Urinary System Flashcards
Describe the elements of the urinary system
Two kidneys two ureters one urinary bladder and one urethra
Eurus produced in the kidneys which filter out harmful and unwanted waste products from the blood and balance water and salt content of the body
Explain how urea is produced and how the liver and kidneys are involved
Proteins have to be used up almost in simultaneously and excess proteins are taken to the liver where they are broken down however the toxic side product urea is formed which must be removed by the body and this is done through the kidneys
What are the kidneys filtration systems called and what are the kidneys Jobs?
The filtration systems of the kidney are called nephrons and there are millions of tiny filtration systems within the kidney that help process about 190 L of blood
Kidneys control blood pressure produce hormones and chemicals that help the production of blood cells and maintain healthy bones although their main job is filtration of the blood that passes to the heart and are important in homeostasis
Where are the kidneys located and what hormones do they produce?
The kidneys are located high in the abdomen towards the back of the abdominal cavity either side of the spine receiving some protection from the lower rib cage
They are encased in fat which helps protect from damage each kidney functions as a blood filter, retaining useful chemicals and removing harmful and needed ones in addition to regulating loss of water and salts from the body whilst maintaining pH of the blood adjusting the acid base balance
Kidneys produce hormones, calcitriol or it’s active form vitamin D that helps regulate calcium in the body
Erythropoietin stimulates the production of red blood cells
The enzyme Renn is produced by the kidneys and helps regulate blood pressure
Describe the anatomy of the kidney
Each kidney has three main functional areas
Cortex the outer part of the kidney it contains functional units of the kidney called nephron
Medulla contains the loop of henle where water and salt are absorbed back into the blood
Pelvis, this is where the connecting ducks combine into the ureter which carries urine down into the bladder
Each adult kidney is 12 cm long and 6 cm wide and 3 cm thick and are plenty full in blood supply. Reno blood is approximately 1200 CM cubed per minute about 25% of all blood in the body.
Describe the blood flow of the nephron
Blood Flow of the Nephron (with Tubular Structures)
1. Renal Artery → Supplies oxygenated blood to the kidney.
2. Afferent Arteriole → Delivers blood to the glomerulus.
3. Glomerulus → Filtration occurs here; plasma and small solutes pass into Bowman’s Capsule.
4. Efferent Arteriole → Carries blood away from the glomerulus, maintaining pressure for filtration.
5. Peritubular Capillaries (in cortical nephrons) / Vasa Recta (in juxtamedullary nephrons) → Surround the nephron tubules for reabsorption and secretion.
Tubular Pathway (Filtered Fluid)
6. Proximal Convoluted Tubule (PCT) → Reabsorbs water, glucose, amino acids, and electrolytes back into the peritubular capillaries.
7. Loop of Henle:
• Descending Limb → Permeable to water; water leaves into the vasa recta.
• Ascending Limb → Impermeable to water; actively transports Na⁺, Cl⁻ into the medulla.
8. Distal Convoluted Tubule (DCT) → Fine-tunes electrolyte balance; influenced by aldosterone.
Blood Drainage
9. Interlobular Vein → Collects blood from peritubular capillaries.
10. Arcuate Vein → Receives blood from interlobular veins.
11. Interlobar Vein → Collects blood from arcuate veins.
12. Renal Vein → Returns filtered, deoxygenated blood to systemic circulation.
This process ensures filtration, reabsorption, and secretion to regulate blood composition and urine formation.
What is a Malpighian body
A Malpighian body (also called a renal corpuscle) is the filtration unit of the kidney. It consists of:
1. Glomerulus – A network of capillaries where blood filtration occurs.
2. Bowman’s capsule – A cup-shaped structure that surrounds the glomerulus and collects the filtrate.
It is the first structure in the nephron, responsible for ultrafiltration of blood, removing waste while retaining essential proteins and cells.
What type of blood leaves the kidney?
No, oxygenated blood does not leave the kidney. By the time blood exits through the renal vein, it is deoxygenated because the kidney cells have already used up the oxygen for metabolism and filtration processes.
How Oxygen is Used in the Kidney
1. Oxygenated Blood Enters
• The renal artery brings oxygen-rich blood into the kidney.
• This blood is distributed to nephrons via afferent arterioles → glomerulus → efferent arterioles → peritubular capillaries/vasa recta.
2. Oxygen is Delivered
• The peritubular capillaries and vasa recta supply oxygen to nephron structures (PCT, Loop of Henle, DCT, and collecting duct).
• Oxygen is used for active transport of ions (e.g., Na⁺ reabsorption in the PCT and DCT) and other metabolic processes.
3. Deoxygenated Blood Leaves
• After oxygen is used up, blood drains into interlobular veins → arcuate veins → interlobar veins → renal vein.
• The renal vein carries only deoxygenated blood back to the heart.
Final Answer:
No, oxygenated blood does not leave the kidney. All blood that exits through the renal vein is deoxygenated because the kidney has extracted the oxygen it needs.
Explain filtration in the kidney
Blood in the afferent arteriole is on the high pressure from the aorta and renal artery resulting in small molecule such as water, glucose amino acids, salt and waste products (urea) passing through the capillary wall into the Bowman’s capsule. This is referred to as glomerular filtrate.
Large molecules such as plasma proteins and blood do not pass through and healthy individuals so there is no blood cells found in healthy urine
150 - 190 L of fluid are filtered every day
Explain how secretion of the renal tuble works
If concentration is too high of some substances after filtration, they can be actively secreted into the renal tubular and removed from the body in the urine. This includes waste product such as urea uric acid and creatinine.
The renal tubal consist of the proximal convoluted tubular the distal convoluted tubular and the loop of henle
Explain reabsorption of glomerular filtrate
After small molecules of filtered out of the Glamer into the Bowermans capsule, they reach the renal tubules, at this .99% of water all of the glucose and most of the minerals are reabsorbed back into the blood by diffusion or active up tech into the efferent arteriole
Although 150–190 litres of glomerular filtrate or process per day this is why you only produce between one to 2 L of urine per day
What are the four stages of urine production?
Filtration small molecules leave the glomerulus into the Bowman’s capsule while large molecules remain in the blood
Secretion if concentration of waste products is too high in the blood the efferent arterioles will actively transport into the renal tubes
Reabsorption glomerular filtrate passes through the tubular 99% of water all of the glucose and most of the minerals are reabsorbed back into the blood
Synthesis kidney tissue can also support activity of the liver by making substances which detoxified toxic chemicals
Explain how urine is transported from the collecting duct and released
The pelvis of the kidney collects urine from the collecting ducks of the nephrons which then drains into two ureters.
Ureters are muscle wall narrow tubules 30 cm long and 6 mm in diameter which connects the kidney with the bladder. Lining of the ureter is continuous with the lining of the bladder as urine passes from the kidney to the bladder by peristaltic action of smooth muscle in the wall of the ureters
Peristaltic waves occur 1 to 5 times each minute depending on kidneys.
The urinary blood is a smooth collapsible muscular organ which acts a temporary reservoir for urine size and position varies depending on the amount of urine stored and is capable of storing half a litre of urine comfortably and a maximum of 1 L in adult men in around 700 to 800 CM cubed in women
Urine exits the blood via the urethra
Explain the concept of micturition
The process of urination is called micturition and occurs due to the combination of voluntary and involuntary muscle contractions. The volume of the urine in the bladder increases stretch receptors in the walls of the bladder transmit nerve impulses to the spinal cord. These eventually trigger a spinal reflex called micturition reflex
Two sphincter close the blood is exit to the urethra and internal sphincter made of smooth muscle which is under autonomic control and an external sphincter made of skeletal muscle which is under voluntary control. This enables us to control urination and these are sometimes referred to as the urethral sphincters.
Men have a 20 CM lung urethra although women only have a 3CM long the shortness of this and the close proximity to the anus means that women often develop urinary tract infections
How does the urinary system contribute to homeostasis?
Kidneys regulate the volume composition and pH of body fluids removing waste excess substances from the blood excreting them in urine
Aid skin health through the synthesis of Calcitrol, which is the active form of vitamin D That is converted by UV light?
Skeletal, the kidneys help adjust blood calcium and phosphate
Muscular system, the kidneys help and just calcium in the blood preventing tremors
Endocrine system kidneys participate in synthesis of Cul control and release erythropoietin that stimulates production of red blood cells
Cardiovascular system Renn and enzyme released by the Juster glomerular cells raises blood pressure/volume in a complex with angiotensin and Aldosterone
System kidney and lungs work together in adjusting pH of body fluids
Digestive system kidneys are involved in synthesis of calcitrol which is needed for absorption of dietary calcium from the gut
Explain the kidneys role in preventing acidosis and alkalosis
The optimum pH of blood is between 7.35 and 7.45 lower is acidosis higher is alkalosis and the kidney helps to balance the pH of blood by absorbing by bicarbonate ions
Explain how the hypothalamus and the kidney are involved in maintaining water balance
The hypothalamus and kidneys work together to maintain water balance (osmoregulation) through a feedback system involving antidiuretic hormone (ADH).
Step-by-Step Process:
1. Osmoreceptors in the Hypothalamus Detect Changes
• If water levels drop (high blood osmolarity), osmoreceptors in the hypothalamus detect this and signal the posterior pituitary to release ADH.
• If water levels are too high (low blood osmolarity), ADH release is inhibited.
2. ADH Acts on the Kidneys
• ADH increases the permeability of the collecting ducts in the kidneys.
• More water is reabsorbed into the bloodstream, reducing urine volume and conserving water.
3. Urine Concentration Adjusts
• High ADH → Concentrated urine (low volume, dark color).
• Low ADH → Dilute urine (high volume, clear color).
4. Restoring Balance
• When normal hydration is restored, the hypothalamus signals to reduce ADH release, bringing urine output back to normal.
This system ensures the body maintains homeostasis, preventing dehydration or overhydration.
Opposingly the production of ADH is reduced if concentration is too low making the tube is less permeable
How does the kidney deal with a reduced blood pressure?
If low blood pressure is detected the kidney releases an enzyme called Renon Renon set off a series of reactions which end in the production of angiotensin two which is a powerful vasoconstrictor narrowing the blood cells
And your attention to also stimulates the release of aldosterone from the adrenal cortex
Aldosterone increases the permeability of the renal tubes to sodium which actively reabsorbs meaning more water is reabsorbed from the kidney tubular this results in an increase in blood volume and therefore increase in blood pressure
Explain how the kidney regulates red blood cells
The hormone erythropoietin is naturally circulating around the blood however in cases of hypoxia the kidneys increased their air production of the whole moon, stimulating the bone marriage to produce more red blood cells. This is sometimes used illegally by athletes in various sports.
Explain glomerular filtration rate what the average male and female is and the hormones involved in his reregulation
The filtrate rate is the amount of filtrate formed in all renal corpuscles in the kidney per minute
Men 125 cm³ per minute
Women 105 cm³ per minute
The home angiotensin II reduce reduces GFR – less blood entering the glomerolous
Atrial natriuretic peptide increases it
Explain Glomerulonephritis
Inflammation of the glomeruli in the nephron commonly an allergic reaction to toxins produced by streplococcal bacteria that have infected another area of the body usually the throat
The Glomeruli become swollen and engorged with blood causing blood cells and plasma to be forced through the membrane into the field, causing a lot of proteins to be passed in urine as well as red blood cells
Acute infection infections are reversible however chronic conditions can be fatal
Explain renal failure
A decrease or cessation in glomerular filtrate
This can be acute or chronic unilateral (one kidney) or bilateral both kidneys
Causes include low blood volume decreased cardiac output damaged renal, tubules kidney stones or reaction to NSAID
Explain chronic renal failure
Usually a progressive and irreversible decline of the glomerular filtrate rate
First phase is 75% of nephrons all lost but patient may have no symptoms because other nephrons have taken up the workload
175% are lost patient is termed renally insufficient eventually end stage renal failure occurs when 90% of nephrons have been lost and regular dialysis therapy or kidney transplant operation is required
Explain urinary tract infections
Either an infection or part of the urinary system or the present of large numbers of microbes in the urine most UTI are caused by gram-negative bacteria most commonly E. coli
UTIs include urethritis (inflammation of the urethra)
Cystitis (inflammation of the urinary bladder
Pyelnephritis inflammation of the kidneys and are
Polycystic kidney disease, common inherited disorder where the kidneys become riddled with thousands of cysts many cells die in the kidney tube and lead to progressive renal failure and eventually end stage renal failure
more common in females due to the short urethra
