heart sounds to the events of the cardiac cycle.
- Sound 1 – atrioventricular valve opening
| - Sound 2 – closing of semilunar valves
71
Describe the pressure and volume changes of the left and right ventricles during systole.
During systole, the pressure in the atria and ventricles are lower and blood begins to fill them. When ventricles are 70% full, atria will contract, increasing pressure in the atria and forcing blood into the ventricles. As ventricles contract, ventricular pressure exceeds atrial pressure and AV valves close. Pressure rapidly builds in the contracting ventricles. When ventricular pressure exceeds blood pressure in the aorta, the aortic valve opens and blood is released into the aorta.
72
Describe the pressure and volume changes of the left and right ventricles during diastole.
During diastole, ventricular pressure falls as blood exits the ventricle. When ventricular pressure is below aortic pressure, the aortic valve closes. When the ventricular pressure drops below the atrial pressure, the AV valve opens and blood flows from atria to ventricle. During this cycle, aortic pressure remains high.
73
How long is a typical cardiac cycle?
Approximately 0.8 seconds
74
Define cardiac output
The amount of blood pumped by the left ventricle in 1 minute
75
What is the unit of measurement used for cardiac output?
mL/minute
76
What is the equation for cardiac output?
Heart rate (beats/min) X Stroke volume (mL/beat)
77
Predict how changes in heart rate (HR) and/or stroke volume (SV) will affect cardiac output (CO).
When heart rate or stroke volume increases, cardiac output is likely to increase also. Conversely, a decrease in heart rate or stroke volume can decrease cardiac output.
78
What is ejection fraction?
The percentage of blood volume ejected in each cardiac cycle and is a representation of left ventricular systolic performance.
79
What is cardiac reserve?
The difference between the rate at which the heart pumps blood and its maximum capacity for pumping blood at any given time.
80
What is the equation to calculate stroke volume?
Stroke volume = EDV - ESV
81
What is end diastolic volume (EDV)?
The amount of blood in each ventricle at the end of ventricular diastole
82
What is end systolic volume (ESV)?
The amount of blood remaining in each ventricle at the end of ventricular systole
83
What is venous return?
The amount of blood returning to the heart through veins. It directly affects pacemaker cells. When venous return increases, the atria receive more blood and the walls are stretched. Stretching of the cardiac pacemaker cells of the SA node leads to more rapid depolarization and an increase in the heart rate.
84
What is preload?
Preload is the degree of stretching in ventricular muscle cells during ventricular diastole. The greater the EDV, the larger the preload. It affects the ability of muscle cells to produce tension.
85
What is afterload?
Afterload is the amount of tension that the contracting ventricle must produce to force open the semilunar valve and eject blood. It increases with increased resistance to blood flow out of the ventricle. The greater the afterload, the longer the period of isovolumetric contraction. The shorter the duration of ventricular ejection, the larger the ESV. As the afterload increases, the stroke volume decreases.
86
State the Frank-Starling Law of the heart and explain its significance.
The Frank–Starling law of the heart indicates that the increased filling pressure of the right heart results in increased cardiac output. Any increase in output of the right heart is quickly communicated to the left heart as an increased filling pressure. More in = more out.
87
Define artery
Arteries carry blood away from the heart. As they enter peripheral tissues, they branch repeatedly, and the branches decrease in diameter
88
Define capillary
Capillaries are delicate vessels that weave throughout active tissues, forming intricate networks that surround muscle fibers
89
Define vein
Veins collect blood from all tissues and organs and return it to the heart
90
List the three tunics associated with most blood vessels
Tunica intima
Tunica media
Tunica externa
91
Describe the composition of tunica intima
Includes the endothelial lining and a surrounding layer of connective tissue with a variable number of elastic fibers
92
Describe the composition of tunica media
Contains concentric sheets of smooth muscle tissue in a framework of loose connective tissue. The collagen fibers bind the tunica media to the tunica intima and tunica externa
93
Describe the composition of tunica externa
A connective tissue sheath. In arteries, it contains collagen fibers with scattered bands of elastic fibers. In veins, it is thicker than the tunica media and contains networks of elastic fibers and bundles of smooth muscle cells
94
Describe the tunic structure of arteries
In tunica intima, the endothelium usually appears wavy due to constriction of smooth muscle. The tunica media is the thickest layer; smooth muscle cells and elastic fibers predominate. The tunica externa is thinner than the tunica media.
95
Describe the tunic structure of veins
In tunica intima, the endothelium appears smooth and there’s no internal elastic membrane. The tunica media is thinner than the tunica externa; smooth muscle cells with elastic and collagen fibers. The tunica externa is the thickest layer.
96
Describe the tunic structure of capillaries
Only have a tunica intima layer, which is thin and composed of a simple squamous epithelium and a small amount of connective tissue.
97
Which type of blood vessel has (a) the largest lumen and (b) the thickest tunica media?
(a) Veins have larger lumens than arteries.
| (b) Arteries, specifically muscular arteries, have the thickest tunica media.
98
Structure of elastic arteries
The walls are not very thick, but they are resilient. The tunica media contains few smooth muscle fibers and a high density of elastic fibers.
99
Function of elastic arteries
Carry large volumes of blood away from the heart
100
Structure of muscular arteries
Have a thicker tunica media with a great percentage of smooth muscle fibers than elastic arteries.
101
Function of muscular arteries
Draws blood from an elastic artery and branches into "resistance vessels" including small arteries and arterioles.
102
Structure of muscular arteries
Have a thicker tunica media with a great percentage of smooth muscle fibers than elastic arteries.
103
Structure of arterioles
Smaller than muscular arteries with a poorly defined tunica externa, and their tunica media consists of scattered smooth muscle fibers that may not form a complete layer.
104
Function of arterioles
Distribute blood flow into capillary beds
105
Structure of capillaries
Only have a tunica intima layer, which is thin and composed of a simple squamous epithelium and a small amount of connective tissue.
106
Function of capillaries
Take waste products away from tissues; exchange oxygen and nutrients for carbon dioxide and waste
107
Structure of venules
Vary widely in size and character. The smallest resemble expanded capillaries, and small ones lack a tunica media.
108
Function of venules
To collect blood from capillaries
109
Structure of veins
Walls can be thinner because blood pressure in veins is lower than arteries. Veins have larger luminal diameters than their corresponding arteries.
110
Function of veins
Collect blood from all tissues and organs and return it to the heart.
111
Define vasoconstriction
When stimulated, arterial smooth muscles contract, constricting the artery
112
Define vasodilation
When smooth muscles relax, the diameter of the lumen increases
113
Name the 3 types of capillaries
Continuous capillaries
Fenestrated capillaries
Sinusoids
114
Where are the 3 types of capillaries found in the body?
Continuous - in all tissues except epithelia and cartilage
Fenestrated - in tissues where a large amount of molecular exchange occurs, such as the kidneys, endocrine glands, and small intestine
Sinusoids- mainly in the liver and spleen
115
Structure/function of continuous capillaries
They have a continuous endothelial lining. They have tight junctions between their endothelial cells through which small molecules can pass.
116
Structure/function of fenestrated capillaries
They have small fenestrations in their endothelia that allows quick movement of macromolecules in and out of the capillary
117
Structure/function of fenestrated capillaries
They have small fenestrations in their endothelia that allows quick movement of macromolecules in and out of the capillary
118
Structure/function of sinusoids
They have endothelial linings with multiple fenestrations which allows blood cells and serum proteins to pass easily through the capillary wall
119
Describe the functional significance of the venous reservoir.
The blood in veins is referred to as a "Reservoir" because it can be mobilized to boost cardiac output and in turn systemic arterial pressure when physiological demands require so.
120
Define anastomosis
The direct or indirect connection of separate parts of a branching system to form a network, especially among blood vessels.
121
Explain the functional significance of anastomosis
Naturally occurring anastomosis refers to how structures are connected biologically in the body. For example, many veins and arteries are connected to each other. This helps us efficiently transport blood and nutrients throughout the body.
122
Describe the pulmonary circuit's pathway
The pulmonary circuit carries oxygen-poor blood from the heart’s lower right chamber (right ventricle) through the pulmonary arteries, to the lungs, and oxygen-rich blood back through the pulmonary veins to the heart’s upper left chamber (left atrium)
123
Describe the systemic circuit's pathway
The systemic circuit carries oxygen-rich blood from the heart’s lower left chamber (left ventricle) through the systemic arteries, and oxygen-poor blood through systemic veins back to the heart’s upper right chamber (right atrium)
124
Explain the functional significance of the pulmonary circuit
Pulmonary circulation transports oxygen-poor blood from the right ventricle to the lungs, where blood picks up a new blood supply. Then it returns the oxygen-rich blood to the left atrium.
125
Explain the functional significance of the systemic circuit
The systemic circulation provides the functional blood supply to all body tissue. It carries oxygen and nutrients to the cells and picks up carbon dioxide and waste products. Systemic circulation carries oxygenated blood from the left ventricle, through the arteries, to the capillaries in the tissues of the body.
126
Identify the major arteries and veins of the pulmonary circuit.
The pulmonary trunk splits into the right and left pulmonary arteries. From the lungs, the pulmonary veins transport blood to the left atrium of the heart.
127
Identify the major arteries and veins of the systemic circuit.
Oxygenated blood is pumped from the left ventricle of the heart through the aorta, to the systemic arteries, then to arterioles and capillary beds. Deoxygenated blood then moves from the capillary beds through venules into the systemic veins. The systemic veins feed into the inferior and superior venae cavae. The venae cavae flow deoxygenated blood to the right atrium of the heart.
128
Define a portal vessel
A blood vessel connecting two capillary beds
129
Define a portal system
A network of portal vessels
130
Describe the structure of the hepatic portal system
A series of veins that carry blood from the capillaries of the stomach, intestine, spleen, and pancreas to capillaries in the liver
131
Describe the function of the hepatic portal system
Blood flowing in the hepatic portal system contains substances absorbed from the stomach and intestines and delivers them to the liver for storage, metabolic conversion, or excretion
132
Describe the role of the placenta, umbilical vessels, ductus venosus, foramen ovale, and ductus arteriosus in fetal circulation.
Diffusion across the placenta provides for the respiratory and nutritional needs of the fetus. Fetal blood flows to the placenta through a pair of umbilical arteries. Blood returns from the placenta in the single umbilical vein, which drains into the ductus venosus. The ductus venosus empties it into the inferior vena cava. The foramen ovale is associated with a long flap that acts as a valve. Blood can flow freely from the right atrium to the left atrium. Blood entering the heart at the right atrium can bypass the pulmonary circuit; the ductus arteriosus is a second short-circuit that exists between the pulmonary and aortic trunks.
133
Trace the pathway of blood flow from the placenta, through the fetal heart and body, and back to the placenta.
Placenta → umblical vein → liver → inferior vena cava → right atrium → foramen ovale → left atrium → left ventricle → aorta → brain, heart, lower body → right atrium → right ventricle → ductus arteriosus → aorta → placenta
134
Describe the changes in major fetal cardiovascular structures that typically occur beginning at birth, and the ultimate postnatal remnants of these structures
- When the placental collection is broken, blood stops flowing in the umbilical vessels, and they degenerate. Remnants of these vessels persist through life as fibrous cords
- When an infant takes the first breath, the lungs expand, and so do the pulmonary vessels. The resistance in the pulmonary circuit declines suddenly, and blood rushes into the pulmonary vessels
- Rising O2 levels stimulate the constriction of the ductus arteriosus, isolating the pulmonary and aortic trunks from one another
- As pressures rise in the left atrium, the valvular flap closes the foramen ovale
- In adults, the interatrial septum bears the fossa ovalis, a shallow depression that marks the site of the foramen ovale
- The remnants of the ductus arteriosus persist throughout life as the ligamentum arteriosum, a fibrous cord
135
Define blood flow
The volume of blood flowing per unit of time through a vessel or a group of vessels; may refer to circulation through a capillary, a tissue, an organ, or the entire vascular network.
136
Define blood pressure
The hydrostatic pressure in the arterial system that pushes blood through capillary beds
137
Define peripheral resistance
The resistance of the arterial system; affected by such factors as vascular resistance, viscosity, and turbulence
138
State and interpret the equation that relates fluid flow to pressure and resistance.
F ∝ BP/PR
| Flow is directly proportional to blood pressure, and inversely proportional to peripheral resistance
139
Describe the role of arterioles in regulating tissue blood flow and systemic arterial blood pressure.
The arterioles play a key role in regulating blood flow into the tissue capillaries. About 10 percent of the total blood volume is in the systemic arterial system at any given time. It not only provides support for the vessel but also changes vessel diameter to regulate blood flow and blood pressure.
140
List the local, hormonal and neural factors that affect peripheral resistance and explain the importance of each.
1 Autonomic activity: sympathetic activity constricts peripheral arteries.
2 Pharmacologic agents: vasoconstrictor drugs increase resistance while vasodilator drugs decrease it.
3 Blood viscosity: increased viscosity increases resistance.
141
Equation to determine mean arterial pressure (MAP)
MAP = diastolic pressure + (pulse pressure/3)
142
Equation to determine pulse pressure (PP)
PP = systolic pressure - diastolic pressure
143
State the equation relating mean arterial pressure (MAP) to cardiac output (CO) and total peripheral resistance (TPR).
MAP = CO x TPR
144
Predict and describe how mean arterial pressure (MAP) would be affected by changes in total peripheral resistance (TPR), cardiac output (CO), heart rate (HR), stroke volume (SV), or preload.
Since cardiac output is the product of heart rate and stroke volume, changes in either of these parameters also influence MAP. If cardiac output increases, MAP increases.
145
Explain the mechanisms of capillary exchange of gases, nutrients, and wastes.
Cells rely on capillary exchange to obtain nutrients and oxygen and to remove metabolic wastes. Blood flows through capillaries slowly, allowing time for the diffusion or active transport of materials across the capillary walls.
146
Describe the forces that create capillary filtration
The primary force driving fluid transport between the capillaries and tissues is hydrostatic pressure, which can be defined as the pressure of any fluid enclosed in a space. If the net hydrostatic pressure is higher than the osmotic pressure, filtration occurs.
147
Describe the forces that create reabsorption
Reabsorption is driven by osmotic pressure. Osmotic pressure is the force of osmotic water movement; the pressure that must be applied to prevent osmosis across a membrane. If the osmotic pressure is higher, reabsorption occurs.
148
Explain how changes in net filtration pressure (NFP) can result in edema
The underlying problem of an edema is a disturbance in the normal balance between hydrostatic and osmotic forces at the capillary level
149
How does a functional lymphatic system normally prevent edema?
By properly removing fluid from tissues
150
Describe how muscular compression aid venous return
The contractions of skeletal muscles near a vein compress it, helping to push blood toward the heart. The cycles of contraction and relaxation that accompany normal movements assist venous return
151
Describe how the respiratory pump aid venous return
As you inhale, your thoracic cavity expands, reducing the pressure within the thoracic cavity. When the pressure in the thoracic cavity drops below atmospheric pressure, air enters the lungs. At the same time, the drop in venous pressure in the chest makes it easier to force blood into the inferior vena cava and right atrium from the smaller veins of your abdominal cavity and lower body
152
Explain how local control mechanisms influences blood flow to tissues.
Regulation of blood flow is managed by adjusting the contraction or relaxation of smooth muscle fibers in the walls of arterioles and capillaries. Arterioles are the primary blood vessel for local control due to their physical location within tissues and ability to vasodilate and vasocontract to influence blood flow.
153
Explain how myogenic autoregulation influences blood flow to tissues.
Myogenic mechanisms are intrinsic to the smooth muscle blood vessels, particularly in small arteries and arterioles. If the pressure within a vessel is suddenly increased, the vessel responds by constricting. Diminishing pressure within the vessel causes relaxation and vasodilation.
154
What would be some of the ways, short-term, I can try to raise blood pressure?
Increase norepinephrine or vasoconstricters at the arterials and increase contractility on the heart
155
What would be some of the ways, long-term, I can try to raise blood pressure?
Increase ADH and Angiotensin II, retaining more fluid at the kidneys
