Nervous, Musculoskeletal, Digestive, and Immune Systems Lecture Review

Vocabulary flashcards covering human physiology, including the nervous, muscular, digestive, respiratory, circulatory, and immune systems.

Synaptic vesicles

Organelles in the presynaptic neuron that fuse with the plasma membrane to release neurotransmitters into the synaptic cleft during exocytosis.

Spatial Summation

A phenomenon where two or more signals hit a neuron at once, combining to reach the threshold for an action potential.

Temporal Summation

A process where a single synapse targets a neuron repeatedly to trigger a signal.

Neuronal Plasticity

The ability to change connections between neurons based on use, specifically by adding or removing synapses.

Long-Term Potentiation (LTP)

The strengthening of individual synapses through frequent use, characterized by more receptors in the membrane and easier action potential triggering.

Transduction

The second step in the sensory pathway where a detected stimulus is converted into an action potential.

Sarcomeres

The fundamental units of muscle structure composed of thick filaments (myosin) and thin filaments (actin).

Sarcoplasmic Reticulum (SR)

A specialized organelle that depolarizes to activate voltage-gated channels and release $Ca^{2+}$ during muscle contraction.

Troponin and Tropomyosin

Proteins that regulate muscle contraction; $Ca^{2+}$ binds to troponin, causing tropomyosin to shift and expose myosin-binding sites on actin.

Cardiac Muscle

Muscle type characterized by striations, autorhythmic behavior, branched cells, and intercalated discs for action potential transmission.

Hydrostatic Skeleton

A type of skeleton that uses fluid in a body compartment to provide structure.

Salivary amylase

An enzyme in the oral cavity responsible for the chemical digestion of carbohydrates.

Peristalsis

The rhythmic contractions used by the esophagus to carry a bolus of food from the throat to the stomach.

Pepsinogen

The precursor released by chief cells in the stomach that is involved in the chemical digestion of proteins.

Bile salts

Substances needed to emulsify hydrophobic lipids in the duodenum before lipase can act on them.

Essential Nutrients

Specific vitamins, minerals, and amino acids that the body cannot synthesize on its own and must be obtained from food.

Water-soluble Vitamins

Vitamins like C, $B_3$ (NADH), and $B_9$ (neural tube development) that are excreted in urine if consumed in excess.

Lipid-soluble Vitamins

Vitamins such as D, K, and A that are stored in adipose tissue; excess amounts are not excreted in urine.

Micronutrients

Trace elements like iron and iodine that are required in amounts less than $200\,mg$ a day.

Insulin

A hormone secreted by the pancreas when blood sugar elevates, signaling the liver and muscles to absorb glucose and convert it to glycogen.

Glucagon

A hormone released when blood sugar drops, causing the liver to break down glycogen into glucose monomers.

Ghrelin

A hormone released by an empty stomach to signal hunger to the brain.

Leptin

A long-term satiety signal secreted by adipose tissue to indicate the body has sufficient stored energy.

Tracheal Systems

Respiratory structures in insects consisting of tubes and openings in the exoskeleton that facilitate gas exchange via diffusion.

Osmoregulators

Organisms that maintain a constant internal environment regardless of changes in outside conditions.

Uric Acid

A low-toxicity, insoluble nitrogenous waste produced by reptiles and birds that requires high energy to make but conserves water.

Purkinje fibers

Fibers that radiate the action potential outwards in the heart, causing the ventricles to contract from the bottom up.

Capillaries

The thinnest blood vessels where gas exchange occurs and fluid exits into the interstitial fluid via blood pressure.

Immunoglobulins

Antibodies found in blood plasma that function in the body's defense system.

Fibrin

The insoluble fibers converted from fibrinogen by the enzyme thrombin to create a permanent blood clot.

Cytokines and Histamines

Chemical signals used in the local inflammatory response to recruit white blood cells to a site of infection.

Helper T cells

Cells in the adaptive immune system that release cytokines via autocrine and paracrine signaling to activate B cells and cytotoxic T cells.

Opsonization

An antibody-mediated process that promotes phagocytosis of pathogens.

Complement System

A defense mechanism where proteins in the blood detect antibodies on a cell surface and punch holes in the cell, leading to lysis.

Zoonosis

A virus or pathogen that exists in a non-human animal and jumps to start infecting humans, such as COVID.

Vector

An animal, such as a mosquito or tick, that transmits a disease or parasite from person to person.