Cell Membrane Transport

Osmolarity and Tonicity

Osmolarity and tonicity are essential concepts for understanding how water and solutes move across cell membranes.

• Osmolarity: The total concentration of solute particles in a solution, measured in osmoles per liter (Osm/L).

• Tonicity: The effect of a solution on the volume of a cell, determined by the concentration of non-penetrating solutes.

• Example: Placing a red blood cell in a hypertonic solution causes it to shrink (crenate) due to water loss.

Membrane Transport Mechanisms

• Diffusion: Passive movement of molecules from high to low concentration.

• Facilitated Diffusion: Passive transport using membrane proteins for larger or polar molecules.

• Osmosis: Diffusion of water across a selectively permeable membrane.

• Active Transport: Movement of substances against their concentration gradient using ATP.

• Vesicular Transport: Movement of large particles via endocytosis and exocytosis.

Resting Membrane Potential

• Definition: The voltage difference across the cell membrane at rest, typically -70 mV in neurons.

• Key Ions: Potassium (K+) is higher inside the cell (ICF), sodium (Na+) is higher outside (ECF).

Fick's Law of Diffusion

• Formula:

• Explanation: The rate of diffusion (J) is proportional to the diffusion coefficient (D) and the concentration gradient ().

Brain Lab / Skeletal Muscle Biopac

Brain Lab Overview

• Purpose: To study brain hemisphere dominance and muscle physiology using Biopac equipment.

• Brain Hemisphere Dominance: Tests to determine left or right hemisphere dominance, often related to handedness and cognitive functions.

Dynamometer and Muscle Fatigue

• Dynamometer: Device used to measure grip strength and muscle fatigue.

• Muscle Fatigue: Decline in muscle's ability to generate force, often shown as a downward trend on a force vs. time graph.

• EMG (Electromyography): Technique to record electrical activity of muscles.

• Motor Unit: A motor neuron and all the muscle fibers it innervates.

• Application: Clenching a dynamometer repeatedly leads to decreased force output due to fatigue.

Skeletal Muscle Lab

Muscle Twitch and Contraction

• Muscle Twitch: A single, brief contraction and relaxation cycle in a muscle fiber.

• Phases: Latent period, contraction phase, relaxation phase.

Excitation-Contraction Coupling

• Definition: The process linking muscle fiber excitation to contraction via calcium release.

• Neuromuscular Junction: Synapse where a motor neuron stimulates a muscle fiber.

Stimulus and Muscle Contraction

• Stimulus Voltage: Increasing stimulus increases muscle contraction up to a maximum (recruitment).

• Length-Tension Relationship: Muscle force depends on initial length of the muscle fibers.

• Isotonic vs. Isometric: Isotonic contractions change muscle length; isometric contractions do not.

• Treppe, Summation, Tetanus: Treppe is the staircase effect; summation is increased force with rapid stimuli; tetanus is sustained contraction.

General Sensation / Cardiovascular Dynamics Lab

Sensory Modality and Transduction

• Sensory Modality: The type of sensation detected (e.g., touch, pain, temperature).

• Transduction: Conversion of physical stimulus into electrical signals by receptors.

• Receptor Types: Mechanoreceptors, thermoreceptors, nociceptors, photoreceptors, chemoreceptors.

• Referred Pain: Pain perceived at a location other than the site of the stimulus.

Cardiovascular Formulas

• Cardiac Output (CO):

• Stroke Volume (SV): The amount of blood pumped by the ventricle per beat.

• Poiseuille's Law:

• Factors Affecting SV: Preload, afterload, contractility.

• Cardiovascular Diseases: Examples include hypertension, atherosclerosis, myocardial infarction.

Special Senses / Vision Lab

Vision Physiology

• Blind Spot: Area on the retina without photoreceptors where the optic nerve exits.

• Astigmatism: Imperfection in the curvature of the eye's cornea or lens.

• Photoreceptors: Rods (dim light) and cones (color vision).

• Visual Acuity: Sharpness of vision, tested with Snellen chart (e.g., 20/20, 20/40, 20/10 vision).

• Color Blindness: Inability to distinguish certain colors due to lack of specific cones.

• Binocular Vision: Use of both eyes for depth perception.

• Eye Anatomy: Includes cornea, lens, retina, optic nerve, etc.

Urinary System / Urinalysis Lab

Kidney and Nephron Anatomy

• Kidney: Organ responsible for filtering blood and producing urine.

• Nephron: Functional unit of the kidney, consisting of glomerulus, tubules, and collecting duct.

• Renal Artery to Renal Vein: Pathway of blood flow through the kidney.

Urine Formation

• Glomerular Filtration: Movement of water and solutes from blood into Bowman's capsule.

• Tubular Reabsorption: Return of filtered substances to the blood.

• Tubular Secretion: Addition of substances from blood to the filtrate.

Urinalysis

• Physical Characteristics: Color, clarity, odor, specific gravity.

• Tests and Procedures: Dipstick tests for glucose, protein, blood, etc.

• Urinary Pathology: Ketonuria (ketones), pyuria (pus), calculi (stones), cast, glycosuria (glucose).

Special Senses (Olfaction and Taste) / Cardiovascular System

Olfactory and Gustatory Systems

• Olfactory System: Sensory neurons in the nasal cavity detect odors; signals processed in the olfactory cortex.

• Gustatory Cortex: Area in the brain responsible for taste perception.

• Taste Receptors: Detect sweet, sour, salty, bitter, and umami flavors.

Limbic System and Heart Conduction

• Limbic System: Brain structures involved in emotion and memory.

• Intrinsic Conduction System: Specialized cardiac muscle cells (SA node, AV node, bundle branches, Purkinje fibers) coordinate heartbeats.

• ECG/EKG: Graphical recording of the heart's electrical activity; P wave, QRS complex, T wave.

• Heart Anatomy: Chambers (atria, ventricles), valves, major vessels.

Blood Typing and Spirometry Lab

Blood Typing

• Antigen: Substance on RBC surface that determines blood type (A, B, AB, O).

• Agglutinin: Antibody in plasma that reacts with antigens.

• Blood Compatibility: Matching donor and recipient blood types to prevent transfusion reactions.

• Hemolysis of Fetus: Occurs in Rh incompatibility (erythroblastosis fetalis).

• ABO/Rh System: Major blood group systems; Rh factor is either positive or negative.

Spirometry

• Spirograph: Device to measure lung volumes and capacities.

• Key Measurements: Tidal volume, vital capacity, inspiratory/expiratory reserve volumes.