Mammalogy (Spring 2015 Althoff) LEC 10A • Urinary (Excretory) Systems Overview Body Fluid Regulation

Overview of Excretion External Environment gut lungs kidney skin liver Blood TISSUES CELLS

Body Fluid Regulation Keys here: ION & H20 concentrations Key ions: Na+, Cl-, K+ and HCO3- Body fluids gain mineral ions from eating foods and drinking fluids Excretion is the primary way the body loses ions H20: in via eating foods that contain H20, and drinking H20…and via metabolism (e.g. cellular respiration produces H20 = metabolic water

Differences in Osmolarity (i.e., solute concentration If difference in concentration between two regions, H2O tends to move from regions of greater concentrations to regions of lower concentrations. Thus H20 moves to regions of highest ION CONCENTRATIONS

Fishes & Body Fluid Regulation FRESHWATER FISH passive gain of water across body surface and through gills DOES NOT DRINK large amounts of hypotonic urine contain little salts salt actively taken up by gills

Fishes & Body Fluid Regulation DRINKS SEAWATER MARINE FISH passive loss of water through gills small amounts of isotonic urine Contains some salts salt actively excreted by gills

Nitrogenous Waste Products NITROGENOUS WASTES = breakdown of various molecules, including nucleic acids and amino acids AMINO ACIDS NOT used for protein synthesis are broken down by the body to generate energy or converted to fats or carbs that can be stored… …this requires amino groups (-NH2) be removed excreted as ammonia, urea, or uric acid

Nitrogenous Wastes PROTEINS amino acids -NH2 Need water to excrete ammonia urea uric acid Need water to excrete Need energy to produce

Nitrogenous waste Ammonia Urea Uric acid habitat animals toxicity water highest aquatic invertebrates. bony fishes amphibian larvae land adult amphibians mammals 2nd highest lowest land insects birds reptiles

Maintenance System (1 of 3…digestive & respiratory other 2) URINARY SYSTEM—kidneys, bladder, & tubes A) rids blood of metabolic wastes B) helps regulate fluid level & chemical content of blood EXCRETION = rids body of metabolic wastes (remember cellular metabolism) and breakdown of substances that enter the body (non-digestive system).

Major role in maintaining HOMESTASIS Metabolic wastes OUT

FUNCTIONS of the Urinary System Regulate water content of blood Regulate ion concentrations: Na+, Ca+, K+, Cl- Regulate pH of blood Produce erythropoietin  RBC production increases Eliminate cellular waste such as urea, drugs, etc.

Organs of the URINARY System Kidney (2) Ureter (1 per kidney) Urinary bladder Urethra

ORGANS KIDNEYS – where urine is made URETERS— muscular tubing carrying urine from kidney to bladder BLADDER— muscular bag that stores urine until urination (holds ~600 ml) URETHRA— carries urine out of body

URETHRA –some important “minute” Bladder infections Length: 20 cm long, 4 cm long Passes through prostate gland in (females don’t have). --prostate gland contributes fluid to semen that serves as buffer by raising pH of semen to >6.5 to overcome 3.5-4.0 pH environment of vagina If prostate gland enlarges, it reduces urethrea’s ability to maintain original diameter

sphincter “relaxed” at 250 ml 600 ml capacity, …..internal sphincter “relaxed” at 250 ml INTERNAL SPHINCTER EXTERNAL SPHINCTER

KIDNEY is “the” functional unit of the urinary system

Kidney MACROanatomy Blood supply Cortex Medulla Renal Pelvis

Kidney- NEPHRON Functional unit of the kidney 1,000,000 per kidney Actually produces urine Transerves the renal cortex and renal medulla Very detailed structurally speaking

Kidney MICROanatomy Nephron

Nephron Detail 4 5 3 2 8 3 1 7 6 Afferent arteriole Efferent arteriole GLOMERULUS Glomerular capsule Proximal convoluted tubule (PCT) Loop of the Nephron Distal convoluted tubule (DCT) Collecting duct 5 3 2 8 3 1 7 6

GLOMERULAR FILTRATION

SEM picture Of a glomerulus

1 2 NEPHRON CAPSULE Site where, if high blood pressure or injury, RBC “escape” and end up in urine 1 2

Proximal convoluted tubule (PCT) CROSS-SECTIONAL view Microvilli (many per cell)

URINE FORMATION 3 1 2 4 GLOMERULAR FILTRATION TUBULAR ABSORPTION TUBULAR SECRETION And….then there is urine 1 2 4

Keep in mind nephron transverses Cortex AND medulla regions of the kidney

Glomerular FILTRATION Blood is “filtered” (but typically only things dissolved…not formed elements of blood) Filtrate is one-way….balance of blood moves on through blood vessel Blood in urine “happens” here….before it gets to the bladder…. BAD!!!!

Tubular REABSORPTION H20 taken out of urine (was part of blood that “filtered out” (60-70%) NaCl (salts) taken out (think….osmosis process here) (60-70%) Urine becomes more and more concentrated

Tubular SECRETION Drugs secreted from blood  DCT (distal convulated tubule) K+, H+, etc. Secreted from blood  DCT (active transport!!!) NaCl could be reabsorbed here ??? (if low in concentration) H2O still being taken out of urine, becomes more and more concentrated

1 3 osmosis active transport 2 diffusion 4

Processes and materials “moved” Osmosis Active Transport H2O NaCl Nutrients SAVED Diffusion Urea NaCl Drugs K+ H+ NH3 EXCRETED

3 1 2 4 Changes in concentrations of H20, salts, etc. INSIDE & OUTSIDE the tubules as urine it flows from renal cortex to renal medulla and back up to renal cortex…. 3 1 2 4

The KING of minimizing H20 loss from the process of urine formation! KANGAROO RATS (Dipodomys sp.)

Controlling pH of the blood….. CAPILLARY H++NH3 NH4 KIDNEY TUBULE HCO3- NH4 = ammonium

Hormones & the Urinary System RENIN – promotes retention of NaCl ANH – (atrial natriuretic hormone) suppresses retention of NaCl ADH – (antidiuretic hormone) increases H20 taken out of urine DIRURETICS including alcohol, caffeine drinks: they inhibit ADH, thus not as much reabsorption of H20 Aldosterone– secreted by kidneys promotes K+ secretion.

SUMMARY: Urine Formation Reabsorption Filtration Secretion Glomerulus Proximal con. tubule Distal con. tubule Ureter Bladder Urethra H20 retention is… decreased increased Diuretics Antidiuretics

Kidney Stones