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Heart failure accounts for _____ of all deaths
in the US.
TERM 2
What is the purpose of the circulatory
system?
DEFINITION 2 Transport nutrients, respiratory gases, hormones, metabolic products, cells, etc., through the body. Temperature control. TERM 3
What are the three basic structural
components of the circulatory system?
DEFINITION 3 Pump (heart) Conduits (vessels) Transport medium (blood) TERM 4
Briefly describe the differences between fish,
reptilian and bird/mammalian circulatory
systems.
DEFINITION 4 Fish have a heart with two chambers: a single atrium and a single ventricle. The reptilian ventricle is partly divided by a septum to direct oxygenated blood to the body and deoxygenated blood to the lungs. Birds and mammals have four-chambered hearts. Their pulmonary and systemic circuits are totally separate. TERM 5
______ blood flows to gas exchange organ
(gills or lungs), ______ blood flows to rest of
body (systemic).
DEFINITION 5 Deoxygenated; oxygenated
______ number of heart chambers permits
______ separation of blood flow to the gas
exchange organs and to the rest of the body.
Increased; increased TERM 7
How many chambers does the human heart
contain?
DEFINITION 7 4 chambers: 2 atria and 2 ventricles. Blood enters atrium, pumped out of ventricle. Right heart -> lungs Left heart -> systemic Valves prevent backflow. Blood flows from right heart to lungs to left heart to body. TERM 8
What are the two phases of the cardiac cycle?
DEFINITION 8 "Systole" = contraction phase "Diastole" = relaxation phase TERM 9
What are heartbeats made by?
DEFINITION 9 Heart valves closing. TERM 10
What is the process by which blood pressure
is measured using a sphygmomanometer and
a stethoscope?
DEFINITION 10 The cuff is inflated beyond the point that shuts off all blood flow. Pressure in the cuff is gradually lowered until the sound of a pulsing flow of blood through the constriction in the artery is heard. At this time, pressure in the cuff is just below the peak systolic pressure in the artery. Pressure is further lowered until the sound becomes continuous. At this time, the cuff is just below the diastolic pressure in the artery.
How are contractions of muscle cells
coordinated within chambers?
Cardiac muscle cells connected by gap junctions. Electrical continuity allows rapid spread of action potentials. No gap junctions between atria and ventricles. TERM 17
Action potentials in cardiac cells differ from
those in neurons or skeletal muscles in terms
of what?
DEFINITION 17 Kinetics Ion channels involved. TERM 18
The Electrocardiogram
(ECG)
DEFINITION 18 Records the electrical activity of the heart. The sounds heard through a stethoscope occur at the beginning and end of systole. TERM 19
How does the nervous system control heart
rate?
DEFINITION 19 Sympathetic nerves release (nor) epinephrine (a.k.a. (nor)adrenaline), which increases heart rate and leads to the " fight or flight " response. Parasympathetic nerves release acetylcholine , which decreases pacemaker activity and leads to a slower heart rate (" rest and digest "). TERM 20
How does norepinephrine increase the heart
rate?
DEFINITION 20 Norepinephrine from sympathetic nerves increases permeability of Na+ and Ca2+ channels. The resting potential rises more quickly and action potentials are closer together.
How does acetylcholine decrease the heart
rate?
Acetylchlolinefrom parasympathetic nerves increases the permeability of K+ and decreases that of Ca2+ channels. The resting potential rises more slowly and action potentials are further apart. TERM 22
What are the five types of blood vessels?
DEFINITION 22 Arteries : carry blood away from the heart. Arterioles : control distribution to specific capillary beds. Capillaries : site of exchange between blood and interstitial fluid. Venules : return blood to veins. Veins : return blood to heart. TERM 23
What are some special properties of arteries
and arterioles?
DEFINITION 23 They have: Elastic fibers, enabling them to withstand high pressures. Smooth muscle cells, allowing them to contract and expand, altering their resistance and thus blood flow. TERM 24
What are some special properties of veins and
venules?
DEFINITION 24 They have: Valves to prevent backflow of blood. Smooth muscle cells, allowing them to contract and expand, altering their resistance and thus blood flow. TERM 25
How does blood reach the capillaries?
DEFINITION 25 Blood flow through a capillary bed is controlled by the constriction of smooth muscle in the arteries and arterioles. Precapillary sphincters can open in response to local hypoxia, low pH, or cytokines, or they can shut off blood supply to the capillary bed.
What is the challenge of the circulatory
system?
To transport gases efficiently via liquid medium, despite low solubility of gas in liquid. TERM 32
What are some mechanisms that increase
efficiency of the blood?
DEFINITION 32 Efficient loading/unloading at gas-exchange surfaces in the lungs (alveoli). Increased O2 capacity of blood by specializations of red blood cells (RBCs). Efficient removal of CO2 from muscles. TERM 33
How does gas travel between the alveolus
and capillary?
DEFINITION 33 In the alveolus, the air is very close to the blood flowing through the networks of capillaries surrounding the alveoli. Alveolar walls and capillary walls are extremely thin, minimizing the distance that O2 must diffuse to about 2 micrometers. TERM 34
Emphysema
DEFINITION 34 A letal condition where inflammation destroys walls of the alveoli. 4th largest cause of death in the US. Principle cause of this disease is smoking. TERM 35
Why are RBCs efficient O
carriers?
DEFINITION 35 They're small and biconcave, thus they're high SA/volume aids diffusion. Contain hemoglobin, which binds O2 directly and cooperatively and increases O2 capacity of blood by 60x Mature RBCs lose most organelles, circulate for ~120 days and get removed by spleen. During normal metabolism (blood PO2 = 40-100 mm Hg), 25% of O2 released, 75% reserved. At low PO2, reserves released.
The oxygen-binding capacity of hemoglobin
decreases a ______ pH.
low; high metabolic rate decreases pH, drives greater O release. TERM 37
What are the oxygen-binding adaptions of
hemoglobin?
DEFINITION 37 Living at low PO2 results in increased binding affinity. Fetal hemoglobin has a higher affinity than maternal (normal). Myoglobin has a higher affinity for O2 than hemoglobin. TERM 38
What are the chain of events that ensue in
cases of limited O2 supply in tissue?
DEFINITION 38 Low O2 supply in tissues causes induction of HIF-. HIF-1 induces kidney's to produce erythropoietin. Erythropoietin stimulates stems cells in bone marrow to produce red blood cells. More RBCs increase O2 supply in tissues. Transcription factor = hypoxia-inducible factor 1 (HIF-1) TERM 39
What are recombinant erythropoietin and
related products produced for?
DEFINITION 39 They're used to overcome anemia from cancer, cancer treatments, or dialysis, and to avoid blood transfusions. Safety issues: overuse leads to strokes and heart attacks. Abuse in endurance sports (cycling). TERM 40
How is CO2 removed from tissues?
DEFINITION 40 In body tissues, CO2 diffuses from cells into plasma and into the red blood cells (RBCs). About 5% of the CO2 is carried in solution in the plasma. About 20% of the CO2 combines with hemoglobin (Hb) In RBCs and in the endothelium, about 70% of the CO2 is rapidly converted to bicarbonate ions because carbonic anhydrase is present. Bicarbonate ions enter the plasma in exchange fro chloride ions. In the lungs, these processes are reversed. Bicarbonate forms carbonic acid, which dissociates, releasing CO2. CO2 diffuses out of the RBCs to the blood plasma and to the air in the alveolus and is exhaled.
