Anatomy and Physiology The Human Body: an orientation
Chapter 1: The Human Body: an orientation.
Studies the Structure of body parts and their relationships to one another.
concerns the functions of the body, in other words, how the body parts work and carry out their life-sustaining activities.
Macroscopic (Gross) anatomy
is the study of large body structures visible to the naked eye, such as the heart, lungs, and kidneys.
*Macroscopic (Gross) Anatomy
all the structures (muscles, bones, blood vessels nerves, etc.) in a particular region of the body, such as the abdomen or leg, are examined at the same time.
Body Structure is studied system by system.
For Example: when studying the cardiovascular system, you would examine the heart and the blood vessels of the entire body.
The study of internal structures as they relate to the overlying skin surface .
Example: you use surface anatomy when you identify the bulging muscles beneath a bodybuilder's skin, and clinicians use it to locate appropriate blood vessels in which to feel pulses and draw blood.
Deals with structures too small to be seen with the naked eye.
For these studies, exceedingly thin slices of body tissures are stained and mounted on glass slides to be examined under the microscope.
Traces structural changes that occur in the body throughout the life span.
Example: Embryology-a subdivision of developmental anatomy, concerns developmental anatomy, concerns developmental changes that occur before birth.
Levels of Structural Organization
*Organ System Level
The simplest level of the structural hierarchy.
At this level, atoms, tiny building blocks of matter, combine to form molecules, such as water and proteins. Molecules, in turn, associate in specific ways to form organelles, basic componenets of the microscopic cells. Cells are the smallest units of living things.
Cells are the simplest living creatures.
all cells have some common functions, but individual cells vary widely in size and shape, reflecting their unique functions in the body.
Tissues are groups of similar cells that have a common function.
Extremely complex functions become possible.
Exampel: the lining of the stomach is an epithelium that produces digestive juices. The bulk of its wall is muscle, which churns and mixes stomach contents (food). its connective tissue reinforces the soft muscular walls. Its nerve fibers increase digestive activity by stimulating the muscle to contract more vigorously and the glands to secrete more digestice juices.
Organ System Level
Organs that work together to accomplish a common purpose make up an organ system.
Example: the heart and blood vessels of the cardiovascular system circulate blood continuously to carry oxygen and nutrients to all body cells.
The highest level of organization, the living Human Being. It represents the sum total of all structural levels working together to keep us alive.
Levels of Structural Organization
Necessary Life Functions
must maintain these boundaries to that its internal environment remains distinct from the external environment surrounding.
Includes the activities promoted by the muscular system, such as propelling ourselves from one place to another by running or swimming, and manipulating the external environment with our nimble fingers. the skeletal system provides the bony framework that the muscles pull on as they work.
on the cellular level, the muscle cell's ability to move by shortening.
the ability to sense changes (which serve as stimuli) in the environment and then respond to them.
the breaking down of ingested foodstuffs to simple molecules that can be absorbed into the blood. The nutrient-rich blood is then distributed to all body cells by the cardiovascular system.
a broad term that includes all chemical reactions that occur within body cells. it includes breaking down substances into their simpler building blocks (catabolism), synthesizing more complex cellular structures from simpler substances (anabolism), and using nutrients and oxygen to produce (via cellular respiration) ATP, the energy-rich molecules that power cellular activities. Depends on the on the digestive and respiratory systems to make nutrients and oxygen available to the blood and on the cardiovascular system to distribute them throughout the body. Regulated by hormones secreted by endocrine system glands.
the process of removing wastes, or excreta, from the body.
occurs at the cellular and the organismal level.
is an increase in size of a body part or the organism. it is usually accomplished by increasing the number of cells.
Taken in via the diet, contain the chemical substances used for energy and cell building.
necessary for many chemical reactions to occur.
accounts for 60%-80% of our body weight and the single most abundant chemical substance in the body. provides the watery environment necessary for chemical reactions and the fluid base for body secretions and excretions.
Normal Body Temperature
Must be maintained in order for chemical reactions to continue at life-sustaining rates. When temp drops below 37C (98.6F), metabolic reactions become slower and slower, and finally stop. When body temperature is too high, chemical reactions occur at a frantic pace and body proteins lose their characteristic shape and stop functioning. at either extreme, death occurs.
Appropriate atmospheric pressure
the force that air exerts on the surface of the body.
descrribes the ability to maintain relatively stable internal conditions even though the outside world changes continuously. It indicates a dynamic state of equilibrium, or a balance, in which internal conditions vary, but always within relatively narrow limits.
Homeostatic Control Variable
the factor or event being regulated.
Homeostatic Control Receptor
The first component, is some type of sensor that monitors the environment and responds to changes, called stimuli, by sending information (input) to the second component, the control center. input flows from the receptor to the control center along the so-called adderent pathway.
Homeostatic Control: Control Center
determines the set point, which is the level or range at which a variable is to be maintained. it also analyzes the input it receives and determines the appropriate response or course of action. Information (output) then flows from the control center to the third component, the effector, along the efferent pathway.
Homeostatic Control: Afferent
Information traveling along the Afferent pathway Approaches the control center.
Homeostatic Control: Efferent
information traveling along the Efferent pathway Exits from the control center.
Homeostatic Control: Effector
provides the means for the control center's response (output) to the stimulus. The results of the response then feed back to influence the effect of the stimulus, either reducing it (in negative feedback) so that the whole control process is shut off, or enhancing it (in positive feedback) so that the whole process continues at an even faster rate.
the output shuts off the original effect of the stimulus or reduces its intensity. These mechanisms cause the variable to change in a direction opposite to that of the initial change, returning it to its "ideal" value; thus the name "negative" feedback mechanisms.