General Animal Physiology and Anatomy Review

Comprehensive vocabulary flashcards covering thermoregulation, cellular biology, histology, cardiovascular dynamics, neurobiology, and digestive physiology based on the lecture transcript.

Homeotherms

Animals that maintain a constant body temperature.

Poikilotherms

Animals whose body temperature fluctuates with the environment.

Endotherms

Animals that regulate their body temperature through internal heat production.

Ectotherms

Animals that rely primarily on environmental heat sources for thermoregulation.

Core temperature

The temperature of the cranial, thoracic, and abdominal cavities; it is the most strictly homeostatically regulated temperature.

Conduction

The transfer of heat through direct molecular contact, affected by temperature gradients and the thermal conductivity of surfaces.

Thermoneutral Zone (TNZ)

The environmental temperature range where an animal maintains its body temperature without extra metabolic effort; in humans, this is $27.8\text{--}30^\circ\text{C}$.

Lower Critical Temperature (LCT)

The environmental temperature threshold below which an animal must increase metabolic heat production to prevent hypothermia.

Anterior Hypothalamus

The heat-losing center of the brain that triggers vasodilation, sweating, and panting in response to heat.

Posterior Hypothalamus

The heat-promoting center of the brain that triggers vasoconstriction, piloerection, and shivering in response to cold.

Nonshivering Thermogenesis

A process occurring in Brown Adipose Tissue (BAT) where Uncoupling Protein-1 (UCP1) allows $H^+$ ions to bypass ATP synthase, converting energy directly into heat.

Lumen

The interior of a hollow organ, such as the heart, lungs, or intestines.

Mitochondria

Double-walled organelles with inner folds called cristae; they are the primary site of ATP synthesis.

Smooth Endoplasmic Reticulum (SER)

A ribosome-free organelle responsible for lipid synthesis and the storage of calcium ions ($Ca^{2+}$).

Gap Junctions

Communicating junctions formed by connexin proteins that allow direct chemical or electrical signals between cells.

Tight Junctions

Occluding junctions formed by claudin and occludin proteins that block paracellular movement.

Endothelium

The simple squamous epithelial lining found in the heart and blood vessels.

Desmosomes

Anchoring junctions that provide strong cell-to-cell adhesion, common in protective epithelia like the skin.

Chondrocytes

Cells found within lacunae that secrete the firm, flexible matrix of cartilage.

Osteoclasts

Large, multinucleated phagocytic cells responsible for bone resorption (dissolving bone).

Hematocrit

The measurement of the packed volume percentage of Red Blood Cells (RBCs) in a blood sample.

Frank-Starling Law

The principle that increased venous return stretches cardiac muscle, increasing contractility and stroke volume.

P Wave

The portion of an ECG representing atrial depolarization.

Hyperplasia

An increase in the total number of cells through cellular multiplication.

Hypertrophy

An increase in the size of existing cells, which is the sole method of postnatal muscle growth.

Creatine Phosphate (CP)

A very rapid energy system used for short bursts of activity, yielding $1\text{ ATP} / \text{CP}$.

Anaerobic Glycolysis

A fast energy pathway that converts glucose to pyruvate and then to lactate when oxygen is absent, yielding $2\text{ ATP} / \text{Glucose}$.

Isotonic Contraction

A contraction where muscle tension remains constant while the muscle length shortens to move a load.

Isometric Contraction

A contraction where tension rises but the muscle length remains unchanged because the load exceeds peak tension.

Mean Arterial Pressure (MAP)

The average pressure in the arteries, calculated as $\text{Cardiac Output (CO)} \times \text{Total Peripheral Resistance (TPR)}$.

Astrocytes

Glial cells that form the blood-brain barrier and provide physical and metabolic support to neurons.

Tonic Receptors

Slowly adapting sensory receptors that fire continuously throughout a prolonged stimulus.

Phasic Receptors

Rapidly adapting receptors that fire when a stimulus begins or ends but remain quiet during constant stimulation.

Substance P

The neurotransmitter released by afferent pain fibers at the spinal cord level.

Thrombin

An enzyme that converts fibrinogen into insoluble fibrin strands during the blood coagulation cascade.

Plasmin

The primary enzyme responsible for dissolving blood clots after a vessel has healed.

Glomerular Filtration Rate (GFR)

The rate at which water and small solutes are filtered from the glomerulus into the Bowman's capsule.

Tubular Maximum ($T_m$)

The maximum workload limit of carrier proteins in the kidney; if crossed, solutes like glucose are excreted in the urine.

Vasopressin (ADH)

A hormone that promotes water reabsorption in the collecting ducts by inserting aquaporins into the membrane.

Type II Alveolar Cells

Cells in the lungs that secrete pulmonary surfactant to reduce surface tension and prevent alveolar collapse.

Bohr Effect

The phenomenon where increased $\text{P}_{\text{CO}_2}$, acidity, and temperature reduce hemoglobin's affinity for oxygen, promoting oxygen unloading.

Peptide Hormones

A chemical class of hormones, such as insulin and growth hormone, that are water-soluble.

Permissiveness

A hormone interaction where one hormone must be present for another hormone to achieve its full effect.

IGF-1 and IGF-2

Somatomedins released by the liver in response to Growth Hormone to drive skeletal and soft tissue growth.

Zona Glomerulosa

The outer zone of the adrenal cortex that secretes mineralocorticoids like aldosterone.

Volatile Fatty Acids (VFAs)

Products of microbial fermentation in the hindgut, including acetic acid, propionic acid, and n-butyric acid.

Ghrelin

An orexigenic hormone produced by an empty stomach that stimulates hunger and feed intake.

Leptin

An anorexigenic hormone released by white adipose tissue that inhibits feed intake in proportion to body fat mass.

Parietal Cells

Stomach cells that secrete $\text{HCl}$ and Intrinsic Factor.

Islets of Langerhans

The endocrine clusters in the pancreas containing alpha cells (glucagon) and beta cells (insulin).