Pulmonary Circulation Flashcards
Pulmonary circulation
Right side of the heart accepts deoxygenated blood returning from the body and moves it to the lungs by way of the pulmonary arteries; constitutes the first pump.
Systemic circulation
Left side of the heart receives oxygenated blood from the left side of the lungs by way of the pulmonary veins and forces it out of the body through the aorta.
Atria
Thin-walled structures where blood is received from either the venae cavae (deoxygenated blood entering the right heart) or the pulmonary veins (oxgyenated blood entering the left heart)
Ventricles
Atria send blood to the ventricles, which contract to send blood to the lungs (right ventricle) and the systemic circulation (left ventricle).
Are atria or ventricles more powerful
Ventricles are more muscular, allowing for more powerful contractions that are necessary to push blood through the rest of the body.
Atrioventricular valves
Separates atria from ventricles
Semilunar valves
Separates ventricles from vasculature. Includes pulmonary and aortic valves, and have 3 leaflets each.
Tricuspid valve
Valve between right atrium and right ventricle
Mitral/bicuspid valve
Valve between left atrium and left ventricle
Pulmonary valve
Separates right ventricle from the pulmonary circulation
Aortic valve
Separates left ventricle from the aorta
Electrical pathway, in order of excitation, of the heart
The sinoatrial (SA) node, the atrioventricular (AV) node, the bundle of His (AV bundle) and its branches, and the Purkinje fibers
SA node
Where impulse initiation occurs in the heart : generates 60-100 signals per minute without requiring any neurological input.
Small collection of cell located in the wall of the right atrium.
As depolarization wave spreads from SA node, it causes the 2 atria to contract simultaneously.
Atrial systole
Contraction, results in an increase in atrial pressure that forces a little more blood into the ventricles.
Atrial kick
Additional volume of blood squeezed into ventricles; accounts for about 5-30 percent of cardiac output
AV node
Sits at the junction of the atria and ventricles. Signal is delayed here to allow the ventricles to fill completely before they contract.
Purkinje fibers
Distribute the electrical signal through the ventricular muscle
Intercalated discs
May contain many gap junctions directly connecting the cytoplasm of adjacent cells: allows for coordinated ventricular contraction.
Systole
Ventricular contraction and closure of the AV valves occurs and blood is pumped out of the ventricles
Diastole
Ventricles are relaxed, the semilunar valves are closed, and blood from the atria fills the ventricles.
Cardiac output
The total blood volume pumped by a ventricle in a minute. The volumes of blood passing through each side must be the same
Equation for cardiac output
Cardiac output (CO) is the product of heart rate (HR, beats/minute) and stroke volume (SV, volume of blood pumped/beat).
CO = HR x SV
Pathway of Circulation
Right atrium –> tricuspid valve –> right ventricle –> pulmonary valve –> pulmonary artery –> lungs –> pulmonary veins –> left atrium –> mitral valve –> left ventricle –> aortic valve –> aorta –> arteries –> arterioles –> capillaries –> venules –> veins –> venae cavae –> right atrium
How many portal systems are there in the heart and what do they do
There are 3; blood will pass through 2 capillary beds in series before returning to the heart
Hepatic portal system
Blood leaving capillary beds in the walls of the gut passes through the hepatic portal vein before reaching the capillary beds in the liver
Hypophyseal portal system
Blood leaving capillary beds in the hypothalamus travels to a capillary bed in the anterior pituitary to allow for paracrine secretion of releasing hormones
Renal portal system
Blood leaving the glomerulus travels through an efferent arteriole before surrounding the nephron in a capillary network called the vasa recta.
Plasma
The liquid portion of blood, an aqueous mixture of nutrients, salts, respiratory gases, hormones, and blood proteins.
What are the 3 main categories that make up the cellular portion of blood
Erythrocytes, leukocytes, and platelets
Why are red blood cells biconcave
The shape assists them in traveling through tiny capillaries
Shape increases the cell’s surface area, which increases gas exchange.
What do mature red blood cells lack compared to other cells, and why
They lack nuclei, mitochondria, and other membrane-bound organelles.
This lack of organelles makes space for molecules of hemoglobin.
Lack of mitochondria means that red blood cells do not consume the oxygen it carries before delivering it to peripheral tissues.
How do red blood cells generate ATP
They rely entirely on glycolysis, with lactic acid (from fermentation) as the main by-product.
What does hematocrit measure
How much of the blood sample consists of red blood cells, given as a percentage.
Leukocytes
Usually comprise less than 1 percent of total blood volume: are a crucial part of immune system.
Leukocytes are generally categorized into what 2 classes
Granulocytes and agranulocytes
Granulocytes
Neutrophils, eosinophils, and basophils.
Contain cytoplasmic granules that contain a variety of compounds that are toxic to invading microbes.
Involved in inflammatory reactions, allergies, pus formation, and destruction of bacteria and parasites.
Agranulocytes
Consist of lymphocytes and monocytes; do not contain granules that are released by exocytosis.`
Lymphocytes
Important in the body’s specific immune response; lymphocytes that mature in the bone marrow are referred to as B-cells –> those that mature in the thymus or T-cells.
Monocytes
Phagocytize foreign matter such as bacteria.
What are monoctyes called once they leave the bloodstream and enter an organ
Macrophages.
Microglia
Macrophages in the CNS
Langerhans cells
macrophages in the skin
Osteoclasts
macrophages in the bone
What are the 2 major antigen families relevant for blood groups
ABO antigens and Rh factor
Are A and B alleles codominant?
Yes
Relationship of O allele (i or O) to A and B
O allele is recessive to both A and B alleles
What are the four blood types
A, B, AB, and O
Universal donors
People with type O blood: because their blood will not cause ABO-related hemolysis in any recipient. HOwever, they can only receive blood from other type O individuals.
Universal recipients
People with type AB blood: they can receive blood from all blood types.
Rh factor
A surface protein expressed on red blood cells
How to indicate Rh factor on blood type
Rh-positive (Rh+) or Rh-negative (Rh-) refers to the presence or absence of a specific allele called D. Can also be indicated with a plus or minus superscript on the ABO blood type (such as O+ or AB-).
What type of inheritance does Rh-positivity follow
Autosomal dominant inheritance; one positive allele is enough for the protein to be expressed
Erythroblastosis fetalis
During childbirth: if a woman is Rh- and her fetus is Rh+, she will become sensitized to the Rh factor, and her immune system will begin making antibodies against it. In any subsequent pregnancy where the fetus is Rh+, maternal anti-Rh antibodies can cross the placenta and attack fetal blood cells, resulting in hemolysis of the fetal cells.
Sphygmomanometer
Measure the gauge pressure in the systemic circulation –> specifically measures the force per unit area exerted on the wall of the blood vessels
How is blood pressure expressed
It is expressed as a ratio of the systolic (ventricular contraction) to diastolic (ventricular relaxation) pressures.
What is considered to be the range of normal blood pressure
Between 90/60 and 120/80
Where does the largest drop in blood pressure in the body occur
It occurs across the arterioles: critical because the capillaries are thin-walled and unable to withstand the pressure of the arterial side of the vasculature.
How can Ohm’s law (V = IR) be applied to circulation
Change in P = CO x TPR
Where change in P is the pressure differential across the circulation, CO is the cardiac output, and TPR is the total peripheral (vascular) resistance,
Oxygen saturation
The percentage of hemoglobin molecules carrying oxygen
Carbonic anhydrase
Catalyzes the combination reaction between carbon dioxide and water to form carbonic acid.
Bohr effect
When a decrease in hemoglobin’s affinity for oxygen causes a right shift in the oxyhemoglobin curve as a shift to the right.
What changes occur in blood due to exercise
Increased partial pressure of CO2
Increased [H+]
Increased temperature
What are the 2 pressure gradients essential for maintaining a proper balance of fluid volume and solute concentrations in the bloodstream
Hydrostatic and osmotic (oncotic) pressures
Hydrostatic pressure
The force per unit area that the blood exerts against the vessel walls. Generated by the contraction of the heart and the elasticity of the arteries.
Pushes fluid out of the bloodstream and into the interstitium through the capillary walls, which are somewhat leaky by design.
Osmotic/oncotic pressure
The “sucking” pressure generated by solutes as they attempt to draw water into the bloodstream. Cuz most of the osmotic pressure is attributable to plasma proteins, it is usually called oncotic pressure.
Starling forces
Balance of opposing pressures (hydrostatic vs oncotic).
At the arteriole end of a capillary bed, hydrostatic pressure (pushing fluid out) is much larger than oncotic pressure (drawing fluid in).
At the venule end of the capillary bed, hydrostatic pressured has dropped below oncotic pressure, and there is net influx of water back into the circulation
Edema
Accumulation of excess fluid in the interstitium
Thoracic duct
Channel that returns most lymphatic fluid to the central circulatory system
Clots
Composed of both coagulation factors (proteins) and platelets, and they prevent (or at least minimize) blood loss.
Coagulation factors
Mostly secreted by the liver; sense tissue factor and initiate a complex activation cascade.
What is the endpoint of the coagulation cascade
The activation of prothrombin to form thrombin by thromboplastin. Thrombin can then convert fibrinogen into fibrin. Fibrin forms small fibers that aggregate and cross-link into a woven structure, like a net, that captures red blood cells and other platelets, forming a stable clot over the area of damage.
What is the function of plasmin (generated from plasminogen)
Breaks down clots.
