Physiology Exam #2 Flashcards
What are the three basic functions of blood
Transportation, Regulation, and Protection
How does blood provide transportation?
- Red blood cells (erythrocytes) transport oxygen to cells
- Blood carries absorbed products of digestions through the liver to the cells of the body
- Metabolic wastes and other molecules not needed by the body are carried by the blood to the kidneys and excreted in urine
How does blood provide regulation?
- Blood carries hormones
- Provides temperature regulation
How does blood provide protection?
- Clotting mechanism protects against blood loss when vessels are damaged
- Immune function is performed by leukocytes that protect against pathogens
What is the total blood volume in the average-sized adult?
About 5 liters (4-6) constituting about 8% of the total body weight
What is blood leaving the heart referred to as?
Arterial blood (bright red because of high concentration of oxyhemoglobin - combination of oxygen and hemoglobin)
What is blood returning to the heart referred to as?
Venous blood (contains less oxygen - darker red than the oxygen-rich arterial blood)
Where is the blood distributed when centrifuged?
- Heavier formed elements are packed into the bottom (red blood cells)
- Buffy coat is in the middle (leukocytes and platelets)
- Plasma is at the top
Formed elements and plasma constitute about how much of the total blood volume?
Formed elements constitute about 45% of the total blood volume and plasma accounts for the remaining 55%.
What is hematocrit?
The percentage of red blood cells volume to total blood volume in a centrifuged blood sample.
What are the hematocrit levels for women? For men?
36% to 46% for women and 41% to 53% in men.
The formed elements of blood include which two types of complete blood cells?
Erythrocytes and Leukocytes
What shape are erythrocytes and what function does it serve?
Flattened, biconcave discs - unique shape related to their function of transporting oxygen; provides an increased surface area through which gas can diffuse.
What parts of the cells are lacking in erythrocytes? How do they obtain energy?
They lack nuclei and mitochondria - they obtain energy through anaerobic metabolism
How long is the lifespan for erythrocytes?
120 days
How are older erythrocytes removed from the circulation?
By phagocytic cells in the liver, spleen, and bone marrow
Where are red blood cells produced and how many are produced in a day?
In the bone marrow - 200 billion each day
How do leukocytes move? What function does this serve?
In an amoeboid fashion - leukocytes can squeeze through pores in capillary walls and move to a site of infection (diapedesis or extravasation)
What are the smallest of the formed elements?
Platelets (thrombocytes)
How long do platelets survive?
5 to 9 days - destroyed by the spleen and liver
What role do platelets play?
Blood clotting - they constitute most of the mass of the clot
What would happen to a cell in a hypertonic solution?
Cell would shrivel up (more solutes outside the cell than inside) caused by dehydration
What would happen to a cell in a isotonic solution?
Remain the same - equal movement back and forth
What would happen to a cell in a hypotonic solution?
Cell would swell and possibly burst (too much water consumption with no electrolytes can cause this)
What is hemoglobin?
The combination of heme pigment and protein with red blood cells that acts to transport oxygen and carbon dioxide.
What causes an increase in erythropoiesis (formation of erythrocytes)?
Kidneys detect low oxygen in the red blood cells and communicate that an increase of production is needed.
What are antigens?
Certain molecules on the surface of all cells in the body that can be recognized as foreign by the immune system of another individual.
Which blood types have which antigens on them?
- A blood type has the A antigen
- B blood type has the B antigen
- AB blood type has both A and B antigens
- O blood type has no antigens
What are antibodies?
Part of the immune response and a class of proteins that are secreted by lymphocytes that bond in a specific fashion with antigens
Which blood types have which antibodies on them?
- A blood type has the B antibody
- B blood type has the A antibody
- AB blood type has no antibodies
- O blood type has both A and B antibodies
What is agglutination?
The clumping of cells (usually erythrocytes) as a result of specific chemical interaction between surface antigens and antibodies.
What is another group of antigens found on the red blood cells of most people called?
Rh factor
In reference to medical significance, what is the Rh factor indicated as?
Rho(D)
If the Rh antigen is present on a person’s red blood cell, are they Rh positive or negative?
Rh positive
What is the order of leukocyte concentrations? (Never Let Monkeys Eat Bananas)
- Neutrophils
- Lymphocytes
- Monocyte
- Eosinophil
- Basophil
What is hemostasis?
The cessation of bleeding
What happens during vasoconstriction?
Veins are made smaller, volume of blood to the area is decreased downstream
When fibrinogen is converted to fibrin, which pathway is fastest?
Extrinsic
Which vitamin is needed by the liver to make several of the needed clotting factors?
Vitamin K
What are the four chambers of the heart and what are their roles?
- Right atrium: receives deoxygenated blood from the body
- Left atrium: receives oxygenated blood from the lungs
- Right ventricle: pumps deoxygenated blood to the lungs
- Left ventricle: pumps oxygenated blood to the body
Which circuit is between the heart and lungs?
Pulmonary
Which circuit is between the heart and body tissue?
Systemic
Pulmonary: blood pumps to lungs via..
pulmonary arteries
Pulmonary: blood returns to heart via..
Pulmonary veins
Systemic: blood pumps to body tissues via..
aorta
Systemic: blood returns to heart via..
superior and inferior vena cava
Which valves are located between the atria and the ventricles and prevent backflow?
Atrioventricular (AV) valves
AV valve between right atrium and ventricle
Tricuspid
AV valve between left atrium and ventricle
Bicuspid (mitral)
What prevents the AV valves from everting (going backwards)
Papillary muscles and chordae tendineae
Which valves are located between the ventricles and arteries leaving the heart; preventing backflow
Semilunar valves
Semilunar valve between right ventricle and pulmonary trunk
Pulmonary
Semilunar valve between left ventricle and aorta
Aortic
What is systole?
Contraction of heart muscles
What is diastole?
Relaxation of heart muscles
What is end-diastolic volume?
Total volume of blood in the ventricles at the end of diastole (relaxation) - the chamber is at its largest size.
What is end-systolic volume?
The amount of blood left in the left ventricle after systole (contraction) - chamber at its smallest size
What is the stroke volume?
The amount of blood ejected
What is the average cardiac rate?
75 beats/min, each cycle lasts 0.8 sec
What happens to the blood flow as ventricles relax?
- Pressure drops inside the ventricles
- Semilunar valves close as blood attempts to back up into the ventricles from the vessels
- AV valves open (between atria and ventricles)
- Blood flows from atria to ventricles
What happens to the blood flow as ventricles contract?
- AV valves close as blood attempts to back up into the atria
- Pressure rises inside of the ventricles
- Semilunar valves open and blood flows into great vessels
What is the blood flow pathway through the chambers?
- Travels from the right atrium through the pulmonary circuit
- Then travels through systemic circuit
- Back to starting point
What are cardiac muscles interconnected by?
Gap junctions called intercalated discs (makes it function as a single unit)
What is the myocardium or functional syncytium?
The area of the heart that contracts from one stimulation event
What separates the atria and the ventricles?
They are separated electrically by the fibrous skeleton
What is automaticity?
Automatic nature of the heartbeat
What is the sinoatrial node (SA node) and where is it located?
Known as the pacemaker; located in the right atrium and is a grouping of specialized cells
What are the AV node and Purkinje fibers?
Secondary pacemakers or ectopic pacemakers; slower rate than the “normal sinus rhythm”
What is pacemaker potential?
A slow, spontaneous depolarization; also called diastolic depolarization - between heartbeats, triggered by hyperpolarization
What do HCN (hyperpolarization cyclic nucleotide) (aka funny channels and/or leaky channels) do?
Open in response to hyperpolarization and allow Na+ to enter to produce depolarization
What do parasympathetic neurons secrete and do?
They secrete acetylcholine, which opens K+ channels (causing an increase in hyperpolarization) and slows the heart rate.
Steps of the Conduction System of the Heart
- Action potentials spread via intercalated discs between right and left atria
- SA node to AV node to stimulate atrial contraction
- AV node at base of right atrium and bundle of His (AV bundle) conduct towards the ventricles
- In the interventricular septum, the bundle of His divides into right and left bundle branches
- Branch bundles become Purkinje fibers, which stimulate ventricular contraction upward
When do the action potentials slow down and speed up during conduction of impulses?
- Action potentials from the SA node spread rapidly (spreads to surrounding myocardial cells)
- At the AV node, things slow down
- Speed picks back up in the bundle of His
What is repolarization?
- Calcium concentrations in cytoplasm reduced by active transport back into the SR
- Extrusion of calcium through the plasma membrane by the sodium calcium exchanger (NCX) - secondary active transport
- Primary active transport of calcium ATPase pump
- Myocardium relaxes
What does the electrocardiograph do?
Records the electrical activity of the heart by picking up the movement of ions in body tissues in response to activity - records electrical events leading to contraction and relaxation
What does P wave read?
Atrial depolarization
What does P-Q wave read?
Atrial systole
What does QRS wave read?
Ventricular depolarization
What does S-T segment read?
Plateau phase, ventricular systole
What does T wave read?
Ventricular repolarization
Heart Sounds - when does the “lub” occur?
After the QRS wave as the AV valves close
Heart Sounds - when does the “dub” occur?
At the beginning of the T wave as the SL valves close
What is cardiac output?
The amount of blood ejected by each ventricle in 1 minute
What is the equation for finding cardiac output?
heart rate x stroke volume = cardiac output
What is the amount of cardiac output at rest?
4 to 6 L/min
What is cardiac reserve?
The difference between a person’s maximum and resting CO levels
How can you increase cardiac output?
- Increase stroke volume
- Increase heart rate
- Increase both
What are the three variables responsible for regulation of stroke volume?
- End diastolic volume (EDV): also called preload (stoke volume is increased with increased EDV)
- Total peripheral resistance: frictional resistance in the arteries (called afterload - increase in resistance decreases stroke volume)
- Contractility: strength of ventricular contraction (stroke volume increases with increased contractility)
What is ejection fraction?
When 60% of the EDV has been ejected
What factors affect blood pressure?
- Blood volume
- Stroke volume
- Total peripheral resistance
- Cardiac rate
(Increase in any of these will increase blood pressure)
How is blood pressure measured and what instrument is used?
Measured in mmHg and sphygmomanometer
What are sounds of Korotkoff?
Turbulent flow of blood in the brachial artery that can be heard using a stethoscope
How is blood pressure taken?
- Cuff is inflated to beyond systolic blood pressure to pinch off the brachial artery
- As pressure is released, the first sound is heard at systole and a reading can be taken
- The last Korotkoff sound is heard when the pressure in the cuff reaches diastolic pressure, and a second reading can be taken - laminar flow returns which has no sound
What is the average blood pressure?
120/80
What does a fall in blood pressure cause?
- Increased sympathetic
- Decreased parasympathetic
- Increased heart rate and vasoconstriction of the vessels
