An Introduction to Human Body - Lecture Notes | BIOL 2403, Study notes of Physiology

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AN INTRODUCTION TO THE HUMAN BODY

Chapter 1

Anatomy and Physiology Lecture

AN INTRODUCTION TO THE HUMAN BODY

Why Study Anatomy and Physiology:

1. Knowledge of the Structure and Function of the human body provides the basis for understanding disease.
2. Knowledge of the Structure and Function of the human body is essential for those planning a career in the health sciences.
3. Knowledge of the Structure and Function of the human body is beneficial to nonprofessional because it helps with understanding overall health and disease, with evaluating, recommended treatment, and with critically reviewing advertisements and articles.

Anatomy and Physiology are two branches of science that will help us understand our body parts and their functions.

Anatomy – Is the scientific discipline that investigates the body’s structure.

LEVELS OF ANATOMY

1. Developmental Anatomy – Is the study of the structural changes that occur between conception and adulthood.
2. Embryology – Is a subspecialty of developmental anatomy, considers changes from conception to the end of the eighth week of development.
3. Cytology – Examines the structural features of cells.
4. Histology – Examines the tissues, which are cells and the materials surrounding them.
5. Gross (Macroscopic) Anatomy – Is the study of structures that can be examined without the aid of a microscope, can be approached from either a systemic or regional perspective.

LEVELS OF STRUCTURAL ORGANIZATION

(Fig. 1.1, page 3)

(Several levels of structural organization that associated with one another in various ways):

A. CHEMICAL LEVEL (the lowest level of organization)

-Contains atoms, such as Carbon (C), hydrogen (H), oxygen (O), Nitrogen (N), Calcium (Ca), Potassium (K), and Sodium (Na).

(1) Atoms - smallest unit of matter (anything that occupies space and has mass.)

(2) Molecules - combination of two or more atoms e.g. proteins, carbohydrates, fats, and vitamins.

B. CELLULAR LEVEL

1. Cells – Are the basic structural and functional units of all living things.
2. Organelles – Formed by the combination of molecules. Are the small structures that make up cells.

C. TISSUE LEVEL

1. Tissue – Is group of similar cells and the substances surrounding them.

Four Basic Types of Tissue in the human body:

(a) Epithelial Tissue - Lines/Covers Functions: -Absorption (e.g.; the lining of the small intestine) -Transport (e.g.; kidney tubules) -Excretion (e.g.; sweat gland) -Protection (e.g.; the skin) -Sensor reception (e.g.; the taste buds in the tongue)

Classified on the basis of shape and number of layers:

On Layers

Simple epithelium - only one layer of cell Stratified epithelium - two or more layers stacked on top of the other.

On Shapes

Squamous epithelium - flat Cuboidal epithelium - cube shaped Columnar epithelium - column like

(b) Connective Tissue - Connection and support.

Adipose Cartilage Bone Blood

(c) Muscle Tissue - Movement

(d) Nervous Tissue - Communication

****(Each type of cell in the tissue has a specific function)****

D. ORGAN LEVEL

Organ : Is composed of two or more tissues types that perform one or more common functions. (For example, Heart, Liver, Lungs, Brain, Stomach)

E. ORGAN SYSTEM LEVEL

Organ System – Is a group of organs that have a common function or set of functions and are therefore viewed as a unit. (For example: Urinary system, Digestive system, Respiratory system, Reproductive system, Integumentary system, Skeletal system,

generalized to specialized.

Morphogenesis – Is changes in shape of tissues, organs and the entire organism.

6. Reproduction – Is the formation of new cells or new organisms.

CONTROL OF HOMEOSTASIS

Homeostasis - Is the existence and maintenance of a relatively constant environment within the body.

Cells need relatively stable conditions (fluids surrounding the cell) to function effectively and contribute to the survival of the body as a whole.

Variable Condition: For cell to function normally, the volume, temperature, and chemical content of the body fluid must remain within a narrow margin.

Set Point : The ideal normal value.

Normal range : Slightly around the set point values.

(Note: If the cell fluid surrounding cells deviate from homeostasis, the do not function normally and can die. Disruption of homeostasis results in disease and sometimes death).

Negative-Feedback

Negative means that any deviation from the set point is made smaller or is resisted.

Note: Most feedback systems in the body are negative.

Three Basic Components of a Negative Feedback Mechanism

1. Control center
2. Receptor
3. Effector
4. Control Center determines the point at which some aspect of the body, called controlled condition, should be maintained.

(Control center receives information about the status of a controlled condition from a receptor and then determines an appropriate course of action.

Hundred of Controlled Conditions exist in the body: (Heart rate, blood pressure, acidity of the blood, blood sugar level, body temperature, breathing rate, etc.)

2. Receptor monitors changes in the controlled condition and then sends the information, called inputs, to the control center.

Stimulus is any stress that changes a controlled condition.

(Example: A stimulus such as exercise raise the body temperature (the controlled condition), and thermal (heat) receptors send input to the control center, which in this case is in the brain.)

3. Effector receives information, called the output, from the control center and produces a response (effect).

(So while you are exercising, your brain (control center) signals for increased secretions by your sweat glands (effectors); as sweat evaporates from the skin, body temperature drops back to normal.)

*The response that occurs is continually monitored by the receptor and feed back to the control center.

Note: The maintenance of normal blood pressure is an example of a

REGIONAL NAMES

Regional names are terms given to specific region of the body for reference.

Examples: Cranial (skull), thoracic (chest), brachial (arm) patellar (knee), cephalic (head), and gluteal (buttock).

DIRECTIONAL TERMS

Direction terms indicate the relationship of one part of the body to another.

-Like regional names, used for uniformity all over the world.

PLANES AND SECTIONS

Planes are imaginary flat surfaces that are used to divide the body or organs into definite areas.

1. Sagittal Plane is a vertical plane that divides the body or an organ into right and left sides.
2. Midsagittal (median) Plane is a vertical plane that passes through the midline of the body or organs and divides it into equal right and left sides.
3. Parasgittal Plane is a sagittal plane that does not pass through the midline but instead divides the body or an organ into unequal right

and left sides.

4. Frontal (coronal) Plane divides the body or organ into anterior (front) and posterior (back) portions.
5. Transverse (cross-sectional or Horizontal) Plane divides the body or organ superior (top) or inferior (bottom) portions.

*Above planes are all at right angles to one another.

6. Oblique Plane passes through the body or organ at an angle between the transverse plane and either the midsagittal, parasgittal, or format plane.

BODY CAVITIES

Body Cavities are confined spaces within the body that contain internal organs.

-Cavities separated from each other by structure such as muscles, bones, or ligaments, help to protect, separate, and support the organs.

Two Principal Body Cavities:

1. Dorsal body cavity
2. Ventral body cavity
3. Dorsal Body Cavity is located near the dorsal (back) surface of the body.

Two principal subdivisions of Dorsal Body Cavity a. Cranial Cavity - formed by the cranial (skull) bones and containing the brain.

b. Vertebral (spinal) canal - formed by the vertebrae of the backbone

(1) Abdominal Cavity contains the stomach, spleen, liver, gallbladder, pancreas, small intestine, and most of the large intestine.

(2) Pelvic Cavity contains the urinary bladder, portions of the large intestine, and the internal organs of reproduction.

ABDOMINOPELVIC REGIONS AND QUADRANTS

Maybe divided into nine regions:

1. Right Hypochondriac region
2. Epigastric region
3. Left Hypochondriac region
4. Right lumbar region
5. Umbilical region
6. Left lumbar region
7. right iliac (Inguinal) region
8. Hypogastric (pubic) region
9. Left iliac (inguinal) region

*Examine Fig determine organs in different regions.

Maybe divided into four quadrants:

1. Right upper quadrant (RUQ)
2. Left upper quadrant (LUQ)
3. Right lower quadrant (RLQ)
4. Left lower quadrant (LLQ)