Untitled Flashcards Set

Homeostasis

The maintenance of stable internal conditions in the body despite changes in the external environment.

Negative feedback

A control mechanism that reduces the output or activity of a system to return to a set point.

Positive feedback

A control mechanism that increases the output or activity of a system, moving it further away from a set point.

Set point

The ideal value or range of a physiological variable that the body attempts to maintain.

Error signal

A difference between the set point and the current level of a physiological variable.

Body Mass Index (BMI)

A derived value calculated from a person's weight and height, used to assess body weight relative to height.

Signs and symptoms of Diabetes

Common indicators include increased thirst, frequent urination, extreme fatigue, and blurred vision.

Diagnosing Diabetes

Tests such as fasting blood glucose (normal <100 mg/dL), Oral Glucose Tolerance Test (OGTT), and HbA1c levels are used to diagnose diabetes.

Total Body Water

Refers to the total amount of fluid in the body, making up a significant percentage of body weight.

Body fluid compartments

The major divisions of body fluids into intracellular fluid and extracellular fluid.

Passive transport

The movement of substances across a cell membrane without the use of energy, such as diffusion and osmosis.

Active transport

The movement of substances across a cell membrane requiring energy, commonly against a concentration gradient.

Chemical Driving Force

Refers to the concentration gradient influencing the direction of movement of solutes across membranes; positive indicates net movement toward the concentration, negative indicates movement away.

Membrane permeability

The ability of a membrane to allow certain substances to pass through while restricting others, influenced by size, charge, and solubility of the substances.

Membrane potential

The difference in electric charge across a cell membrane, calculated using the Nernst equation.

Equilibrium Potential

The membrane potential at which there is no net movement of a specific ion across the membrane.

Sodium/Potassium pump

A type of active transport that moves sodium out of and potassium into the cell to maintain the electrochemical gradient.

Glucose transport

The process by which glucose enters cells via transport proteins, often through facilitated diffusion.

Simple Diffusion

The passive movement of molecules from an area of high concentration to an area of low concentration without the aid of transport proteins.

Facilitated Diffusion

The process of transporting molecules across a membrane through protein channels, following a concentration gradient.

Primary Active Transport

Transport mechanisms that require energy directly from ATP to move substances against their concentration gradient.

Secondary Active Transport

Transport that uses the energy from the electrochemical gradient created by primary active transport to move other substances.

Osmosis

The movement of water across a semipermeable membrane from an area of lower solute concentration to an area of higher solute concentration.

Osmolarity

A measure of the concentration of solute particles in a solution; categorized as iso (equal), hypo (lower), or hyper (higher) osmolality compared to another solution.

Tonicity

The ability of a solution to change the shape or tone of cells by altering their internal water volume.

Endocytosis

The process by which cells internalize substances from their external environment through the engulfing of molecules.

Exocytosis

The process of vesicles fusing with the plasma membrane and releasing their contents outside the cell.

Paracrine chemical messenger

A signaling molecule that acts on nearby cells to mediate local cellular responses.

Lipophobic ligands

Molecules that do not easily pass through cell membranes due to their hydrophilic nature.

Lipophilic ligands

Molecules that easily pass through cell membranes due to their hydrophobic nature.

Messenger half-life

The time it takes for half of a chemical messenger to be eliminated from the bloodstream.

Receptor Binding and Properties – Affinity

The strength of the interaction between a receptor and its ligand, influencing the effectiveness of signal transduction.

Transport proteins

Proteins that assist in the movement of ions and molecules across a cell membrane.

Magnitude of Target Response

The extent of a biological response resulting from the binding of a chemical messenger to its target receptor.

Up-regulation & Down-regulation

Processes that increase (up-regulation) or decrease (down-regulation) the number or sensitivity of receptors in response to changing stimuli.

Agonists

Substances that activate receptors and mimic the effects of naturally occurring substances.

Antagonists

Substances that block or dampen the biological response of an agonist by binding to and inhibiting receptors.

G Protein–Coupled Receptors

A large family of membrane receptors that transmit signals inside cells via G proteins.

Second Messenger Systems

Intracellular signaling pathways activated by the binding of a chemical messenger to a receptor, leading to a cellular response.

Signal Amplification

The process by which a small number of signaling molecules can produce a large response in a target cell.

Primary Endocrine Organs

Organs that produce hormones directly, including the hypothalamus, pituitary gland, and adrenal glands.

Secondary Endocrine Organs

Organs that contribute to hormone production but are not primarily endocrine in function.

Regions of the adrenal gland

Includes the adrenal cortex, which produces corticosteroids, and the adrenal medulla, which releases catecholamines.

Abnormal Secretion of Hormones

A condition resulting from the overproduction or underproduction of hormones, leading to various metabolic disorders.

Hormone Interactions

The ways in which different hormones can influence each other's actions and effects in the body.