Introduction to Anatomy and Physiology Lecture I. The Sciences of Anatomy and Physiology

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Introduction to Anatomy and Physiology Lecture
I. The Sciences of Anatomy and Physiology

There are over 6 billion human bodies on the Earth today. Outside and inside, each one of these humans has the same basic design: two eyes, two ears, one heart, two lungs, etc.

Even so, there is an incredible variation in body shapes, sizes, and health of each of these humans.
This is why you are here today. Most of you here are interested a career that is health-related. It is important for you to understand the human body so that you can help your patients when some part of the human body is not functioning as it should.
In this course we will examine in detail the structures that make up human beings and the way in which these structures function together to keep humans alive.
That is, we are going to spend the next 16 weeks studying anatomy and physiology. What then does each of these terms mean?
A. Anatomy

(ana = up or apart; tomy = to cut)

Anatomy is the study of the internal and external structure of living organisms and the physical relationships between structures.
B. Physiology

(physio = nature; ology = study of)

In relation to the human body, physiology is the study of body function. It is the study of how living organisms perform their vital functions.
The word physiology is from two Greek words. Physio = nature and ology = study of. Thus physiology means "the study of nature".
Like anatomy, physiology can also be studied at different levels.
Anatomy and physiology are studied together to give a full appreciation and understanding of the body.

Anatomy and physiology are inseparable because what a structure does (its physiology) depends on its form or structure or shape (anatomy).

For example, bones can provide support and protection to internal organs (their function) because bones contain hard mineral deposits (their structure).

One concept I will be pointing out throughout the semester is the concept of how structure and function go together. Parts of the body have specific structures that make them suitable to perform their specific functions. As a matter of fact, by the end of the semester you will be sick of hearing me say the function of XXX is a result of its structure.

You are probably already familiar with this concept of structure and function.
[Delete below if time is tight]
For example, imagine you are going to be in a car race. The structure of the car you choose to drive will depend on the type of race (its function).
If the race is laps around a paved road, what shape should the car have? (small, sleek, etc).
If the race is through bumpy dirt roads, what type of car would you have? (monster truck, big wheels, etc).
The structure is dependent on the function just as in the human body.
Think about human teeth? Flat molars grind food, sharp pointed canines tear food, and incisors cut food.
II. Subdisciplines of Anatomy

Anatomy can be studied at different levels.

A. Microscopic Anatomy

(micro= small; scope = to view

Microscopic anatomy is the study of structures that are not visible to the unaided eye.
Most of the time microscopes ranging from the light microscopes we will use in lab to powerful electron microscopes are used to study microscopic anatomy.
1. Cytology

(cyto = cell; ology = study of)

Cytology is the study of the internal structure of individual cells.
2. Histology
(histo = tissue; ology = study)
Histology is the microscopic study of tissue structure (histo = tissue).
Tissues are groups of cells that carry out a specific function. We study the tissues of the organs to understand the organ's structure and function.
B. Gross Anatomy

For example, under anatomy, gross anatomy studies features visible to the naked eye (without a microscope). The word gross in this case means “immediately obvious or glaringly noticeable,” not “vulgar or disgusting”!

Gross anatomy is the study of large structures such as organs, bones, muscles, etc. and involves the technique of dissection. Dissection means "to section" or "to cut."
In this class we will study gross anatomy by dissecting cats during our lab time. Cats have bodies that are very similar in structure to human bodies so by studying the cats we can learn a lot about the human body.
1. Approaches to Studying Gross Anatomy
There are several approaches to studying gross anatomy
a. Regional Anatomy - study of the structures in a specific region of the body such all of the structures in the thoracic cavity (heart, lungs, trachea, esophagus, etc)
b. Surface Anatomy – study of the superficial (on the skin) anatomic markings in relation to the internal body structures. For example, by taking a person’s pulse, you can make observations about their blood vessels and even their heart.
By palpating (feeling) a person’s knee you can make assumptions about their knee joint, physical therapists use this type of gross anatomy quite a bit.
c. Systemic Anatomy - study of the components of an organ system. In a little bit we will define the term organ system.
For example when studying the digestive system the health care worker would study the mouth, esophagus, stomach, small intestine, large intestine, and rectum.
II. Levels of Organization

How do you begin to study the anatomy and physiology of humans, given that we are so complex? Think of how you try to understand how other complex things work. For example, how would you try to learn how a car works? A car is pretty complex. But what if you study each part of the engine (the starter, the transmission, the battery, etc) and then figure out how they all fit together? Wouldn't that make it easier to learn?

In this class, that is exactly what we will be doing. First we must simplify the human body and from there study each of its parts. Only then can we begin to understand how all of the parts of a living human being interact.
The human body consists of many levels of structural complexity. Let’s start with the most simple level:
A. Chemical Level

Atoms are the smallest unit of matter unique to an element. (Matter is anything that has mass and takes up space.)
E.g. carbon, hydrogen, oxygen, and nitrogen.
Atoms interact with each other to make up molecules. Molecules are substances made up of 1 or more atoms.
What are the 4 major organic molecules (molecules made of chains or rings of carbon atoms) that make up all living organisms, including human beings? carbohydrates, proteins, lipids, and nucleic acids
B. Cellular Level

Thousands or millions of molecules interacting together make up organelles.

Organelles are small structures that make up cells.
E.g. mitochondria, Golgi bodies, lysosomes.
Organelles interact to form cells. A cell is the basic unit (building block) of structure and function of all living things. All living organisms are made up of one or more cells.
Some living organisms such as bacteria are made up of one cell-they are unicellular.
Other organisms, such as humans and plants are made up of billions of cells- we are multicellular. In multicellular organisms the cells are further organized into different levels of organization.
C. Tissue Level

Many cells with a common structure and function together form tissues. A tissue is a group of similar cells that carry out a specialized job.

The four major types of tissue are epithelial, connective, muscular, and nervous
D. Organ Level

Many tissues interacting with each other can then form an organ. An organ is a structure made up of 1 or more tissues that carries out one or more special and specific functions.

For example, your stomach is an organ that helps to break down your food. It is made up of epithelial tissue, smooth muscle tissue, and connective tissue.

Your heart is an organ that pumps blood so that the blood will reach all corners of the body. It is made up of epithelial tissue, cardiac muscle tissue, nervous tissue, etc.

E. Organ System Level

Several organs working together can to form an organ system. An organ system is several organs that work together to carry out a specific function.

For example your digestive system is made up of the following organs all working together to break down food so that it can be absorbed by the body: mouth, esophagus, stomach, small intestine, large intestine, etc.
All organ systems interact and are interdependent. For example, the respiratory system needs the cardiovascular system to carry oxygen from the lungs to the body's cells.
A dysfunction in one system can cause the other systems to malfunction as well. For example, diabetes is a malfunction of the endocrine system. Diabetes causes abnormal increases in blood sugar levels, which can result in blindness, kidney shutdown and circulation problems. This is all due to side effects brought on by the abnormal increase of blood sugar levels.
F. Organism Level

All of the organ systems working together form a total functioning unit or organism.

In this course we will study ALL of these levels!
III. Systemic v. Regional Anatomy

Systemic – study of anatomy by system, Regional – study of anatomy by region.

Most students use a combination of regional and systemic study
A. The Integumentary System - Forms external body covering, protects deeper tissues from injury, synthesizes vitamin D, site of cutaneous receptors (pain, pressure, etc.) and sweat and oil glands
B. The Skeletal System - Protects and supports body organs, provides a framework for muscles, blood cells formed within bones, stores minerals
C. The Muscular System - Allows manipulation of environment, locomotion, facial expression, maintains posture, produces heat
D. The Nervous System - Fast-acting control system, responds to internal and external changes
F. The Endocrine System - Glands secrete hormones that regulate growth, reproduction, and metabolism
G. The Cardiovascular System - Blood vessels transport blood, carries oxygen and carbon dioxide, also carries nutrients and wastes, heart pumps blood through blood vessels
H. The Lymphatic System - Picks up fluid leaked from blood vessels, disposes of debris in the lymphatic system, houses white blood cells (lymphocytes), mounts attack against foreign substances in the body
J. The Respiratory System - Keeps blood supplied with oxygen, removes carbon dioxide, gas exchange occurs through walls of air sacs in the lungs
K. The Digestive System - Breaks down food into absorbable units, indigestible foodstuffs eliminated as feces
L. The Urinary System - Eliminates nitrogenous wastes, regulates water, electrolyte, and acid-base balance
M. Reproductive System - Overall function is to produce offspring, testes produce sperm and male sex hormones, ovaries produce eggs and female sex hormones, mammary glands produce milk

IV. Gross Anatomy: An Introduction

A. The Anatomical Position - Learning the anatomical position is essential because most of the directional terminology used in anatomy refers to the body in this position.

B. Directional and Regional Terms

1. Regional terms name the specific body areas.

2. The standardized terms of direction are: superior/inferior, anterior (ventral)/posterior (dorsal), medial/lateral, superficial/deep.

C. Body Planes and Sections

1. The body and/or organs are cut into sections along a flat surface called a plane.

2. Planes are identified as sagittal, frontal (coronal), transverse (horizontal), and oblique.

3. Sagittal planes are midsagittal (median) planes or parasagittal planes.

D. Body Cavities and Membranes

1. The dorsal body cavity is subdivided into the cranial cavity and the vertebral cavity.

a. The cranial cavity houses the brain.

b. The vertebral cavity runs through the vertebral column and encloses the spinal cord.

2. Ventral body cavity

a. Thoracic cavity – divided into three parts

1. Two lateral parts each containing a lung surrounded by a pleural cavity

2. Mediastinum – contains the heart surrounded by the pericardial sac

b. Abdominopelvic cavity – divided into two parts

1. Abdominal cavity – contains the liver, stomach, kidneys, and other organs

2. Pelvic cavity – contains the bladder, some reproductive organs, and rectum

3. Three serous cavities are all enclosed body cavities with no openings to the external surface of the body.

a. The pericardial cavity surrounds the heart.

b. The pleural cavity surrounds the lung.

c. The peritoneal cavity surrounds abdominopelvic viscera.

4. Several smaller cavities of various types are located mostly in the head.

a. The oral and nasal cavities with openings to the external surface of the body are lined with mucous membranes.

b. Orbital cavities house the eyeballs.

c. Middle ear cavities are located within the temporal bones of the skull and house the tiny ear ossicles.

d. Synovial cavities are joint cavities.

G. Abdominal Regions and Quadrants

1. The abdomen is divided into nine regions: the right and left hypochondriac region, the epigastric region, the right and left lumbar regions, the umbilical region, the right and left iliac region, and the hypogastric region.

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Biol 2304 Human Anatomy Fall 2007

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