THE HUMAN BODY PLAN
INTRODUCTION TO THE STUDY OF
ANATOMY and PHYSIOLOGY
SECTION 46-1, THE HUMAN BODY PLAN
The human body begins to take shape during the earliest stages of embryonic development. While the embryo is a tiny hallow ball of dividing cells, it begins forming the tissues and organs that compose the human body. By the end of its third week, human embryo has bilateral symmetry (a body plan in which the left and right sides mirror each other) and is developing vertebrate characteristics that will support an upright body.
OBJECTIVES: Define Anatomy and Physiology, and explain how they are related. List and describe the major characteristics of life. Define homeostasis, and explain its importance to survival. Describe a Homeostatic Mechanism.List and describe the four types of tissues that make up the human body. Explain how tissues, organs, and organ systems are organized. Summarize the functions of the primary organ systems in the human body. Name and locate four human body cavities, and describe the organs that each contain. Properly use terms that describe relative positions, body sections, and body regions.
1. The human body is a precisely structured container of Chemical Reactions.
2. Biology is the Study of Living Things including the Study of the Human Body.
3. The Study of BODY STRUCTURE, which includes Size, Shape, Composition, and perhaps even Coloration, is called ANATOMY.
4. The Study of HOW the BODY FUNCTIONS is called PHYSIOLOGY.
5. The purpose of this course is to enable you to gain an understanding of Anatomy and Physiology with the emphasis on Normal Structure and Function. You will examine the anatomy and physiology of the major body systems.
1. CHEMICAL LEVEL
A. The Chemicals that make up the body may be divided into TWO major categories: INORGANIC AND ORGANIC.
B. INORGANIC CHEMICALS are usually simple molecules made of one or more elements other than CARBON. Examples: Water, Oxygen, Carbon Dioxide (an exception), and Minerals such as iron, calcium, and sodium.
C. ORGANIC CHEMICALS are often VERY Complex and ALWAYS CONTAIN THE ELEMENTS CARBON AND HYDROGEN. Examples: Carbohydrates, Fats, Proteins, and Nucleic Acids.
2. CELLULAR LEVEL
A. The SMALLEST LIVING UNITS OF STRUCTURE AND FUCTION ARE CELLS.
B. Cells are the smallest living subunits of a multicellular organism such as a human being.
C. There are many different types of cells; each is made of chemicals and carries out specific chemical reactions.
3. TISSUE LEVEL
A. A Tissue is a group of cells with similar structure and function.
B. There are FOUR Groups of Tissue.
C. EPITHELIAL TISSUE – Cover or line body surfaces; some are capable of producing secretions with specific functions. The outer layer of the Skin and Sweat Glands are examples of Epithelial Tissue.
D. CONNECTIVE TISSUE – Connects and supports parts of the body; some transport or store materials. Blood, Bone, and Adipose Tissue (Fat) are examples.
E. MUSCLE TISSUE – Specialized for CONTRACTION, which brings about movement. Our Skeleton Muscles and the Heart are examples.
F. NERVE TISSUE – Specialized to generate and transmit Electrochemical Impulses that regulate body functions. The Brain and Optic Nerves are examples.
4. ORGAN LEVEL
A. An Organ is a group of TWO or more different types of Tissues precisely arranged so as to accomplish Specific Functions and usually have recognizable shape.
B. Heart, Brain, Kidneys, Liver, Lungs are Examples.
5. ORGAN SYSTEMS (System Level)
A. An Organ System is a group of organs that all contribute to a Particular Function.
B. Examples are the Circulatory, Respiratory, and Digestive Systems.
C. Each organ system carries out its own specific function, but for the organism to survive the organ systems must work together- this is called INTEGRATION OF ORGAN SYSTEM.
6. ORGANISM LEVEL
A. The MOST Complex Level.
B. ALL the Organ Systems of the body functioning with one another constitute the TOTAL ORGANISM – ONE LIVING INDIVIDUAL.
LIFE PROCESSES or CHARACTERISTICS OF LIFE
1. All living organisms carry on certain processes that set them apart from nonliving things.
2. The Following are Several of the more important life processes of Humans:
A. METABOLISM is the sum of all the chemical reactions that occur in the body. One phase of Metabolism called CATABOLISM provides the ENERGY needed to sustain life by BREAKING DOWN substances such as food molecules. The other phase called ANABOLISM uses the energy from catabolism to MAKE various substances that form body structures and enable them to function.
B. ASSIMILATION is the changing of Absorbed substances into forms that are chemically different from those that entered body fluids.
C. REPONSIVNESS is the ability to Detect and Respond to changes Outside or Inside the Body. Seeking Water to quench thirst is a response to water loss from body tissue.
D. MOVEMENT includes motion of the whole body, individual organs, single cells, or even structures inside cells.
E. GROWTH refers to an Increase in Body Size. It may be due to an increase in the size of existing cells, the number of cells, or the amount of substance surrounding cells. It occurs whenever an organism produces new body materials faster than old ones are worn out or replaced.
F. DIFFERENTIATION is the process whereby unspecialized cells become specialized cells. Specialized Cells differ in Structure and Function from the cells from which they originated.
G. REPRODUCTION refers either to the formation of new cells for Growth, Repair, or Replacement or to the making of a New Individual.
H. Others Include:
Respiration – obtaining Oxygen.
Digestion – Chemically and Mechanically breaking down food substances.
Absorption – The passage of substances through certain membranes.
Circulation – the movement of substances within the body in Body Fluids.
Excretion – Removal of wastes that the body produces.
MAINTENANCE OF LIFE OR SURVIVAL NEEDS
1. The structures and functions of almost all body parts help maintain the Life of the Organism. The ONLY Exceptions are an Organisms Reproductive Structures, which ensure that its species will continue into the future.
2. Life requires certain Environmental Factors, including the Following:
A. WATER – this is the most abundant chemical in the body and it is required for many Metabolic Processes and provides the environment in which Most of them take place. Water also transports substances within the organism and is important in regulating body temperature.
B. FOOD – the Substances that provide the body with necessary Chemicals (Nutrients) in addition to Water. Food is used for Energy, supply the raw materials for building new living matter, and still others help regulate vital chemical reactions.
C. OXYGEN – It is required to release Energy from food substances. This energy, in turn, drives metabolic processes. Approximately 20% of the air be breathe is oxygen.
D. HEAT (BODY TEMPERATURE) – a form of energy, it is a product of Metabolic Reactions. Normal Body Temperature is around 37 C or 98 F. both low or high body temperatures are dangerous to the organism.
E. PRESSURE (ATMOSPHERIC) – Necessary for our Breathing.
PRINCPAL ORGAN SYSTEMS OF THE HUMAN BODY (TABLE 46-1)
1. INTEGUMENTARY SYSTEM
A. The Skin and Structures derived from it, such as hair, nails, and sweat and oil glands.
B. Is a barrier to pathogens and chemicals (Protects the body), Helps regulate body temperature, Eliminates waste, Helps synthesize vitamin D, and receives certain stimuli such as Temperature, Pressure, and Pain.
2. SKELETAL SYSTEM
A. All the Bones of the body (206), their associated Cartilage, and the Joints of the Body.
B. Bones Support and Protect the body, assist in body movement, They also house cells that produce blood cells, and they store minerals.
3. MUSCULAR SYSTEM
A. Specifically refers to Skeletal Muscle Tissue and Tendons.
B. Participates in bringing about movement, maintaining posture, and produces heat.
4. CIRCULATORY A nd CARDIOVASCULAR SYSTEM
A. The Heart, Blood and Blood Vessels.
B. Transports oxygen and nutrients to tissues and removes waste.
5. LYMPHATIC SYSTEM- Sometimes included with the Immune System or Circulatory System becuase it works closely with Both Systems.
A. The Lymph, Lymphatic Vessels, and Structures or Organs (Spleen and Lymph Nodes) containing Lymph Tissue.
B. Cleans and Returns tissue fluid to the blood and destroys pathogens that enter the body.
6. NERVOUS SYSTEM
A. The Brain, Spinal Cord, Nerves, and Sense Organs, such as the eye and ear.
B. Interprets sensory information, Regulates body functions such as movement by means of Electrochemical Impulses.
7. ENDOCRINE SYSTEM
A. ALL Hormone producing Glands and Cells such as the Pituitary Gland, Thyroid Gland, and Pancreas.
B. Regulates body functions by means of Hormones.
8. RESPIRATORY SYSTEM
A. The Lungs and a series of associated passageways such as the Pharynx (Throat), Larynx (Voice Box), Trachea (Windpipe), and Bronchial Tubes leading into and out of them.
B. Exchange oxygen and carbon dioxide between the air and blood.
9. DIGESTIVE SYSTEM
A. A long tube called the Gastrointestinal (GI) Tract and associated organs such as the Salivary Glands, Liver, Gallbladder, and Pancreas.
B. Breaks down and absorbs food for use by cells and eliminates solid and other waste.
10. URINARY And EXCRETORY SYSTEMS
A. The Kidneys, Urinary Bladder, and Urethra that together produce, store, and eliminate Urine.
B. Removes waste products from the blood and regulates volume and pH of blood.
11. IMMUNE SYSTEM
A. The Immune System Consists of Several Organs, as well as White Blood Cells in the Blood and Lymph.
Includes the Lymph Nodes, Spleen, Lymph Vessels,Blood Vessels, Bone Marrow, and White Blood Cells (Lymphocytes).
B. Provides protection against Infection and Disease.
12. REPRODUCTIVE SYSTEM
A. Organs that produce, store, and transport reproductive cells (Sperm and Eggs).
B. Produces eggs and sperm, in women, provides a site for the developing embryo-fetus.
1. All of the above systems function together to help the Human Body to Maintain HOMEOSTASIS.
2. A person who is in good health is in a state of Homeostasis.
3. Homeostasis reflects the ability of the body to maintain relative Stability and to Function Normally despite constant Changes.
4. Changes may be External or Internal, and the body must Respond Appropriately.
5. As we continue to study the Human Body, keep in mind that the Proper Functioning of each Organ and Organ System has a role to perform in maintaining HOMEOSTASIS.
6. The Human Body uses Homeostasis Mechanisms to maintain its stable internal environment. Homeostasis Mechanisms work much like a Thermostat (NEGATIVE FEEDBACK) that is sensitive to temperature and maintains a relative constant room temperature whether the room gets to Hot or Cold.
1. Many organs and organ systems in the human body are housed in compartments called BODY CAVITIES. (Figure 46-2)
2. These cavities protect delicate internal organs from injuries and from the daily wear of walking, jumping, or running.
3. The body cavities also permit organs such as the lungs, the urinary bladder, and the stomach to expand and contract while remaining securely supported.
4. The human body has FOUR Main Body Cavities:
A. CRANIAL CAVITY – encases the brain.
B. SPINAL CAVITY – extending from the cranial cavity to the base of the spine, surrounds the Spinal Cord.
THE TWO MAIN CAVITIES IN THE TRUNK OF THE HUMAN BODY ARE SEPARATED BY A WALL OF MUSCLE CALLED THE DIAPHRAGM.
C. THORACIC CAVITY – The upper compartment, contains the heart, the esophagus, and the organs of the respiratory system – the lungs, trachea, and bronchi.
D. ABDOMINAL CAVITY – The lower compartment, contains organs of the digestive, reproductive, and excretory systems.
To communicate effectively with one another, researchers and clinicians have develop a set of Terms to describe anatomy that have precise meaning. Use of these terms assumes the body in the ANATOMICAL POSITION. This means that the body is standing erect, face forward with upper limbs at the sides and with the palms forward.
Terms of Relative position describe the location of one body part with respect to another. The include the following:
1. SUPERIOR – means that a body part is above another part or is closer to the head.
2. INFERIOR – means that a body part is below another body part or toward the feet.
3. ANTERIOR – means toward the front.
4. VENTRAL – also means toward the front
5. POSTERIOR – is the opposite of anterior; it means toward the back.
6. DORSAL – also is the opposite of anterior; it means toward the back.
7. MEDIAL – relates to an imaginary midline dividing the body in equal right and left halves. Sample: The nose is medial to the eyes.
8. LATERAL – means toward the side with respect to the imaginary midline. Sample: The ears are lateral to the eyes.
9. PROXIMAL – describes a body part that is closer to a point of attachment or closer to the trunk of the body than another part. Sample: The elbow is proximal to the wrist.
10. DISTAL – is the opposite of proximal. It means that a particular body part is farther from the point of attachment or farther from the trunk of the body than another part. Sample: The fingers are distal to the wrist.
11. SUPERFICIAL – means situated near the surface.
12. PERIPHERAL – also means outward or near the surface.
13. DEEP – describes parts that are more internal.
14. CORTEX – the outer layer of an organ
15. MEDULLA – the inner portion of an organ.