Untitled Flashcards Set

Nervous System

1. Action Potential

   • All-or-nothing principle: A neuron fires at full strength or not at all.

   • Steps: Resting potential → Depolarization (Na+ influx) → Repolarization (K+ efflux) → Refractory period.

2. CNS vs. PNS

   • CNS (Central Nervous System): Brain and spinal cord (integration center).

   • PNS (Peripheral Nervous System): Nerves outside CNS (sensory/motor pathways).

3. Neurons

   • Most common type: Multipolar neuron (e.g., motor neurons).

   • Structure: Dendrites (receive signals), cell body, axon (transmits signals), myelin sheath (insulation).

   • Functional types: Sensory (afferent), motor (efferent), interneurons.

4. Reflex Arc

   • Example: Knee-jerk reflex.

   • Path: Receptor → Sensory neuron → Spinal cord → Motor neuron → Effector (muscle).

5. Senses

   • Vision:

     • Most acute vision: Fovea centralis (cones for color/detail).

     • Accommodation: Lens changes shape to focus light.

     • Disorders: Myopia (nearsightedness), hyperopia (farsightedness), cataracts.

   • Taste/Smell: Chemoreceptors detect chemicals (taste buds, olfactory epithelium).

Cardiovascular System

1. Blood

   • Cell types:

     • Erythrocytes (RBCs: carry O₂/CO₂ via hemoglobin).

     • Leukocytes (WBCs: immunity).

     • Platelets (clotting).

   • Plasma: Liquid portion (water, proteins, electrolytes).

   • Normal pH: 7.35–7.45 (slightly alkaline).

2. Blood Vessels

   • Arteries: Carry oxygenated blood away from heart (thick walls).

   • Veins: Return deoxygenated blood to heart (valves prevent backflow).

   • Capillaries: Site of gas/nutrient exchange (thin walls).

3. Heart

   • Path of blood: RA → RV → Lungs → LA → LV → Body.

   • Pacemaker: SA node (initiates heartbeat).

   • Heart sounds: "Lub-dub" (AV valves closing, then semilunar valves).

   • Layers: Pericardium (outer sac), myocardium (muscle), endocardium (lining).

Respiratory System

1. Pulmonary Ventilation

   • Inspiration: Diaphragm contracts (volume ↑, pressure ↓).

   • Expiration: Diaphragm relaxes (volume ↓, pressure ↑).

2. Key Structures

   • Epiglottis: Covers trachea during swallowing.

   • Larynx: Voice box (vocal cords).

   • Pleural membrane: Reduces friction around lungs.

3. Lung Volumes

   • Tidal volume: Normal breath (~500 mL).

   • Vital capacity: Max inhalation/exhalation.

4. CO₂ Role: Regulates blood pH (converted to bicarbonate in blood).

Digestive System

1. Path of Food

   • Mouth → Esophagus → Stomach → Small intestine → Large intestine → Anus.

2. Key Organs

   • Liver: Produces bile, detoxifies blood.

   • Gallbladder: Stores bile.

   • Pancreas: Releases digestive enzymes (e.g., amylase, lipase) and insulin.

3. Absorption

   • Nutrients: Mostly in small intestine (villi increase surface area).

4. Teeth

   • Adult count: 32 teeth.

   • Structure: Enamel (hardest substance), dentin, pulp (nerves/vessels).

5. Terms

   • Bolus: Chewed food mixed with saliva.

   • Chyme: Partially digested food leaving stomach.