Podcast
Questions and Answers
What is the primary substance produced during deamination in the liver?
What is the primary substance produced during deamination in the liver?
Which part of the nephron is responsible for ultrafiltration?
Which part of the nephron is responsible for ultrafiltration?
What anatomical feature of the nephron helps prevent proteins and blood cells from entering the filtrate?
What anatomical feature of the nephron helps prevent proteins and blood cells from entering the filtrate?
What drives the movement of fluid from the glomerulus into Bowman's capsule?
What drives the movement of fluid from the glomerulus into Bowman's capsule?
Signup and view all the answers
What is the approximate glomerular filtration rate in humans?
What is the approximate glomerular filtration rate in humans?
Signup and view all the answers
What occurs in the proximal convoluted tubule of the nephron?
What occurs in the proximal convoluted tubule of the nephron?
Signup and view all the answers
During selective reabsorption, which ion is actively pumped out of the distal convoluted tubule?
During selective reabsorption, which ion is actively pumped out of the distal convoluted tubule?
Signup and view all the answers
Which structure in the kidney is primarily responsible for water reabsorption?
Which structure in the kidney is primarily responsible for water reabsorption?
Signup and view all the answers
What substance is NOT typically found in the filtrate produced in Bowman's capsule?
What substance is NOT typically found in the filtrate produced in Bowman's capsule?
Signup and view all the answers
What type of tissue primarily makes up the glomerulus?
What type of tissue primarily makes up the glomerulus?
Signup and view all the answers
Study Notes
Excretion Overview
- Excretion removes waste products from metabolic reactions.
- Carbon dioxide (CO2) and urea are the major waste products.
- CO2 is removed via the lungs during aerobic respiration.
- Urea is produced in the liver from excess amino acids.
Deamination
- Excess amino acids are broken down.
- The liver deaminates amino acids, removing the amine group (-NH2) and a hydrogen atom.
- This forms ammonia (NH3).
- The remaining keto acid can enter the Krebs cycle or be converted to glucose or glycogen.
Kidney Structure
- Kidneys receive blood from the renal artery (aorta branch).
- Blood exits via the renal veins (inferior vena cava).
- Ureters carry urine from the kidneys to the bladder.
- The urethra carries urine from the bladder to the exterior.
Kidney Macroscopic Structure
- The kidney has three main regions:
- Capsule (outer covering)
- Cortex (beneath the capsule)
- Medulla (central region)
Kidney Microscopic Structure
- Nephrons are the functional units of the kidney, numerous small tubules.
- Each nephron has associated blood vessels:
- Glomerulus (network of capillaries)
- Bowman's capsule (surrounds glomerulus)
- Proximal convoluted tubule (PCT)
- Loop of Henle (long U-shaped loop in the medulla)
- Descending limb
- Ascending limb
- Distal convoluted tubule (DCT)
- Collecting duct
Blood Vessels and Nephrons
- Nephrons are supplied by branches of the renal artery (afferent arterioles).
- Blood from the glomerulus passes into the efferent arteriole.
- This blood flows into peritubular capillaries (surrounding nephron).
- Eventually, blood exits the kidney via the renal vein.
Urine Formation
- Urine is formed in two stages:
- Ultrafiltration: Small molecules from blood are filtered into Bowman's capsule.
- Selective Reabsorption: Useful molecules are reabsorbed from the filtrate as it moves through the nephron.
Ultrafiltration
- Blood in the glomerulus is separated from Bowman's capsule by a filter (endothelium of capillary + basement membrane + podocytes).
- Small molecules (water, urea, glucose, salts) pass through this filter.
- Larger molecules (proteins, blood cells) are retained.
- Filtrate contains useful and waste substances.
Glomerular Filtration Rate (GFR)
- GFR is the rate of fluid filtration from the glomerulus into Bowman's capsule.
- Normal GFR is approximately 125cm³/min.
- High glomerular blood pressure (afferent vs. efferent arteriole size) drives ultrafiltration.
Selective Reabsorption in the Proximal Convoluted Tubule (PCT)
- Active transport reabsorbs glucose and amino acids.
- Passive transport reabsorbs water and ions (sodium, chloride).
- A large portion of the filtrate is reabsorbed in the PCT.
Reabsorption in the Loop of Henle and Collecting Duct
- The loop of Henle establishes a concentration gradient in the kidney medulla.
- Water is reabsorbed in the descending loop due to the high salt concentration.
- Sodium and chloride are actively reabsorbed in the ascending loop, maintaining the concentration gradient.
- The collecting duct fine-tunes water reabsorption based on the body's hydration needs. Active transport of sodium contributes to creating a gradient for water reabsorption.
Reabsorption in Distal Convoluted Tubule (DCT) and Collecting Duct
- Active transport pumps out sodium ions.
- Potassium ions are passively transported into the tubule.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Description
This quiz covers the basics of excretion and the structural anatomy of the kidneys. It explains the process of waste removal in the body, including the roles of carbon dioxide and urea, as well as the macroscopic and microscopic structures of the kidneys. Test your understanding of how these systems work together in renal physiology.
