An Introduction to the Structure and Function of the Body Chapter 1 An Introduction to the Structure and Function of the Body

Objectives Define anatomy and physiology. Describe the process used to form scientific theories. List and discuss in order of increasing complexity the levels of organization of the body. Pages 3-6

Anatomy & Physiology Anatomy – study of the structure of an organism and the relationship of its parts * Anatomists learn about the body by dissection Physiology – the study of the functions of living organisms and their parts * Physiologists use scientific experimentation

Levels of Study Gross Anatomy Microscopic Anatomy Large structures Easily observable Microscopic Anatomy Very small structures Can only be seen with a microscope 4

Scientific Method No single approach but many scientists follow these steps. The process of science is active and changing as new experiments add new knowledge.

Key Terms Hypothesis – reasonable guess based on previous observations or experiments Experiment – series of tests of a hypothesis; should be as simple as possible to avoid errors Experimental controls are used to ensure that the test situation is not affecting the results Control group receives no treatment Treatment group receives treatment or intervention Theory or law – a hypothesis that has gained a high degree of confidence 6

Flashcards series of tests of a hypothesis that eliminates biases or outside influences Experiment idea or principle to be tested in experiments Hypothesis receives no treatment Control Group a hypothesis that has been proven to have a high degree of confidence Theory or law 7

Levels of Organization

Levels of Organization Cell –the small structural “living” units of structure and function in the body Tissue – organization of similar cells that act together to perform a common function ( epithelium, muscle, nervous, etc.) Organ – tissues that act as a unit to perform a specific function (skin, femur, heart, kidney, etc.) Organ System – organs working together to perform complex functions (skeletal system, digestive system, etc.) Organism – the human being

Flashcards small structural “living” units of structure and function in the body Cell Organ tissues that act as a unit to perform a specific function Organism the human being organs working together to perform complex functions Organ System organization of similar cells that act together to perform a common function Tissue 10

Quick Check What is the difference between anatomy, physiology and pathology? What are the major levels of organization in the body? How is tissue different than an organ?

Objectives 4 - 8 Define anatomical position, supine and prone. List and define the principal directional terms and sections (planes) used in describing the body and the relationship of body parts to one another. List the major cavities of the body and the subdivisions of each. List the nine abdominopelvic regions and the abdominopelvic quadrants. Discuss and contrast the axial and the appendicular subdivisions of the body and identify anatomical regions in each area.

Anatomical Position Anatomical Position – a point of reference with the body standing erect, facing forward, upper limbs at the sides, palms facing forward and thumbs out The body has bilateral symmetry. Supine and prone are terms to describe the position of the body when it is not in anatomical position.

Flashcards Standing erect, arms by the side with palms forward Laying face up or “on the spine” Supine Standing erect, arms by the side with palms forward Anatomical position Laying face down or “posterior up” Prone 14

Anatomical Directions Superior / Inferior (Cranial vs. Caudal) Anterior / Posterior (Ventral vs. Dorsal) Medial / Lateral Proximal / Distal Superficial / Deep Internal / External

Flashcards - Directions Toward the side of the body or away from the midline Lateral Toward the midline of the body Medial Front, in front of Anterior Superior Toward the head, upper or above Back, in back of Posterior Toward the feet, lower or below Inferior 16

Flashcards - Directions Proximal Toward or nearest the trunk or point of origin Away from or farthest from the trunk or point of origin Distal Superficial Nearer the body surface Farther away from the body surface Deep 17

Planes of the Body Sagittal or Medial – divides body into left and right portions Mid-sagittal – divides body into equal left and right Transverse or Horizontal – divides body into superior and inferior portions Coronal or Frontal – divides body into anterior and posterior portions

Transverse Section

Flashcards - Planes Divides the body into upper and lower sections Frontal or Coronal Divides the body into anterior and posterior sections Divides the body into upper and lower sections Tranverse Sagittal Divides the body into right and left sections Divides the body into two equal halves Midsagittal 21

Body Cavities

Abdominal Quadrants

Abdominal Regions

Body Regions

Axial & Appendicular Divisions

Quick Check Name and describe the planes of the body. Describe anatomical position. List and describe the body cavities. Describe the abdominal quadrants. Name the nine abdominal regions. List 4 body regions and describe the location. What is the difference between the axial and appendicular divisions?

Objectives 9. Explain the meaning of the term homeostasis and give an example of a homeostatic mechanism.

The Balance of Body Functions Copyright © 2016 by Elsevier Inc. All rights reserved. The Balance of Body Functions Survival depends on the body maintaining relatively constant conditions Body mechanisms act as heaters, air pumps, and the like, to maintain the relatively stable conditions Although they may have very different structures, all living organisms maintain mechanisms that ensure survival of the body and success in propagating its genes through its offspring. What is homeostasis? (Homeostasis is what physiologists call the relative constancy of the internal environment.)

The Body’s Internal Environment Figure 1-10 shows a diagram of the body’s internal environment. The human body is like a bag of fluid separated from the external environment. Tubes, such as the digestive tract and respiratory tract, bring the external environment to deeper parts of the bag where substances can be absorbed into the internal fluid environment or excreted into the external environment.

Feedback Control Feedback loop: Body’s general control system . Feedback Control Feedback loop: Body’s general control system Nerve endings feed information to a control center in the brain that compares actual temp to the normal temp Negative feedback: Opposes change in controlled condition Positive feedback: Amplifies occurring change The idea of a feedback loop is borrowed from engineering. Shivering produces heat that increases our body temperature. Most homeostatic control loops in the body involve negative feedback because reversing changes back toward a normal value tends to stabilize conditions. A positive feedback loop feedback loop causes an ever-increasing rate of events to occur until something stops the process.

Copyright © 2016 by Elsevier Inc. All rights reserved. Negative Feedback Figure 1-11, A, is an engineer’s diagram showing how a relatively constant room temperature (controlled condition) can be maintained. Figure 1-11, B, is a physiologist’s diagram illustrating how a relatively constant body temperature (controlled condition) can be maintained.

Positive Feedback Loop Copyright © 2016 by Elsevier Inc. All rights reserved. Positive Feedback Loop Figure 1-12 is an example of positive feedback that occurs when a baby is born. As the baby is pushed from the womb (uterus) into the birth canal (vagina), stretch receptors detect the movement of the baby. Stretch information is fed back to the brain, triggering the pituitary gland to secrete a hormone called oxytocin (OT). OT travels through the bloodstream to the uterus, where it stimulates stronger contractions. Stronger contractions push the baby farther along the birth canal, thereby increasing stretch and stimulating the release of more OT.

Copyright © 2016 by Elsevier Inc. All rights reserved. Normal Fluctuations Homeostatically controlled conditions don’t remain absolutely constant Conditions fluctuate near an ideal value Ability to maintain balance is related to age Developmental processes Aging processes Thus body temperature, for example, rarely remains exactly the same for very long. It usually fluctuates up and down near a person’s normal body temperature. Changes and functions occurring during the early years are called developmental processes. Those occurring after young adulthood are called aging processes.

Quick Check Why is homeostasis also called the “balance” of body function? What is a feedback loop and how does it work? How does negative feedback differ from positive feedback?