The Urinary System

On the basal surface of principle cells are extensive ___________________ and ___________________. It is in this area that many _______________ are pumped back into the blood.

-Infoldings and mitochondria -solutes

location -- The paired kidneys are located just ___________ the waist, between the _______________ ________________ and the _________________ ________________ __________ (retroperitoneal). They lie at vertebral levels T12 - L3 and are partially protected by ribs 11 and 12.

-above -parietal peritoneum -posterior abdominal wall

The glomerulus is a tuft of capillary loops sitting in the "cup" formed by Bowman's capsule. Blood enters a glomerulus via an __________________________ and exits glomerulus via an _________________________. This is a significant departure from the usual vascular pattern of artery, capillary, vein.

-afferent arteriole -efferent arteriole

appearance in coronal section -- In coronal (frontal) section, the kidney presents an outer area, the _________, a middle region, the ____________, and an innermost area, the _________________________.

-cortex -medulla -renal pelvis

The basement membrane of the glomerulus consists of the fused basement membranes of the ____________________ and the ______________________________ epithelium of Bowman's capsule. It acts to restrict passage of the _________________________________________ but allows all other solutes to pass into the filtrate.

-endothelium -visceral layer -larger plasma proteins

Since the role of the kidneys is to filter the blood, it is not surprising that they have an abundant blood supply. The right and left renal arteries carry 25% of resting cardiac output to the kidneys (1,250 ml/min). Each renal artery enters its respective kidney at the __________, and then divides several times before it enters the ____________________, where the branching continues down to the level of the __________________________. There is one afferent arteriole leading into each nephron, dividing within the cup of Bowman's capsule to form the _________________. The glomerular capillaries merge to exit Bowman's capsule as the ____________________________. The efferent arteriole has a _____________ diameter than the afferent arteriole; this helps to ____________ glomerular blood pressure ____________ than would be found in a normal tissue capillary bed. The efferent arteriole leaves Bowman's capsule and participates in the formation of two separate capillary networks: List them both These capillary beds merge to form venules, then veins, which eventually merge to form the right and left renal veins that leave the respective kidney at the hilus and join the inferior vena cava.

-hilus -parenchyma -afferent arteriole -efferent arteriole -smaller -raise/higher -peritubular capillaries surround the PCT and DCT, while the vasa recta follow the loop of Henle.

In a nephron, the loop of Henle connects the PCT with DCT. The first portion of the loop, the descending limb dips into the ________________, while the ascending limb, returns to the _____________.

-medulla -cortex

What is the driving force of glomerular filtration? Blood hydrostatic pressure forces water and solutes from ______________ through the __________________________________, the fused basement membrane, and the filtration slits of the visceral layer of Bowman's capsule, into the ______________________.

-plasma -endothelial fenestrations -capsular space

The epithelial cells of the visceral layer of Bowman's capsule are specialized cells called_____________________. Each cell has thousands of foot-like processes called __________________, between which are open spaces called _________________________.

-podocytes -pedicels -filtration slits

Within the medulla are 8 - 18 cone-shaped structures called ____________________________ that look striated due to a high number of straight parallel tubules (_____________________) and blood vessels. The bases of the renal pyramids face the cortex, while their apices, called _______________ face toward the center of the kidney, opening into the _______________________

-renal pyramids -collecting ducts -renal papillae -renal sinus

The loop itself is formed of proximal and distal straight segments, composed of ____________________________ cells, and the loop portion, composed of _________________________________ cells.

-simple cuboidal -simple squamous

Histologically, the renal corpuscle consists of the ____________________________ of Bowman's capsule and the ___________________ of the glomerular capillaries.

-visceral layer -endothelium

List in order of appearance the sections of a nephron.

1--Bowman's capsule, 2--proximal convoluted tubule, 3--proximal straight tubule, 4--loop of Henle, 5--distal straight tubule, 6--distal convoluted tubule, and 7--collecting duct.

Identify the three important functions carried out by the nephrons.

1. control blood concentration and volume by removing selected amounts of water and solutes. 2. regulate blood pH 3. remove toxic wastes from the blood

Urine formation requires three processes. Name them in order of when they occur in the nephron.

1. glomerular filtration by the renal corpuscle 2. tubular reabsorption by the renal tubule 3. tubule secretion by the renal tubule

Identify and give a brief description of the five major functions of the kidneys.

1. regulate blood volume and composition 2. regulate blood pressure by secreting renin 3. secrete erythropoietin 4. participate in the synthesis of calcitriol 5. participate in glucose metabolism

5 Major Functions of the Kidney: 1. regulate blood volume and composition by removing _____________, _____________, and ____________ to form urine 2. regulate blood pressure by secreting ____________, which activates the __________________-_________________ ________________ 3. secrete erythropoietin in response to __________________________________________________________________ 4. participate in the synthesis of calcitriol, the active form of ____________________ 5. participate in glucose metabolism by performing _________________________________________________________

1. wastes, ions, and water 2. renin, the angiotensin-aldosterone pathway 3. decreased blood oxygen to stimulate 4. Vitamin D 5. gluconeogenesis during fasting or starvation

These two hormones are involved in the control of water excretion

ADH & aldosterone

This is a mass of fatty tissue that surrounds the two kidneys.

Adipose capsule

This structure is used to protect the kidneys from trauma and help hold them in place within the abdominal cavity

Adipose capsule

The filtration slits do not present much of a barrier to filtration, although the pedicels are negatively charged and help prevent passage of ______________.

Anions

How much filtrate is formed per day?

Approximately 180 liters of filtrate are formed per day. This is some 60 times the entire blood plasma volume.

What is the net effect of these functions?

As the nephrons accomplish these functions, they remove materials from the blood, return the ones that the body requires, and excrete (eliminate) from the body the remainder as urine.

What is the driving force for glomerular filtration?

Blood hydrostatic pressure

The urinary system maintains homeostasis by controlling what three things?

By controlling the composition, volume, and pressure of blood.

The lungs excrete these three things into _______________.

Carbon dioxide, heat, and water into exhaled air

The terminal ends of many DCTs enter a single ______________________________.

Collecting duct

The loops of Henle are particularly important in the formation of _______________________________________, especially those of the juxtamedullary nephrons.

Concentrated urine

Name the two types of nephrons

Cortical and juxtamedullary nephrons

The gastrointestinal tract excretes these four things.

Feces, water, ions, and heat

most substances in the blood are permitted to pass from the blood into the lumina of the nephrons, while others are kept out. This is called

Filtration

Define the principle of filtration.

Filtration is the forcing of fluids and solutes through a membrane by mechanical pressure (all capillaries move fluids in this manner).

Name the membrane across which filtration occurs in the kidney.

Filtration occurs in the renal corpuscle across the endothelial-capsular membrane.

Name the three basic functions of the nephron

Filtration, reabsorption, and secretion

It is through the visceral layer of the bowman's capsule that water and most of the solutes of plasma in the glomerulus pass into the capsular space. What elements do not cross the visceral layer?

Formed elements and plasma proteins

What does filtrate contain?

In a healthy person filtrate contains everything in blood except formed elements and plasma proteins.

Where do tubular reabsorption and tubular secretion occur?

In the PCT, loop of Henle, and the DCT

How does the urinary system control the composition, volume, and pressure of blood?

It does so by removing and restoring selected amounts of water and solutes from the blood.

What are the functions of the juxtaglomerular apparatus?

It is involved in the regulation of blood pressure and the rate of blood filtration by the kidneys by secreting renin when blood pressure is too low and by decreasing its secretion of an as yet unnamed vasoconstrictor substance when there is decreased delivery of sodium, chloride, or water in the filtrate..

Together, the macula densa and the juxtaglomerular cells form the _____________________________________.

Juxtaglomerular apparatus

These are the nephrons that allow the formation of either very dilute or very concentrated urine.

Juxtamedullary nephrons

Name the three other ways in which the body rids itself of waste products besides the kidneys

Lungs, sudoriferous glands, and gastrointestinal tract

At the point of contact, the cells of the DCT are specialized to form _____________________ cells

Macula densa

What are nitrogenous wastes?

Nitrogenous wastes, such as ammonia and urea, are formed as a result of protein catabolism (breakdown).

How many afferent arterioles lead into each nephron?

One

These cells of the distal tubules and collecting ducts, bear receptors for the hormones ADH and aldosterone

Principle cells

The simple cuboidal cells of the ____________________________ have an extensive brush border (microvilli) for increased surface area for tubular reabsorption. Thus, some 65% of water and almost 100% of some solutes in filtrate move back into the blood via the proximal tubule.

Proximal tubule

The loop of Henle is composed of simple squamous cells, these cells allow for what primary function of the loop of Henle?

Rapid transport of materials

As the filtered liquid, known as filtrate, flows through nephrons, useful materials are returned to the blood by the process of

Reabsorption

This structure is a thin, transparent dense CT that forms the outer surface of the kidney itself

Renal capsule

This structure serves as a barrier against trauma and the spread of infection to the kidney

Renal capsule

The cortex is the smooth-textured area extending from the renal capsule to the bases of the pyramids and into the spaces between the pyramids, forming the ______________________________.

Renal columns

Each minor calyx receives urine from a renal pyramid and delivers it to a major calyx. From there, urine drains into the ________________ and out through the ureter to the urinary bladder.

Renal pelvis

In the renal sinus of the kidney is a large cavity called the

Renal pelvis

Collecting ducts are gathered to form _______________________, and eventually merge to form the large papillary ducts that open into the minor calyces to drip newly formed urine into the renal pelvis.

Renal pyramids

The distal tubules and collecting ducts are formed of _____________________________ cells that lack a brush border.

Simple cuboidal

The loop of Henle is composed of these types of cells

Simple squamous cells

What two structures form the parenchyma of the kidney?

The cortex and renal pyramids

Which type of nephron is more common, cortical or juxtamedullary nephrons?

The cortical nephron is more common. Only 15 - 20% of all nephrons are of the juxtamedullary type.

These nerves are associated with the blood supply, particularly the afferent and efferent arterioles, and thus regulate blood flow to the glomerulus (and therefore the rate of filtrate formation) by regulating what?

The diameters of the arterioles

What is the resulting fluid in the capsular space called?

The fluid found in the capsular space is known as filtrate.

What is the role of the urinary system in maintaining normal body homeostasis?

The kidneys excrete water, nitrogenous wastes, some bacterial toxins, hydrogen ions, essential ions, some heat, and some carbon dioxide from the body in the form of urine.

The cortex is divided into two zones, what are they?

The outer cortical zone and the inner juxtamedullary zone

What is the primary function of the urinary system?

The primary function of the urinary system is to help maintain homeostasis

What are the three main sections of the renal tubule?

The proximal convoluted tubule (PCT), the loop of Henle, and the distal convoluted tubule (DCT)

What are the two functions of juxtamedullar cells?

They function in monitoring blood pressure in the afferent arteriole and to secrete the molecule renin when blood pressure in the afferent arteriole falls too low.

What is the function of the endothelial-capsular membrane?

To act as a filter for the blood

Sudoriferous glands excrete these four things into ______________.

Water, ions, urea, and heat into sweat.

What do essential ions, such as sodium, chloride, sulfate, phosphate, and hydrogen ions, tend to do in the extracellular fluids?

accumulate in excess of the body's needs

The cortex extends from the renal capsule to the _____________________________________

bases of the pyramids

How is filtration similar to capillary exchange?

because it is driven by pressure across an endothelium

How does reabsorption occur?

by diffusion and active transport

How is the kidney anchored to its surrounding structures?

by the renal fascia

The outer wall of Bowman's capsule is the parietal layer and the inner wall is the visceral layer. Between the two layers is the _________________________, into which the blood is filtered.

capsular space

Name some by-products of cellular metabolism of nutrients.

carbon dioxide, nitrogenous wastes, excessive water, and heat

Where is the glomerulus and the loop of a cortical nephron located?

cortical nephrons -- A cortical nephron has its glomerulus in the outermost portions of the cortex and its loop barely reaches the medulla.

Renal fascia is a thin layer of _______________________________

dense CT

The endothelium of the glomerulus consists of a single layer of ___________________________________________________ (3) cells.

fenestrated simple squamous

The endothelium of the glomerulus prevents passage of the ______________________________ from the blood into the filtrate, but allows all other blood components to pass.

formed elements

The renal corpuscle has two components, what are they?

glomerulus and bowman's capsule

Also at the point of contact, the smooth muscle cells of the afferent arteriole are specialized to form _______________________ cells.

juxtamedullar

Where is the glomerulus and the loop of the juxtamedullary nephron located?

juxtamedullary nephrons -- A juxtamedullary nephron has its glomerulus deep in the cortex, close to the medulla. Its loop is quite long, reaching deep into the medulla to approach the renal papillae.

The urinary system consists of:

kidneys (2) ureters (2) urinary bladder urethra

The juxtamedullary apparatus contains these two types of cells

macula dense cells and juxtaglomerular cells

The edge of the renal pelvis contains cup-like extensions called

major and minor calyces

This is the functional unit of the kidney

nephron

This structure consists of about 1 million microscopic tubules called nephrons.

parenchyma

Where in the nephron is plasma filtered into the nephron?

renal corpuscle

A nephron consists of two portions, what are they?

renal corpuscle and renal tubule

The nerves supplying the kidneys are derived from the ___________________ of the sympathetic nervous system.

renal plexus

The hilus serves as the entrance to a cavity in the kidney called the

renal sinus

From the capsular space, filtrate moves into the _____________________, which has three main sections.

renal tubule

What is this function of the nephron? As filtrate moves through the nephrons, cells of the nephron (tubule cells) secrete some additional materials (particularly hydrogen ions) directly into the filtrate.

secretion

The juxtaglomerular apparatus is a combined structure that is formed where

the final portion of the ascending limb of the loop of Henle (beginning of the distal convoluted tubule) comes to lie in contact with the afferent arteriole.

What do macula densa cells monitor?

the flow of filtrate

What is the functional portion of the kidney?

the parenchyma

renal fascia -- Surrounding each kidney are three layers of connective tissues. From outermost, these layers are:

the renal fascia, the adipose capsule, and the renal capsule

What is the function of the pedicels?

to hold the visceral layer of Bowman's capsule to the glomerular capillaries.

hilus -- Near the center of the medial concave border is the hilus, an indentation through which these 5 structures enter and exit the kidney. What are the five structures?

ureter, renal artery, renal vein, nerves, and lymphatics

shape and size -- The average adult kidney is about 4 - 5 inches long, 2 - 3 inches wide, and 1 inch thick. It is shaped like a bean, with its concave medial surface facing the _______________ _____________.

vertebral column