BReceptor cells are rods and cones Table

- Rods and cones are not present on the optic disk the result is a blind spot. c. Bipolar cells. The receptor cells (i.e., rods and cones) synapse on bipolar cells, which synapse on the ganglion cells. (1) Few cones synapse on a single bipolar cell, which synapses on a single ganglion cell. This arrangement is the basis for the high acuity and low sensitivity of the cones. In the fovea, where acuity is highest, the ratio of cones to bipolar cells is 1 1. (2) Many rods synapse on a single...

The adrenal medulla releases epinephrine and norepinephrine

Which supplement the actions of the sympathetic nervous system on the heart and blood vessels. 7. The renin-angiotensin-aldosterone system is activated by the decrease in renal perfusion pressure. Because angiotensin II is a potent vasoconstrictor, it reinforces the stimulatory effect of the sympathetic nervous system on TPR. Aldosterone increases NaCl reabsorption in the kidney, increasing the circulating blood volume. 8. ADH is released when atrial receptors detect the decrease in blood...

Answers and Explanations

Coordination of movement (synergy) is the function of the cerebellum. Lesions of the cerebellum cause ataxia, lack of coordination, poor execution of movement, delay in initiation of movement, and inability to perform rapidly alternating movements. The premo-tor and motor cortices plan and execute movements. Lesions of the substantia nigra, a component of the basal ganglia, result in tremors, lead-pipe rigidity, and poor muscle tone (Parkinson's disease). 2. The...

The mean values for arterial Po2 and Pco2 do not change during exercise

- Arterial pH does not change during moderate exercise, although it may decrease during strenuous exercise because of lactic acidosis. 3. On the other hand, venous Pco2 increases during exercise because the excess C02 produced by the exercising muscle is carried to the lungs in venous blood. Table 4-7. Summary of Respiratory Responses to Exercise 02 consumption C02 production Ventilation rate T (matches 02 consumption C02 production) No change No change in moderate exercise 4- in strenuous...

Diuretics Table 511 XI Integrative Examples

- A woman has a history of weakness, weight loss, orthostatic hypotension, increased pulse rate, and increased skin pigmentation. She has decreased serum Na* , decreased serum osmolarity, increased serum K* , and arterial blood gases consistent with metabolic acidosis. 2. Explanation of hypoaldosteronism a. The lack of aldosterone has three direct effects on the kidney decreased Na* reabsorption, decreased K* secretion, and decreased H' secretion. As a result, there is ECF volume contraction...

Review Test

Directions Each of the numbered items or incomplete statements in this section is followed by answers or by completions of the statement. Select the ONE lettered answer or completion that is BEST in each case. 1. The inability to perform rapidly alternating movements (dysdiadochokinesia) is associated with lesions of the 2. A patient with chronic hypertension is treated with prazosin by his physician. The treatment successfully decreases the patient's blood pressure to within the normal range....

Stretch myotatic reflexknee jerk Figure 29 is monosynaptic

Muscle is stretched, and the stretching stimulates group la afferent fibers. Table 2-7. Summary of Muscle Reflexes Table 2-7. Summary of Muscle Reflexes b. Group la afferents synapse directly on a-motoneurons in the spinal cord. The pool of a-motoneurons that is activated innervates the homonymous muscle. c. Stimulation of a-motoneurons causes contraction in the muscle that was stretched. As the muscle contracts, it shortens, decreasing the stretch on the muscle spindle and returning it to...

Calculation of reabsorption and secretion rates

- The reabsorption or secretion rate is the difference between the amount filtered across the glomerular capillaries and the amount excreted in urine. It is calculated with the following equations Filtered load GFR x plasma Excretion rate V x urine Reabsorption rate Filtered load - Excretion rate Secretion rate Excretion rate - Filtered load - If the filtered load is greater than the excretion rate, then net reabsorption of the substance has occurred. If the filtered load is less than the...

Is also called isosmotic volume expansion

(1) ECF volume increases, but no change occurs in the osmolarity of ECF or ICF. Because osmolarity is unchanged, water does not shift between the ECF and ICF compartments. (2) Plasma protein concentration and hematocrit decrease because the addition of fluid to the ECF dilutes the protein and red blood cells (RBCs). Because ECF osmolarity is unchanged, the RBCs will not shrink or swell. Figure 5-2. Shifts of water between body fluid compartments. Volume and osmolarity of normal extracellular...

Increasing TPR causes a decrease in both cardiac output and venous return Figure 314

a A counterclockwise rotation of the venous return curve occurs. Increased TPR results in decreased venous return as blood is retained on the arterial side. b A downward shift of the cardiac output curve is caused by the increased aortic pressure increased afterload as the heart pumps against a higher pressure. Figure 3-14. Effect of increased total peripheral resistance TPR on the cardiac and vascular function curves and on cardiac output. c As a result of these simultaneous changes, a new...

Central chemoreceptors in the medulla

- are sensitive to the pH of the cerebrospinal fluid CSF . Decreases in the pH of the CSF produce increases in breathing rate hyperventilation . - H does not cross the blood-brain barrier as well as C02 does. a. C02 diffuses from arterial blood into the CSF because C02 is lipid-soluble and readily crosses the blood-brain barrier. b. In the CSF, C02 combines with H20 to produce H and HCO-r. The resulting H acts directly on the central chemoreceptors. c. Thus, increases in Pco2 and H stimulate...

This process results in net secretion of H and net reabsorption of newly synthesized HC03

Mechanism for excretion of H as titratable acid. CA carbonic anhydrase. Figure 5-19. Mechanism for excretion of H as titratable acid. CA carbonic anhydrase. 3 As a result of H secretion, the pH of urine becomes progressively lower. The minimum urinary pH is 4.4. 4 The amount of H excreted as titratable acid is determined by the amount of urinary buffer and the pK of the buffer. b. Excretion of H as NH4 Figure 5-20 - The amount of H excreted as NH4 depends on both the amount of NH3...