Arsi University

School of Medicine
Biomedical Department
Human Anatomy Unit

Introduction to Human Anatomy

For Medical Laboratory students

By Zerihun A. (BSc,MSc.)

1
 Outline
Definition of anatomy
Subdivisions of anatomy
Approaches to studying Anatomy
Levels of Structural Complexity/organization of the body
The Language of Anatomy
Body Planes and Sections
Body Cavities
Regions of the body

5/25/2021 2
 Definition

• Anatomy: derived from Greek ‘anatome’: meaning to dissect

or cutting up
• Anatomy is the study of structure of body parts and their
relationships to one another

5/25/2021 3
 Subdivisions of anatomy

• 4 major
– Gross Anatomy: study of body structures visible to
naked eye
– Cellular Anatomy: study of structure of cells
• Histology: study of the microscopic structure of tissues
• Developmental Anatomy: study of changes in an
individual from conception to old age
• Embryology: study of the developmental changes that occur
before birth

5/25/2021 4
 Approaches to studying Anatomy
3 main
1. Regional Anatomy: study all structures located in a
particular region of the body
2. Systemic Anatomy: study body systems
3. Clinical (applied) Anatomy: emphasizes on features
important in practice of medicine

5/25/2021 5
Levels of Structural Complexity/Organization of the body

• Chemical (Atom)
• Cellular(Cell)
• Tissue
• Organ
• System
• Organism

5/25/2021 6
 Chemical Level
• Atoms and molecules essential for life
– Atoms: C, H, O, N, Ca, K, Na
– Molecules: proteins, carbohydrates, fats, vitamins,
water,DNA

5/25/2021 7
 Cellular Level
• Cells are the basic structural and functional units of
living organism
E.g : Hepatocytes
• muscle cells
• RBC
• nerve cell

5/25/2021 8
 Tissue Level

• Consists of groups of similar cells that have a common

function
• 4 types of tissue
• epithelium
• muscle
• connective
• nervous

5/25/2021 9
 Tissue
•The human body contains about 100 trillion cells.

•However, no one cell can carry out all the necessary bodily
functions by itself. So, cells aggregate and form TISSUES

Collection of cells with a similar structure and function.

•The study of tissues is known as histology

5/25/2021 10
There are 4 primary tissue types in the human body:

1. Epithelial (covering/lining)
2. Connective (support)
3. Muscle (movement)
4. Nervous (control)

• These tissues differ in the types and functions of their cells,

and the products of those cells

5/25/2021 11
 Epithelial Tissue
•Covers the surface of the body, lines the body cavities, forms the external
and internal linings of most organs, and constitutes the bulk of most glands.

•Functions include:
1.Protection 4. Absorption
2.Secretion 5. Filtration
3.Sensory reception

•It’s found all over the place!

5/25/2021 12
We classify epithelia based on the number of cell layers present and
the shape of the cells in the apical layer.

• If there is only one layer of cells, the epithelium is simple.

• If there is more than one layer, the epithelium is stratified.

•There are 3 cell shapes:

1.Squamous = flat, scale-like
2.Cuboidal = cube-shaped
3.Columnar = column-shaped

5/25/2021 13
Types of Epithelia

•You can see that we’ve got at least 6:

1.Simple squamous
2.Simple cuboidal
3.Simple columnar
4.Stratified squamous
5.Stratified cuboidal
6.Stratified columnar

•There are actually 2 other ones that are special –transitional epithelium
and pseudo stratified columnar epithelium.

5/25/2021 14
 Simple Squamous Epithelium

•Locations:
–Air sacs (alveoli) of lungs
–Glomerular capsules of kidneys
–Some kidney tubules
–Lining of heart and all blood vessels
•Here it’s called the endothelium
–Serous membranes
–External lining of visceral organs
. Here it’s called the mesothelium

5/25/2021 15
 Simple Cuboidal Epithelium

•Microscopic Appearance:
–Single layer of square or round cells.
–Centrally-placed spherical nuclei.
–Apical layer often has microvilli.
•Microvilli are small extensions of the cell membrane that
increase the surface area of the cell.
•You usually want a cell to have more surface area when it is
involved with secretion or absorption

5/25/2021 16
 Locations:
–Liver
–Pancreas
–Thyroid, salivary, and most other
glands
–Most kidney tubules
–Bronchioles (small tubes within the lungs)

Functions:
–Absorption
–Secretion

5/25/2021 17
 Simple Columnar Epithelium
Microscopic Appearance:
–Single layer of tall, narrow cells.
–Oval shaped nuclei, vertically-oriented, usually located in the basal
half of the cell.
–Secretory vesicles sometimes visible in apical portion of the cell.
–Microvilli occasionally present.
–Cilia occasionally present.
•Cilia are hair-like extensions of the cell membrane that can move
and sweep material across the cell surface
–Goblet cells often interspersed.
•Secrete a lubricating mucus

5/25/2021 18
Locations:
–Inner lining of stomach, intestines, and rectum.
–Inner lining of gallbladder
–Inner lining of uterus and uterine tubes
Functions:
–Absorption and secretion
•Columnar cells in small intestine have microvilli to increase the
available surface area for the absorption of nutrients.
–Movement of egg and embryo in uterine tube.
•Hence the presence of cilia.
–Secretion of mucus.
•Lots of goblet cells in the large intestine so as to lubricate it and
ease the passage of feces.

5/25/2021 19
 Stratified Squamous Epithelium
•Microscopic Appearance:
–Multiple cell layers with cells becoming flatter and flatter
toward surface.

–In keratinizedstratified squamous epithelium, the apical layers are

layers of dead cells lacking nuclei and packed with the tough protein
keratin.

–Nonkeratinizedstratified squamous epithelium lacks the layers of dead

cells at the surface.

5/25/2021 20
•Location of keratinized version:
–Epidermis. Palms and soles of feet are typically heavily keratinized.

•Locations of non-keratinized version:

–Lining of oral cavity and surface of tongue
–Lining of esophagus
–Lining of vagina and anal canal
Functions:
–Protection!
–Keratinized version ( dry epithelium) protects against mechanical abrasion,
water loss, and pathogen entry.
•Keratin is very strong, waterproof, and is bacteriostatic (prevents
bacteria from reproducing).
–Non-keratinized version (wet epithelium) also protects from mechanical
abrasion.
•Eating food, swallowing, sexual intercourse, birth, defecation.

5/25/2021 21
 Stratified Cuboidal Epithelium
•Microscopic Appearance:
–2 or more layers of cells.
–Surface layers are square or round (cuboidal).
•Locations:
–Some sweat gland ducts.
–Ovarian follicle
•Cells that surround the developing egg
Functions:
–Contributes to sweat secretion.
–Secretion of ovarian hormones (e.g., estrogens)
5/25/2021 22
 Stratified Columnar Epithelium
•Microscopic Appearance:
–2 or more layers of cells.
–Surface cells tall and narrow with basally located nuclei.
•Locations:
–Rare.
–Small portions of anal canal, pharynx, epiglottis, and male
urethra.
–Sometimes seen in large ducts of sweat and salivary glands.
•Functions:
–Often seen where 2 other tissue types meet
–Structural integrity of gland ducts

5/25/2021 23
 Pseudo stratified Columnar
Epithelium
Microscopic Appearance:
–Looks multi-layered, but it’s NOT!
•All cells touch the basement membrane.
•In stratified epithelia, only the bottom cell layer touches the
basement membrane.
–Cells are of varying heights which gives the appearance of
stratification. Nuclei are at several levels.
–Often has goblet cells interspersed.
–Cells often have cilia.

5/25/2021 24
Locations:
–Respiratory tract from nasal cavity to bronchi.
•Ciliated
•Goblet cells
–Portions of male reproductive tract
•Non-ciliated

5/25/2021 25
Functions:
–In the respiratory tract there are lots of mucus-secreting
goblet cells.
–The mucus traps dust and bacteria
–Cilia ― sweep the bacteria-laden mucus up the respiratory
tract towards the pharynx where it can be swallowed.
–Smoking paralyzes cilia –smokers have to cough violently
to expel their mucus. Then they die!

5/25/2021 26
 Transitional Epithelium

•Microscopic Appearance:
–Somewhat resembles stratified squamous epithelium, but
the surface cells are rounded and often bulge above surface
(dome-shaped).
–Typically 5-6 cell layers thick when relaxed and 2-3 cell
layers thick when stretched.
–Cells may be flatter and thinner when epithelium is
stretched.
–Some cells are binucleate, i.e., they have 2 nuclei.

5/25/2021 27
Locations:
–Predominant epithelium lining the urinary tract
–Found in part of the kidney, the ureters (tubes that connect the
kidney to the urinary bladder), the urinary bladder, and part of
the urethra.
•Functions:
–Stretches to allow filling of the urinary tract.
–Originally called ― transitional because it was thought to be an
intermediate between stratified squamous and stratified
columnar epithelium.
• This isn’t true but the name has persisted.

5/25/2021 28
 Connective Tissue
Most abundant, widely distributed, and histologically variable of
the 4 primary tissue types.
•Consists of cells that are typically widely separated by lots of
extracellular material –referred to as the extracellular matrix.

•Most cells are not in contact with each other but are distributed
throughout the extracellular matrix.

5/25/2021 29
 Functions of Connective Tissue

1.Binding of organs
2.Support
3.Physical protection
4.Immune protection
5.Movement
6.Storage
7.Heat production
8.Transport

5/25/2021 30
 Categories of CT

1.Fibrous connective tissue (connective tissue proper)

.dense ct
.Loose ct
.Fibrous ct
2.Supporting connective tissue
.Bone
.Cartilage
3.Fluid connective tissue
.Blood

5/25/2021 31
 Muscle tissue
The muscle tissue can be classified into three
categories:
1. Skeletal muscle :Striated &voluntary
2. Cardiac muscle : striated & involuntary
3. Smooth muscle: non striated & involuntary

Specialized to contract and exert forces on other tissues.

 Major function is the creation of movement.
Nervous Tissue
 Nervous tissue contains two types of cells
I. Nerve cells or neurons
II. Supporting cells or neuroglia
I. Neuron is the basic structural and functional unit of the
nervous system.
• All neurons have a cell body (soma).
– The body contains, nucleus, nucleolus, cytoplasmic membrane,
cytoplasm contains organelles .
• The nerve cells have processes called dendrites, which act like
antennae for the cell that they receive impute to the cell.
• There is only one axon in each neuron.
 Axons are able to transmit nerve impulse from the cell body to
some distant target in the brain or the periphery.
 It is like a nerve cell sits in the spinal cord possesses an axon
which contacts a muscle in the foot.
Function:
Detects stimuli, integrates information, and transmits signals.
 Organ Level

● A structure that is composed of at least two tissue types

which performs a specific function for the body
E.g.: Brain, Heart, Kidneys,Lungs,stomach, bladder, etc

5/25/2021 39
 System Level

• Organs that cooperate with one another to perform a

common function
• E.g. Nervous System, Respiratory System, Cardiovascular
System

5/25/2021 40
 Organism Level

• The highest level of organization, the living organism

5/25/2021 41
5/25/2021 42
 Systems of the body
 The 11 human systems
 Integumentary
 Skeletal
 Muscular
 Nervous
 Endocrine
 Circulatory
 Cardiovascular
 Lymphatic
 Respiratory
 Digestive
 Urinary
 Reproductive
 Immune system
5/25/2021 43
 The Language of Anatomy

• Anatomical position
• Directional terms
• Regional terms
• Body planes and sections
• Body cavities and membranes

5/25/2021 44
 Anatomical Position
 Anatomical position
 Body erect
 Head, eyes and toes directed
forward
 feet together
 Arms at side with palms facing
forward
 All anatomical descriptions are
expressed in relation to the anatomical
position

5/25/2021 45
 Directional Terms

• Superior: Toward the head or upper part of a structure or

the body (Cranial)
• Inferior: Away from the head or toward the lower part of a
structure or the body (Caudal)
• Anterior (ventral) : Toward or at the front of the body

• Posterior (dorsal): Toward the back of the body; behind

5/25/2021 46
 Directional Terms
• Proximal: closer to the origin of the body part, or the point
of attachment of a limb to the body trunk (point of
reference)
• Distal: farther from the origin of a body part or the point of
attachment of a limb to the body trunk
• Medial: Toward or at the midline of the body
• Lateral: Away from the midline of the body
• Superficial: toward or at the body surface
• Deep: away from the body surface; more internal

5/25/2021 47
 Shoulder – point of reference

Elbow – proximal (nearer, closer)

Wrist – distal (further)

5/25/2021 48
 Body Planes and Sections
• The body is sectioned along an
imaginary flat surface called a
plane
• The most frequently used
body planes are
– Sagittal
– Frontal (Coronal)
– Transverse
– Median(Mid sagitttal)
• The 3 are at right angles to
each other

5/25/2021 49
 Body Planes
• Sagittal plane lies vertically
and divides the body into
right and left parts

5/25/2021 50
 Body Planes

• Frontal (coronal) plane

divides the body into
anterior(ventral) and
posterior(dorsal) sections

5/25/2021 51
 Body Planes

• Transverse plane (Horizontal/Cross

sectional plane)runs horizontally
and divides the body into superior
and inferior sections

5/25/2021 52
 Terms of movement
• Flexion: decreasing angle
• Extension: increasing angle
• Abduction: moving away from plane
• Adduction : toward the sagittal
• Protraction: moving forward
• Retraction : backward along a surface
• Elevation: raising
• Depression: lowering a structure
• Medial rotation :movement around an axis of a bone
• Lateral rotation
• Pronation: placing palm backward
• Supination : forward (in anatomical position)
• Circumduction: combined movements of flexion,
extension, abduction, adduction
medial and lateral rotation
circumscribe a cone
• Eversion
• Inversion
• Opposition: bringing tips of fingers and thumb together as in picking something up
5/25/2021 53
5/25/2021 54
5/25/2021 55
5/25/2021 56
5/25/2021 57
5/25/2021 58
5/25/2021 59
5/25/2021 60
5/25/2021 61
 Regional terms
 There are two fundamental divisions of our body
 Axial
 Head
 Neck
 Trunk
 Thorax
 Abdomen
 Back
 Pelvis and perineum
 Appendicular
 Upper limb
 Lower limb
 Pelvic gridle
 Shoulder gridle
5/25/2021 62
5/25/2021 63
5/25/2021 64
 Body cavities
• Are potential spaces that serve to confine organs and systems that have related
functions.
• The major portion of the nervous system occupies the posterior cavity;
• the principal organs of the respiratory and circulatory systems are in the
thoracic cavity;
• the primary organs of digestion are in the abdominal cavity; and the
reproductive organs are in the pelvic cavity.
• Not only do these cavities house and support various body organs, they also
effectively compartmentalize them so that infections and diseases cannot spread
from one compartment to another.
 For example, pleurisy of one lung membrane does not usually spread to the other, and an
injury to the thoracic cavity will usually result in the collapse of only one lung rather
than both.

5/25/2021 65
 Body Cavities
2 main: dorsal(posterior) and ventral(anterior)

5/25/2021 66
 Dorsal Body cavity

• Divided into 2
– cranial cavity which encases the brain
– vertebral cavity (canal) which houses the
spinal cord

5/25/2021 67
 Ventral Body cavity

• Divided into 2 parts

– Thoracic cavity
– Abdominopelvic cavity

5/25/2021 68
 Thoracic Cavity

• Surrounded by the ribs and

muscles of the chest
• It is further divided into
– pleural cavities
– mediastinum
– Pericardial cavity

5/25/2021 69
 Abdominopelvic Cavity

• lies below the

diaphragm
• It is further divided
into
– Abdominal cavity
– Pelvic cavity

5/25/2021 70
 Body Membranes

 MEMBRANES- flat sheets of pliable(flexabil) tissue that cover or

line a part of the body.

1.Epithelial Membranes-
 layer of Epithelial Tissue and underlying Connective Tissue
A. Mucous membrane(Mucosa)- lines a body cavity that opens directly
to the outside (digestive, respiratory etc.)

5/25/2021 71
B. Serous Membrane (Serosa)-lines a body cavity that does not open
directly to the outside and covers organs in the cavity
-consist thin layers of areolar CT covered by mesothelium
1. Pleura is serous membrane of the thoracic cavity
a. Parietal pleura lines the cavity
b. Visceral pleura covers organs
c. Pericardium is special visceral serous membrane that covers
the heart
2. Peritoneum is the serous membrane of the abdominopelvic cavity
a. Parietal peritoneum lines the cavity
b. Visceral peritoneum covers organs
C. Cutaneous membrane- the skin

5/25/2021 72
2.Connective tissue membranes
A, Synovial Membranes -line the cavities of freely movable joints.
 These contain no epithelium, composed of areolar CT with elastic fibers
and fat.
 They secrete synovial fluid which lubricates the joint and nourished the
cartilage.
Synovial membranes also form:
 Bursae -cushioning sacs
 Tendon sheaths-ease movement

B. The meninges
 are three connective tissue membranes that lie just external to CNS
organs : Dura matter, arachnoid and pia matter

5/25/2021 73
 Membranes in Ventral body Cavity
• Serous membrane (serosa)
– a thin double layered membrane that lines the walls of
ventral body cavity and covers outer surface of the organs in
them
– 2 layers
• Parietal serosa is the layer of the membrane that lines the walls of
the cavity
• Visceral serosa is the layer that covers the organs in the cavity
– a lubrication fluid (serous fluid) is found between the two
layers

5/25/2021 74
 Serous Membranes

• Specific serous membranes are named for the cavity in

which they are found
– Parietal and visceral pericardium surrounds the heart
– Parietal and visceral pleura surrounds the lungs
– Parietal and visceral peritoneum covers the abdominal
cavity

5/25/2021 75
5/25/2021 76
 Serous Membrane Relationship

• A serous membrane is double

layered membrane separated by
fluid
• Although there is a potential
space in actuality the
membranes lie close to one
another

5/25/2021 77
 Other Body Cavities

• In addition to the large closed body cavities, there are also

many smaller body cavities
– Oral and digestive cavities
– Nasal cavities
– Orbital cavities
– Middle ear cavities
– Synovial cavities

5/25/2021 78
5/25/2021 79
 Thank You!!

5/25/2021 80