Chapter 2

The Human Body in Health and Disease

Chapter 2 Objectives• Define and decipher common terms associated with the

structural organization of the body

• Identify the body cavities and list the organs contained within those cavities

• Locate and name the anatomical divisions of the back

• List and define terms related to positions, direction and planes of the body

• Analyze unfamiliar terms using knowledge of word roots, suffixes and prefixes

Branches of Science that Study the Human Body

Anatomy – studies the structure of the body

Physiology – studies the normal functions of the structures of the human bodyBiology – the study of all forms of life and living things

Embryology– the study of the origin and development of an organism– Covers from 2nd to 8th week after conception, the

embryonic stage– After 8 weeks, the developing organism is known as a

fetus

• Histology – the study of the structure, composition and functions of tissues

• Cytology – the study of the anatomy, physiology, pathology, and chemistry of the cell

• Pathology – the study of the nature and cause of diseases that involve changes in structure and function.

• Epidemiology – study of outbreaks of disease within a population group

Anatomic Reference Systems

• Describe the location and functions of body parts using:

– Body planes

– Body directions

– Body cavities

– Structural units (ex. A cell, a tissue, an organ)

Anatomic Position

• Body Erect• Arms at side• Palms forward• Head and neck forward

So…what’s up with page 30?

Body PlanesImaginary horizontal and vertical lines used to divide the body

Vertical plane – an up and down line that is a right angle to the horizon

• Midsagittal plane –also known as the midline, divides the body into equal left and right sides

• Sagittal plane – divides the body into left and right portions

• Frontal plane – divides the body into anterior (front) and posterior (back) portions. Also known as the coronal plane

Horizontal plane – a flat crosswise plane, such as the horizon

• Transverse plane – a horizontal plane that divides the body into superior (upper) and inferior (lower) portions. Can be at the waist or at any other level across the body

Directional TermsUsed for the most precise descriptions possible

Ventral Dorsal Anterior PosteriorSuperior InferiorCephalic CaudalProximal DistalMedial Lateral

Let’s Put it All Together

Major Body Cavities

There are 2 major body cavities (spaces) that contain and protect internal organs

1) Dorsal cavity – located along the back of the head and body and contains:

»Cranial cavity – located in skull protects the brain

»Spinal cavity – located in the spinal column . Surround and protects the spinal cord

2) Ventral Cavity – located along the front of the body and contains:

»Thoracic cavity – AKA chest or thorax, surrounds and protects the heart and lungs

Note: the diaphragm is a muscle used in breathing that divides the thoracic cavities!

»Abdominal cavity – contains primarily the major organs of digestion and is often just referred to as the abdomen

»Pelvic cavity – the space formed by the hip bones and contains the reproductive and excretory organs

Major Body Cavities

Regions of the Thorax & Abdomendescriptive system that divides the lower part of the

thorax and abdominopelvic area into 9 parts

Quadrants of the Abdomen

The Peritoneuma multi-layered membrane that protects and holds the organs in

place within the abdominal cavity

• Parietal Peritoneum – the outer layer that lines the interior of the abdominal wall

• Visceral Peritoneum – the inner layer that surrounds the organs of the abdominal cavity

• Mesentery – fused double layer of the parietal peritoneum that attaches sections of the intestines to the abdominal wall

• Retroperitoneal – means located behind the peritoneum

• Peritonitis – inflammation of the peritoneum

Levels of Structural Organization (6) 1. Chemical level – atoms combine to form molecules

2. Cellular level – molecules combine to form cells

3. Tissue level – groups of similar cells that have a common function

4. Organ level – at least 2 tissues combined (usually 4) that perform a specific function

5. Organ system level – consists of multiple organs working closely together to accomplish a

common purpose

6. Organismal level – the result of all structural levels working together

6. Organismal Level

Cytology

• The study of the formation, structure, and function of cells, including:

– Chromosomes

– DNA

– Genetics

• Cells- the basic structural and functional unit of the body. When cells are specialized and grouped together, they form tissues.

The Structure of Cells

Cell membrane – the tissue that surrounds and protects the contents of the cell and separates it from the external environment

Cytoplasm – the material within the cell membrane that contains and suspends the organelles

Nucleus – the control center of the cell and is involved in cell division

Stem Cells• unspecialized cells that are able to renew

themselves for long periods of time by cell division

• in contrast, specialized cells (liver cells, muscle cells, etc..) have a shorter life span

• May be transformed into a specialized cell (ex. Pancreatic cell that is capable of producing insulin)

Adult Stem Cells – undifferentiated, and can potentially be transplanted from one person to another (bone marrow transplant) but matching must be very close to prevent rejection

Embryonic Stem Cells• Undifferentiated cells, can grow rapidly and indefinitely in

a lab and could potentially provide a source for adult muscle, liver, bone, or blood cells.

• More primitive than adult stem cells which means there does not need to be a donor/recipient match – there is little risk for rejection

• Come from cord blood found in the umbilical cord and placenta of new born infants.

• Can be harvested at the time of birth without danger to mother or child and kept frozen until needed for treatment purposes.

• Can also be obtained from extra embryos produced by in vitro fertilization with the informed consent of the donor couple.

GeneticsThe study of how genes are transferred from parents to

their children and the role of genes in health and disease

• Gene – fundamental physical and functional unit of heredity. This is what determines whether you will have blue eyes or brown, curly hair or strait

• Dominant gene – when inherited the offspring will display that genetic condition or trait

• Recessive gene – if inherited from both parents, offspring will have the condition or trait. Ex. Sickle cell disease. If inherited from only one parent the child will not display the condition or trait but will carry trait and can still pass it to their offspring

Remember: inside each cell there are 23 chromosomes made up of DNA molecules that contain the body’s genes.

When there is a genetic mutation there is a change in the sequence of a DNA molecule. This can sometimes be caused by exposure to radiation or environmental pollution.

A genetic disorder, on the other hand, is a pathological condition caused by an absent or defective gene. Some examples of genetic disorders are:

• Cystic fibrosis• Down syndrome• Hemophilia• Huntington’s disease• Muscular dystrophy• Phenylketonuria• Tay-Sachs disease

Histology

• The study of tissues, which are composed of groups of similar cells that join together to perform specific functions, including:

– Stem Cells

– Epithelial Tissues

– Connective Tissues

– Muscle Tissue

Epithelial Tissuesform a protective covering for all the internal and external surfaces of the body and also form glands

• Epithelium- specialized epithelial tissue that forms the epidermis of the skin and the surface layer of the mucous membranes.

Epi- means _____________________

• Endothelium – specialized epithelial tissue that lines the blood and lymph vessels, body cavities, glands and organs

Endo- means _____________________

Connective tissues4 types that support and connect organs and other

body tissues

1. Dense connective tissue: form the joints and framework of the body. Ex: bone and cartilage

2. Adipose tissue: provides protective padding, insulation, and support. Also known as fat

3. Loose connective tissue: surrounds various organs and supports both nerve cells and blood vessels

4. Liquid connective tissue: transport nutrients and waste products. Ex: blood and lymph

• Muscle tissue – contains cells with the special ability to contract and relax

More to come in chapter 4!

• Nervous tissue – contains cells with the specialized ability to react to stimuli and to conduct electrical impulses

More to come in chapter 10!

Tissue Formation = -plasia

Incomplete Tissue Formation

Aplasia – the defective development, or the congenital absence or an organ or a tissue

Hypoplasia – the incomplete development of an organ or tissue usually due to a deficiency in the number of cells

Example: Spina bifida

Spina bifida is a congenital disorder (birth defect) in which the backbone and spinal canal do not close before birth.

Abnormal Tissue Formation

Anaplasia – the change in the structure of cells and their orientation to each other

Dysplasia – abnormal development or growth of cells, tissues, or organs

Hyperplasia – the enlargement of an organ or tissue because of an increase in the number of cells in the tissue

Hypertrophy - a general increase in the bulk of a body part or organ that is due to an increase in the size, but not the number of cells in the tissue

Here’s another way to look at it….

Anaplastic alphabet – Letter structure is unrecognizable

Dysplastic alphabet – abnormal development of letters but you can still recognize them

ABCDEFGHIJKLMNOPQRSTUVWXYZ

Hyperplastic alphabet – same letters just more of them

AABCDDEFGGHIJKLLLMNOPQRRSTUVWWXYYZZZZZ

Hypertrophic alphabet – same letters just larger letters

ABCDEFGHIJKLMNOPQRSTUVWXYZ

Hyperplasia = increase in the number of cells

Hypertrophy = increase in the size of the cells

Glands

• Specialized cells that secrete material used elsewhere in the body, including:

Exocrine Glands – secrete substances that lead to other organs or outside the body. Ex. Sweat glands

Endocrine Glands – produce hormones that are secreted directly into the bloodstream, do not have ducts. Ex. Thyroid gland

More to come later…

A communicable disease is any condition that can be spread from one person to another. There are several ways this can happen….

Indirect contact transmission- you catch the disease by coming into contact with a contaminated surface

Disease Transmission

Bloodborne transmission disease is spread through contact with blood or other body fluids that are contaminated with blood. Ex. HIV

Airborne transmissionoccurs through contact with contaminated respiratory droplets spread by a cough or sneeze. Ex. TB, flu, cold

Food-borne and waterborne transmission - also known as fecal-oral transmission, is caused by eating or drinking contaminated food or water that has not been properly treated to remove contamination or kill pathogens that are present

Vector-borne transmission – disease spread by the bite of a vector (insect or animal) that is capable of spreading disease

Rabies Lyme diseaseRocky Mountain Spotted Fever

West NileMalaria

Outbreaks of Diseases• Endemic – the ongoing presence of a disease

within a population, group, or area. Ex. The common cold

• Epidemic – a sudden and widespread outbreak of disease within a specific population group or area. Ex. A sudden widespread outbreak of the flu

• Pandemic –an outbreak of a disease occurring over a large geographic area, possibly worldwide. Ex. AIDS

Types of Diseases• Functional disorder- produces symptoms for

which no physiological or anatomical cause can be identified. Ex: panic attack

• Iatrogenic illness – an unfavorable response due to prescribed medical treatment. Ex: severe burns after radiation therapy

• Idiopathic disorder – an illness without a known cause

Types of Diseases• Infectious disease – an illness caused by a living

pathogenic organism such as bacteria or viruses

• Nosocomial infection – a disease acquired in a hospital or clinical setting. Ex: ventilator acquired pneumonia, MRSA

• Organic disorder – produces symptoms caused by a detectable physical change in the body. Ex. The rash associated with chicken pox is caused by a virus