Nervous System

Glial Cells and Neuroglia

Glial cells, also known as neuroglia, are non-neuronal cells in the central and peripheral nervous systems that provide support and protection for neurons. They make up 75-90% of the CNS.

• CNS Glial Cells:

  • Astrocytes: Maintain the blood-brain barrier, communicate with neurons, and regulate the chemical environment.

  • Oligodendrocytes: Produce myelin sheaths in the CNS, which insulate axons and increase the speed of electrical transmission.

  • Microglia: Act as phagocytes, removing debris and pathogens from the CNS.

  • Ependymal cells: Line the ventricles of the brain and produce cerebrospinal fluid (CSF).

• PNS Glial Cells:

  • Schwann cells: Form myelin sheaths around peripheral neurons.

  • Satellite cells: Surround neuron cell bodies in ganglia, providing support and regulating the environment.

Example: Multiple sclerosis is a disease where myelin sheaths are damaged, affecting nerve transmission.

Neurotransmitters

Neurotransmitters are chemical messengers that transmit signals across synapses between neurons. Examples include acetylcholine, dopamine, and serotonin.

• Function: Enable communication between neurons and target cells.

• Clinical relevance: Imbalances can lead to neurological disorders such as depression or Parkinson's disease.

Renal System

Renal Corpuscle and Filtration

The renal corpuscle is the site in the kidney where blood is filtered to form urine. It consists of the glomerulus and Bowman's capsule.

• Glomerulus: Network of capillaries that filters blood to form glomerular filtrate.

• Bowman's capsule: Cup-shaped structure that collects the filtrate from the glomerulus.

Filtration: Movement of water and solutes from the capillaries into the Bowman's capsule.

GFR (Glomerular Filtration Rate)

GFR is the volume of plasma filtered per unit time by the kidneys. It is a key indicator of kidney function.

• Normal value: 125 mL/min or 180 L/day

• Clinical relevance: Decreased GFR indicates impaired kidney function.

Cortical Nephron

Cortical nephrons are located mainly in the kidney cortex and are responsible for most filtration and reabsorption.

Respiratory System

Lung Volumes

• Tidal volume: Amount of air inhaled or exhaled in a normal breath; typically 500 mL.

• Residual volume: Air remaining in lungs after maximal exhalation; average 1200 mL.

• Functional residual capacity: Volume of air in lungs at rest between breaths.

Primary Respiratory Muscles

• Diaphragm: Main muscle for inspiration; contracts to increase thoracic volume.

• External intercostals: Assist in elevating the rib cage during inspiration.

Alveolar Cells

• Type I cells: Thin epithelial cells forming the alveolar wall, allowing gas exchange.

• Type II cells: Secrete surfactant to decrease surface tension and prevent alveolar collapse.

Surfactant

Surfactant is a phospholipid secreted by type II alveolar cells that lowers alveolar surface tension and prevents lung collapse.

FEV and FEV1

• FEV (Forced Expiratory Volume): Percentage of vital capacity exhaled within a time frame; decreased in obstructive pulmonary diseases.

• FEV1 (Forced Expiratory Volume in 1 Second): Amount of air exhaled in 1 second; normal is 80%.

Endocrine System & Metabolic Disorders

Diabetes Mellitus

• Type 1: Autoimmune destruction of insulin-producing cells; usually occurs before age 20.

• Type 2: Insulin resistance; commonly after age 40, but age is decreasing.

• Gestational: Occurs during pregnancy; insulin resistance due to hormones.

Symptoms of Hypoglycemia (Glucose < 60 mg/dL)

• Sweating

• Shakiness

• Palpitations

• Hunger

• Tingling sensation

• Anxiety

• Coma (severe cases)

Hormones Responsible for Satiety

• Leptin: Suppresses hunger and increases metabolism.

• CCK (Cholecystokinin): Signals fullness.

Glycosuria

Glycosuria is the presence of excess sugar (glucose) in the urine, often a sign of diabetes mellitus.

Hypothermia

Hypothermia occurs when body temperature drops below 95°F/35°C, leading to impaired physiological function.

Immune System

Cells and Functions

• Monocytes: Precursors to macrophages, which phagocytose pathogens.

• Plasma cells: Differentiated B cells that produce antibodies.

Classic Symptoms of Inflammation

• Redness

• Heat

• Swelling (edema)

• Pain

Immune Responses

• Active immunity: Body produces antibodies after exposure to antigen (e.g., vaccination).

• Passive immunity: Antibodies are transferred from another source (e.g., breast milk, immunoglobulin injection).

Antibody in Breast Milk

• IgA: Provides passive immunity to infants.

MAC (Membrane Attack Complex)

The MAC is part of the complement system that forms pores in the membrane of pathogens, leading to cell lysis.

Body Fluids and Transport

Total Body Water (TBW) and Compartments

• TBW: Total body water, consists of water and dissolved materials; 42 liters in adults (60% of body weight).

• ICF (Intracellular Fluid): Fluid inside cells; 28 liters.

• ECF (Extracellular Fluid): Fluid outside cells; 14 liters.

• Plasma: Surrounds blood cells; 3 liters.

• Interstitial fluid: Fluid between cells; 11 liters.

Active and Passive Transport

• Active transport: Requires energy to move substances against their concentration gradient.

  • Sodium-potassium pump (Na/K pump): Pumps 3 Na+ out and 2 K+ in; maintains nerve and muscle function.

  • Calcium pump (Ca2+ pump): Moves calcium ions to control muscle contraction.

  • Hydrogen-potassium pump (H/K pump): Secretes acid into the stomach.

• Endocytosis: Cell engulfs fluids (pinocytosis) or large particles (phagocytosis).

• Exocytosis: Release of materials outside the cell.

• Passive transport: Does not require energy; includes diffusion, osmosis, and facilitated diffusion.

Relevant Equations

• GFR Equation: Where is urine concentration of inulin, is urine flow rate, and is plasma concentration of inulin.

• FEV1 Percentage: Where is forced expiratory volume in 1 second, is forced vital capacity.

Table: Body Fluid Compartments

Additional Key Terms

• Angiogenesis: Formation of new blood vessels from pre-existing ones; important for wound healing and tissue growth.

• Kupffer cell: Specialized macrophages in the liver that remove pathogens and toxins.

• Opsonization: Process of coating pathogens with antibodies to enhance phagocytosis.

• Mast cells: Secrete histamine, causing vasodilation and inflammation.

• Fertilization: Union of sperm and egg to form a zygote.

• Hematocrit: Fractional representation of red blood cells in blood.

• Tendons: Connect muscle to bone.

• Ligaments: Connect bone to bone.

• Erythropoietin: Hormone from the kidney that increases red blood cell synthesis.

Summary Table: Types of Immunity

Additional info: Some explanations and examples have been expanded for clarity and completeness based on standard Anatomy & Physiology curriculum.