Topics in Human Biology: Synapses to Infectious Diseases

Synaptic Transmission

Process of neurotransmitter release at synapse.

Action Potential

Electrical signal traveling down a neuron.

Presynaptic Neuron

Neuron sending signals to another neuron.

Voltage-Gated Ca2+ Channels

Channels that open due to depolarization.

Synaptic Vesicles

Contain neurotransmitters for release.

Exocytosis

Process of neurotransmitter release from vesicles.

Synaptic Cleft

Gap between presynaptic and postsynaptic neurons.

Ligand-Gated Ion Channels

Receptors that open upon neurotransmitter binding.

Excitatory Postsynaptic Potential (EPSP)

Depolarization that increases likelihood of action potential.

Inhibitory Postsynaptic Potential (IPSP)

Hyperpolarization that decreases likelihood of action potential.

Summation

Combining multiple signals to determine action potential.

Temporal Summation

Repeated firing from one synapse builds potential.

Spatial Summation

Multiple synapses firing simultaneously at one cell.

Long-Term Potentiation

Strengthening of synapses through increased receptor numbers.

NMDA Receptors

Type of receptor involved in synaptic plasticity.

AMPA Receptors

Receptors that mediate fast synaptic transmission.

Hearing Process

Sequence of events from sound to perception.

Tympanic Membrane

Eardrum that vibrates in response to sound.

Cochlea

Fluid-filled structure in inner ear for hearing.

Sensory Reception

Initial detection of stimulus by sensory organs.

Sensory Transduction

Conversion of stimulus into action potential.

Muscle Contraction

Process initiated by action potential in muscle fibers.

Myofibrils

Long fibers within muscle fibers containing sarcomeres.

Sliding Filament Model

Mechanism of muscle contraction involving actin and myosin.

ATP

Primary energy currency of the cell.

Creatine Phosphate

Recycles ADP back to ATP.

Glycogen

Stored glucose for energy during low blood sugar.

Lipids

Used for energy when carbohydrates are depleted.

Skeletal Muscle

Voluntary, striated muscle with cylindrical cells.

Cardiac Muscle

Involuntary, striated muscle with intercalated discs.

Smooth Muscle

Involuntary, non-striated muscle not attached to bone.

Sarcomeres

Basic contractile units in striated muscle.

Pepsin

Enzyme in stomach that breaks down proteins.

HCl

Acid secreted in stomach for protein digestion.

Salivary Amylase

Enzyme that digests carbohydrates in the mouth.

Nucleases

Enzymes that break down nucleic acids in small intestine.

Lipases

Enzymes that digest lipids in small intestine.

Bile Salts

Emulsify fats for digestion in small intestine.

Bolus

Chewed food mass swallowed from the mouth.

Chyme

Partially digested food in the stomach.

Vitamins

Organic compounds essential for various bodily functions.

Vitamin C

Essential for collagen synthesis and iron absorption.

Vitamin A

Important for vision and skin health.

Vitamin D

Facilitates calcium absorption for bone health.

Vitamin K

Necessary for blood clotting processes.

Essential Nutrients

Nutrients required for health that cannot be synthesized.

Vitamin K

Essential for blood clotting; deficiency causes problems.

Minerals

Inorganic nutrients; categorized as macronutrients or micronutrients.

Macronutrients

Required in large amounts; >200 mg/day.

Calcium

Important for bone health and muscle function.

Phosphorus

Vital for energy transfer and bone structure.

Sulfur

Component of amino acids and vitamins.

Sodium

Regulates fluid balance and nerve function.

Potassium

Crucial for heart and muscle function.

Chlorine

Maintains osmotic balance and acid-base balance.

Trace Elements

Required in small amounts; <200 mg/day.

Iron

Essential for hemoglobin; deficiency leads to anemia.

Iodine

Necessary for thyroid function; deficiency causes hypothyroidism.

Ghrelin

Hormone that stimulates hunger.

PYY

Hormone that suppresses appetite after eating.

Insulin

Hormone that lowers blood sugar and appetite.

Leptin

Hormone that suppresses appetite; regulates energy balance.

Gastrin

Hormone that stimulates secretion of gastric acid.

Cholecystokinin (CCK)

Stimulates digestion by releasing digestive enzymes.

Secretin

Hormone that neutralizes stomach acid in small intestine.

Respiratory Structures

Organs involved in gas exchange across organisms.

Countercurrent Exchange

Efficient gas exchange mechanism in gills.

Tracheal Systems

Network of tubes for gas exchange in insects.

Alveoli

Tiny air sacs in lungs for gas exchange.

Oxygen Pathway

Sequence of structures oxygen travels through during inhalation.

Breathing Regulation

Controlled by CO2 levels during cellular respiration.

pH

Measure of acidity or alkalinity in solutions.

Carbonic Acid

Formed from CO2, lowers blood pH.

Respiration Rate

Increased to eliminate CO2 and stabilize pH.

Nitrogenous Waste

Waste products from protein metabolism.

Ammonia

Highly toxic, excreted by aquatic organisms.

Urea

Less toxic, energy-intensive, water-soluble waste.

Uric Acid

Insoluble, energy-costly waste, suited for deserts.

Filtration

Process in kidneys to remove waste from blood.

Bowman's Capsule

Initial nephron structure for filtration.

Glomerulus

Capillary bed for blood filtration in kidneys.

Reabsorption

Process of reclaiming needed substances in kidneys.

Loop of Henle

Site for reabsorption in nephron.

Secretion

Removal of excess ions and urea in nephron.

Excretion

Process of urine leaving the body.

Open Circulatory System

Blood partially fills vessels, not always contained.

Closed Circulatory System

Blood remains within vessels at all times.

Fish Circulation

Two heart chambers; low pressure, single circuit.

Frog Circulation

Three heart chambers; pulmocutaneous circuit for oxygen.

Mammal Circulation

Four heart chambers; efficient oxygen delivery.

Heartbeat Initiation

Starts at SA node with leaky Ca2+ channels.

Autorhythmic Tissue

Tissue responsible for heart's rhythmic contractions.

Lymphatic Functions

Returns interstitial fluid to blood circulation.

Plasma

Liquid component of blood containing various substances.

Red Blood Cells

Erythrocytes that transport oxygen via hemoglobin.

White Blood Cells

Leukocytes involved in immune responses.

Platelets

Cell fragments that aid in blood clotting.

Fibrin Clot

Permanent clot formed from fibrinogen conversion.

Innate Immunity

Non-specific defense mechanisms against pathogens.

Phagocytic Cells

Cells that ingest and destroy pathogens.