Urinary system

Question 1

Urinary system consists of

Answer 1

Includes kidneys, ureters, urinary bladder, and urethra

Question 2

Functions of kidneys

Answer 2

Blood filtration, reabsorption and secretion
Acid-base balance
Fluid-electrolyte balance
Hormone production
Blood pressure regulation

Question 3

Blood filtration, reabsorption and secretion in the kidneys

Answer 3

Through altering plasma composition by
Filtering plasma constituents from the blood
Selectively reabsorbing water and useful components
Secreting waste products as urine

Question 4

Acid base balance is done by the kidneys by

Answer 4

Eliminates hydrogen and bicarbonate ions in urine

Question 5

How do kidneys regulate acid-base balance

Answer 5

Controls water and electrolytes, removing them from blood to equal amount being put in
Correct water to maintain healthy internal environment, through
Diuresis (excess water so more urine formed)
Oliguria (insufficiency of water so less urine formed)
Anuria (deficiency in water so no urine formed)
Under hormonal control (function of the endocrine system) – ADH and aldosterone

Question 6

What hormones are produced in kidneys

Answer 6

Renin: to help increase blood pressure if drops through the renin-angiotensin system
Erythropoietin: to increase RBC production if hypoxic
Prostaglandins: to help maintain renal perfusion

Question 7

How does Kidney help with blood pressure regulation

Answer 7

Receptor monitor blood pressure
Renin
To help increase blood pressure when BP is low, through the renin-angiotensin system

Question 8

the nephron of the kidney is and does what

Answer 8

The nephron is the functional unit
It is a microscopic, epithelial structure
Consists of a blood filtration unit attached to a long tube that absorbs and secretes to deliver urine as its end product

Question 9

In order, the parts of the nephron are:

Answer 9

Bowman’s capsule (filtration)
Proximal Convoluted Tubule
Loop of Henle
Distal convoluted tubule
Collecting Duct

Question 10

Where are the kidneys located

Answer 10

The kidneys are located in the abdominal cavity just to each side of the midline and are retroperitoneal (behind/outside of peritoneal cavity)
Generally, the right kidney is more cranially and dorsally than the left kidney

Question 11

What does the kidney look like

Answer 11

A thick layer of fat surrounds and protects the kidneys
Called peritoneal fat
This allows us to visualize the kidneys on abdominal x-rays

Generally, the shape and color of kidney beans and smooth-surfaced

Question 12

Capsule of the kidney is

Answer 12

a thin, but tough, connective tissue layer which surrounds the kidney

Question 13

Hilus is what of the kidney

Answer 13

Located in the depression on the medial side of the kidney
The renal artery and nerves enter, and the ureter, renal vein and lymphatic vessels leave at the hilus

Question 14

Renal pelvis is the

Answer 14

the expanded part of the ureter just inside the hilus
Receives urine from the collecting tubules of the kidney
Not found in cattle

Question 15

Renal cortex is located

Answer 15

immediately beneath the capsule

Question 16

Renal medulla is located and contains

Answer 16

Inner layer of kidney
Appears striated due to the arrangement of the collecting tubules
Also contains some loops of Henle (which contain the most concentrated fluid)

Question 17

Renal cortex is

Answer 17

(aka papilla):
Ridge that projects into the renal pelvis .
The collecting tubules of medulla empty here.

Question 18

Calyces are and do what

Answer 18

Funnels that medulla projects into
Direct fluid straight into the ureter

Question 19

What does the bovine kidney look like

Answer 19

Kidneys are lobulated and do not have a renal pelvis or crest
Instead the ureter branches into each lobe and forms calyces, (calyx singular)

Question 20

Porcine kidney shape

Answer 20

Also has calyces. Funnels fluid into the renal pelvis.

Question 21

Nerve supply to the kidney

Answer 21

Supplied mainly by sympathetic nerves from the autonomic nervous system.
Sympathetic stimulation reduces renal blood flow
Not necessary for function: can rely on other controls (for example, if transplanted)

Question 22

How much blood does the kidney get

Answer 22

The kidneys receive approximately ¼ of the cardiac output and convert about one thousandth of this into urine.

Question 23

Renal artery is and goes where

Answer 23

enters the hilus
divide into smaller and smaller branches
become the afferent glomerular arterioles

Question 24

What goes the afferent glomerular arterioles branch into

Answer 24

The afferent glomerular arterioles branch to form the glomerular capillary network of the renal glomerulus

Question 25

Glomerular capillaries does what

Answer 25

Filter out some of the water and small molecules from the blood The only capillary network in the body where blood is oxygenated going into and coming out

Question 26

The efferent arteriole: leaves what

Answer 26

leaves each glomerulus Surrounds the rest of the nephron From capillary networks around the tubules and lupus of Henle

Question 27

Where does the blood go from the kidney

Answer 27

These capillary networks then reform as veins Getting larger and larger Become the renal vein passing out of the kidney at the hilus Drain into the cranial vena cava

Question 28

When blood is within the capillary networks of the nephron it does what

Answer 28

Waste and excesses are removed from the blood into the nephron Water and useful constituents can be reabsorbed from the filtrate into the blood.

Question 29

Ureters are

Answer 29

Muscular tubes Carry urine from the kidneys to the bladder They exit the kidney at the hilus Enter the urinary bladder near the neck Enter bladder at an oblique angle When it is full, the ureter collapses to prevent backflow of urine

Question 30

Ureter wall 3 layers

Answer 30

Outer fibrous Middle smooth muscle Inner transitional epithelium (allows stretching as urine passes through)

Question 31

What is the function of the ureters

Answer 31

Functions to move urine from kidneys to bladder through peristalsis Can continue to move urine into a full bladder with a collapsed ureter because of the peristaltic movements

Question 32

Anatomy of urinary bladder

Answer 32

Hollow muscular organ capable of stretching Size and position vary, depending on fullness Empty – will be almost inside the pelvis, thick walls Filling – pear-shaped, extends cranially, thin walls Lined with transitional epithelium Has layers of smooth muscle At the neck, a sphincter of skeletal muscles allows voluntary control of urination Trigone: the area between urethra and ureteral opening. Landmark for ultrasound

Question 33

Bladder function

Answer 33

Collect, store, release urine Urine is formed continuously, released intermittently

Question 34

Three steps to urination

Answer 34

Urine accumulation Muscle contraction Sphincter muscle control: voluntary release of skeletal muscles at sphincter.

Question 35

Urine accumulation in the bladder

Answer 35

Bladder fills until critical point Activates stretch receptors

Question 36

Muscle contraction for urination

Answer 36

Spinal reflex activated Causes contraction of smooth muscles Results in sensation of needing to urinate

Question 37

Sphincter muscle control: voluntary release of skeletal muscles at sphincter for urination

Answer 37

If wait too long, continuing filling of bladder may result in ‘leakage’ Loss of voluntary control of the bladder is known as urinary incontinence (inability to urinate when and/or where desired) ***a full bladder is very prone to rupture!!! Use care if palpating!

Question 38

Anatomy of the urethra

Answer 38

Continues from neck of the bladder Has transitional epithelium Short & straight in females Opens onto the floor of the vestibule Longer and curved in males Runs down center of penis Carries urine out of the body from the bladder In males, also carries semen during ejaculation and is surrounded by a urethral muscle.

Question 39

Kidneys are composed of what and what do they do

Answer 39

Kidneys are composed of hundreds of thousands of microscopic structures called nephrons Basic functional unit of kidney Have different parts that specialize in filtration, reabsorption, and secretion.

Question 40

Parts of a nephron

Answer 40

Renal corpuscle Proximal Convoluted Tubule Loop of henle Distal Convoluted Tubule

Question 41

Renal corpuscle is composed of

Answer 41

In the kidney cortex Composed of: Glomerulus: tiny capillary network Bowman’s capsule: double walled capsule surrounding the glomerulus Inner layer lines the capillaries The visceral layer Outer layer surrounds it The parietal layer Space between the 2 layers an extension of the proximal tubule Capsular space - continues with the proximal convoluted tubule

Question 42

Function of the renal corpuscle

Answer 42

Glomerulus filters blood through the capillaries Creates glomerular filtrate Collects filtrate in Bowman's capsule

Question 43

Proximal convoluted tubule is

Answer 43

Highly coiled (hence the name) In the renal cortex Continuous with Bowman’s capsule Lined with cuboidal epithelial cells with microvilli Increases surface area x20 to have the microvilli Lined with simple, cuboidal epithelial cells with microvilli- to increase the surface area

Question 44

Function of the proximal convoluted tubule

Answer 44

Reabsorption and secretion Responsible for about 65% of the total reabsorption 80% of all water, sodium, chloride, and bicarbonate absorption 100% of the glucose and amino acid absorption

Question 45

Loop of henle is and where it is

Answer 45

U-shaped Extends from within the cortex into the medulla and returns to the cortex Divided into the descending and ascending limbs Smaller diameter than rest of renal tubule

Question 46

Function of the loop of henle

Answer 46

Reabsorption Sodium exchanged for other ions Water is reabsorbed Creates a concentration gradient that favors reabsorption of water

Question 47

Distal convoluted tubule is

Answer 47

In the cortex Coiled Joins a collecting duct, along with other nephrons

Question 48

Distal convoluted tubule function

Answer 48

Reabsorption and secretion Sodium exchange for other ions

Question 49

Nephrons join and continue

Answer 49

Nephrons join to common collecting ducts, which extend into the renal papilla Collecting ducts are important for potassium levels, secretion of hydrogen and ammonia and acid base balance Antidiuretic hormone (ADH) has its greatest effect here

Question 50

Filtration of blood occurs in

Answer 50

Renal corpuscle

Question 51

Renal capillaries differ from normal capillaries because they:

Answer 51

Connect 2 small arterioles Have small pores to increase fluid leakage Not big enough to allow proteins or cells to leak out. So, protein in the urine on urinalysis is a sign of glomerular disease Renal capillaries differ from normal capillaries because Are under high pressure Especially since the afferent arteriole is larger than the efferent arteriole Causes pressure build-up in glomerulus Forces fluid out – called filtration Collects in Bowman’s capsule

Question 52

GFR is

Answer 52

glomerular filtration rate (ml per minute) How fast plasma is filtered Depends on the rate of flow through the kidney Blood pressure is critical for maintaining GFR Needs to keep mean arterial pressure about 60 mm Hg

Question 53

Glomerular filtrate contains what and for what reasons

Answer 53

Glomerular filtrate contains many substances the body needs to maintain balance of nutrients, minerals, electrolytes and acid base i.e. sodium, potassium, calcium, magnesium, glucose, amino acids, chloride, bicarbonate, and water Normally ABOUT 99% of water is reabsorbed.

Question 54

Reabsorption occurs in

Answer 54

Occurs in Proximal Convoluted Tubule (PCT)

Question 55

Proximal Convoluted Tubule (PCT) does what for reabsorption

Answer 55

Passive diffusion or active transport: substances move through the tubular epithelium, interstitial space, and into the peritubular capillaries Sodium co-transport occurs: Active transport of sodium out of tubular epithelium cell by a carrier protein on the basement cell membrane – uses energy Co-transport of sodium into cells with glucose and amino acids Conserves glucose and amino acids

Question 56

What is the limit on the amount of glucose in the body called

Answer 56

there is a limit on the amount of glucose the body can reabsorb Called the renal threshold If blood glucose levels exceed the threshold, some glucose will remain in the urine Occurs with diabetes mellitus and other conditions causing high blood glucose Can cause an osmotic diuresis Leading to clinical symptoms of PU/PD

Question 57

Reabsorption in the loop of Henle and DCT

Answer 57

Sodium is reabsorbed in exchange for hydrogen, ammonium, or potassium ion Chloride follows sodium due to electrical gradient Controlled by aldosterone (mineralocorticoid from the adrenal cortex)

Question 58

What happens after ions move out of the lumen

Answer 58

Potassium, calcium and magnesium are also reabsorbed Once ions have moved out of the lumen, water follows by osmosis Much of this occurs in the DCT and collecting ducts This increases the concentration of the remaining molecules in the filtrate within the lumen Some substances, like urea, will increase concentration to the point of being more concentrated than the blood Some reabsorption of urea will take place here This is minor and keeps urea levels in body at normal levels

Question 59

Secretion is primarily occurred in

Answer 59

PCT for substances like histamine, uric acid, creatine and hydrogen DCT for substances like hydrogen (more), potassium, and ammonia Aldosterone helps promote secretion of potassium and reabsorption of sodium in DCT

Question 60

Secretions of the kidneys steps

Answer 60

Also secretes drugs like penicillin and some sulfonamides Substances are moved from peritubular capillaries, through the interstitial fluid and tubular epithelial cells to the lumen Secretion is particular important for molecules that are not filtered in the glomerulus

Question 61

Urine volume regulation is controlled by

Answer 61

Primarily controlled by antidiuretic hormone (ADH) from posterior pituitary and aldosterone from adrenal cortex

Question 62

ADH does what for urine regulation

Answer 62

Increases water reabsorption from DCT and collecting ducts Increased number of water pores in cells If levels of ADH are too low, can result in inadequate reabsorption of water This causes high volume of urine (poor concentration, low SG) and increased drinking to compensate for water loss (PU/PD) Called diabetes insipidus (differentiate from DM by glucose in urine)

Question 63

Aldosterone does what for urine reagulation

Answer 63

Increases sodium reabsorption from DCT and collecting ducts Creates osmotic imbalance Draws water back into the blood (BUT, requires presence of ADH to occur!!)

Question 64

Water intake is regulated by

Answer 64

Water intake is regulated by a thirst center in the hypothalamus Responds to blood pressure and water concentration in the blood