Urinary System

Human Physiology - From Cells to Systems | 9e Lauralee Sherwood. Chapter 14

Homeostasis

Kidney’s are responsible for _______ by maintaining:

• stable volume

• electrolyte composition

• osmolarity of ECF

• excretion of wastes

Kidney

Functions of what?

• maintain H2O balance

• maintain proper osmolarity of body fluids

• maintain proper plasma volume

• regulate the quantity and concentration of ECF

• excrete foreign compounds

• produce renin & erythropoietin

• convert vitamin D into its active form

kidneys

What structure forms urine?

Bowman’s capsule

What’s the tubular component of the nephron?

Vascular component

These structures are considered to be what part of the nephron?

• glomerulus

• afferent arterioles

• efferent arterioles

• peritubular capillaries

outer

Outer or inner cortex layer?

Glomeruli of cortical nephrons

Inner

Outer or inner cortex layer?

Glomeruli of juxtamedullary nephrons

Glomerulus

tuft of capillaries that filters a protein-free plasma into the tubular component

Afferent arteriole

carries blood to the glomerulus

Efferent arteriole

carries blood from the glomerulus

Peritubular capillaries

supple the renal tissue; involved in exchanges with the fluid in tubular lumen

Bowman’s capsule

collects glomerular filtrate

Loop of Henle

establishes an osmotic gradient in the renal medulla that is important in the kidney’s ability to produce urine of varying concentration

Proximal tubule

uncontrolled reabsorption and secretion of selected substances occur here

distal tubule

variable, controlled reabsorption of Na+ and H2O and secretion of K+ and H+ occur here

Glomerular filtration

the process of blood filtration in the kidney, in which fluid, ions, glucose, and waste products are removed from the glomerular capillaries

• protein-free plasma from glomerulus into Bowman’s capsule

Tubular reabsorption

the process that moves solutes and water out of the filtrate and back into your bloodstream

Tubular secretion

transfer of materials from peritubular capillaries to the renal tubular lumen

Urine excretion

the process by which toxins, drugs, and their metabolites are removed from the body

permeable

The glomerular membrane is considerably more _______ than capillaries elsewhere.

endothelial

Glomerular capillary wall consists of a single layer of flattened ___________ cells.

blood pressure

Changes in the GFR result mainly from changes in glomerular capillary ________ _______.

Filtration coefficient

depends on the surface area and permeability of the glomerular membrane

• GFR can be influenced by a change in this

Transepithelial transport

moves water and a large array of substances between the lumens of the tubules and the nearby network of blood vessels

• tubular reabsorption involves this

Passive absorption

water and electrolytes are absorbed into the blood from the gastrointestinal tract

• think: does this require energy?

Active reabsorption

process in which water, electrolytes, and other substances are absorbed into the blood through epithelial cells

Tubular reabsorption

quantity reabsorbed of each substance is the amount required to maintain proper internal fluid environment composition and volume

• involves transepithelial transport

• highly selective and variable

Na+ reabsorption

depends on the Na+-K+ ATPase pump in the basolateral membrane

natriuresis

Atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) produce what?

Na+

The natriuretic peptides inhibit the reabsorption of what?

glucose and amino acids

What is reabsorbed by Na+-dependent secondary active transport?

Glucose

What is an actively reabsorbed substance NOT regulated by the kidneys?

Phosphate

What is an actively reabsorbed substance that IS regulated by the kidneys?

acid-base balance

Hydrogen ion secretion is important in what?

H

Renal ____+ secretion is extremely important in regulating acid-base balance in the body.

aldosterone

Potassium ion secretion is controlled by what?

organic ion secretory system

Functions of what?

• secretion of organic ions that gained entry into tubular fluid by glomerular filtration

• Elimination of nonfilterable organic ions in urine

• Removal of foreign organic chemicals, including food additives, environmental pollutants. etc.

Plasma clearance

the volume of plasma cleared of a particular substance per minute

Long Henle’s Loops

This structure establishes the verticle osmotic gradient by countercurrent multiplication.

• the ascending limb pump and descending limb passive fluxes reestablish the 200 mOsm/L gradient at each horizontal level

Vasopressin

a hormone that helps blood vessels constrict and helps the kidneys control the amount of water and salt in the body

Vasa Recta

preserve the Verticle Osmotic Gradient by Countercurrent Exchange

• allows blood to leave the medulla and enter the renal vein essentially isotonic to incoming arterial blood

25

Percentage of Na+ reabsorption in the Loop of Henle

• active, uncontrolled

67

Percentage of Na+ reabsorption in the proximal tubule

• active, uncontrolled

8

Percentage of Na+ reabsorption in the distal and collecting tubules

• active, variable and subject to aldosterone control

Renal failure

Causes

• infectious organsims

• inappropriate immune responses

• obstruction of urine flow

• insufficient renal blood supply

Types

• acute or chronic

• end-stage

Uremic toxicity

caused by the retention of waste products

• a potential outcome of renal failure

• nausea, vomiting, diarrhea, and ulcers caused by a toxic effect on the digestive system

Urinary incontinence

loss of bladder control; urine can leak

urethral sphincters

Role of what?

used to control the exit of urine in the urinary bladder through the urethra

Metabolic acidosis

caused by the inability of the kidneys to adequately secrete H+ that is continually being added to the body fluids as a result of metabolic activity

• recall what H+ is

  • (acid or base?)

Plasma proteins

Loss of what?
as a result of increased “leakiness” of the glomerular membrane

• edema caused by a reduction in plasma-colloid osmotic pressure

Anemia

caused by inadequate erythropoietin production

Hypertension

arising from the combined effects of salt and fluid retention and vasoconstrictor action of excess angiotensin II

Hypotonicity

_______ of body fluids if too much H2O is ingested.

Hypertonicity

_______ of body fluids if too little H2O is ingested.

too much

Too much or too little?

Elevated blood pressure, generalized edema, and congestive heart failure if ________ Na+ is consumed.

Too little

Too much or too little?

Hypotension, and, if severe enough, circulation shock if ________ Na+ is consumed.