Question

A. Define a buffer system and describe the three major buffer systems of the body fluids. Explain how a buffer system adjusts when either a strong acid or strong base is added to an aqueous solution (describe the relevant chemistry. Explain how modifying the rate and depth of ventilation can permit respiratory compensation for a metabolic acid-base disorder (describe the chemistry).

B. Compare and contrast the physiology of the human sexual response in the male and the female, including stimuli, nervous regulation, and effector targets. How are they similar and how are they different? How does this relate to reproductive developmental homology?

C. Discuss the structure and function of the juxtaglomerular apparatus. What factors determine GFR? Why is it so important to keep GFR stable? Explain in terms of nephron function. Briefly describe the autoregulatory mechanisms used in the kidney to maintain GFR on an ongoing basis.

D. Discuss the different mechanisms of reabsorption in the renal tubule. How are valuable nutrients reabsorbed from the filtrate? How are ions and water reabsorbed? In which parts of the renal tubule do these events occur? Distinguish between obligatory and facultative reabsorption.

Answer 1

A)

Buffer system( buffers) are solution whichc can resist changes in PH when acid or alkali is added.

• Three major buffer systems are :-

1. Bicarbonate buffer system
2. Phosphate buffer system
3. Alkali reserve.

• Bicarbonate buffer system :-The most important buffer system in plasma is the bicarbonate - carbonic acid system.It accounts for 65% of buffering capacity in plasma and 40% of buffering action in the whole body.
• The bicarbonate carbonic acid buffer system is the most important because the presence of bicarbonate in relatively high concentrations.
• The components are under physiological control,by lungs and bicarbonate by kidneys.

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• ​​​​​​​Phosphate buffer system :- It is mainly an intercellular buffer.Its concentration in plasma is very low.The pKa value is 6.8 .
• The phosphate buffer system is found to be effective at a wide pH range,because it has more than one ionizable group and the pKa values are different for both.

• Alkali Reserve :- Bicarbonate represents the alkali reserve and it has to be sufficiently high to meet the acid load.If it was too low to give a ratio of 1,all the HCO3-would have been exhausted within a very short time,and buffering will not be effective,so the ratio of 20 ensures high buffering efficiency against acids.

​​​​​​​B)

Male Sexual Act

• Erection of sexual organ
• Penetration of male sexual organ to female sex organ
• Ejaculation

​​​​​​​Erection :- Erection occurs due to the dialation of the penile arterioles filling the erectile tissues of the male sex organ by blood.The erectile tissues of male sex organ are three in numbers : two corpora cavernosa and a corpus spongiosum.

Ejaculation :- Ejaculation is the emission of semen from the male genital tract and its propulsion out of the urethra at the time of orgasm.Thus,it is a two part reflex response :the emission and ejaculation.

Female Sexual Act

• The female responses are characterized by marked increase in blood flow and muscular activities in many parts of the body.
• Sexual desire in women is possibly dependent on androgens,because sex drive is maintained long after the menopause,when estrogen level in plasma is very low..