Final exam study guide : Urinary System

What are the functions of the kidneys?

Regulates nitrogenous wastes, regulates plasma concentrations of water and Na+, K+, Ca++, Mg++, PO4, and Cl-, regulates blood volume and pressure, helps stabilize blood pH, conserves valuable nutrients (gluconeogenesis), assists in detoxifying the blood - removes metabolic waste products.

The outer layer of the kidney is the ____ and it is the site of___. While the inner part of the kidney is the ___ and it is the location of the ___ and ___.

Renal cortex: glomerular filtration. Renal medulla: longer hoops of Henle: collecting ducts connecting to the renal pelvis.

What is the functional unit of the kidney?

The nephron

What causes glomerular filtration? What systolic pressure must be achieved?

Hydrostatic pressure forces filtrate into Bowmans capsule. Systolic needs to be at least 60 to offset colloid pressure of albumin in plasma.

How does the macula densa control blood pressure? What do the juxtaglomerular cells release and how does this secretion affect blood pressure?

Can either induce vasodilation of the afferent arteriole to cause increased filtration of excess sodium. Juxtaglomerular cells release renin to increase BP when sodium is low.

Know the order of urine formation is 1) glomerular filtration, 2) tubular reapportion, and 3) tubular secretion

What occurs in each step of urine formation?

• Glomerular filtration: refers to the movement of fluid and solutes from the glomerular capillaries into Bowman's space

• Tubular reabsorption: refers to the movement of materials from the filtrate in the tubules into the peritubular capillaries.

• Tubular secretion: refers to the secretion of solutes from the peritubular capillaries into the tubules

What is absorbed in the proximal convoluted tubule?

70% water, amino acids = most, uric acid 90%, urea passively absorbed throughout the nephron makes gradient for water absorption, proteins via pinocytosis.

What is the function of the loop of Henle?

Concentrates urine. Reclaims water and concentrates uring. 1/5 nephrons have long loops. Kidney difference between salt water and fresh water fish.

What is the counter current mechanism?

Method for concentrating urine depends on the counter current mechanism. Refers to fluid flowing in opposite directions in adjacent limbs of tubules and surrounding blood vessels.

Know the information on page 4, slides 2 and 3

Slide show… loop of henle

What part of the nephron is the last place water can be claimed?

Collecting duct

What hormone increases water permeability of the collecting duct?

ADH

Know that the kidney is the chief regulator of sodium (Na)

When does edema occur?

If kidney is unable to actively transport sodium (water follows passively)

What factors influence sodium absorption?

GFR, adrenocorticoid hormones - aldosterone, renin, atrial naturetic factor, SANS, estrogen, osmotic diuretics, diuretic drugs, dietary sodium

Does increasing or decreasing the glomerular filtration rate increase the reabsorption

Increasing the glomerular filtration rate

Know that potassium is the major osmotically active substance in the cells.

In acidosis potassium moves ___ of the cells in exchange for hydrogen, while in alkalosis potassium moves ___ the cells in exchange for hydrogen.

Out: into

What is hypokalemia? What is hyperkalemia?

Hypokalemia: decreased potassium resulting in muscle weakness

Hyperkalemia: increased potassium resulting in cardiac irregularities

What are ways that the body loses potassium?

Loss occurs with diuretic drugs and alkalosis. Diarrhea, vomiting, reduced dietary potassium and sweating are other losses. Disfunction in excretion may lead to imbalance.

What does a diuretic drug do?

Increased flow rate through nephron causes loss of potassium

What causes aldosterone to be released? What is the effect of aldosterone?

Released from adrenal cortex when blood potassium levels are increased, hormone causes sodium retention and potassium secretion.

What hormone is used to regulate calcium?

PTH

Where are osmoreceptors located?

Hypothalamus

Where is antdiuretic hormone produced? Where is it released from? What are the effects of ADH on water regulation?

Produced in hypothalamus and released in posterior pituitary. Increases water permeability