17 March wk3-D Flashcards
What heart related factors affect cardiac output during exercise and how do they change?
What accounts for the majority of increased CO during intense exercise?
As muscles begin to contract during exercise, mechano and chemoreceptors tune up sympathetics and down PS leading to increased HR and SV of the heart.
At higher intensity exercise, it is mostly the HR that causes the increased CO because of decreased filling and ejection times.
How does overall vascular resistance change in the body during exercise?
Exercise causes increased sympathetic tone which vasoconstricts everywhere in the body except the muscles that are being used. This causes an increase in systolic BP, but the MAP does not rise as high because there is an overall decrease in systemic vascular resistance due to the vasodilation that takes place in the active muscles due to release of adenosine, potassium, lactate, ATP, CO2.
Pulmonary vascular resistance also decreases though the pressure through the lungs rises.
What is spectrin?
Spectrin is a structural protein in the membrane of RBCs that allow flexibility of the cell.
Loss of spectrin makes the cell susceptible to hemolysis
Explain how CO2 is transported from the tissues through the blood and to the lungs.
There are three ways that CO2 is transported to the lungs through the blood. The primary way is as bicarbonate within the RBCs. The second way is as carbamate which is CO2 bound to hemoglobin-NH3. The last way is as dissolved CO2 in the plasma.
Explain the reason why RBCs have a higher Chloride ion concentration in venous blood than in arterial blood.
In venous blood, CO2 diffuses from the tissues into the RBCs where carbonic anhydrase converts CO2 + H2O into carbonic acid which then spontaneously dissociates into H+ and HCO3-. The bicarb will build up in the cell and some will diffuse out into the plasma. To balance the ion movement, Cl- ions will diffuse into the cell causing a higher Cl- concentration. Process is called “Chloride Shift”
Explain the different conformations of Hb and the molecules/factors that affect its affinity for O2 and how this relates to fetal Hb.
Hb can be in a Taught or Relaxed form.
Taught in the Tissues decreases affinity for O2 and shifts the O2 dissociation curve to the right allowing for O2 unloading.
Relaxed in the Respiratory tract increases O2 affinity and shifts the curve to the left allowing for better O2 uptake from the lungs.
2,3-BPG, CO2, Temperature, Cl-, H+ all increase the affinity of Hb for O2
Fetal Hb has a lower affinity for 2,3-BPG and therefore a left shift in the O2 curve meaning it has a higher affinity for O2 allowing it to take O2 from the maternal blood.
Explain Functional Hypothalamic Amenorrhea
FHA is a type of secondary amenorrhea that is caused by low fat stores in the body and is often seen in dancers, athletes, models, etc.
Strenuous exercise, low body weight, chronic illness, or eating disorders cause a low amount of fat tissue.
Low fat leads to low Leptin
Low Leptin causes decreased GnRH secretion and thereby low LH/FSH
Low LH/FSH causes low estrogen levels and thereby causes amenorrhea
Describe some of the features of Huntington’s disease including inheritance, pathophysiology, and effects on the brain.
Huntington’s disease is known for having CAG repeats that lengthen from generation to generation in a pattern known as anticipation where each generation will have an earlier onset of the disease because of increasing amounts of the repeats.
Autosomal dominant disease
Mutation on chromosome 4
SX: choreiform movements, aggression, depression, dementia
Increased levels of Dopamine, decreased GABA and Ach
Atrophy of the caudate nucleus in the brain, and decreased metabolic activity of the striatum (putamen & caudate)
