Lecture 7 (Renal Systems) Flashcards
What functions do the renal system and kidneys carry out?
- Regulate the composition of body fluids
- Regulate fluid volume
- Excrete wastes from the body
Where are kidneys located in humans?
- Retroperitoneal (outside the peritoneum or lining of abdomen)
Explain the renal system Anatomy
Kidney
- Bilateral
- Produces Urine
Ureter
- Muscular tube that propels urine from kidneys to bladder
Bladder
- Stores Urine
Urethra
- Connects bladder to external environment
How is the kidney organized?
- Outer layer (Cortex)
- Inner layer (Medulla)
Where do the collecting ducts of the kidney converge at?
- Converge at Renal papilla (found in inner medulla)
- Inner medulla region known as Renal Pelvis
What are the components of a Monocalyceal kidney?
- One single renal pelvis and set of papillae
- Also known as a Calyx
What are Multicalyceal kidneys divided into?
- Multiple calices
What are the components of a Multireniculated kidney?
- Contain distinct lobes, each individual lobe called RENICULUM
What is a Reniculum (plural: reniculae)?
What is the color?
- They act as separate little kidneys having its own cortex and medulla
- Has its own cortex, medulla, and pelvis
- Medulla = pale pink
- Cortex = darker red
- Helps conserve more fresh water
What is a Calyx?
- One single renal pelvis
- set of papillae
Describe the Minor Calyx
- One papillae leading to the renal pelvis
Describe the Major Calyx
- Multiple minor calices converging to one calyx
What comes in and out of the Hilus?
- Renal artery entrance
- Renal vein exits
- Ureter exits
What is the renal capsule?
- connective tissue
- peritoneum (surrounds kidney over the cortex)
What are the functional filtration units of the kidney?
NEPHRON
What functions do nephrons carry out?
- Filter the blood to remove metabolic wastes and excess minerals and excrete it as urine
- Filter out everything SMALLER than 68 kDa
- Selectively reabsorb what is required
Where are the more concentrated portions of the kidney?
- Deeper in medulla relative to cortex = more concentration
- Longer loop of henle = more concentrating ability
How is the medulla different in marine mammals?
- Thicker medulla
- scientist unsure of why this is though
What is the nephron function and urine concentrating ability dependent on?
- Cortico-medullary axis of the kidney
- Establishes a counter-current concentrator to produce urine
The Urine that mammals excrete is dependant on what?
- What is filtered out
- What is reabsorbed
- What is actively secreted
What strategies have marine mammals developed to minimize water loss?
- Increase reabsorption of water
- Increased filtration of secretions of salts and waste products
What does Excretion equal?
Excretion = Filtration - Reabsorption + Secretion
What are the challenges marine mammals face?
- Coping with increased salt intake
- Coping with long fasting periods
- Finding fresh water
What have marine mammals adapted their renal systems to do?
- excrete the large amounts of minerals ingested
- Control amount of water loss to prevent dehydration
What does the number of reniculi correlate to?
- Salinity of the diet
- associated with an increased capacity to excrete urine
What marine mammals have the largest amount of reniculi?
- Mysticete whales
- > 3000 reniculi per kidney
Describe the kidneys of sirenia
- Do NOT have true reniculated kidneys
- Cortex is continuous
- Little is know regarding Dugongs
What are the three basic sources of water that mammals obtain?
- Drinking fresh water (from streams)
- H2O in food: Most fish and invertebrates consists of 60-80% fresh water
- Metabolic water: Breakdown of fat or metabolism of protein
How do some marine mammals obtain fresh water from the environment (specific examples)?
- some live in freshwater lakes or rivers such as manatees or Amazon river dolphins
- some pinnipeds (Weddell seal) observed chewing snow or ice
- Captive pinnipeds drink from hose or trough
How do some marine mammals obtain water from food?
- West indian manatee feed on leafy green vegetables
- vegetables (about 70% fresh water)
- produce normal urine output
How do some marine mammals obtain metabolic water?
Fatty acid catabolism (Beta-Ox)
- 1 gram of Palmitate (16:0) -> 1.07g H2O
- Oxidation of NADH and FADH2
Proteolysis
- 1 gram of protein -> 0.4g H2O
Why are fattier fish more favorable as a source of food?
- Fattier fish give more water
- provides more stored fat and protein to use during fasting
How does fasting produce water?
- Production of metabolic water from catabolism of own fats
- Sea lion deprived of salt and fresh water for 45 days and survived
During fasting what happens to urine output?
- Decrease in urinary output to conserve water
When protein is broken down to produce water, what builds up?
UREA
- must be excreted in urine, results in water loss
How do marine mammals counteract the formation of Urea?
- Mariposa
- Intentional ingestion of sea water
- Benificial to marine mammals with higher protein intakes
How much seawater do sea otters ingest during Mariposa?
average 62ml/kg per body weight of sea water per day
How much salt water does the Northern Fur Seal ingest during Mariposa?
- 1.8ml/kg per body weight
How much salt water does the Harbor Seal ingest during Mariposa?
4.8 mL/kg per body weight
How much salt water does the Common dolphins ingest during Mariposa?
12-13 mL/kg per body weight
What are the non-renal adaptations to conserve water?
- Skin of pinnipeds have FEW sweat glands
- Skin of Cetaceans have NO sweat glands
- Water loss from breathing is reduced by conserving breaths and cooling expelled air (using counter current exchange)
