Physiology Exam 2 Terms and Concepts

Biol 118 Exam 2 stuff to memorize and understand. Go to slides if it talks about pathways or processes cuz pictures might help better

Stress (Kim & Diamond Definition)

A state aroused by aversive stimuli perceived as negative and uncontrollable, which one would avoid if possible.

Physiological Effects of Stress

Triggers glucose release into the bloodstream to provide immediate energy for “fight or flight” responses.

HPA Axis (Hypothalamic–Pituitary–Adrenal Axis)

System regulating stress: the hypothalamus releases CRH

Adrenal Gland – Short-Term Stress (Alarm Stage)

Adrenal medulla releases epinephrine and norepinephrine, increasing heart rate, blood glucose, and blood pressure for rapid energy mobilization.

Adrenal Gland – Long-Term Stress (Resistance Stage)

Adrenal cortex secretes cortisol and aldosterone; cortisol promotes gluconeogenesis and increases insulin resistance, raising risk for Type II diabetes.

Cortisol

A hydrophobic steroid hormone derived from cholesterol; crosses membranes easily to regulate metabolism and stress responses.

Aldosterone

A steroid hormone that regulates Na⁺ and water balance, increasing blood pressure and volume.

Chronic Stress Effects

Sustained cortisol levels increase insulin resistance, suppress immunity, and contribute to metabolic disorders.

Sympathetic Division

“Fight or flight” system; uses ACh at preganglionic and norepinephrine (NE) at postganglionic synapses; prepares body for emergency responses.

Parasympathetic Division

“Rest and digest” system; uses acetylcholine (ACh) at both synapses; promotes digestion, relaxation, and energy storage.

Dual Innervation

Most visceral organs receive input from both sympathetic and parasympathetic divisions, providing balanced control.

Allostasis

The process of maintaining stability through physiological or behavioral change.

Allostatic Load

The cumulative physiological burden of chronic stress on body systems involved in adaptation, contributing to health disparities.

Bone Composition

Primarily collagen (soft protein) and hydroxyapatite (a calcium–phosphate mineral); bone is a dynamic connective tissue.

Calcium Storage

99% of body calcium resides in bones and teeth; 1% circulates in blood.

Osteoprogenitor Cells

Multipotent stem cells that differentiate into osteoblasts during bone growth and repair.

Chondrocytes

Cartilage cells replaced by osteocytes during endochondral bone growth.

Osteoblasts

Bone-forming cells that secrete osteoid (organic bone matrix) and initiate mineralization.

Osteocytes

Mature bone cells that maintain bone matrix and detect mechanical stress; derived from osteoblasts.

Osteoclasts

Large multinucleated cells that break down bone matrix by secreting acids and enzymes; release calcium into blood.

Vitamin C and Bone Health

Deficiency causes scurvy, impairing collagen synthesis and osteoblast differentiation.

Osteoporosis

Condition caused by greater osteoclast activity than osteoblast activity, leading to bone weakening.

Vitamin D (Calcitriol)

Active form of vitamin D; promotes calcium absorption in intestines and regulates bone mineralization.

Rickets

Bone softening in children due to vitamin D deficiency; impaired mineralization at growth plates.

Osteomalacia

Adult version of rickets; impaired bone mineralization due to vitamin D deficiency.

Parathyroid Hormone (PTH)

Increases blood Ca²⁺ by stimulating bone resorption and renal reabsorption.

Calcitriol

Enhances intestinal Ca²⁺ absorption.

Calcitonin

Lowers blood Ca²⁺ by inhibiting osteoclast activity.

Blood Composition

92% water, 8% solutes (proteins, nutrients, gases, waste, ions).

Plasma

Liquid matrix of blood; carries proteins, nutrients, and hormones.

Erythrocytes (Red Blood Cells)

Transport O₂ (via hemoglobin) and CO₂; lack nuclei and mitochondria; live ~120 days.

Leukocytes (White Blood Cells)

Immune cells involved in defense against pathogens.

Thrombocytes (Platelets)

Cell fragments involved in clotting and hemostasis.

Plasma Proteins

Include albumin, globulins, and fibrinogen; function in transport, clotting, and pH buffering.

Albumin

Liver-produced carrier protein with hydrophobic interior pockets; transports lipids, hormones, and vitamins.

Hemoglobin

Iron-containing protein in RBCs; binds O₂ and CO₂ reversibly.

Anemia

Reduction in oxygen-carrying capacity due to low RBC count or hemoglobin levels.

Iron-Deficiency Anemia

Caused by insufficient iron for hemoglobin synthesis.

Pernicious Anemia

Caused by vitamin B12 deficiency, impairing RBC formation.

Erythropoiesis

Production of RBCs from hemocytoblasts; regulated by erythropoietin (EPO) from kidneys.

EPO (Erythropoietin)

Hormone that stimulates RBC production; used illegally for blood doping to enhance athletic performance.

Hemostasis

Process of stopping bleeding via vascular spasm, platelet plug formation, and coagulation.

Vascular Spasm

Initial vasoconstriction following vessel injury.

Platelet Plug Formation

Platelets adhere to exposed collagen via von Willebrand Factor (vWF) and aggregate to form a temporary seal.

Coagulation

Conversion of fibrinogen to fibrin to form a stable blood clot.

Extrinsic Pathway

Triggered by external trauma releasing tissue factor (thromboplastin).

Intrinsic Pathway

Initiated by damage within the blood vessel; involves factors XII, XI, IX, and VIII.

Common Pathway

Factor X activation, prothrombinase converts prothrombin , thrombin to fibrinogen, then fibrin clot.

Vitamin K

Required by the liver to produce clotting factors II, VII, IX, and X.

Calcium (Ca²⁺)

Essential cofactor in all steps of coagulation.

Thrombopoietin (TPO)

Hormone that stimulates platelet production in bone marrow.

Thrombocytopenia

Low platelet count; causes prolonged clotting time and bleeding risk.

Lymphatic System

Collects interstitial fluid (lymph), filters it through lymph nodes, and returns it to circulation; crucial for immune defense.

Edema

Accumulation of excess interstitial fluid due to lymphatic or circulatory imbalance.

Lymph Nodes

Filter lymph and house immune cells (lymphocytes, macrophages) that detect and destroy pathogens.

Pathogen

Microorganism capable of causing disease (bacteria, viruses, parasites).

Antigen

Foreign substance that triggers an immune response.

Innate Immunity (Nonspecific)

First and second lines of defense, including physical barriers, phagocytes, inflammation, and NK cells.

Adaptive Immunity (Specific)

Third line of defense; involves antigen-specific B and T lymphocytes and memory formation.

Phagocytes

“Eating cells” that engulf pathogens; include macrophages, neutrophils, and dendritic cells.

Natural Killer (NK) Cells

Lymphocytes that destroy virus-infected or cancerous cells using perforin to induce apoptosis.

Cytokines

Small signaling proteins that coordinate immune and inflammatory responses.

Inflammation

Local or systemic immune response causing redness, heat, swelling, and pain; involves histamines and cytokines.

B Cells (Humoral Immunity)

Mature in bone marrow; produce antibodies against antigens.

T Cells (Cell-Mediated Immunity)

Mature in the thymus; cytotoxic T cells kill infected cells, helper T cells activate B cells, and regulatory T cells suppress immune responses.

Antibodies (Immunoglobulins)

Y-shaped proteins produced by plasma cells that bind specific antigens, neutralizing pathogens or marking them for destruction.

Clonal Selection Theory

Specific B or T lymphocytes are activated and cloned upon encountering their matching antigen.

Autoimmune Diseases

Result when antibodies or T cells attack self tissues.

Vaccines

Introduce antigens to stimulate immune memory without causing disease.

mRNA Vaccines

Deliver genetic instructions for antigen production, training the immune system to recognize pathogens.

Herd Immunity

Protection of a population when enough individuals are immune, reducing disease spread (requires ~93–95% vaccination for measles).

Interferons

interfere with viral replication and increase resistance of cells to viral infection. They DO NOT prevent viruses from entering, just inhibit replication and spreading.

Perforin

causes apoptosis of abnormal/infected cells by forming pores in their membranes

Complement System

Attacks and breaks cell walls; attracts phagocytes; stimulates inflammation

Fever

Mobilizes defenses; accelerates repairs; inhibits pathogens