Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

05 FdSc Bioscience - Human Physiology and Disease > Week 5 - the urinary system > Flashcards

Week 5 - the urinary system Flashcards

1
Q

What is the function of the urinary system and what is the urinary system made of?

What can be the consequence of an incorrectly functioning urinary system?

A
  • The urinary system has a key role in maintaining homeostasis in the body
  • The urinary system is composed of: kidneys, ureters, bladder, and urethra
  • If the urinary system does not function correctly, the normal composition of the blood cannot be maintained for long which leads to detrimental effects
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the function of the kidney?

A
  • The kidney functions as the bodys main filtering system for extracellular fluid (ECF) and the blood, by removing waste products
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Describe the shape of the kidneys and their location in the body

A
  • They kidneys are paired vascular organs what are bean-seized and roughly the size of a fist
  • The kindeys are protected by their position within the ribcage and perinephric structures
  • The right kidney is slightly lower than the left kidney because of the liver
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Describe the structure of the kidney

A
  • A tough capsule encloses each kidney and a layer of fat acts as a cushion that helps support and secure the kidneys in position
  • The outer region of the kidney is the renal cortex and the inner region is the renal medulla
    • The renal medulla is subdivided into the outer medulla (closer to the cortex) and an inner medulla (further from the cortex)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Describe the renal cortex

A
  • The renal cortex has a reddish-brown colour and a coarse appearance because of the structures it contains
    • Glomeruli
    • Proximal tubules
    • Distal and cortical collecting tubules
    • Peritubular capillaries
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Decribe the renal medulla

A
  • The medulla has a lighter colour and contains triangular wedges that havea striped appearance
  • The triangular wedges are the renal pyramids that consist of long loopls of Henle, medullary collecting tubules and vasca recta
    • The innermost end of the pyrimid is called the renal papilla which direct urine to the major and minor calyces
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are the ureters and what is their function?

A
  • The ureters are hollow tubes that start at the renal pelvis and extend downwards and join to the renal bladder
  • The ureters carry the urine generated in the kidney to the bladder where it is stored
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Where is urine excreted from the body?

A

Urine is excreted from the body through the urethra

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Descrine the supply of blood to the kidneys

A
  • The kidneys are highly vascularised organs that receive ~20% of the resting cardiac output
  • The aorta gives rise to the renal artery which enters the kidney at the hilar region
  • The renal artery branches into smaller vessels including the afferent arterioles that branch to form the first capillary bed - the glomerulus
  • The efferent arterioles take blood away from the glomerular capillaries which gives rise to antoher capillary bed - the peritubular capillaries
  • In the medulla these capillaries, called the vasa recta, formlong loops that run parallel to the loops of Henle
  • The renal vein drains blood away from the kidney which attaches to the inferior vena cava
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the nephron and what does it consist of?

A
  • The nephron is the functional unit of the kidney
  • There are approximately 1.2 million nephrons in each human kidney
  • The nephron consists of a renal corpuscle and a renal tubule
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is a renal corpuscle?

A
  • The renal corpuscle is composed of the glomerulus and the Bowman’s capsule
  • The glomerulus is a specialised capillary bed surrounded by the cup-shaped Bowman’s capsule
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the renal tubule divded into?

A
  • The renal tubule is divided into four segments:
  1. The proximal tubule
  2. The loop of Henle
  3. The distal tubule
  4. The collecting tubule
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the proximal tubule?

A
  • It is the first part of the renal tubule which follows from the Bowman’s capsule
  • This segment is divided into the proximal convoluted tubule and the proximal straight tubule
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the loop of Henle?

A
  • The loop of Henle is the segment after the proximal tubule and consists of the thin descending limb and the thick ascending limb
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the distal tubule?

A
  • The distal tubule is the extension of the ascending limb of the loop of Henle
  • Several distal tubules join together to form the straight collecitng tubule or duct
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are the main functions of the kidney?

A
  • The kidney is a complex organ responsible for several homeostatic functions of the body
  • The main functions of the kidney are:
    • Regulate the concentrations of several ions of the blood plasma: Cl-, Mg2+, Ca2+, K+, Na+, HCO3-. Regulate the homeostasis between water and salt content by selectively reabsorbing or excreting these substances
    • Role in acid-base homeostasis by excreting H+ when there is excess acid or HCO3- when there is too much base
    • Role in maintaining adequeate numbers of RBCs by stimulating erythropoiesis
    • Excrete toxins and waste products of metabolism such as creatinine, urea and uric acid
    • Assist in regulation of blood pressuer by adjusting Na+ excretion and producing substances that can also affect blood pressure
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

When is creatinine, urea and uric acid produced?

A
  • Creatine is produces during muscle metabolism
  • Urea is produced during protein metabolism
  • Uric acid is produced during purine metabolism
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How many lobes is the kidney composed of?

A
  • The kidney is composed of up to 18 lobes, each lobe is composed of nephrons
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the glomerular filtration membrane made out of?

A
  • The glomerular filtration membrane is made out of three layers of capillary wall:
  1. Endothelium
  2. Basement membrane
  3. Epitheliu

It allows some components of the blood to pass through but not all

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Describe the generation of urine in the nephron

A
  1. Plasma-like fluid (filtrate) is filtered from the glomerulus, through the glomerular filtration membrane and into the Bowman’s space
  2. Filtrate diffuses across the Bowman’s space and into the Bowman’s capsule
  3. Filtrate enters the proximal convoluted tubule where almost all nutritionally important substances are reabsorbed
  4. Filtrate enters the loop of Henle where water and ions are reabsorbed from the urine, the loop of Henle plays a role in determining the concetration of the urine
  5. Filtrate enters the distal convoluted tubule which regulates the levels of Na+, K+ and pH and is where further dilution of the urine takes place
  6. Urine enters the collecting tube and here final Na+ regulation takes place
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What are the processes involved in urine formation?

A
  • Three processes are involved in the formation of urine:
  1. Glomerular filtration
  2. Reabsorption
  3. Secretion
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What does glomerular filtration involve?

A
  • It involves the ultrafiltration of plasma in the glomerulus
  • The plasma filtrate travels from the blood in the glomerulus into the Bowman’s capsule space through the glomerular filtration barrier which is aided by glomerular blood pressure
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Describe the glomerular filtration barrier

A
  • The first endothelial layer lines the the capillary lumen and contains pores (fenestrae) that permit the filtration of small solutes and fluid
  • The second layer is the glomerular basement membrane (GBM) which contains a mesh of fine fibrils embedded in a gel-like matrix
    • GBM provides size and charge barrier to the passage of large particles out of the capillary lumen
  • The third layer is the epithelial cells of the Bowman’s capsule, or the podocytes, which have cytoplasmic foot processes that rest on the outer layer of the basement membrane
    • Spaces between podocytes are called slit-pores which allow the filtrate to enter the Bowman’s space
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is the function of the glomerular filtration barrier?

What affects the filterability of the glomerulus?

Give an example of a factor affecting a molecules ability to cross the GFB

A
  • The glomerular filtration barrier permits filtration of fluid and small molecules
  • Molecular size, molecular shape and electrical charge are though to influence the filterability of the glomerulus
  • Endothelial cells and podocytes have a negatively charged surface coat (glycocalyx) and the GBM contains negatively charged proteins
    • The negative charges repel the passage of negatively charged macromolecules
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What do the epithelial cells of the renal tubules play an important role in?

A
  • The epithelial cells of the renal tubules have a central role in regulating the composition and volume of tubular fluid
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What is glomerular filtration rate and what is it used for?

A
  • Glomerular filtration rate (GFR) is the rate at which plasma is filtered by the glomeruli
  • GFR is equal to the sum of all the filtration rates of all functional nephrons
  • It is used in the evaluation of kidney function
    • E.g. decrease in GFR is generally a sign that kidney function is impaired
27
Q

What does tubular reabsorption involve?

A
  • Tubular reabsorption involves the movement of substances out of of the tubular filtrate into the peritubular capillaries
  • This process allows the body to retain fluids and desired solutes
  • The substances that are returned to the peritubular capillaries include ions (Ca2+, Na+, K+, Cl- and HCO3-), metabolites (amino acids and glucose), some waste products (urea) and water
28
Q

What are the barriers that tubular fluid travels on their journey from tubular urine to blood?

A
  • There are three barriers for tubular fluid to pass across:
  1. Substances in tubular urine are transported across the luminal membrane ofthe tubules (this is the membrane that is in contact with the tubular urine)
  2. Substances that are being reabsorbed must then transverse the interior of the tubular cell and be tranported across the plasma membrane of the cell that faces the interstitial that surrounds the tubular cells
  3. Substances in the interstitial fluid are transported across the endothelial lining of the peritubular capillaries and enter the blood
29
Q

Outline reabsorption in the proximal convoluted tubule

A
  • Reabsorption begins in the proximal convoluted tubules and continues through the nephron
  • The proximal convoluted tubule is the major site of reabsorption in the nephron, approximately 65% of filtered water and sodium is reabsorbed
  • Reabsorption involves both passive and active mechanisms
  • Other susbstances reabsorbed here include all of the filtered glucose and amino acids, vitamins, Cl-, K+, urea, bicarbonate, magnesium, calcium and other solutes.
30
Q

Outline reabsorption in the loop of Henle

A
  • Loops of Henle are counter-current multipliers
  • The thin descending limb is highly permeable to water and less permeable to NaCl so water is reabsorbed out of the thin descending limb by osmosis because of the highly concentrated medullar interstitial fluid
  • The removal of water from the descending limb causes a rise in [NaCl] in the loop fluid which become more concentrated than the composition of the interstitual fluid
  • The thin ascending limb is impermeable to water but permeagble to NaCl and urea
  • In the ascending limb NaCl is reabsorbed by passive diffusion which becomes deposited in the medullary interstitial fluid
  • In the thick ascending limb, Na+, is actively reabsorbed via an ATPase pump
31
Q

Outlimne reabsorption in the distal tubule

A
  • The early part of the distal tubule transports a number of solutes including sodium, chloride, calcium, bicarbonate and magnesiu
  • The early part of the distal tubule is impermeable to water
  • The late distal tubule is permeable to water which is regulated by the antidiuretic hormone (ADH)
32
Q

Outline reabsorption in the collecting tubule

A
  • The cells of the collecting tubule play a role in the absorption of Na+, water, hydrogen and bicarbonate play a key role in the acidification of urine
  • ADH regulates water permeability along the collecting tubules
  • Reabsorption of fluids and solutes is regulates to meet the body’s requirements through neural and hormonal systems such as angiotensin II, aldosterone, and ADH
33
Q

What is tubular secretion and what does it play a role in?

A
  • It involves the transport of substances into the tubular urine
  • Substances are taken up by tubular cells from the surrounding peritubular blood and are added to the tubular urine
  • Important in clearing the blood from excess H+, K+, drugs (e.g. penicillin) and waste products such as urea and creatinine
  • Some substances, H+ and urea, are produced in the tubular cells and are secreted directly into the tubular urine
  • Secretion occurs by both passive and active mechanisms
  • Tubular secretion plays a role in regulating body’s fluid, acid-base and electrolyte balance
34
Q

How does the body regulate the amount and composition of the urine?

A
  • The amount of water and solute reabsorbed by the tubular system is controlled to regulate the amount and composition of the urine
35
Q

What is antidiuretic hormone, what is it produced by and when is it produced?

A
  • Often described as the water-retaining hormone
  • Release by theposterior pituitary gland in response to many stimuli
    • E.g. decrease in blood plasma volume
36
Q

What is the effect of the presence of antidiuretic hormone (ADH) in the blood on the kidney?

A
  • When present in the blood, the collecting tubules are permeable to water which causes water to be reabsorbed into the blood by osmosis
  • Less water is lost from the body as urine, urine is concentrated
37
Q

What is the effect of the absence of antidiuretic hormone (ADH) in the blood on the kidney?

A
  • The collecting duct tubules become impermeable to water so little or no water is reabsorbed
  • Leads to the excretion of dilute urine
38
Q

What is the effect of the presence of the hormone aldosterone in the blood on the kidneys?

A
  • Aldosterone is described as the sodium and water retaining hormone
  • Secreted by adrenal cortex, central role in controlling the reabsorption of sodium
  • It stimulates the renal tubules to reabsorb sodium at a faster rate
    • As sodium is reabsorbed water follows by osmosis down its water potential gradient
39
Q

What is the effect of the presence of atrial natriuretic hormone in the blood on the kidneys?

A
  • Described as the salt and water losing hormone
  • Secreted from the hearts atrial wall, has opposite effect of aldosterone
  • Simulates renal tubules to secrete more Na+ into the tubular urine
    • Resuts in more water loss from the body
40
Q

What does the amount of hormones targeting the kidney secreted by the body depend on?

A
  • Depending on the hoeostatic balance of body fluids, the body will secrete different amounts of ADH, ANH and aldosterone
41
Q

What is the normal adult urine output per day?

A
  • 1,500 mL - 1,600 mL per day
42
Q

Why may the kidneys not excrete the normal amount of urine and what can be the result of this?

What is the signficance of noticing differences in urine volume?

A
  • Kidneys may not excrete normal amounts of urine due to dehydration, cardiovascular disease, kidney diseases or stress
  • May result in
    • Polyuria - unusually large amounts of urine
    • Anuria - absence of urine
    • Oliguria - scantly amounts of urine
  • Changes in urine output serve as an indicators of many types of fluid alterations and diseases
43
Q

Describe the function and structure of the ureters

A
  • Peristaltic movements propel the urine from the collecting tubules into the renal pelvis and down the urters into the urinary bladder
  • Mucous membranes line both the ureters and each renal pelvis
  • Ureters have thick muscular wall
    • Contraction of these muscular cells induces the peristaltic movement of urine
44
Q

What is the urinary bladder and what does it consist of?

A
  • The urinary bladder is a hollow musclar organ which consists of the bladder cavity and the bladder wall
  • Smooth muscle in the bladder wall is called the detrusor
45
Q

What is the contractibility of the detrusor muscle important in?

A
  • The contractibility of the detrusor muscle determines the bladder function during storing and dispensing urine
46
Q

What is the storing and dispensing of urine regulated by?

A
  • Strictly regulated by nervous and hormonal mechanisms and the detrusor contains several receptors and signalling pathways
47
Q

What is the trigone?

A
  • Trigone is a small muscular area in the bladder body which prevents the reflux of urine to the upper urinary tract during voiding
48
Q

What lines the urinary bladder?

A
  • The urothelium is a specialised type of epithelial membrane which linesthe urinary bladder
49
Q

What is the bladder neck?

A
  • The bladder neck si the funnel-like opening of the bladder into the urethra
  • The involuntary internal sphincter is composed of smooth muscle and is located on the neck of the bladder
  • The external sphincter is composed of skeletal muscle which is innervated by nerve fibres
50
Q

How is distension of the bladder sensed?

What is the result of this?

A
  • Sensed by stretch receptors in the bladder wall whch induces the reflex contration of the detrusor and relaxation of internal and external sphincters
51
Q

Describe micturition

A
  • A.k.a urination
  • Urine flows through the urethra causes further contraction of the derusor and relaxation of the external sphincter
  • In healthy adults micturition is under voluntary control
  • In young children micturition occurs solely due to reflex when the bladder is distended
    • Comes under complete voluntary control by the age of 3
      *
52
Q

Why may abnormalities of micturition occur?

A
  • Abnormalities of micturition and incontinence may occur due to the damage of the nerves that supply the bladder and its sphincters
53
Q

What is benign prostatic hyperplasia (BPH)?

What are some symptoms?

A
  • BPH is a condition in men caused by the enlargement of the prostrate gland resulting in an increased resistance of the urethra
  • BPH results in overdistention of the bladder, decreasd urine stream and increased urgency and frequency of urination
54
Q

What is the urethra?

A
  • The urethra is the lowest part of the urinary tract, it carries urine away from the bladder and out ofthe urinary meatus (the external opening)
55
Q

Describe the structure of the urethra and the significance of one of the constituents

A
  • The urethra has a lining of mucous membrane in the same way as the renal pelvis, ureters and bladder
  • The importance of the mucous sheet is evident in infections of the urethra which can spread upwards through the urinary tract
56
Q

What is the difference of the urethra in men and women?

A
  • In women the urethra is part of only the urinary tract
  • In men the urethra is both the terminal portion of the urinary tract and it is the passageway for movement of semen from the body
57
Q

Outline chronic kidney disease (CKD)

A
  • CKD is usually progressive and can lead to kindey failure
    • When kidneys fail problems occur
  • Causes of CKD include: diabetes, hypertension, polycystic kidney disease and glomerulonephritis
  • Renal damage can occur over a long period of time but only be detected when considerably nephron function loss has occured
58
Q

What are common forms of treatment for end-stage irreversible renal failure?

A
  • Kidney transplantation and dialysis
59
Q

How is dialysis used to treat end-stage irreversible renal failure?

A
  • Dialysis is a procedure that acts as a substitue for some renal functions e.g. filtration and waste removal
  • Haemodialysis is one method of dialysis that is efficient at removing waste
  • Blood is pumped through a dialyser and a semipermeable membrane is used to separate smaller molcules (e.g. urea) from larger molecules (e.g. blood cells)
  • Applying pressure to the blood and filtering it can remove excess fluid
  • Haemodialysis is doen three times a week and enables patients to live productive lives
60
Q

How is end-stage renal failure treated?

A
  • Only by kidney transplantation
61
Q

What is polycystic kidney disease?

A
  • Most common genetic cause of kidney failure in adults and children
  • Genetic disorder characterised by the growth of numerous fluid-filled cysts in the kidney
  • PKD can be inherited by autosomal recessive or dominant trait
  • PKD cysts cna enlarge kidneys and cause distortion of the normal structure resulting in decline in kidney function
  • 50% of people with PKD progress to end-stage renal disease
62
Q

What is actute renal failure?

A
  • Acute renal failure (ACF) is generic term for rapid and sustained decrease in renal function characterised by rapid decline in GFR
  • ARF causes accumulation of toxins in bloodstream (urea and creatinine), disruptions in the acid-base balance of blood, imbalance of blood electrolytes and dehydration
  • Reversible if diagnosed early
  • Typically asymptomatic and in clinical practice, biochemical monitoring of patients show a increase in serum creatinine and urea concentrations
63
Q

What are Starling forces?

A
  • Starling forces govern the passive exchange of water between the capillary microcirculation and the interstitial fluid
  • The forces determine the directionality of net water movement and the rate at which water exchange occurs
64
Q

What are the key variables in Starling forces?

A
  • Hydrostatic pressure gradient - the physical force of fluids against their barriers, plasma in capillaries has a positive hydrostatic pressure (from heart) whist fluid in interstitial speces has negative
  • Oncotic pressure gradient - osmotic pressure generated by the presence of proteinaceous solutes, these cannot cross the capilary barrier so oncotic pressure is higher within the plasma
  • Vascular permeability - histological architecture of capillaries determines the permeability of capilaries to water, e.g. glomerulus has high water permeability whereas blood brain barrier has very low water permeability

05 FdSc Bioscience - Human Physiology and Disease (8 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions