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Anatomy Urinary system cards Flashcards

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1
Q

What is the main function of the urinary system

A

maintain homeostasis by controlling the volume and composition of blood.

Maintain pH though buffer system and breathing

Blood Buffer that bind H ions (happens fast)

Most important function- maintains the pH of blood

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2
Q

What are the major components of the urinary system?

A

2 kidneys

2 ureters

1 bladder

1 urethra

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3
Q

Where are the kidneys located

A

They are located (retroperitoneal) along with the adrenal glands and the ureters.
Located in the posterior/ superior abdominal cavity
Partially protected by the 11th and 12th ribs.
The right kidney is slightly lower than the left.

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4
Q

What do the kidneys get rid of

A

bicarbonate

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5
Q

What is the nephron in the kidney?

A

The main functional unit of the kidney. (filtration unit of the kidney)

Approx. 1 million per kidney.

The nephron consists of a microscopic renal tubule and it’s vascular component.

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5
Q

What are the three layers surronding the kidneys?

A

1) Renal Fascia – outermost layer of thin fibrous connective tissue that anchors the kidneys to the surrounding structures.

2) Adipose Capsule – 2nd layer, a mass of fatty tissue surrounding the capsule, which serves to protect the kidney. Layer of Fat. The last areas to lose abdominal fat.

3) Renal Capsule – the innermost layer made of a transparent thick fibrous membrane.

The layers:

Peritoneal -> Layer of fat -> Renal capsule

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6
Q

How much filtrate is produced by the nephrons?

A

Produces upward of 50 gallons of filtrate a day, but a majority is reabsorbed as blood.

The kidneys retain most of it,

Returns most back to the body

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7
Q

how much of the filtrate turns into urine in a day?

A

1500 mL

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8
Q

What are the two types of nephrons?

A
  1. Cortical Nephron
    2.Juxtamedullary Nephron
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9
Q

Explain the cortical nephrons location and functions

A

it’s glomerulus is located in the cortical region of the kidney.
Makes up a majority of the nephrons
Do the vast majority of urine concentration, but not as much as the Juxtamedullary Nephron, due to shorter loop
Larger quantity/ larger amount of urine

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10
Q

What is the main blood supply of cortical nephrons

A

peritubular capillary

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11
Q

explain the location and functions of Juxtamedullary Nephron

A

Lies next to the medulla

The loop of henle is longer

The longer the loop = the greater the concentrating of the urine

The urine is more highly concentrated

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12
Q

What is the main blood supply for the juxtamedullary nephron

A

the vasa recta that surround the loop of henle

Long, straight vessels

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13
Q

How much blood passes through the kidneys each minute?

A

Approx. 1200 ml

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14
Q

List the vessels for blood flow: Blood In-

A

Renal artery
Branches into the segmental arteries
Segmental arteries:
Interlobar arteries:
Travel through the renal column
Arcuate arteries:
It arches over the pyramids
Interlobular arteries:
Branches of the arcuate arteries

Afferent Arteriole

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15
Q

List the vessels for blood flow: Blood out-

A

Glomerulus/Nephron
Efferent Arteriole
Venules
Interlobular veins
Arcuate vein
Interlobar vein
Segmental veins
Renal vein

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16
Q

Define the Vecta Recta?

A

loops of thin walled vessels that dip along with the loop of henle into the deeper regions of the cortex and into the medulla. Found predominantly with the juxtamedullary nephrons

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17
Q

Define the The Bowman’s Capsule

A

The initial portion of the nephron that surrounds the glomerulus. Functions to filter water and solutes in the blood.

Very delicate structure (outer)

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18
Q

What are Glomerulus

A

The capillary bed

1 cell layer thick

They have cells that surround the capillary bed called: Podocytes

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19
Q

What are Podocyte

A

Feet that stick out that allow inter-digitation

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20
Q

Define Pedicles

A

projections off the podocytes

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21
Q

What are the two main components of the Juxtaglomerular Apparatus

A
  1. Juxtaglomerular cells

Are sandwiched between the afferent and efferent arterioles

  1. Macula Densa:

Cell of the DCT (distal convoluted tubule) come in contact with the juxtaglomerular cells

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22
Q

What do the The Macula Densa and the Juxtaglomerular Cells secrete

A

renin and erythropoietin

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23
Q

What does renin do

A

increases blood pressure

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24
What does Erythropoietin do
increases red blood cell production
25
The wider the afferent arteriole...
he more blood and more filtration occurs. The different pressure gradient allows blood to be pushed into the Bowman’s capsule
26
What happens if the kidney is exposed to high blood pressure for a long time?
lead the kidney to vasoconstriction the afferent arteriole into the glomerulus to decrease blood flow to the kidney b/c we are tearing the structure up. This is bad b/c we want to get rid of the excess blood volume which could lead to Malignant Hypertension
27
Explain step 1 of urine production
Step 1 - Glomerular Filtration Forcing components of the plasma through the endothelial-capsular membrane of the Bowman’s capsule and into the proximal convoluted tubule. Due to pressure differences between the efferent and afferent arterioles Some of the blood is pushed into the Bowman’s capsule, which allows fluid in the tubular system
28
What factors are involved in filteration
a)Blood pressure forces water and other small solutes into the Bowman’s capsule. This fluid is now called filtrate. b) The efferent arteriole leaving the capsule is smaller than the afferent arteriole, so there is a resistance to outflow of blood from the glomerulus and capsule, thus forcing H2O, etc. to flow into the Bowman’s capsule and then the tubule.
29
What factors oppose filteration
a)capsular hydrostatic pressure – filtrate that is already in the Bowman’s capsule and the proximal convoluted tubule push back against the components of the blood trying to enter the capsule. (larger pressure gradient) b) blood osmotic pressure – the increased number of solute molecules in the blood versus the smaller number of solute molecules in the filtrate pull water back toward the higher solute concentration in the plasma.
30
What is GFR (Glomerular Filtration Rate)
the amount of filtrate flowing into the capsule per unit time. This equals about 50 gallons per day and only about 1500ml leaves the body per day as urine.
31
Explain step 2 of urine production
Tubular Reabsorption The movement of filtrate from the tubules back into the blood of the vasa recta and peritubular capillaries.
32
explain the Proximal Convoluted Tubule
60-70% of the volume of filtrate is reabsorbed here. · Almost 100% of the glucose and amino acids are reabsorbed back into the blood at this location. · Sodium, potassium, magnesium and bicarbonate ion are actively transported out of the filtrate here. A large amount of NaCl is reabsorbed here
33
The microvillus increase surface area for absorption =
increase absorbing and extremely metabolic active (a lot of ATP used)
34
What are the permeability characteristics of the thin descending limb of the loop of Henle?
Permeable to water (H₂O) Relatively impermeable to solutes (e.g., Na⁺, Cl⁻) As it descends into the hyperosmotic medulla, → Water is drawn out of the tubule via osmosis Results in an increase in osmotic pressure (concentration of filtrate)
35
What are the key characteristics of the thick ascending limb of the loop of Henle?
Impermeable to water (H₂O) Actively transports NaCl out of the tubule into the peritubular space As filtrate ascends toward the cortex → mOsm/L concentration decreases Lower medulla: High osmolarity (~1200 mOsm/L) due to NaCl accumulation Water stays in, but salt is pumped out
36
What is the purpose of the countercurrent multiplier mechanism in the kidney?
Allows the kidney to concentrate solutes in the medulla Establishes a hyperosmotic environment to pull water out of the tubules Essential for water reabsorption and urine concentration
37
How does the countercurrent multiplier mechanism work?
NaCl is actively pumped out of the ascending limb Descending and ascending limbs are close together, so the NaCl increases osmolarity around both This creates a high osmotic gradient in the medulla → pulls water out of the descending limb As water leaves the descending limb, filtrate becomes more concentrated This concentrated filtrate enters the ascending limb, where more NaCl is available to be pumped out Cycle repeats, increasing medullary osmolarity further
37
38
Why does water exit the descending limb in the loop of Henle?
Medulla is hyperosmotic due to NaCl from ascending limb Water moves out by osmosis into the peritubular (interstitial) space Helps concentrate filtrate inside the nephron
39
What maintains the hyperosmotic environment in the medulla?
Active NaCl transport from the ascending limb Countercurrent flow keeps the concentration gradient in place Ensures continuous water reabsorption from the descending limb and collecting duct
40
What is the vasa recta and where is it found?
A network of capillaries and arterioles Surrounds the juxtamedullary nephron Runs alongside the loop of Henle Plays a key role in maintaining concentration gradients in the medulla
41
What is the function of the vasa recta?
Returns reabsorbed water and solutes from the interstitial space to the blood Preserves the osmotic gradient of the medulla without washing it out Facilitates countercurrent exchange
42
How does the length of the vasa recta affect urine concentration?
Longer vasa recta + longer loop of Henle → greater ability to concentrate urine More time and surface area for water and solute exchange
43
What are the two types of nephrons and their proportions?
Cortical nephrons: 70–80% Juxtamedullary nephrons: 20–30% Juxtamedullary nephrons have long loops of Henle and are important for urine concentration
44
What is the direction of blood flow in the vasa recta relative to the loop of Henle?
Opposite (countercurrent) to the filtrate flow in the loop of Henle Helps remove water and solutes from the medulla Maintains medullary hyperosmolarity
45
What is the role of ADH in the collecting duct?
Without ADH: Walls are impermeable → no water reabsorption With ADH: Aquaporins are inserted → water flows out Helps produce concentrated urine
46
How does the speed of blood flow in the vasa recta compare to filtrate flow?
Capillary blood flow is faster than filtrate flow Creates a concentration gradient between the interstitial space and capillaries Because capillary blood is hypo-osmotic, solutes and water are pulled in and swept away quickly
47
47
What does ADH do in the nephron?
Increases water permeability of the collecting duct Promotes water reabsorption from filtrate into blood Helps produce concentrated urine Released in response to dehydration or low blood pressure
48
What happens in Diabetes Insipidus?
Decreased ADH production or response Water isn’t reabsorbed from the collecting duct Results in excessive urine output (polyuria) Urine is very dilute
49
What does aldosterone do in the nephron?
Made by the adrenal cortex Acts on the DCT and collecting duct Increases Na⁺ reabsorption (via Na⁺/K⁺ pumps) K⁺ is secreted into urine Water follows Na⁺, increasing blood volume and pressure
50
When is aldosterone released and what does it do?
Released when blood pressure is low Promotes Na⁺ reabsorption → water follows → increased blood volume Helps to reduce urine volume
51
How can too much aldosterone be dangerous?
Causes excess K⁺ secretion Can lead to hypokalemia (low blood potassium) Hypokalemia can be life-threatening
52
If aldosterone increases water reabsorption, does it concentrate urine?
No — water follows salt, but urine doesn't necessarily become more concentrated Concentration depends more on ADH and osmolarity of the medulla
53
What happens during the third step of urine production — tubular secretion?
Active transport of harmful substances from blood into the nephron tubule Substances bypass Bowman’s capsule and enter directly into the tubule Helps eliminate toxins, drugs, excess ions (e.g. H⁺, K⁺)
54
How is tubular secretion different from filtration at Bowman’s capsule?
Filtration = Passive process at Bowman’s capsule Secretion = Active transport into the tubule after filtration Secretion targets substances not efficiently filtered
55
What is the purpose of tubular secretion?
Removes substances that weren’t filtered at Bowman’s capsule Fine-tunes blood pH, K⁺, drug levels Ensures waste and excess ions are fully removed from the body
56
What is the ureter and what is its function?
A 10–12 inch muscular tube (varies with height) Retroperitoneal – attached to abdominal wall Transports urine from kidneys to bladder Uses peristaltic waves (muscle contractions) to move urine
57
How is urine moved from the kidneys to the bladder?
Peristaltic waves (muscular contractions) Push urine from renal pelvis → bladder Not gravity-dependent
58
What are the 3 layers of the ureter wall?
Inner (Mucosa) Lined with transitional epithelium Epithelium is stretchable – changes shape as urine passes Circular-shaped cells that flatten as bladder fills Middle (Muscular Layer) Longitudinal & circular smooth muscle fibers Responsible for peristaltic motion Outer (Fibrous Coat) Connective tissue layer Continuous with renal capsule & peritoneum
59
What is the urinary bladder and where is it located?
Hollow, muscular organ Located posterior to the symphysis pubis Protected by the pelvic bones when full Stores urine before elimination
60
What are the important anatomical features of the bladder?
Ureter openings: smooth area where urine enters Rugae: folds in mucosa that allow bladder expansion Trigone: smooth triangular area with no rugae, funnels urine to urethra for complete emptying
61
What are the bladder sphincters and their functions?
Internal sphincter: involuntary, controlled by autonomic nervous system External sphincter: voluntary, controlled by skeletal muscle; allows conscious control of urination Both work together to completely empty the bladder
62
What are the four layers of the bladder wall?
Mucosa: Innermost layer Transitional epithelium that stretches from cuboidal to squamous when full Submucosa: Dense connective tissue Binds mucosa to muscular layer Detrusor muscle: (under parasympathetic control) Three layers: inner longitudinal, middle circular, outer longitudinal Serosa: Outer layer of peritoneum covering the bladder top
63
How does the micturition reflex work?
Bladder fills to 200–400 mL, sends signals to S2, S3, S4 spinal cord segments Parasympathetic nerves cause detrusor muscle contraction and internal sphincter relaxation External sphincter controls voluntary urination Sensation of fullness develops but can adapt if urine not released Bladder capacity can reach 1000 mL or more
64
What is the urethra and where does it start?
Small tube from bladder to body exterior Begins at the internal urethral sphincter Conducts urine out of the body
65
Describe the female urethra.
About 1.5 inches long Has 3 coats: Inner mucosa (transitional epithelium) Middle spongy layer with venous plexus Outer smooth muscle layer Smooth muscle helps women stop urine flow voluntarily Shorter length → easier for infections to occur
66
Describe the male urethra.
About 8 inches long Has 2 coats: Inner mucosa layer Outer submucosa layer No smooth muscle layer → men cannot stop urine midstream as easily Longer urethra → less prone to infections compared to females

Anatomy Test 3 (4 decks)

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