Urinary System: Functions and Organs

• Modules cover 4 body systems: urinary, nervous, endocrine, and immune.
• Learning objectives include describing system structures/functions, explaining interdependence, analyzing health issues, and demonstrating understanding.

Urinary System

• Also known as the renal system, which helps to maintain homeostasis.
• Primary functions include blood filtration, waste removal, fluid/electrolyte balance, and hormone production.
• Key functions:
  • Filtration of blood for waste and excess.
  • Waste converted to urine and removed.
  • Regulation of fluid, electrolyte, and pH balance.
  • Erythropoietin hormone produces red blood cells
  • Renin hormone regulates blood pressure.
• Organs include kidneys, ureters, urinary bladder, and urethra.
• Kidneys are bean-shaped organs located in the back of the abdominal cavity.
  • They contain nephrons, the functional units that filter blood.
• Ureters are tubes transporting urine from the kidneys to the bladder.
• The urinary bladder stores urine until elimination.
• The urethra is a tube carrying urine from the bladder to outside the body.
• Parts of the kidney:
  • The renal cortex is the outer layer containing renal corpuscles.
  • The renal medulla is the inner layer containing renal pyramids.
  • Renal pyramids are cone-shaped structures containing loops of Henle and collecting ducts.
  • The renal pelvis is a funnel-shaped structure collecting urine from the renal pyramids and leading to the ureter.
• Nephrons are the functional units of the kidney; each kidney has millions.
• Key parts of a nephron:
  • Glomerulus: Capillary network for blood filtration.
  • Bowman's Capsule: Cup-shaped structure surrounding the glomerulus.
  • Proximal Convoluted Tubule (PCT): Where essential substances are reabsorbed.
  • Loop of Henle: Concentrates urine.
  • Distal Convoluted Tubule (DCT): Further reabsorption and secretion.
  • Collecting Duct: Collects and transports urine to the renal pelvis.
• Urine formation involves glomerular filtration, tubular reabsorption, and tubular secretion.
  • Glomerular Filtration: Blood pressure forces water and small solutes into Bowman's capsule, forming filtrate. Large molecules are retained.
  • Tubular Reabsorption: Essential substances are reabsorbed back into the bloodstream, regulated by hormones.
  • Tubular Secretion: Waste products are secreted from the bloodstream into renal tubules to fully eliminate waste.
• Kidneys filter blood, reabsorb necessities, and secrete waste to form urine for fluid/electrolyte balance.
• Common disorders:
  • Kidney Stones: Hard mineral/salt deposits causing pain moving through the urinary tract.
  • UTIs: Infections typically in the bladder or urethra and commonly caused by bacteria.
  • Kidney Failure: Loss of ability to filter waste/maintain fluid balance.

Nervous System

• Body's control center, responsible for controlling activities, processing sensory information, and coordinating responses.
• Controls voluntary and involuntary movements.
• Receives and interprets information through sensory organs.
• Integrates sensory input and initiates responses such as muscle contractions or glandular secretions.
• Organs include the brain, spinal cord, and nerves.
• The brain is the central processing unit.
  • The brain is responsible for higher-level functions like thought, memory, emotion, and language.
• The spinal cord connects the brain to the peripheral nervous system.
  • It transmits nerve impulses and controls reflexes.
• Nerves are bundles of axons transmitting electrical impulses.
  • They connect the central nervous system to muscles, glands, and sensory organs.
• Divisions of the nervous system:
  • Central Nervous System (CNS): Consists of the brain and spinal cord.
  • Peripheral Nervous System (PNS): Nerves outside the CNS connect to the rest of the body.
• The PNS is further divided into the somatic nervous system and the autonomic nervous system.
  • Somatic controls voluntary movements.
  • Autonomic controls involuntary functions and is divided into sympathetic (fight or flight) and parasympathetic (rest and digest).
• Disorders:
  • Stroke: Interrupted blood flow causes brain damage. It leads to paralysis, speech problems, and cognitive deficits.
  • Alzheimer's Disease: Neurodegenerative, progressive disease that causes dementia and cognitive decline.
  • Epilepsy: Recurrent seizures caused by abnormal brain electrical activity.

Endocrine System

• A network of glands that produce and secrete hormones.
• Hormones act as chemical messengers, and travel through the bloodstream to target organs and tissues.
• Functions:
  • Regulation of metabolism, growth and development, reproduction, mood and behavior, homeostasis maintenance, and stress response
• Major Parts:
  • The pituitary gland is located at the base of the brain and is the "master gland".
    • Secrete growth hormone, adrenocorticotropic hormone, thyroid-stimulating hormone, luteinizing hormone, follicle-stimulating hormone, prolactin, and antidiuretic hormone
    • These hormones help with growth, stress, reproduction, milk production, and water balance.
  • The thyroid gland is found in the neck around the trachea.
    • Plays role in regulating metabolism, energy production, and body temperature.
    • Secrete thyroxine and triiodothyronine, and calcitonin.
  • Adrenal glands are located on top of each kidney.
    • They produce hormones that help respond to stress, regulate metabolism, maintain blood pressure, and balance electrolytes.
    • Secrete cortisol, aldosterone, epinephrine, and norepinephrine
  • The pancreas is located in the abdomen, behind the stomach.
    • It regulates blood sugar levels through hormone production.
    • Secrete insulin and glucagon.
  • Gonads (ovaries and testes) are the ovaries found in females and the testes found in males.
    • Responsible for producing sex hormones to regulate reproductive development.
    • The ovaries secrete estrogen and progesterone, and the testes secrete testosterone.
• Each of these glands plays an essential role in maintaining homeostasis through hormones.
• Disorders;
  • Diabetes: High blood sugar levels due to insulin production or action problems. It causes complications like heart/kidney disease and nerve damage.
  • Hypothyroidism: Low thyroid hormone production. It leads to slowed metabolism, fatigue, and weight gain.
  • Cushing's Syndrome: Prolonged exposure to high cortisol levels. It can cause weight gain, high blood pressure, weak muscles.