Practice Questions Exam 2 Flashcards
What is the role of arterial pO2 in regulation of breathing?
Breathing is normally regulated by the arterial pCO2 rather than by the arterial pO2. However, the lower PO2 of higher altitudes can enhance the chemoreceptor sensitivity to the arterial PCO2, thereby causing hyperventilation at higher altitudes. Conversely, at high arterial PO2 caused by breathing 100% oxygen, this can blunt the chemoreceptor response to elevated arterial PCO2, allowing a person’s breath to be held longer. At very high altitudes, or in emphysema, a person can breathe in response to stimulation of the carotid by a fall in arterial PO2. This is known as hypoxic drive.
How does the pressure in the left ventricle vary during the cardiac cycle?
Pressure changes during cardiac cycle
- As ventricles begin contraction, the intraventricular pressure rises, causing the AV valves to snap shut. Ventricles are not being filled or ejecting blood: isovolumetric contraction
- When the pressure in the left ventricle becomes greater than the pressure in the aorta, the phase of ejection begins as the semilunar valves open
- As pressure in ventricles falls below pressure in arteries, the back pressure causes the semilunar valves to snap shut. Isovolumetric relaxation: AV and semilunar valves are closed. This phase lasts until the pressure in the ventricles falls below the pressure in the atria
- When the pressure in the ventricles falls below the pressure in the atria, the AV valves open and a phase of rapid filling of ventricles occurs
- Atrial contraction (atrial systole) delivers final amount of blood into ventricles
Why is the left ventricle more musclar?
The left ventricle is thicker because it must force blood to all body parts, with a much higher resistance to blood flow
Erythropoietin
The enzyme secreted by the kidney that stimulates erythropoiesis, or the production of red blood cells, under conditions of tissue hypoxia, or low blood oxygen levels.
Inferior vena cava
The blood vessel that the deoxygenated blood flows into the heart to be oxygenated, from all other vessels and organs that are located below the heart
Sinoatrial node
Known as the “pacemaker” because it is where electrical impulses begin, causing the heart to contract.
Fibrin
Fibrin is produced from plasma chemical cascade that involves thrombin converting fibrinogen to fibrin, it is degraded by plasmin and is used in hemostasis (blood clotting) when the fibrin and platelets form a plug or clot over the wound site.
Atrial natriuretic peptide
ANP is a powerful vasodilator, and a protein hormone secreted by heart muscle cells. It lowers blood pressure by acting as a vasodilator, increasing the radius. Stimulated by excessive stretch receptors detected by atrial stretch receptors, causes decreased salt (+ water) absorption by kidneys, so increases urine.
What is the cardiac output (be specific) and how does the body regulate it?
CO = SV * CARDIAC RATE
Cardiac rate is regulated by autonomic nervous system primarily. SV is proportional to EDV due to Frank- Starling law as EDV increases, more stretch, stronger contractility → increased SV, and therefore CO
What will happen to perfusion of the lungs in an atmosphere with lower pO2 such as at altitude) and how is the cardiovascular system affected?
- Atmospheric - primarily O2 and N2
- Alveolar - Less O2, similar N2, more CO2/H2O
- *N2 is actually the highest in both
What cranial nerves are involved with speech?
5: upper jaw/soft palate
7: face/lower jaw-some lips
9: swallowing
10: vagus nerve, pharynx
11: back in pharynx/trachea
12: tongue
What is the bicarbonate buffer system?
Carbonic anhydrase within the red blood cells quickly convert the CO2 into H2CO5 carbonic acid. Carbonic acid is unstable, intermediate molecule that immediate dissociates into bicarbonate ions and hydrogen ions. Since carbon dioxide is quickly converted into bicarbonate ions, this reaction allows for the continued uptake of carbon dioxide into the blood, down its concentration gradient. It also results in the production of H+ ions. If too much H+ is produced, it can alter blood pH. However, hemoglobin binds to the free H+ ions, limiting shifts in pH. The newly synthesized bicarbonate ion is transported out of the red blood cell into the liquid component of the blood in exchange for a Cl- ion. This is called the chloride shift. When the blood reaches the lungs, the bicarbonate ion in transported back into the RBC in exchange for the Cl-. The H+ ion dissociates from the hemoglobin and binds to the bicarbonate on. This produces the carbonic acid intermediate, which is converted back into the carbon dioxide through the enzymatic action of CA. The CO2 produced is expelled through the lungs during exhalation.
What is the bicarbonate buffer system?
carbon dioxide is finally expelled from the body through the lungs during exhalation.
Importantly, the bicarbonate buffer system allows little change to the pH of the body system; it allows for people to travel and live at high altitudes because the system can adjust itself to regulate carbon dioxide while maintaining the correct pH in the body.
What is the bicarbonate buffer system?
carbon dioxide is finally expelled from the body through the lungs during exhalation.
Importantly, the bicarbonate buffer system allows little change to the pH of the body system; it allows for people to travel and live at high altitudes because the system can adjust itself to regulate carbon dioxide while maintaining the correct pH in the body.
What are thebenefits of the bicarbonate buffer system?
The benefit of the bicarbonate buffer system is that carbon dioxide is “soaked up” into the blood with little change to the pH of the system. This is important because it takes only a small change in the overall pH of the body for severe injury or death to result. The presence of this bicarbonate buffer system also allows for people to travel and live at high altitudes. When the partial pressure of oxygen and carbon dioxide change at high altitudes, the bicarbonate buffer system adjusts to regulate carbon dioxide while maintaining the correct pH in the body.
