DEFINITION OF ANATOMY & PHYSIOLOGY

Anatomy = study of structures by dissection, imaging, and microscopy

macro - gross & systemic, embryology & development

micro - cytology, histology

Physiology = study of functions by chemical and physical means: cells, organs, systems

[Pathology = study of anatomy and physiology during illness or after death]

INTRODUCTION TO THE HUMAN BODY

ANATOMY is the study of the structure of the body and of the relationship of its constituent parts to each other.

In regional anatomy a geographical study is made and each region, e.g., arm, leg, head, chest, etc., is found to consist of a number of structures common to all regions such as bones, muscles, nerves, blood vessels and so on.

From this study it follows that a number of different systems exist.

These have been grouped together and described under the heading systematic anatomy.

A study of the position and relationship of one part of the body could not be separated from a consideration of the use of the terms functional anatomy, which is closely allied to the study of physiology.

Then again it was found that certain structures could be examined by the naked eye and the term macroscopic anatomy was introduced to describe this study, in distinction to microscopic anatomy, which necessitates the use of a microscope.

Closely allied to the study of anatomy are histology, the study of the fine structures of the body, and cytology, the study of the cells.

PHYSIOLOGY is the study of the functions of the normal human body.

It is closely linked with the study of all living things in the subject of biology; as well as this three is the work of cytologist, interested in detail of the structure of cells, and that of the biochemist, dealing with the chemical changes and activities of cells and investigating the complex chemistry of life, and there is physics, the study of the physical reactions and movements taking place in the body.

The body is made up of many tissues and organs, each having its own particular function to perform.

The cell is the unit or the smallest element of the body of which all parts are comprised.

The cells are adapted to perform the special functions of the organ or tissue they are in.

Some cells, such as those in the nervous system and muscle, are very specialized indeed; others, such as those in the connective tissues, are less highly developed.

As a general rule the most highly specialized cells are the least able to withstand damage and also are the most difficult to repair or replace.

Levels of Organization

chemicals cells tissues organs systems

TISSUES: (epithelial, muscle, connective, nervous)

ORGANS: (contain several types of tissues)

SYSTEMS: (accomplish a complete function)

Every living organism is made up of units called cells.

These are tiny structures seen only through the microscope.

Cells are held together by special, intercellular material.

In the human body there are approximately 100 trillion cells.

The cells differ according to the function, which they do.

For example, the blood, muscle, and all cells have certain features in common.

All cells use oxygen from the air we breathe and substances from the food we eat to produce energy.

Production of waste material is common to all cells.

Also most cells can produce new cells, an whenever a cell dies (for whatever reason) new cells are formed.

In order to be able to produce energy, give rise to waste substances, and form new cells when needed, cells have tiny, specialized structures inside them, which can be observed with a very powerful microscope.

SIMPLEST FUNCTIONAL UNIT

CELL

A collection of cells all of which perform the same function is called tissue.

For example muscle (tissue) is made up of muscle cells, all of which can contract.

SEVERAL CELLS

TISSUE

A tissue is an organized group of cells of different types as well as their extracellular material (matrix)

There are only 4 classes of tissue :

epithelial tissue covers surfaces (e.g., skin, lining of body cavities, lining of hollow organs like bladder, stomach)

muscle tissue performs work or alters the shape of an organ

nervous tissue includes neurons and their support cells (called neuroglia)

connective tissue is all the rest (e.g., blood cells, bone & cartilage cells) cells & matrix that fill body spaces and bind tissues together

A collection of tissues forming a structure which has a particular function, is called an organ.

For example, the stomach has muscular, glandular, and other tissues, and is concerned with the churning (mixing) of food and digestion (breaking

down of food into

simple substances

which the body can use).

SEVERAL TISSUES

TOGETHER

ORGAN

Several organs, each performing a specific function, together make a system.

Each system has a particular part to play, in the overall functioning of an individual.

SEVERAL ORGANS

TOGETHER

SYSTEM

For example the digestive system has many organs.

Among them are – the mouth (chew and moisten food), esophagus (deliver food to stomach), stomach (grind

and dissolve food), small

intestine (finishes digesting

food and absorbs

nutrients), large intestine

(reabsorbs water to prevent

loss), and rectum

(stores feces).

TERMS USED IN ANATOMY

Superior - toward the head Inferior - away from the headAnterior - the front of the

body or body partPosterior - the back of the

body or body partMedial - toward the midline

that divides left and rightLateral - to the side away

from the midline

Proximal - closer to the torsoDistal - farther away from the

torso

Anatomical position - standing erect, facing the observer, arms are at the sides with palms facing forward.

Many parts of the body are symmetrically arranged.

For eg., the right and left limbs are similar, there are right and left eyes and ears, right and left lungs, and right and left kidneys.

But there is also a good deal of asymmetry in the arrangement of the body.

The spleen lies entirely on the left side; the largest part of the liver lies on the right side, the pancreas lies partly on each side.

The human body is studied from the erect position with the arms by the sides and the palms of the hands facing forwards, the head erect and eyes looking straight in front.

This is described as the anatomical position.The various parts of the body are described in

relation to certain imaginary lines or planes.The median plane runs through the centre of

the body.The terms internal and external are used to

describe the relative distance of an organ or structure from the centre of the cavity.

Anatomical Position

Eg., the internal carotid artery is within the cranial cavity and the external is outside the cavity.

The terms superficial and deep are used to denote relative distance from the surface of the body, and the terms superior and inferior denote positions relatively high or low, particularly in relation to the trunk, such as the superior and inferior surfaces of the clavicle.

The terms anterior and posterior are synonymous with ventral and dorsal.

The terms proximal or distal are employed to describe nearness to or distance from a given point.

When three structures are in a line running from the medial plane of the body outwards, they are described as being placed in medial, intermediate, and lateral positions.

Similarly three structures run from front to back – anterior to posterior or from downwards – superior to inferior.

SYSTEM OF THE BODY

According to the functions they perform andUnder the heading of the different terms

employed to indicate the knowledge of certain parts.

Systematic anatomy or the division of the body into systems is arranged:

ExampleOsteology – is a knowledge of – bones.Myology – is a knowledge of – muscles.Neurology – is a knowledge of – nerves and

nerve structure.

INTRODUCTION TO THE CHEMISTRY OF LIFE

Living systems obey chemical and physical laws.

For example, energy transformations in the cell occur by the formation and breaking of chemical bonds.

These chemical reactions result in the reorganization of subatomic particles.

The element carbon forms a vast number of compounds.

Over 16 million carbon-containing compounds are known, and about 90% of the new compounds synthesized each year contain carbon.

The study of carbon compounds constitutes a separate branch of chemistry known as organic chemistry.

This term arose from the 18th century belief that organic compounds could be formed only by living systems.

This idea was disproved in 1828 by the German chemist Friedrich Wohler when he synthesized urea (H2NCONH2), an organic substance found in the urine of mammals, by heating ammonium cyanate (NH4OCN), an inorganic substance.

The notion that organic chemicals and living organisms are connected is certainly true in one sense: Life as we know it could not exist without a vast array of complex, biologically important organic molecules. The study of the chemistry of living species is called biological chemistry, or biochemistry.

Life is recognized by certain characteristics:Metabolism:

The sum of chemical processes in an organismAnabolism = chemical reactions that build-up

or synthesizeCatabolism = chemical reactions that break-

down or fragment

Equilibrium exists when the organism is in "steady state",

i.e., amount of anabolism equals amount of catabolism. eg: healthy adult is in steady state; eg: growing healthy child is in anabolic state

Responsiveness: Ability to detect and respond to external stimuli eg: afferent nervous system monitors external

environment, and then the efferent nervous system alters the body to accommodate the environment.

Movement: Displacement of the whole organism as well as

rearrangement of the relative positions of the organism's parts

eg: skeletal muscle impels legs to run; eg: smooth muscle causes intestine to move food along.

Growth: Increase in organism size (may be cyclical as in

bacteria) caused when anabolism exceeds catabolism.

Differentiation Is mostly present in multicellular organisms.

Different cells or tissues or organs specialize to perform one function and lose the ability to perform any other function.

eg: lymphocytes in the blood detect and respond to foreign materials in the body (e.g., bacteria); they are not able to carry oxygen or phagocytose debris or cause the blood to clot.

Reproduction: Forming new cells to replace damaged or

senescent cells or even to "replace" the whole organism.

eg: sperm and ova can result in a baby; eg: "stem cells" in your epidermis can reproduce to replace the damaged epithelium when you injure your skin

Homeostasis in the normal, healthy, adult state = equilibrium

A major mechanism for homeostasis is communication and exchange of materials between intracellular fluid (ICF), interstitial fluid (between cells) and plasma (the liquid portion of blood).

(Extracellular fluid (ECF) = plasma plus interstitial fluid.)

A major mechanism for homeostasis is "negative feedback“

Negative Feedback: a specific stimulus causes a specific response, and the response "fixes" (i.e., reverses) the stimulus.

Stimulus and response mechanisms are

commonly hormones and nerves

eg: stimulus is scary situation, response is secretion of hormone adrenalin which sends blood and oxygen to heart, lungs, and muscles so you can escape, result is decrease in adrenalin due to escape from the original stimulus; blood and O2 transport return to resting state

eg: sensors in the tendons of your legs detect stretching when you are about to lose your balance, reflex neuron causes contraction of the muscle attached to the tendon, muscle pulls you upright & releases the stretch stimulus, result is restoration of balance

Positive feedback: specific stimulus causes a specific response that makes the stimulus even stronger even stronger response….

note: this can be a vicious circle unless something else ("termination mechanism") intervenes.

eg: stretching of cervix during childbirth stimulates secretion of hormone (oxytocin) which causes uterus to contract and stretch the cervix even more, etc.

Here the "termination mechanism" is baby's birth which interrupts the feedback by eliminating the source of cervical stretching.

Feedback systems always involve 3 components:

receptor - senses the stimulus

control center - interprets the stimulus & determines response

effector - produces the response If any of the 3 components is missing or

malfunctions, then the feedback system won't work.

eg: Site in the hypothalamus of the brain is responsible for keeping the body at 37oC (98.6oF) by regulating heat loss through the skin, breath, etc.

When bacterial toxins are released into the body, chemicals called prostaglandins are produced which cause the hypothalamus to set the equilibrium temp at a higher value.

Bacterial infections cause fever (“failure” of temperature equilibrium).