11. Urinary System Flashcards
The tubes that connect the kidneys to the bladder
Ureters
The tube exiting the bladder to remove urine from the body
Urethra
List 4 functions of the urinary system
- Excretion of unwanted substances
- Maintenance of water & electrolyte balance
- pH regulation of body fluids
- Production of hormones
- Regulation of red blood cell production
- Regulation of blood glucose levels
- Regulation of blood pressure, volume and osmolarity
What gas is found in all metabolic waste products?
Nitrogen
List the 3 metabolic waste products.
- Urea (from protein metabolism)
- Uric Acid (from purine metabolism)
- Creatine (from muscle metabolism)
What is the main ion excreted in urine?
Hydrogen (H+)
What is the minimum urine content required to clear body waste?
500 ml/day
What are electrolytes?
Charged atoms in solution
Name the 3 most important electrolytes that are regulated by the kidney.
Sodium (Na+)
Potassium (K+)
Hydrogen (H+)
An excess in what electrolyte is a reflection of an acidic solution?
Hydrogen (H+)
What pH should blood be?
7.35 - 7.45
What are the two primary pH control systems in the body and how do they work?
- Lungs - excrete CO2 through respiration
- Kidneys - excrete H+ into urine and produce the buffer HCO3 (bicarbonate)
What are the two main hormones produced by the kidneys and what are their functions?
Calcitriol - the active form of vitamin D that increases bone formation by increasing calcium.
Erythropoietin - stimulates erythropoiesis
How does calcitriol increase bone formation?
1) Stimulates calcium and magnesium update in the GIT
2) Reduces calcium loss in the kidneys
Bone formation increases due to the increase in calcium.
What hormone is released by the kidneys in response to hypoxia?
Erythropoietin
In renal failure, erythropoietin production is inadequate and hence results in what pathology?
Anaemia
What is the renal threshold for glucose?
9 mmol/L
What is a normal blood glucose level?
4 - 7 mmol/L
How do the kidneys make glucose?
The kidneys are able to make glucose from the amino acid glutamine to help elevate blood sugar levels when hypoglycemia.
NB this is called gluconeogenesis
How do the kidneys control blood volume, pressure and concentration?
1) Conserving or eliminating water in urine.
2) Regulating the solute loss in the urine helps maintain a constant blood concentration.
3) Secrete the enzyme renin which activates the renin-angiotensin-aldosterone pathway increasing blood pressure.
Where are the kidneys located?
- Partially protected by the 11th & 12th ribs.
- Between vertebra levels T11 - L3
- Right kidney is lower because the liver occupies space on the right.
What are the 3 layers surrounding the kidney?
1) Renal capsule - deep later of connective tissue
2) Adipose capsule - middle layer of fatty tissue
3) Renal fascia - superficial layer of connective tissue
What are the two regions within the kidneys?
1) Renal cortex - superficial, light red area
2) Renal medulla - dark area consisting of several cone-shaped structures
Describe the functional portions of the kidneys.
Several cone-shaped structures called renal pyramids.
The apex of each renal pyramid is called the renal papilla.
What is the term for the function unit of the kidneys and how many are there in each kidney?
Nephrons
1 million per kidney
Name the artery and vein going in and out of the kidneys.
Renal artery and vein
Name the two parts of a nephron.
1) Renal corpuscle
2) Renal tubule
Describe the route urine travels once it’s formed
Once formed within the nephrons, urine drains into the renal papilla, then into the minor and major calyces.
From there, urine travels out of the kidney into the ureter, into the bladder, and then the urethra.
Name the artery and vein going in and out of the kidney
Renal artery and vein
Describe what the renal corpuscle consists of.
Consists of the glomerulus & Bowman’s capsule:
The glomerulus is a tangled capillary network that receives blood from an afferent arteriole and is 50x more leaky than normal capillaries.
The Bowman’s capsule is a double-walled epithelial cup that surrounds the glomerulus and receives contents of filtered blood.
Name the 3 sections of the renal tubule and their location in the kidney
1) Proximal convoluted tubule
2) Loop of Henle
3) Distal convoluted tubule
Proximal and distal convoluted tubules sit in the renal cortex.
The Loop of Henle often extends into the renal medulla.
What is the overall role of the renal tubule?
Filtered fluid passes through the tubules where the reabsorption and secretion of various solutes occur.
What part of the nephron does antidiuretic hormone (ADH) act on?
Distal convoluted tubule
What are the arterioles that enter and exit the nephron called?
Afferent arteriole (entering)
Efferent arteriole (exiting)
What prevents the backflow of urine from the bladder back into the ureters?
A physiological valve
Name and briefly describe the 3 layers of tissue that form the wall of the ureters.
1) Inner mucous membrane
Transitional epithelium that can stretch, along with goblet cells secreting mucous for protection.
2) Muscularis
Smooth muscle fibres for peristaltic contractions
3) Adventita
Outer coating of connective tissue with blood and lymph vessels, and nerves.
What is the total capacity of the bladder and at what point does the desire to urinate occur?
Total capacity is 600-700ml
Desire to urinate from about 200ml
What is the triangular area on the posterior floor of the bladder called and what is found there?
Called the trigone.
The two ureteral openings enter here along with the urethral opening at the base.
Briefly describe the 3 layers of tissue in the bladder.
1) Inner mucosa layer
Transitional epithelium supported by connective tissue. The mucosa folds to permit expansion.
2) Muscularis aka detrusor muscle
At the urethral opening smooth muscle fibres form the internal urethral sphincter
3) Adventita
Outer layer of connective tissue
How do the lengths of the female and male urethras differ?
Female urethra is 4cm long
Male urethra is about 20cm long
Name the 3 portions of the male urethra
Prostatic, membranous, and spongy
What is the role of the prostate?
The male urethra passes through the prostate where it receives semen during ejaculation.
What are the 3 basic processes of urine formation?
1) Glomerular filtration
2) Tubular reabsorption
3) Tubular secretion
Briefly describe what occurs during glomerular filtration.
Glomerular capillaries present a large surface area for filtration.
Water and small molecules pass through pores into the glomerular capillaries into the Bowman’s capsule.
Blood cells, plasma proteins, and other large molecules are too big to filter through.
What are the two ways the glomerular is adapted for filtration?
Diameter of efferent arteriole is smaller than that of the afferent arteriole creating higher pressure and therefore helping push molecules out of the capillaries.
Glomerular capillaries are also 50x leakier than normal capillaries.
List 4 of the blood constituents that pass into the glomerular filtrates, and that remain in the capillaries
Pass into glomerular filtrate:
Water
Mineral salts
Amino acids and glucose
Ketoacides
Hormones
Creatine
Urea
Uric acid
Toxins
Remain in capillaries:
Leukocytes
Erythrocytes
Platelets
Plasma proteins
What does GFR stand for and what is it?
Glomerular Filtration Rate
The amount of filtrate formed in the renal corpuscles of both kidneys each minute.
What is the normal GFR and how is it tested?
Normal GFR should be over 90ml/min.
Calculated through a blood test and is important in determining severity of kidney disease.
What is colloid osmotic pressure and how might it occur?
A form of osmotic pressure exerted by proteins (notably albumin).
Damage to the glomerular capillaries can lead to plasma protein loss in urine.
Less albumin in the blood makes it hypotonic and fluid moves via osmosis from the blood into the tissues causing oedema.
Name 3 substances that are often reabsorbed and where most reabsorption occurs.
1) Water
2) Amino acids and glucose
3) Electrolytes
Occurs most in the proximal convoluted tubule.
Name 3 common substances that are often secreted in the tubules.
1) Waste products such as creatinine & urea
2) Certain drugs such as penicillin
3) Excess ions such as H+ (pH regulation)
Name the 5 hormones that affect the kidneys’ reabsorption of sodium, chloride, calcium and water as well as the secretion of potassium.
1) Angiotensin II
2) Aldosterone
3) Antidiuretic hormone
4) Atrial natriuretic peptide
5) Parathyroid hormone
What is RAAS and describe its process?
Renin-Angiotensin-Aldosterone System - a system of hormones that affect blood pressure.
- BP below 100mmHG results in the afferent arteriole wall being stretched less, causing…
- The Enzyme renin released by kidneys into the blood
- Angiotensinogen to be converted to angiotensin I in the liver
- Angiotensin I is converted to angiotensin II by angiotensin-converting enzymes (ACE) in the lungs
- Angiotensin II causes release of aldosterone from the adrenal cortex
- Aldosterone stimulates kidneys to reabsorb salt and water
What 3 things does angiotensin II do?
1) Vasoconstriction
2) Triggers the pituitary gland to release anti-diuretic hormone (ADH)
3) Stimulates adrenal cortex to produce aldosterone
What effect does antidiuretic hormone have on the urinary system?
Increases the permeability of the distal convoluted tubules, increasing water resorption in the kidneys.
What’s the role of Atrial Natriuretic Peptide (ANP)?
ANP inhibits reabsorption of Na+ and water reducing blood pressure.
ANP is released in the heart when myocardium is stretched.
It suppresses the release of ADH and aldosterone, resulting in increased urine output.
What 3 ways does the Parathyroid Hormone (PTH) increase blood calcium levels?
1) Stimulates renal reabsorption of calcium & magnesium
2) Increases osteoclast activity
3) Stiumlates calcitriol release increasing gut calcium reabsorption
Describe the flow of urine from formation.
1) Urine formed in the nephrons drains into papillary ducts in the renal papillae of the renal pyramids.
2) The papillary ducts drain into the minor and major calyces.
3) From here, urine drains into the renal pelvis before into the ureters, bladder and then urethra
What is micturition and when does it occur?
It is the discharge of urine from the bladder and occurs when the bladder exceeds 200 - 400ml
List 3 components of urine
1) Water (96%)
2) Urea (2%), uric acid & creatinine
3) Ammonia
4) Na, K, Cl, P, S
5) Hormones
6) Oxalates
List 4 ways the urinary systems interacts with other body systems.
1) Integumentary system - Kidneys convert vit D precursor made in the skin into active form (calcitriol)
2) Skeletal system - Kidneys help adjust blood levels of calcium & phosphate
3) Muscular system - Kidneys help adjust blood calcium levels
4) Nervous system - Kidneys can perform gluconeogenesis to provide glucose for neurons
5) Endocrine system - Kidneys produce calcitriol and erythropoietin
6) Respiratory system - lungs and kidneys help adjust pH of body fluids
(and more)
List 4 signs/symptoms commonly indicating a urinary tract pathology.
- Frequent and painful urination with urgency
2) Red urine (check not beetroot!)
3) Pain in the loin
4) High urine volume with great thirst
5) Low or no urine volume
6) Nausea and vomiting
7) Oedema
8) Exhaustion
List 4 signs of renal disease
1) Pallor (due to anaemia)
2) Frothy urine (due to proteinuria)
3) Oedema (due to protein loss)
4) Signs of itching skin (due to uraemia)
5) Altered mental state (common in UTIs)
6) Puffy face and bags under the eyes
7) Dehydration and flapping tremor
What are the two forms of urinalysis?
Dipstick & urine microscopy
List 4 parameters of urinalysis and what they’re indicative of.
1) Leukocytes - UTI
2) Nitrites (bacteria) - UTI
3) Erythrocytes - UTI, tumour, kidney stones
4) Ketones - Keto-acidosis (complication of diabetes mellitus)
5) Protein - kidney disease
6) Glucose - diabetes mellitus
What might be measured in a blood test?
- Glomerular filtration rate (GFR)
- Urea
- Creatinine
- Electrolytes
- Inflammatory markers
- Leukocytes
What is the term used for painful, burning urination?
Dysuria
What is the term used for a large quantity of urine?
Polyuria
What is the term used for little urine (under 400ml/day)?
Oliguria
What is the term used for no urine?
Anuria
What is the term used to describe protein in urine and how might the urine appear?
Proteinuria
Frothy
What is the term for blood in the urine?
Haematuria
List 4 signs/symptoms of a UTI
Dysuria
Frequent urination
Nocturia (nocturnal urination)
Cloud & smelly urine
Suprapubic pain
Haematuria
Confusion
Nausea
What might be found on a urine dipstick with someone with a UTI?
Nitrites
Leukocytes
Erythrocytes
What is the term used for a bladder infection?
Cystitis
What bacteria most commonly causes cystitis?
E.coli
List 3 possible causes of cystitis.
- Bacteria being pushed into urethra
- Post-menopausal (thinned lining)
- Enlarged prostate (chronic cystitis)
List some signs and symptoms of cystitis
- Pain in the abdomen
- Dysuria and frequent/urgent need to urinate but only passed small amounts
- Dark, smelly/cloudy urine
What’s the allopathic treatment for cystitis
Antibiotics
What is Pyelonephritis?
a microbrial infection of the renal pelvis and medulla (kidney infection)
What is the risk of chronic pyelonephritis?
It can lead to destruction (necrosis) and scarring of the renal tissue
List 3 causes of pyelonephritis
- Infection spreading up from the bladder
- Diabetes mellitus
- Immunocompromised patients
- Obtructured flow of urine (enlarged prostate or kidney stones)
- Pregnancy
- Gout
List 3 signs/symptoms of pyelonephritis
- Loin pain and tenderness
- Dysuria
- Haematurea
- Fever
- Fatigue
List one complication of acute pyelonephritis and one for chronic pyelonephritis.
Acute:
- Septicaemia
- Renal abcess
- Secondary hypertention
Chronic:
- Chronic kidney disease and renal failure
What allopathic treatment is given for pyelonephritis?
- Strict bed rest
- Drink lots of fluids (>2L)
- Antibiotics
What is glomerulonephritis?
An immune-mediated disease that causes glomerular inflammation
Describe the pathology of glomerulonephritis
- Antigen and antibody join together creating an immune response
- These formed immune complexes deposit into the glomeruli wall creating inflammation.
- Inflammation causes damage to the wall resulting in leaky capillaries
- Larger substances such as proteins and erythrocytes escape into the urine.
Give a primary and secondary cause of glomerulonephritis
Primary - autoimmune response often occuring 1-3 weeks after a bacterial infection (i.e. post-streptococcal glomerulonephritis)
Secondary - Lupus
Name 3 clinical presentations of glomerulonephritis
- Asymptomatic haematuria and/or proeinuria
- Back pain
- Fluid retention / oedema
- Oliguria
- Hypertension
How might you diagnose glomerulonephritis?
Urinalysis - Erythrocytes and protein
Blood - Elevated ESR and CRP, low GFR
What allopathic treatment is given for glomerulonephritis?
Corticosteroids
Antibiotics
Diuretics
Define nephrotic syndrome
A collection of signs and symptoms associated with increased glomerular permeability (leaking) and heavy proteinuria
What do 40% of diabetics develop?
Diabetic nephropathy
(And renal failure is the cause of death in 10% diabetics)
Describe the pathogenesis of diabetic nephropathy.
- Diabetes mellitus elevates blood pressure
- Glomerulosclerosis occurs as a result of the increased pressure in the glomerular
- Glomeruli become damaged and proteins leak
What is the medical term for kidney stones and what are they most commonly made of?
Renal calculi
Calcium oxalate and phosphate (80%)
What’s the main cause of kidney stones?
Dehydration causing an imbalance in water and minerals in the body
List two signs/symptoms of kidney stones
- Often asymptomatic
- Sever loin pain radiating to the groin
