sinusumpa ko talaga si ano

Urinary System & Renal Function

• Kidneys are the primary organs of the urinary system, responsible for filtering the blood, removing waste, and excreting waste in the urine.
• The kidneys are located between the 12th thoracic and 3rd lumbar vertebrae, one on each side of the vertebral column, and are protected by the lower ribs.

Kidney Structure

• The adult human kidney measures approximately 12.5 cm (length), 6 cm (width), and 2.5 cm (depth).
• The kidney has 2 major parts: glomerulus and tubules (PCT, DCT, and loop of Henle).

Nephron

• The nephron is the functional unit of the kidney, with approximately 1 to 1.5 million in number.
• There are 2 types of nephrons: cortical nephrons (shorter loops of Henle) and juxtamedullary nephrons (longer loops of Henle).

Renal Functions

• The kidneys control the clearing of waste products and maintaining water and electrolytes through:
  • Renal blood flow
  • Glomerular filtration
  • Tubular reabsorption and secretion
• The kidneys also regulate:
  • Acid-base balance
  • Electrolyte balance
  • Toxin removal
  • Blood pressure regulation
  • Erythropoietin production
  • Vitamin D metabolism

Urine Formation

• A. Filtration:
  • Blood pressure in the glomerular capillaries forces fluid and small molecules out of the blood.
  • The filtered fluid is referred to as the filtrate.
  • The filtration process is non-selective and separates based on size or molecular charge.
• B. Tubular Reabsorption:
  • Cells in the nephron contain transport proteins that move water and filtered molecules back into the blood.
  • The process of reabsorption prevents the loss of important solutes from the body.
  • Most filtered water and useful solutes are returned to the blood by the time the filtrate is modified into urine.
• C. Tubular Secretion:
  • The movement of non-filtered substances from the blood into the filtrate.
  • Certain tubule cells transport additional solutes from the blood into the filtrate.

Renal Blood Flow

• The renal artery supplies blood to the kidney.
• The human kidneys receive approximately 25% of the blood pumped through the heart at all times.
• Peritubular capillaries surround the proximal and distal convoluted tubules and reabsorb essential nutrients.
• Vasa recta are located adjacent to the ascending and descending loops of Henle in the juxtamedullary nephrons.

Urine Composition

• The main constituents of urine include:
  • Water
  • Urea
  • Uric acid
  • Creatinine
  • Sodium
  • Potassium
  • Chloride
  • Calcium
  • Magnesium
  • Phosphates
  • Sulfates

Blood Components

• Blood is a specialized connective tissue consisting of cells and fluid extracellular material called plasma
• Approximately 5 L of blood in an average adult moves unidirectionally within the closed circulatory system

Blood Cells

• Formed elements circulating in the plasma are:
  • Erythrocytes (red blood cells)
  • Leukocytes (white blood cells)
  • Platelets

Plasma Composition

• Aqueous solution with a pH of 7.4
• Contains substances of low or high molecular weight that make up 7% of its volume
• Dissolved components in plasma include:
  • Proteins
  • Nutrients
  • Respiratory gases
  • Nitrogenous waste products
  • Hormones
  • Electrolytes

Major Plasma Proteins

• No specific information provided

Erythrocytes

• Lack nuclei
• Filled with oxygen-carrying hemoglobin
• Appear as biconcave flexible discs
• Approximately 7.5 um in diameter, 2.6 um thick at the rim, 0.75 um thick at the center
• Biconcave shape provides a large surface to volume ratio and facilitates gas exchange
• Can undergo large elastic deformations when passing through narrow blood vessels
• Large flexibility of the cell is primarily attributed to the cell membrane

Leukocytes

• Divided into 2 major groups:
  • Granulocytes (has azurophilic and specific granules)
  • Agranulocytes (only has azurophilic granules)
• Key players in the constant defense against invading microorganisms and in the repair of injured tissues
• Chemotaxis: attraction of neutrophils to bacteria involves chemical mediators
• Diapedesis: leukocytes send extensions through the openings between endothelial cells, migrate out of the venules into the surrounding tissue space

Platelets

• AKA thrombocytes
• Very small, non-nucleated membrane-bound cell fragments
• Ranging from 2-4 um in diameter
• Promote blood clotting and help repair minor tears or leaks in the walls of small blood vessels

Hemopoiesis

• All cells arise from a single type of pluripotent hemopoietic stem cell in the bone marrow
• The pluripotent stem cells are rare, proliferate slowly, and give rise to 2 major lineages of progenitor cells:
  • Lymphoid (lymphocytes)
  • Myeloid cells (granulocytes, monocytes, RBC, megakaryocytes)

Immune System Introduction

• The immune system provides defense against infectious agents such as viruses, fungi, bacteria, and parasites.
• The immune system consists of a diverse population of leukocytes located within every tissue of the body and lymphoid organs.
• Lymphoid organs are interconnected by the lymphatic circulation.

Types of Immunity

• There are two types of immunity: innate immunity and adaptive immunity.

Innate Immunity

• Innate immunity provides immediate defense against infection.
• It involves physical barriers, such as skin and mucous membranes, and cellular responses, such as neutrophils and macrophages.

Cytokines

• Cytokines are signaling molecules that coordinate immune responses.
• They are involved in cell-to-cell communication and activate immune cells.

Antigens and Antibodies

• Antigens are substances that stimulate an immune response.
• Antibodies are proteins produced by B cells in response to antigen recognition.
• Antibodies bind to specific antigens, marking them for destruction.

Classes of Antibodies

• There are five classes of antibodies: IgA, IgD, IgE, IgG, and IgM.
• Each class has distinct functions and characteristics.

Action of Antibodies

• Antibodies neutralize pathogens by binding to them.
• They also activate complement proteins, which help eliminate pathogens.

Antigen Presentation

• Antigen presentation is the process by which antigen-presenting cells (APCs) present antigens to T cells.
• APCs, such as dendritic cells, process and display antigens on their surface.

Cells of Adaptive Immunity

• Adaptive immunity involves the activation of T cells and B cells.
• T cells directly kill infected cells, while B cells produce antibodies.

T Lymphocytes

• T lymphocytes are a type of T cell that matures in the thymus.
• They recognize and respond to antigen-presenting cells.

Types of T Lymphocytes

• There are two main types of T lymphocytes: CD4+ (helper) T cells and CD8+ (cytotoxic) T cells.
• CD4+ T cells help activate B cells and other immune responses, while CD8+ T cells directly kill infected cells.

B Lymphocytes

• B lymphocytes are a type of B cell that produces antibodies.
• They mature in the bone marrow and recognize antigens through their surface receptors.