biourine

• Excretory System


  Vital biological system that removes excess and waste products to maintain homeostasis
• Excretory System


  • Eliminates nonsolid waste of the body
  • Eliminated through the lungs, skin, and kidneys
• Urinary System


  Major excretory system in the body
• Functions of Urinary System


  • Excretion
  • Regulation of Blood Volume and Pressure
  • Regulation of Blood Solute Concentration
  • Regulation of Extracellular fluid pH
  • Regulation of red blood cell synthesis
  • Regulation of Vitamin D synthesis
• Kidneys


  • Two bean-shaped organs, each about the size of a fist
  • Located just below the rib cage, one on each side of the spine
  • Right kidney is slightly lower than the left
  • Adrenal gland atop each kidney
  • Healthy kidney filters about half cup of blood every minute
• Kidney Functions


  • Remove waste products from the body
  • Remove drugs from the body
  • Balance the body's fluids
  • Release hormones that regulate blood pressure
  • Produce an active form of vitamin D that promotes strong, healthy bones
  • Control the production of red blood cells
• Renal Capsule


  • Surrounds each kidney
  • Covered in a thick layer of adipose tissue
  • Provides protection to the kidney
  • Helps keep the kidney in its correct location
• Regions of the Kidney

  • Renal Cortex - outer region
  • Renal Medulla - Inside the cortex
  • Renal Pelvis - Inner collecting tube
• Kidney Structure

  • Medullary Pyramids - Triangular region of tissue in the medulla
  • Renal Columns - Extension of Cortex-like material inward
  • Calyces - Cup shaped structure that funnel urine towards the renal pelvis
• Nephrons


  • Structural and functional units of kidney
  • Each kidney has over one million nephrons responsible for forming urine
  • Two types: Juxtamedullary and Cortical
• Ureters


  • Bilateral thin (3 to 4 mm) tubular structures that connect the kidneys to the urinary bladder
  • Muscular layers responsible for the peristaltic activity that moves urine from the kidneys to the bladder
• Urinary Bladder


  • Smooth, collapsible, muscular sac that temporarily stores urine
  • Can hold a few ml to a maximum of 1000 milliliters
  • Trigone - three openings (two from ureters, one to urethra)
• Urethra


  • Thin-walled tube that carries urine from the bladder to the outside of the body by peristalsis
  • Male - 20 cm (8 inches) in length, through prostate and penis, carries urine and sperm
  • Female - 3-4 cm (1 inch) in length, along wall of vagina, only carries urine
• Urine Formation

  1. Filtration

  2. Reabsorption

  3. Secretion
• Filtration


  • Movement of water, ions, small molecules through Bowman's capsule membrane
  • 19% of plasma becomes filtrate
  • 180 Liters of filtrate produced daily, 1.8 liters become urine
• Reabsorption


  • 99% of filtrate is reabsorbed and reenters circulation
  • Proximal tubule is primary site for reabsorption
  • Descending Loop of Henle concentrates filtrate
  • Reabsorption controlled by hormones
• Secretion


  • Tubular secretion removes substances from blood that are byproducts, toxic, or not normally produced
  • Occurs through active or passive mechanisms
• Urine Composition


  • Water
  • Inorganic Salts
  • Nitrogenous organic compounds (Urea, Uric Acid, Creatinine, Hippuric acid, purine, and other amino acids)
  • Non-nitrogenous organic compound (Traces of glucose, acetone bodies, oxalates, and organic sulfur compounds)
• Characteristics of Urine

  • Color - Amber yellow
  • Volume - Rate of secretion
  • Specific Gravity - 1.015 to 1.025
  • Reaction - pH 4.8 to 7.5
  • Odor - Aromatic
  • Turbidity - Clear and transparent
• Feces


  • Solid bodily waste discharged from the large intestine through the anus during defecation
  • 100 to 250 grams (3 to 8 ounces) excreted daily by a human adult
• Fecal Composition and Characteristics

  • Bacterial Biomass - Major component (25-54% of dry solids)
  • Color - Usually brown
  • Odor - Due to indole, skatole, methane, hydrogen sulfide
  • Reaction - Slightly alkaline, 7-7.5 pH
  • Consistency - Varies from thin pasty to firmly formed
  • Amount - 80 to 120 grams per day
• Sweat


  • Produced by glands in the dermis
  • 99% water, 1% salt and fat
  • Up to a quart evaporates each day
  • Specific gravity of 1.002 to 1.003
  • pH 5.2 to 7.3
  • Main function is temperature control
• Chemical Messenger


  Allows cells to communicate and regulate body activities
• Gland


  Organ of epithelial cells that specialize in secretion
• Types of Secretion

  • Autocrine - Secreted by cells, influences same cell or type
  • Paracrine - Secreted into extracellular fluid, has localized effect
• Endocrine Glands


  Secrete hormones into the bloodstream to have widespread effects
• Functions of Endocrine System

  • Regulating nutrient metabolism, water and electrolyte balance
  • Inducing adaptive changes to cope with stress
  • Promoting growth and development
  • Controlling reproduction
  • Regulating red blood cell production
  • Integrating circulatory and digestive systems
• Exocrine Glands

  Have ducts that carry secretions to outside of body or into hollow organs
• Types of Chemical Messengers


  • Local Chemical Messengers
  • Neurotransmitters
  • Neuropeptides
  • Hormones
  • Pheromones
• Nature of Hormones


  • Lipid-Soluble - Nonpolar, travel in bloodstream bound to proteins
  • Water-Soluble - Polar, large molecules that don't diffuse through capillaries
• Hormones


  • Specialized chemical messengers produced and secreted by endocrine glands or tissues
  • Circulate in body fluid and affect target cells/tissues
• Neuropeptides


  Secreted by neurosecretory cells or specialized neurons
• Hormones


  Secreted by endocrine gland
• Pheromones


  Chemical messenger released to the exterior of one animal
• Lipid-Soluble Hormones


  • Nonpolar, insoluble in water-based fluid
  • Travel in the bloodstream attached to binding proteins
  • Without binding proteins, they would quickly diffuse out of capillaries
• Water-Soluble Hormones


  • Polar molecules that dissolve in blood
  • Free hormones that are large in size, they do not diffuse through the walls of capillaries
• Hormones


  • Specialized chemical messenger and transmitter that endocrine gland or tissue produce and secrete
  • Circulate through the body fluid and affect the metabolic activity of a target cell or tissue in a specific way
• Chemical Transmitter


  Released in small amount and transported in the bloodstream
• Chemical Messenger


  Transfers information and instruction from one set of cells to another
• Hyposecretion


  When the number of hormones released is too low