Flashcards in Kaplan Ch. 7 - The Cardiovascular System Deck (45):
What is the heart?
Two pumps supporting two different circulations in series with one another
What is the right side of the heart responsible for?
Providing pulmonary circulation (pumps deoxygenated blood returning from body through the right side of the heart and out to the lungs)
What is the left side of the heart responsible for?
Providing systemic circulation (oxygenated blood from the lungs arrives at the heart via the pulmonary veins, heart then pumps blood out to body)
1) Where are the atria located?
2) how do the musculature of the atria compare to the ventricles?
3) what is their function?
1) Each side of the heart has an atria, on the right side it is where deoxygenated blood arrives before being pumped to ventricle. On left side it is where oxygenated blood arrives before being pumped to left ventricle.
2) the atrial walls are thinner
3) to push blood into the ventricles
The valves that separate the atria from the ventricles
Atrioventricular valve between the right atrium and right ventricle
Bicuspid valve (mitral valve)
Atrioventricular valve between left atrium and left ventricle
Semilunar valve, separates the right ventricle from pulmonary artery
Semilunar valve, separates the left ventricle from the aorta
How does the musculature of the right and left sides of the heart compare?
The left side is more muscular than the right because it needs to pump blood over a much longer distance so it needs to be able to generate more force per contraction
The valves that separate the ventricles from the vasculature, responsible for creating pressure that is needed to pump blood to lungs or body and also prevent backflow
Describe the path of electrical conduction in the heart.
The sinoatrial (SA) node generates 60-100 signals per minute. As these signals travel to the Atrioventricular node (AV), they cause the atria to contract simultaneously. The atria constantly pass blood to the ventricles, but this contraction (atrial systole) causes a larger amount of blood to fill the ventricles. The signals then reach the AV node where they wait until the ventricles are filled completely. Once filled, the signals travel down the bundles of His to the Purkinje fibers which branch out on either side of the ventricles. The signals are passed from the Purkinje fibers to local cells which stimulate ventricular contraction.
What is cardiac output?
Heart rate x stroke volume
What happens during systole?
The AV valves close, the ventricles contract and blood is pushed out of the heart into circulation.
What happens during diastole?
The heart relaxes, the semilunar valves close, the AV valves allow blood to fill the atria and into the ventricles
How does the pressure in systole compare to diastole?
Systole > diastole
There are only 2 arteries that do not carry oxygenated blood. What are they?
The pulmonary artery and the umbilical artery
The arteries are highly muscular and elastic. What impact does this have on systemic circulation pressure?
It must be very high in order to overcome the resistance to blood flow created by the arteries
1) What is the layer of endothelial cells in capillaries like?
2) What does this wall structure allow the capillaries to do?
1) It is a single layer of cells
2) easy diffusion of gasses, nutrients, and waste
1) how do the walls of veins compare to those of arteries?
2) which 2 veins are the only veins to carry oxygenated blood?
3) volume of blood in venous circulation vs arterial?
4) the right side of the circulatory system has to carry blood against gravity. How does it do this? What effect does this have on the pressure in the legs?
1) the walls are thinner and in elastic
2) the pulmonary veins and the umbilical veins
3) venous volume is larger
4) pressure in legs is very high due to column of blood exerting hydrostatic pressure above it. The veins pump blood against gravity by using the surrounding muscles and valves. The valves ensure that once blood passes through it cannot pass back down so blood can be continually moved upward. The surrounding muscle contractions also help squeeze the veins causing blood to be pushed upward.
What is varicose veins?
Failure of the venous valves to close properly, results in distended veins where blood has pooled. Especially likely I’m pregnant women.
Deep vein thrombosis
A blood clot that occurs in the deep veins of the leg, sitting still for long periods of time can cause blood flow in the legs to become sluggish and increases the risk of clotting (DVT)
When a DVT clot becomes dislodged and travels up the right heart to the lungs
In a given sample of blood, what is the ratio of plasma to actual cells?
55% plasma, 45% cells
What are the 3 main types of cells in the blood?
Erythrocytes, leukocytes, platelets
When blood cells die, how are more made?
All blood cells arise from hematopoietic stem cells in bone marrow
How is the shape of erythrocytes important?
They are biconcave, which allows for increased surface area for hemoglobin and helps them fit in small capillaries
How is the internal structure of red blood cells unique?
What result did this have on their metabolism and reproduction?
They lack nuclei, mitochondria, and other important organelles upon maturation. The reason for this is to provide the most room for hemoglobin.
Because they lack mitochondria they can only undergo glycolysis for energy and they cannot divide, so when they die new cells must be made by stem cells in bone marrow to replace them.
What are measures of hemoglobin and hematocrit?
Hemoglobin measures the amount of hemoglobin present in the sample.
Hematocrit measures how much of the sample is red blood cells.
Red blood cells, responsible for transporting oxygen in the blood
How do erythrocytes carry oxygen?
Each erythrocyte has ~250 million molecules of hemoglobin protein on its surface, each of which can bind 4 molecules of oxygen and carry it in the blood
What 2 categories are leukocytes subdivided into?
Granulocytes (neutrophils, eosinophils, basophils) - contain granules in cytoplasm that are visible under light microscope
Agranulocytes (lymphocytes and monocytes) do not contain granules
What is the function of granulocytes?
In response to a detected pathogen, these cells release contents of granules via exocytosis to attack and degrade invader
What is the function of lymphocytes?
Important in specific immune response, acting as primary responders against infection or serving as a memory bank of pathogen information
What are the 2 locations for lymphocytes to mature?
Bone marrow —> B cells (responsible for antibody generation)
Thymus —> T cells, kill virally infected cells and activate other immune cells
1) what are blood antigens?
2) what is the heritability of the A and B antigens?
3) what is the heritability of O?
1) proteins expressed on the surface of the blood cells that is a target for the immune system
2) A and B antigens are codominant, this if the genotype is I_A I_B the person will express both, person would be universal recipient
3) recessive, also denoted i, person with ii blood type will express neither A nor B antigens, this person would be universal donor
What is the Rh factor?
How is it denoted in blood types?
Also a surface protein expresses on red blood cells
If a person expresses the Rh protein, they have superscript +, if person does not express it then they have superscript -
Where does the largest drop in blood pressure occur?
From the arterioles to the capillaries
Because the capillaries would not be able to withstand the large pressure in the arterioles (go from much larger diameter to much smaller diameter, capillaries have higher resistance to flow than arterioles)
What are the 2 kinda of receptors that are used to regulate blood pressure?
1) baroreceptors - detect changes in mechanical forces on walls of vessels. When BP too low, they can stimulate sympathetic NS to contract vessels and increase BP
2) Chemoreceptors - sense when osmolality of blood is too high (release ADH) or too low (aldosterone)
Describe the binding of oxygen to red blood cells.
Oxygen bonds in a cooperative manner. When 1 oxygen molecule bonds to 1/4 hemoglobin binding sites, it causes a conformational change in the RBC such that it makes it easier for subsequent oxygen molecules to bind.
The same is true in reverse - if one oxygen molecule is removed, the RBC changes shape and it becomes easier to lose subsequent oxygen molecules.
What causes a right shift (decreased affinity of hemoglobin for oxygen) in the O2 saturation curve?
Mnemonic: Exercise is the right thing to do
Increased body temp
Increased partial pressure CO2
Increased [H+] (decreased pH)
What causes a left shift (increased affinity of hemoglobin for oxygen) in the O2 saturation curve?
Decreased body temperature
Decreased partial pressure CO2
Decreased [H+] (increased pH)
Describe the process of a blood clot
When endothelium of blood vessel is damaged, connective tissue (collagen) is exposed. When platelets contact exposed collagen they sense that damage has been done and they release their contents and aggregate. Coagulation factors sense this formation and initiate a cascade that ultimately results in prothrombin forming thrombin, which then converts fibrinogen into fibrin, which ultimately forms small fibers that act as a net to trap red blood cells and other platelets to form a stable clot over the damaged area.
What is albumin?
Albumin is the most abundant protein in the blood and it is responsible for transporting fatty acids and steroids, regulating osmotic pressure, and facilitating transfer of substances across the capillary walls