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Anatomy 2 - Urinary
Urinary system study
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Science
04/05/2011

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Term

·         Trace the flow of urine from creation to leaving the body.

Definition

Glomerulus- Bowman's Capsule- proximal convoluted tubule- loop of henle- distal convoluted tubule- collecting tubule- calcyx- renal pelvis- ureter- bladder- urethra. 
Or more simply: kidney-ureter-bladder-urethra

Term
What are the funtions of the kidneys?
Definition

Eliminating toxins, metabolic wastes, excess ions from blood

Regulation of blood volume and chemical makeup of the body

Maintaining balance between water and salts and acids and bases

Other functions: Producing renin (regulate bp and kid function)

Producing erythropoetin (rbc production)

metabolizing vitamin D to its active form

Term
What is the structure and function of the ureters?
Definition

Covey urine from kidneys to bladder

 

Enter base of bladder through posterior wall

 

Strength and frequency of muscle contractions change with amount of urine present

Term
What is the structure and function of the urinary bladder?
Definition

Muscular sac for temporary storage of urine.

 

Trigone -smooth of triangular area outlined by openings for ureters and urethra

 

Layers of bladder well

 

1. Mucosa with transitional epithelium

2. Smooth muscle (3 layers)

3. Fibrous adventia 

Colappses when empty; rugae appear

Term
Structure and function of urethra
Definition

Muscular tube

 

Lining epithelium is mostly pseudostratified columnar epithelium, except,

Transitional epithelium near bladder

Stratified squamous epithelium near external urethral orifice

Term
Structure and function of spinchters
Definition

1. Internal urethral spinchter

involuntary (smooth muscle) at bladder-urethra junction

contracts to open

 

2. external urethral spinchter

Voluntary (skeletal) muscle surounding urethra as it passes through pelvic floor

Term
Diff between male and female urethra
Definition

female is shorter. male is longer and carries semen and urine. 3 regions

prostatic urethra

membranous urethra

spongy urethra

Term
What are the functions of the supporting layers around the kidneys?
Definition

Renal fascia - dense connective tissue; anchors kidney

Perirenal fat (adipose) capsule - cushioning

Fibrous capsule - prevents spread of infection to kidney

Term
Describe the 3 kidney regions.
Definition

Rental cortex - granular, superficial region

 

Renal medulla - cone shaped medullary (renal) pyramids separated by renal columns

 

Renal Pelvis - funnel shaped tube within renal sinus

Term

·         What are calyces & what is their function in urine collection?

Definition

The calyx is a portion of the human renal system, predominantly located in the kidney. The calyx is limited specifically to mammalian kidneys, and is part of the urinary collecting subsystem.

 

The calyx is the method by which urine is passed from the kidney to the bladder.

Term
Definition
Term
What is a nephron?
Definition

The structural and functional units of the kidneys that form urine.

 

1 million per kidney

 

2 main parts: glomerulus and renal tubule.

 

Processes in the kidney involve the interaction between incming blood and the tubular components of the kidneys (nephrons) where urine is processed

Term
Definition
Term
What are the nephron capillary beds?
Definition

1. Glomerulus - afferent arteriole > glomerulus > efferent arteriole. it is specialized for filtration. Blood pressure is high in glomerulus

 

2. Peritubular capillaries

Low-pressure, porous capillaries adapted for absorption

Term

What are the 2 major types of nephrons?

 

Definition

Cortical nephrons - 85% of nephrons; almost entirely in cortex (of kidneys)

 

Juxtamedullary nephrons - important in production of concentrated urine

Term
Name/describe the parts and processes of a nephron.
Definition

Glomerulus - tufts of capillaries; filtration

Bowman's capsule - enlarged, cup-shaped capsule surrounding glomerulus - collects filtrate

Proximal convoluted tubule (pct) - tubular reabsorption

Loop of henle - Sodium (Na+) and water balance

Distal convoluted tubule (DCT) - tubular secretion

Term
What are the collecting ducts?
Definition

Glomerulus > proximal convoluted tubule (pct) > loop of henle > distant convoluted tubule (dct) > collecting ducts

 

collecting ducts - receive filtrate from many nephrons

 

principle cells of collecting ducts - help maintain water and salt balance

fuse together to deliver urine into minor calyces

Term
Vocabulary
Definition

Renal Artery - The blood vessel bringing blood to the kidney.

Renal Vein - The blood vessel draining the kidney.

Ureter - A duct leading from the kidney to the urinary bladder.

Urethra - A tube that releases urine from the body near the vagina in females and through the

penis in males; also serves in males as the exit tube for the reproductive system.

Renal Cortex - The outer portion of the vertebrate kidney.

Renal Medulla - The inner portion of the vertebrate kidney, beneath the renal cortex.

Nephron - The tubular excretory unit of the vertebrate kidney.

Glomerulus - A ball of capillaries surrounded by Bowman’s capsule in the nephron and serving as

the site of filtration in the vertebrate kidney.

Bowman’s capsule - A cup–shaped receptacle in the vertebrate kidney that is the initial,

expanded segment of the nephron where filtrate enters from the blood.

Proximal Tubule - In the vertebrate kidney, the portion of a nephron immediately downstream

from Bowman’s capsule that conveys and helps refine filtrate.

Loop of Henle - The long hairpin turn, with a descending and ascending limb, of the renal tubule

in the vertebrate kidney; functions in water and salt reabsorption.

Distal Tubule - In the vertebrate kidney, the portion of a nephron that helps refine filtrate and

empties it into a collecting duct.

Collecting Duct - The location in the kidney where filtrate from renal tubules is collected; the

filtrate is now called urine.

Renal Pelvis - Funnel–shaped chamber that receives processed filtrate from the vertebrate

kidney’s collecting ducts and is drained by the ureter.

Cortical Nephrons - Nephrons located almost entirely in the renal cortex. These nephrons have a

reduced loop of Henle.

Juxtamedullary Nephrons - Nephrons with well–developed loops of Henle that extend deeply

into the renal medulla.

Afferent Arteriole - The blood vessel supplying a nephron.

Efferent Arteriole - The blood vessel draining a nephron.

Peritubular Capillaries - The network of tiny blood vessels that surrounds the proximal and distal

tubules in the kidney.

Vasa Recta - The capillary system that serves the loop of Henle.

Term
What is the difference between filtrate and urine?
Definition

Until the liquid reaches the renal pelvis, it is "glomerular filtrate," when it reaches the pelvis, it is called "urine"

 

filtrate is blood plasma minus proteins

urine contaisn metabolic wastes and uneeded substances. less than 1% filtrate.

Term

·         What are the 3 steps in forming urine? Where does each occur?

Definition

1. Glomerular filtration - material passes from blood to tubules

location: glomerulus

 

2. tubular reabsorption - material passes back from tubules to blood

location: primarily in the proximal tubule

 

3. tubular secretion - material selectively transferred from blood to tubules

location: distal tubules

Term
Why is pressure important in glomerular filtration?
Definition
The pressure helps to force liquid out of the blood.
Term
What is net filtration pressure?
Definition
The pressure responsible for forming filtrate from plasma (10 mm hg)
Term
What is the opposing forces of net filtration pressure?
Definition

Glomerular hydrostatic pressure (HP g) - chief force pushing water and solutes out of glomerulus and into the capsule

55 mmHg

2 opposing forces that drive fluids back into glomerulus:

1. glomerular osmotic pressure - (30 mmHg)

2. Hydrostaric pressure of the capsule (15 mmHg)

Term

 What characteristics make the glomerulus ideal for filtration?

Definition
The glomerulus has special characteristics which make it an efficient filter: (1) fenestrated capillaries and very permeable to water and solutes (which allows free passage of everything except blood cells and plasma proteins) and (2) the glomerular blood pressure is higher resulting in a higher filtration pressure.
Term

What is GFR? What is the major limiting factor of GFR? Explain.

Definition

 

GFR is the amount of fluid filtered from the blood into the capsule each minute. Factors governing the filtration rate at the capillary beds are:

            

 

(1) total surface area available for filtration

            (2)        filtration membrane permeability

            (3)        net filtration pressure

 

 

GFR is directly proportional to net filtration pressure because the capillaries are exceptionally permeable and have a huge surface area. So therefore, net filtration pressure is the limiting factor. Normal GFR in both kidneys in adults is approximately 120 ml/min. A change in any of the pressures acting at the filtration membrane changes the NFP and thus the GFR. An increase in arterial blood pressure in the kidneys increases GFR, whereas dehydration inhibits filtrate formation.

 

Term

What are macula densa cells? What do they do?

Definition

They are specialized cells in the walls od DCT (justaglomerular apparatus - JGA)

 

If filtrate is flowing too slow - they stimulate vasodilation of afferent arterioles

If filtrate is flowing too rapidly - it stimulates vasoconstriction

 

Slows blood flow to glomerulus; decreases gfr

Term

·         In tubular reabsorption, substances are returned to the __________ from the ____________.

Definition
           Distal convoluted tube   from the Proximal convoluted tubule (pct)
Term

What substances in tubular reab moves actively?

 

Definition

glucose, amino acids, vitamins, most ions (na+)

most substances are transported with sodium on a carrier molecule.

Term
What substances move through passive reabsorption?
Definition

Sodium movement (via active transport) establishes an osmotic gradient

 

water moves by osmosis out of filtrate and back into the blood

 

as water leaves, substances (in filtrate) follow their concentration gradients back into the blood

Term
In the loop of Henle, how does the descending & ascending loop differ in their permeability to water & sodium? 
Definition

Loop of henle - descending limb: impermeable to Na+, but permeable to water

h2o reabsorbed

 

ascending - permeable to na+ but impermeable to water

na+, k+, Cl-

Term

·         Explain the renin-angiotensin-aldosterone mechanism. What is its goal?

Definition

If mean arterial pressure (map) into kidney is too low, cells of juxtaglomerular apparatus (jga) secrete renin.

 

angiotensinogen (a plasma globulin)

renin > V

angiotensin I

angiotensin converting enzyme (ace) > V

angiotensin II

Term
What are the effects of angiotensin II?
Definition

1. Constricts arteriolar smooth muscle, causing map to rise

2. stimulates reabsorption of Na+

Triggers adrenal cortex to release aldosterone

Aldosterone increases na+ reabsorption

3. Stimulates hypothalamus to release antidiuretic hormone (ADH) and activates thirst center

ADH - causes water to be retained

4. Constricts efferent arterioles, decreasing capillar hydrostatic pressure and increasing fluid reabsorption

5. Causes glomerular cells to contract, decreasing surface area available for filtration

Term

·         If you wanted to create a more concentrated urine, what would your body do?

Definition

To form more concentrated urine, ADH causes the DCT and collecting ducts to be more permeable to water

 

Water can leave tubules and go into blood

 

blood volume increases

99% of h2O in filtrate is reabsorbed

Term

 How does alcohol impact urine formation?

Definition
Alcohol promotes more urine production, this is referred to as diuretic.
Term

·         What are 2 ways you could check someone’s renal health?

Definition
Urinalysis & renal clearance test ...is that of the glomerular filtration rate (GFR). The GFR is calculated by measuring the specific clearance from the body of a substance believed to be excreted solely by glomerular filtration. The renal clearance of any substance is the volume of plasma containing that amount of the substance that is removed by the kidney in unit time (e.g., in one minute). 
Term
What is ADH?
Definition
water regulator in the body.
Term
What is anp
Definition
Atrial natriuretic peptide (ANP), atrial natriuretic factor (ANF), atrial natriuretic hormone (ANH), or atriopeptin, is a powerful vasodilator, and a protein (polypeptide) hormone secreted by heart muscle cells.[1][2] It is involved in the homeostaticcontrol of body water, sodium, potassium and fat (adipose tissue). It is released by muscle cells in the upper chambers (atria) of the heart (atrial myocytes), in response to high blood pressure. ANP acts to reduce the water, sodium and adipose loads on the circulatory system, thereby reducing blood pressure.[1]
Term
What is renin
Definition
An enzyme secreted by and stored in the kidneys that promotes the production of the protein angiotensin
Term
What is aldosterone?
Definition
 A corticosteroid hormone that stimulates absorption of sodium by the kidneys and so regulates water and salt balance
Term
Definition