week 6 Flashcards
(27 cards)
What are the primary functions of the urinary system?
The urinary system performs three major functions:
- Excretion – Removal of organic waste products from body fluids.
- Elimination – Discharge of waste products into the environment.
- Regulation – Regulates blood volume, blood pressure, plasma concentrations of ions, and helps stabilize blood pH.
What are the components of the urinary system involved in urine formation, transport, storage, and elimination?
The major components of the urinary system include the kidneys, ureters, bladder, and urethra. The kidneys filter blood to form urine, the ureters transport urine to the bladder for storage, and the urethra eliminates urine from the body.
What are the primary functions of the kidneys?
The kidneys filter blood to remove waste products, regulate water and electrolyte balance, and help control blood pH. They also assist in the regulation of blood volume and blood pressure.
Where are the kidneys located and what is their structure?
The kidneys are located on either side of the spine, just below the rib cage. They have a complex structure consisting of the renal cortex, renal medulla, renal pelvis, and nephrons, and they receive blood supply from the renal arteries.
What is the nephron, and what are its main functions?
The nephron is the functional unit of the kidney responsible for filtration and urine formation. It consists of the renal corpuscle (where filtration occurs) and the renal tubule (where reabsorption and secretion occur).
What are the two types of nephrons?
The two types of nephrons are:
1. Cortical nephron – with a shorter nephron loop located in the cortex.
2. Juxtamedullary nephron – with a longer nephron loop that extends into the medulla.
What is the structure of the renal corpuscle?
The renal corpuscle consists of the glomerulus (a capillary network) and the glomerular capsule (Bowman’s capsule), where blood filtration occurs.
What are the main functions of the renal tubule?
The renal tubule is responsible for reabsorbing organic substrates (like glucose), reabsorbing about 90% of water, and secreting waste products into the urine.
What blood vessels supply the nephron?
The nephron is supplied by the afferent arteriole, which leads to the glomerulus (capillaries), then blood exits through the efferent arteriole. The peritubular capillaries surround the renal tubule.
What are the main parts of the renal tubule?
The renal tubule consists of the proximal convoluted tubule, nephron loop (loop of Henle), distal convoluted tubule, and the collecting duct.
What role do the kidneys play in regulating blood volume and pressure?
The kidneys help regulate blood volume and blood pressure by controlling water and electrolyte balance and by releasing hormones like renin that influence blood pressure.
What are some structural features of the nephron?
The nephron has fenestrations (pores) in the glomerulus that allow for filtration, and structures like the distal convoluted tubule and nephron loop help in reabsorption and secretion.
What is the role of erythropoietin (EPO) in kidney function?
Erythropoietin (EPO) is produced by the kidneys and stimulates the production of red blood cells in response to low oxygen levels in the blood.
What are the main processes involved in the formation of urine?
The main processes involved in urine formation are:
1. Filtration – Blood is filtered in the glomerulus to remove waste and small solutes.
2. Reabsorption – Useful substances like water, glucose, and ions are reabsorbed back into the bloodstream.
3. Secretion – Excess substances, such as ions and waste products, are secreted into the renal tubule for elimination.
What is the analogy used to describe the process of filtration in the kidneys?
Filtration in the kidneys is compared to cleaning out a fridge: removing everything (waste) and then deciding what to put back (reabsorption), while disposing of unwanted items (secretion).
What factors influence filtration pressure and the rate of filtrate formation?
A: Filtration pressure is influenced by:
- Glomerular Hydrostatic Pressure (GHP) – Pushes water and solutes out of the capillaries.
- Capsular Hydrostatic Pressure (CsHP) – Opposes GHP, pushing filtrate back into the blood.
- Blood Colloid Osmotic Pressure (BCOP) – Created by proteins in blood, also opposing filtration.
The net filtration pressure (NFP) determines the rate of filtrate formation.
What is the Glomerular Filtration Rate (GFR) and how is it controlled?
GFR is the amount of filtrate produced by the kidneys each minute (approximately 125 mL/min). It is controlled by:
1. Autoregulation – Local adjustments.
2. Autonomic regulation – Sympathetic nervous system, which can decrease GFR.
3. Hormonal regulation – Involves the renin-angiotensin system and natriuretic peptides.
How do hormones influence the volume and concentration of urine?
Hormones regulate urine volume and concentration by controlling water reabsorption:
1. Antidiuretic Hormone (ADH) – Increases water reabsorption in the collecting ducts.
2. Aldosterone – Increases sodium reabsorption, and water follows sodium, increasing reabsorption.
3. Natriuretic Peptides (ANP, BNP) – Oppose ADH, promoting water elimination.
What is the role of the proximal convoluted tubule (PCT) in urine formation?
The PCT reabsorbs 60-70% of filtrate, including organic nutrients, ions, and water. It also secretes waste products into the filtrate.
What is the function of the nephron loop (loop of Henle)?
The nephron loop helps concentrate urine by reabsorbing water in the thin descending limb and sodium and chloride ions in the thick ascending limb. The ascending limb is impermeable to water.
How does the distal convoluted tubule (DCT) contribute to urine formation?
The DCT further reabsorbs sodium, chloride, and calcium ions, influenced by hormones like parathyroid hormone (PTH) and calcitriol. It also secretes potassium and hydrogen ions into the filtrate.
What is the role of the collecting duct in urine formation?
The collecting duct regulates urine volume and osmolarity by reabsorbing sodium (in exchange for potassium), bicarbonate, and urea. It also secretes hydrogen ions when blood pH decreases.
What is the process of reabsorption and secretion in the kidneys?
Reabsorption is the movement of substances from the renal tubules back into the bloodstream, while secretion involves the active transport of substances (e.g., ions, waste, drugs) from the blood into the renal tubules for elimination.
What are the three types of filtration pressures in the glomerulus?
The three types of filtration pressures are:
1. Glomerular Hydrostatic Pressure (GHP) – Forces filtrate out of the capillaries.
2. Capsular Hydrostatic Pressure (CsHP) – Opposes filtration, pushing filtrate back into the capillaries.
Blood Colloid Osmotic Pressure (BCOP) – Caused by proteins in the blood, also opposing filtration.
