Chapter 1 (Vander's Human Physiology)

Physiology

The study of how living organisms function

Pathophysiology

The study of disease states

Physiology

The study of how living organisms function

Pathophysiology

The study of disease states

Cells

The simplest structural units into which a complex multi-cellular organism can be divided and still retain the functions characteristic of life

Cell Differeniation

The process of transforming on un-specialized cell into a specialized cell

Tissue

Aggregate of single type of specialized cell; also denotes general cellular fabric of a given organism

Muscle Tissue

1 of 4 major tissue types in the body, comprising smooth, cardiac, and skeletal muscle; can be under voluntary or involuntary control

Muscle Cells

Specialized cell containing actin and myosin filaments and capable of generating force and movement

Nervous Tissue

1 of 4 major tissue types in the body, responsible for coordinated control of muscle activity, reflexes, and conscious thought

Epithelial Tissue

1 of 4 major tissue types in the body, comprised of aggregates of epithelial cells

Epithelial Cells

Cell at surface of body or hollow organ; specialized to secrete or absorb ions and organic molecules; with other epithelial cells, forms an epithelium

Epithelium

Tissue that covers all body surfaces, lines all body cavities, and forms most glands

Connective Tissue

1 of 4 major tissues in the body, major component of extracellular matrices, cartilage, and bone

Connective-Tissue Cells

Cell specialized to form extracellular elements that connect, anchor, and supply body structures

Organs

Collection of tissues joined in structural unit to serve a common function

Organ Systems

Organs that together serve an overall function

Tissues

Aggregates of single type of specialized cell; also denote general cellular fabric of a given organ

Neuron

Cell in nervous system specialized to initiate, integrate and conduct electrical signals

Basement Membrane

Thin layer of extracellular proteinaceous material upon which epithelial and endothelial cells sit

Extracellular Matrix

A complex consisting of a mixture of proteins (and in some cases minerals) interspersed with extracellular fluid

Fibers (Muscle/Nerve)

Muscle cell/axon of a neuron

Nerve

Group of many axons from numerous neurons encased in connective tissue and traveling together in peripheral nervous system

Collagen Fibers

Strong, fibrous protein that functions as extracellular structural element in connective tissue

Elastin Fibers

a protein with elastic fiber or springlike properties; found in larger arteries and in the airways

Functional Units

1 of a number of small structures within an organ that act similarly to carry out an organ's function

Internal Environment

Extracellular fluid (interstitial fluid and plasma)

Intracellular Fluid

Fluid in cells; cytosol plus fluid in cell organelles, including nucleus

Extracellular Fluid

Fluid outside cell; interstitial fluid and plasma

Plasma

Liquid portion of blood; component of extracellular fluid

Interstitial Fluid

Extracellular fluid surrounding tissue cells; excludes plasma

Interstitium

Interstitial space; fluid filled space between tissue cells

Homeostasis

Relatively stable condition of internal environment that results from regulatory system action; a "steady state"

Dynamic Constancy

A way of describing homeostasis that includes the idea that a variable such as blood glucose may vary in the short term but is stable and predictable when averaged over the ling term

Homeostatic Control Systems

Collection of interconnected components that keeps a physical or chemical variable of internal environment within a predetermined normal range of values

Steady State

No net change; continual energy input to system is required, however, to prevent net change; compare equilibrium

Equilibrium

No net change occurs in a system; requires no energy

Set Point

Steady-state value maintained by homeostatic control system

Negative Feedback

Characteristic of control systems in which system's response opposes the original change in the system

Positive Feedback

Characteristic of control systems in which an initial disturbance sets off train of events that increases the disturbance even further

Feedforward

Aspect of some control systems that allows system to anticipate changes in a regulated variable

Reflex

Biological control system linking stimulus with response and mediated by a reflex arc

Acquired (Learned) Reflexes

Behaviors that appear to be stereotypical and automatic but that in fact result from considerable conscious effort to be learned

Reflex Arc

Neural or hormonal components that mediate a reflex; usually includes receptor, afferent pathway, integrating center, efferent pathway, and effector

Stimulus

Detectable change in internal or external environment

Receptor (for messengers)

Protein either on cell surface, in the cytosol, or in the nucleus that binds a chemical messenger such as a hormone or neurotransmitter and mediates its actions

Integrating Center

Brain region that compares the actual value of a variable such as body temperature to a set point

Afferent Pathway

Component of reflex arc that transmits information from receptor to integrating center

Effector

Cell of cell collection whose change in activity constitutes the response in a control system

Efferent Pathway

Component of reflex arc that transmits information from integrating center to effector

Hormone

Chemical messenger synthesized by specific endocrine cells in response to certain stimuli and secreted into the blood, which carries it to target cells

Local Homeostatic Responses

Responses acting in immediate vicinity of a stimulus, without nerves or hormones, and having net effect of counteracting stimulus

Target Cells

Cells influence by certain hormones

Endocrine Glands

Group of epithelial cells that secrete into the extracellular space hormones that then diffuse into bloodstream

Neurotransmitters

Chemical messengers used by neurons to communicate with each other or with effectors

Paracrine Substances

Chemical messengers that exert their effects on cells near their secretion sites; by convention, exclude neurotransmitters

Autocrine Substances

Chemical messengers secreted into extracellular fluid that act upon the cell that secreted them

Adaptation

A biological characteristic that favors survival in a particular environment; (neural) decrease in action potential frequency in a neuron despite constant stimulus

Acclimatization

Environmentally induced improvement in functioning of a physiological system with no change in genetic endowment

Circadian Rhythm

Occurring in an approximately 24 h cycle

Entrainment

Adjusting biological rhythm to environmental cues

Free-Running Rhythm

Cyclical activity driven by biological clock in absence of environmental cues

Phase-Shift

A resetting of the circadian clock due to altered environmental cues

Pacemaker

Neurons that set rhythm of biological clocks independent of external cues; any neuron or muscle cell that has an inherent autorhythmicity and determines activity pattern of other cells

Pineal Gland

Part of epithalamus of the brain; produces melatonin involved in circadian rhythms

Melatonin

An amine derived from tryptophan produced in the pineal gland and that plays a role in circadian rhythms

Pool

The readily available quantity of a substance in the body; often equals amounts in extracellular fluid

Negative Balance

Loss of substance from body exceeds gain, and total amount in body decreases; also used for physical parameters such as body temperature and energy

Positive Balance

Gain of substance exceeds loss, and amount of that substance in body increases

Stable Balance

Net loss of substance from body equals net gain, and amount of substance in body neither increases nor decreases