THE HUMAN BODY PARTS

2. 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]

3. 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.

4. 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.

5. 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.

6.  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.

7. 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.

8. Levels of Organization
chemicals → cells → tissues → organs → systems
TISSUES: (epithelial, muscle, connective, nervous)
ORGANS: (contain several types of tissues)
SYSTEMS: (accomplish a complete function)

9. 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.

10. 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.

11. 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

12. 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

13.  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

14. 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

15. 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

16. 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).

17. TERMS USED IN
ANATOMY
Superior - toward the head
Inferior - away from the head
Anterior - the front of the
body or body part
Posterior - the back of the
body or body part
Medial - toward the midline
that divides left and right
Lateral - to the side away
from the midline

18. Proximal - closer to the torso
Distal - farther away from the
torso
Anatomical position - standing
erect, facing the observer, arms
are at the sides with palms
facing forward.

19. 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.

20. 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.

21. Anatomical
Position

22.  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.

23. 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.

24. SYSTEM OF THE BODY
According to the functions they perform and
Under 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:
Example
Osteology – is a knowledge of – bones.
Myology – is a knowledge of – muscles.
Neurology – is a knowledge of – nerves and
nerve structure.

25. 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.

26. 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.

27. 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

28. Life is recognized by certain
characteristics:Metabolism:
The sum of chemical processes in an organism
Anabolism = chemical reactions that build-up
or synthesize
Catabolism = 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

29. 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.

30. 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.

31. 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

32. 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“

33. 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

34. 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

35.  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.

36.  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.

37.  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).