Question

Explain how intrinsic myogenic mechanisms within the kidney would regulate the following situations. Consider first how glomerular filtration rate (GFR) is affected by the situation and how the kidney would use its intrinsic mechanisms to help maintain consistent GFR. (6 pts) a. Systolic blood pressure raises to 150 mmHg b. Dehydration has caused systolic blood pressure to drop to 105 mmHg c. Macula densa cells in the juxtaglomerular complex sense low NaCl levels.

Answer 1

Intrensic myogenic mechanism of kidney is the ability of afferent arteries to constrict when blood pressure rises and to dilate when blood pressure decreases.

1. As the systolic blood pressure increases, it starches the arterioles hence by intrensic myogenic mechanism there is vasoconstriction of the arteriole hence decreses the blood volume & pressure in Glomerular capillary so that the GFR are mainted normal.

2. If Systolic Blood pressure decreses, afferent arteriole dilate and hence Increases the blood supply to glomerular capilary hence GFR is maintained normal.

3. Macula densa sense the concentration of NaCl in the DCT, it stimulates Juxtaglomerular apparatus to secrete Reninn hence Reninin angiotensin aldosterone system is stimulation to increase BP and salt and water reabsorption. Also macula densa signals to decrease Resistant to blood flow in afferent arteriole and hence Increases glomerular hydrostatic pressure and GFR is maintained.