Homeostasis and Body Organization Flashcards

Vocabulary flashcards covering human physiology concepts, tissue types, homeostatic control mechanisms, intercellular messengers, and body chemical balances from Chapter 1.

Physiology

The study of how living organisms function, ranging from molecular processes to whole organ systems.

Pathophysiology

Physiology gone wrong.

Skeletal muscle

Muscle tissue made of long cylindrical striated cells with many nuclei that attached mostly to the skeleton and controls voluntary movement.

Cardiac muscle

Muscle tissue composed of branching striated cells with one nucleus found in the wall of the heart that involuntarily pumps blood through the body.

Smooth muscle

Muscle tissue made of cells tapered at each end with one nucleus, found in walls of hollow internal organs and tubes to involuntarily control movement and tube diameter.

Neuron

A cell of the nervous system specialized to initiate, integrate, and conduct electrical signals to other cells.

Nervous tissue

A collection of neurons forming structures such as the brain or spinal cord.

Nerve

A structure formed by packaging together axons from many neurons.

Epithelial cells

Cells specialized for protection, as well as the selective secretion and absorption of molecules.

Simple epithelium

An epithelial layer that is one-cell thick.

Stratified epithelium

An epithelial layer consisting of numerous cell layers.

Areolar connective tissue

Widely distributed connective tissue found under skin, around organs, and between muscles that wraps and cushions organs.

Dense connective tissue

Connective tissue found in tendons and ligaments that forms strong bands attaching bone to muscle or bone to bone.

Extracellular matrix

The environment surrounding cells composed of proteins, polysaccharides, and minerals that provides a scaffold for cellular attachment and transmits chemical signals.

Functional unit

Smaller subunits of an organ that perform the organ's function, such as a nephron in a kidney.

Intracellular fluid

Body fluid contained within the cells.

Extracellular fluid

Body fluid present in the blood and surrounding the cells.

Homeostasis

A dynamic process in which living organisms maintain a relatively constant internal environment.

Dynamic constancy

A pattern in physiological variables where levels change over short periods of time but remain relatively constant over time.

Negative feedback loop

A homeostatic control mechanism that counteracts changes to physiological variables and stops once the set point has been reached.

Feedforward regulation

A homeostatic mechanism where changes to regulated variables are anticipated and prepared for before they occur.

Reflex

A specific, involuntary, unpremeditated, unlearned built-in response to a particular stimulus.

Reflex arc

The pathway that mediates a reflex.

Hormone

An intercellular chemical messenger secreted by endocrine glands that travels through the blood to target cells.

Neurotransmitter

An intercellular chemical messenger released by neurons onto other neurons, muscle cells, or glands.

Paracrine substance

A chemical messenger that targets cells in close proximity to the cell that secreted it.

Autocrine substance

A chemical messenger that acts directly on the same cell that secreted it.

Adaptation

An inherited characteristic that favors survival in specific environments.

Acclimatization

The improved functioning of an already existing homeostatic system based on an environmental stress.

Circadian rhythm

A biological rhythm cycle lasting $24\,\text{hr}$ that enables homeostatic mechanisms to activate before an anticipated change occurs.

Stable balance

A state of total-body chemical balance where gain equals loss ($\text{gain} = \text{loss}$).

Positive balance

A state of total-body chemical balance where gain exceeds loss ($\text{gain} > \text{loss}$).

Negative balance

A state of total-body chemical balance where loss exceeds gain ($\text{loss} > \text{gain}$).