Unit 6A: Cardiovascular System - Blood and Blood Vessels

Question 1

General Functions of the Cardiovascular System

Transportation of the Blood Through the Body

Answer 1

Allows exchange of substances between capillaries and cells
Perfusion: delivery of blood per time pre gram of tissue
Adequate perfusion
- Sufficent blood delivered to maintain health of body cells (mL/min/g)
Requires continual pumping of the heart and open vessels

Question 2

General Functions of the Cardiovascular System

If System Fails (Heart Fails to Pump or Vessels Blocked)

Answer 2

• Cells have inadequate blood
• Deprived of oxygen and nutrients
• Accumulation of waste products
• Cell death possible

Question 3

Cardiovascular System Consists of

Blood

Answer 3

Only fluid connective tissue in the body
Carries dissolved materials towards and away from the body’s tissues
Continuously regenerated
- Blood cells are completely replaced roughly every 3-4 months

Question 4

Cardiovascular System Consists of

Heart

Answer 4

Muscular pump that moves the blood throughout the body

Question 5

Cardiovascular System Consists of

Blood Vessels

Answer 5

• Arteries: carry blood away from the heart
• Veins: carry blood towards the heart
• Capillaries: allow exchange of nutrients, gases, waste products between the blood and the body tissues

Question 6

Cardiovascular System Overview

Pulmonary Circulation

Answer 6

• Deoxygenated blood from right side of heart to lungs
• At lungs, blood picks up oxygen and releases carbon dioxide
• Blood vessels return blood to left side of heart

Question 7

Cardiovascular System Overview

Systemic Circulation

Answer 7

• Oxygented blood from left side of heart to systemic cells
• At systemic cells (e.g. skin, muscles), blood exchanges gases, nutrients, and wastes
• Blood vessels return blood to right side of heart

Question 8

Cardiovascular System Overview

Basic Pattern

Answer 8

Right heart - lungs - left heart - systemic tissues - right heart

Question 9

Functions of Blood

Transportation

Answer 9

Transports fromed elements, dissolved molecules and ions
- Carries oxygen from and carbon dioxide to the lungs
- Transports nutrients, hormones, heat and waste products

Question 10

Functions of Blood

Protection

Answer 10

• Leukocytes, plasma proteins, and other molecules (of immune system) protect against pathogens
• Platelets and certain plasma proteins protect against blood loss

Question 11

Functions of Blood

Regulation of Body Conditions (Help Maintain Homeostasis)

Answer 11

Body Temperature
- Blood absorbs heat from body cells (especially muscle) and releases it at skin
Body pH
- Blood absorbs acid (H+) and base (OH-) from body cells
- Blood contains chemical buffers
Fluid Balance
- Water is added to blood from GI tract
- Water lost through urine, skin, respiration
- Fluid is exchnaged between blood and interstitial fluid

Question 12

Physcial Characteristics of Blood

Color

Answer 12

• Oxygen-rich is bright red
• Oxygen-poor blood is dark red

Question 13

Physcial Characteristics of Blood

Volume

Answer 13

• About 5 liters in an adult (males > females)
• Normal blood volume essential for maintaining blood pressure

Question 14

Physical Characteristics of Blood

Blood pH

Answer 14

Plasma slightly alkaline - between 7.35 and 7.45
Plasma protein dependent upon H+ concentration
- With pH alternation, proteins denatured

Question 15

Physical Characteristics of Blood

Viscosity

Answer 15

• 4 to 5 times more viscous than water (thicker)
• Depends on amount of dissolved substances in blood

Question 16

Physical Characteristics of Blood

Plasma Concentration

Answer 16

• Relative concentration of solutes in plasma
• Determines whether fluids move into or out of plasma by osmosis

Question 17

Physical Characteristics of Blood

Temperature

Answer 17

• 1 degree higher than measured body temperature
• Warms are through which it travels

Question 18

Compositon of Blood

Answer 18

Blood is a colliod - formed elements are suspended in the plasma
Formed Elements:
- Erthyrocytes (red blood cells) - transport respiratory gases (especially oxygen) in the blood
- Leukocytes (white blood cells) - defend against pathogens
- Platelets - help clot blood, prevent blood loss from damaged vessels
Plasma
- Fluid portion of blood
- Contains plasma proteins and dissolved solutes

Question 19

Composition of Blood

Blood Plasma

Answer 19

Plasma portion of blood is a solution
Composed of:
- Water (92%)
- Plasma proteins (7%)
- Dissolved molecules and ions (1%)
Similar composition to interstital fluid, but portein higher in plasma than interstitial fluid
- Transports dissolved - ions, hormones, lipids, antibodies, clotting factors, enzymes, gasses (CO2, O2 - mostly in RBC’s))

Question 20

Compostion of Blood

Hematocrit

Answer 20

Percentage of volume of all formed elements
Clinical definition: percentage of only erythrocytes
- Adult males: 42 to 56%; females 38 to 46%
- Testosterone casues more erythropoietin secretion by kidney

Question 21

Compostion of Blood

Blood Smear

Answer 21

Thin layer of blood placed on microscope slide and stained
Formed elements differ in appearance
- Erythrocytes (RBC’s) are most numerous - pink, anucleate, biconcave discs
- Leukocytes (WBC’s) - larger than erthryocytes, varied in form, noticable nucleus
- Platelets - small fragments of cells

Question 22

Compostion of Blood

Erythrocytes

Answer 22

• Small, flexible formed elements
• Lack nucleus and cellular organelles; packed with hemoglobin
• Have biconcave disc structure
• Transport oxygen and carbon dioxide between tissues and lungs
• Each contains approximately 280 million haemoglobin molecules

Question 23

Compostion of Blood: Erythrocytes

Haemoglobin

Answer 23

Red-pigmented protein that transports oxygen and carbon dioxide
Termed oxygenated when maximally loaded with oxygen
Termed deoxygenated when some oxygen lost
Oxygen binding to hemoglobin
- Each hemoglobin capable of binding four molecules oxygen
- Transport O2 from lungs to body tissues
- Binding fairly weak - allows rapid attachment of O2 in lungs and rapid detachment of O2 in body tissues
Carbon dioxide binding to hemoglobin
- Transport CO2 from body tissues to lungs
- Binding fairly weak

Question 24

Compostion of Blood: Erythrocytes

Erythrocyte Destruction

Answer 24

Lacking organelles, erythrocytes cannot synthesize proteins for repairs
Maximum life span is 120 days
- Old erythrocytes phagocytized in spleen or liver
- Iron from hemoglobin transported to liver, then to red bone marrow as needed for erythrocyte production (erythropoiesis)

Question 25

Compostion of Blood

Leukocytes (White Blood Cells)

Answer 25

Defend against pathogens
Contain nucleus and organelles, but not hemoglobin
Motile and flexible - most not in blood but in tissues after squeezing through capillary walls
Five leukocyte types; Meutrophil, Lymphocyte, Monocyte, Eosinphil, Basophil
- All function in immunity
- Each has a specific role in the immune system

Question 26

Composition of Blood

Platelets

Answer 26

• Small, membrane-encoled cell fragments
• No nucleus
• Important role in blood clotting
• Normally 150,000 to 400,000 per cubic milimeter blood
• 30% stored in spleen
• Circulate for 8 to 10 days; then broken down and recycled

Question 27

Haemostasis

Vascular Spasm

Answer 27

Blood vessel contriction
Limits blood leakage
Lasts from few to many minutes
- Platelets and endothelial cells release chemicals that stimulate further constriction
Greater vasoconstriction with greater vessel damage

Question 28

Haemostasis

Platelat Plug Formation

Answer 28

• Collagen fibres in vessel wall exposed
• Platelets stick to collagen
• Platelets develop long processes allowing for better adhesion
• Many platelets aggregate and close off injury
• Occurs in response to release of eicosanoids

Question 29

Haemostasis

Coagulation

Answer 29

Blood clotting
Network of fibrin (insoluble protein) froms a mesh
- Fibrin comes from soluble precurose fibrinogen
Mesh traps erythrocytes, leukocytes, platelets, and plasma proteins to from clot
Plasma dries out to form a scab
Clotting requires calcium, clotting factors, platelets, vitamin K

Question 30

Haemostasis

Answer 30

Stoppage of bleeding
- Three overlapping phases

Question 31

Haematopoiesis

Answer 31

Production of formed elements of blood
Occurs in the red bone marrow of certain bones
- Skull bones
- Vertebrae
- Ribs
- Sternum
- Ossa coxae
- proximal epiphysis of humerus
- distal epiphysis of femur
Hemocytoblasts: stem cells
- Pluripotent: can differentiate into many types of cells (erythrocytes, leukocytes, thrombopoiesis)
- Triggered by hormones (e.g. erythropoietin is produced mainly in the kidneys and is stimulated by low oxygen levels)

Question 32

Blood Types

Answer 32

ABO Blood Groups
- Named for antibodies
Rhesus Factor
- Postive/negative

Question 33

Blood Type Terminology

Antigens

Answer 33

• Substances that casue a state of sensitivity or responsiveness and react with antibodies or immune cells (e.g. pollen, viruses, bacteria, surface proteins, etc.)
• Can be foreign substances that are introduced to the body or can be naturally occuring proteins on a cell surface (as in erythrocytes)

Question 34

Blood Type Terminology

Antibodies

Answer 34

• Immunoglobulin proteins produced against a particular, specific antigen
• Immobilize antigens, ultimately casuing elimination by other immune cells (phagocytes)
• Especially effective in binding viral particles, bacteria, toxins, yeast spores

Question 35

Blood Type Terminolgy

Agglutination

Answer 35

• Clumping of blood that occurs when person transfused with blood of incompatible type
• Can block blood vessels and prevent normal circulation
• Can casue haemolysis, rupture of erythrocytes, and organ damage
• Successful transfusion requires compatability between donor and recipient (determined prior to blood donation using aggulation test)

Question 36

Blood Groups and Transfusions

Answer 36

Presence or absence of Rh factor (surface antigen D) on erythrocytes determines if blood type is positve or negative
Antibodies to Rh factor (anti-D antibodies) not usually there
- Only appear after Rh negative person exposed to Rh postive blood
ABO group and Rh type are reported together
- For example if all 3 antigens are present, blood type is described as AB+

Question 37

Application

Pregnancy

Answer 37

Rh negative mom
- May be exposed to Rh+ blood during childbirth of Rh+ baby
- Mom now has anti-D anitbodies
- In future pregnancy, may cross placenta, destroy detal RBC’s\
Results in hemolytic disease of the newborn (HDN)
- Infant with anemia, hyperbilirubinemia, heart failure
- Prevention: Give pregnant Rh negative women special immunoglobulins

Question 38

Overview of Blood Vessels

Common Traits of Arteries and Veins

Answer 38

Walls composed of three layers called tunics
Space insdie of vessel called its lumen
Tunics:
Tunica intima
- Innermost layer of vessel wall
- Endothelium of simple squamous epithelium
Tunica Media
- Middle layer of vessel; circulatory arranged layers of smooth muscle cells with elastic fibres
- Contraction casues vasocontriction: narrows lumen
- Relaxation casues vasodilation: widens lumen
Tunica externa
- Outermost layer of vessel; aerolor connective tissue with elastic and collagen fibres
- Helps anchor vessel to other structures

Question 39

Three Types of Blood Vessels

Arteries

Answer 39

• Transport blood away from heart to capillaries
• Most carry oxygenated blood (except pulmonary arteries)
• Thick walls with lots of elastic and collagen fibres; surrounded by smooth muscle
• Thicker tunica media and smaller lumen than veins
• Branch into smaller arteries called arterioles

Question 40

Three Types of Blood Vessels

Capillaries

Answer 40

• Connect arteries and veins
• Microscopic porous blood vessel
• Walls are one cell layer thick (to facilitate quick diffusion)
• Only tunic is tunica intima
• Exchnage substances (gasses, ions, minerals, hormones, nutrients, waste products, etc.) between blood and tissues

Question 41

Three Types of Blood Vessels

Veins

Answer 41

Transport blood from capillaries heart
Most carry deoxygenated blood (except pulmonary veins)
Thin walls with little elastic and collagen fibres; little smooth muscle
- Collapse when not filled with blood
Thinner tunica media and larger lumen than arteries
Have valves to prevet backflow of blood
Merge from smaller vessels called venules

Question 42

Capillary Beds

Answer 42

Precapillary sphincter
- Smooth muscle ring at rue capillary origin
- Sphincter relaxation permits blood to flow into true capillaries
- Sphincter contraction casues to bypass capillary bed
Vasomotion: cycle of contracting and relaxing of precapillary sphincters
- At any time only 1/4 of body’s capillary beds are open
Perfusion
- Amount of blood entering capillaries per unit time per gram of tissue (mL/min/g)

Question 43

Blood Pressure

Answer 43

Force of blood against vessel wall
Blood pressure gradient: change in pressure from one end of vessel to other
- Propels blood through vessels
- Pressure is highest in arteries and lowest in veins

Question 44

Arterial Blood Pressure

Answer 44

Blood flow in arteries pulses with cardiac cycle
Systolic pressure occurs when ventricle contracts (systole)
- Highest pressure generated in arteries (they are stretched)
- Recorded as the upper number of the blood pressure ration
- e.g. systolic pressure is 120 mmHg, if blood pressure is 120/80
Diastolic pressure occurs when ventricles relax (diastole)
- Lowest pressure generated in arteries (they coil)
- Recorded as the lower number of blood pressure ratio
- e.g. diastolic pressure is 80 mmHg, if blood pressure is 120/80
Pulse pressure: pressure in arteries added by heart contraction
- Equals the difference between systolic and diastolic blood pressure
- e.g. pluse pressure = 40 mmHg if blood pressure 120/80
- If reflects the elasticity and recoil of arteries, which tend to decline with age and disease
- Pulse pressure allows for palpation of a throbbing pulse in elastic and muscular arteries

Question 45

Blood Pressure

Systemic Blood Pressure

Answer 45

In the capillaries, pressure no longer fluctuates between systolic and diastolic
- Flow and pressure are smooth
- Needs to be high enough for exchange of substances
- Needs to be low enough not to damage vessels
- Arterial end of capillary at about 40 mmHG
- Venous end of capillary is below 20 mmHg
- Accounts for filtration and reaborption at respective ends
Systemic gradient is the difference between pressure in arteries near heart and in vena cava (e.g. in the organ systems)
- Mean blood pressure is arteries, 93 mmHg
- Blood pressure in vena cava 0
- Blood pressure gradient 93 mmHg
Systemic gradient is the driving force to move blood through vasculature
- Increasing gradient increases total blood flow
- Gradient increased by increased cardiac output

Question 46

Regulation of Blood Pressure

Answer 46

Blood pressure must be kept in proper range
- High enough to maintain tissue perfusion, but not so high as to damage vessels
- Pressure depends on cardiac output, resistance, blood volume (these variables regulated by nervous and endocrine systems)

Question 47

Neural Regulation of Blood Pressure

Answer 47

Cardiovacular Centre of Medulla Oblongata
- Reacts to sudden changes in BP - like standing up quickly
- Reacts to signals from baroreceptors and chemoreceptors in aorata vis vagus nerve (CN X) and carotid arteries vis glossopharyngeal nerve (CN IX)
- Cardiac centre - regulates heart rate and stroke volume (cardiac output)
- Vasomotor centre - regulates blood vessel diameter
High brain centers
- Hypothalamus can increase cardiac output and resistance - Causes might include increased body temperature or fight-or-flight reponse
- Limbic system can alter blood pressure in response to emotions or memories

Question 48

Endocrine Regulation of Blood Pressure

Answer 48

Sympathetic and Parasympathetic Nervous Pathways
- flight or flight pathways
Thyroid Hormone
- regulates metabolic activity