1. Organiza+on of the Body
You should know what the anatomical posi3on of the body is and in what direc3on the transverse, sagi;al & coronal
planes of the body lie. Direc3onal terms such as: proximal/distal; deep/superficial; superior/inferior: lateral/medial;
anterior/posterior; caudal/ cranial (also called rostra or cephalic); dorsal/ventral; central/peripheral allow the loca3on
of one anatomical feature to be placed rela3ve to another. You should know the difference between physiology and
anatomy and the defini3ons of metabolism, anabolism, and catabolism.
h;ps://wikieducator.org/Direc3onal_Terms_Worksheet_1
h;ps://wikieducator.org/Tissues_Worksheet
Chapter 4. Anatomy and Physiology of Animals/Body Organiza+on
h=ps://en.wikibooks.org/wiki/Anatomy_and_Physiology_of_Animals/Body_Organisa+on#Summary
1. Organiza+on of Animal Bodies
Living organisms consist of cells organized into 3ssues, which, in turn, combine to form organs and systems. Rather
than being randomly sca;ered, cells with similar func3ons are arranged in groups, forming what we refer to as 3ssues.
This organiza3onal structure enhances the efficiency of specific func3ons performed by these groups of similar cells.
There are four main types of 3ssues in animals. These are:
• Epithelial +ssues that form linings, coverings, and glands.
• Connec+ve +ssues for transport and support.
• Muscle +ssues for movement.
• Nervous +ssues for carrying messages.
2. Epithelial Tissues
Epithelium (plural epithelia) is 3ssue that covers and lines. It covers an organ or lines a tube or space in the body. There
are several different types of epithelia, dis3nguished by the different shapes of the cells and whether they consist of
only a single layer of cells or several layers of cells.
2.1 Simple Epithelia – with a single layer of cells
Simple epithelia, composed of a single layer of cells, are categorically classified into dis3nct types, including (1)
squamous epithelium, (2) cuboidal epithelium, (3) columnar epithelium, and (4) columnar epithelium with cilia.
(1) Squamous epithelium, resembling 'crazy paving,' lines structures such as the heart, blood vessels, lung alveoli, and
body cavi3es, facilita3ng the easy diffusion of molecules due to its thin composi3on. (2) Cuboidal epithelium, featuring
cube-shaped cells, is less common but found lining kidney tubules, allowing for the passage of molecules through
diffusion, osmosis, and ac3ve transport. (3) Columnar epithelium, composed of column-shaped cells, lines the diges3ve
tract, facilita3ng the movement of digested food products into the bloodstream. (4) Columnar epithelium with cilia on
the apical side is present in the respiratory tract, fallopian tubes, and uterus. The rhythmic bea3ng of cilia aids in the
transporta3on of par3cles in these regions.
,2.2 Transi+onal epithelium – with a variable number of layers
The cells in transi3onal epithelium can move over one another allowing it to stretch. It is
found in the wall of the bladder.
2.3 Stra+fied epithelia – with several layers of cells
Stra3fied epithelia, composed of a several layers of cells, are categorically classified into dis3nct types, including (1)
stra3fied squamous epithelium, and (2) kera3nized stra3fied squamous epithelium.
(1) Stra3fied squamous epithelium is characterized by
mul3ple layers of fla;ened cells (figure), found lining
areas such as the mouth, cervix, and vagina. The cells at
the base con3nuously divide, pushing up cells above
them, while those at the top are either worn off or
pushed off the surface. This type of epithelium plays a
protec3ve role for underlying layers and has a rapid self-repair mechanism when damaged. (2) Kera3nized stra3fied
squamous epithelium takes this protec3on a step further by deposi3ng a tough, waterproof protein called kera3n in
its cells. This specific type forms the skin covering the outer surface of mammals.
3. Connec+ve Tissues
Various 3ssues, including (1) blood, (2) lymph, (3) proper/loose/dense connec3ve 3ssue, (4) adipose 3ssue, (5)
car3lage, and (6) bone fall under the category of connec3ve 3ssues. These 3ssues serve the crucial func3ons of
suppor3ng the body and facilita3ng the transporta3on of substances within it. Connec3ve 3ssues share a common
structure, comprising cells suspended in a matrix or ground substance, o^en accompanied by fibers.
(1) Blood consists of a matrix called plasma, incorpora3ng various types of cells and cell fragments. Fibers become
evident in blood that has clo;ed. (2) Similar to blood plasma, lymph contains various types of white blood cells and
flows through lympha3c vessels. (3) Connec3ve 3ssue 'proper' is characterized by a jelly-like matrix, a dense network
of collagen and elas3c fibers, and various embedded cells. It encompasses different forms, including loose connec3ve
3ssue (le^ figure), which fills spaces between organs, dense connec3ve 3ssue, forming tendons, ligaments, and heart
valves, and (4) adipose 3ssue, consis3ng of fat-filled cells found in various regions such as under the skin and around
organs. (5) Car3lage (right figure), o^en referred to as the 'gristle' of meat, features a tough jelly-like matrix with
suspended cells. It is flexible yet durable and is located at the ends of bones, in the nose, ear, trachea, and between
the vertebrae. (6) Bone is characterized by a solid matrix rich in calcium salts, providing hardness, and collagen fibers
for strength. Bone cells are situated within spaces in the matrix. Two types of bone, spongy and compact, differ in their
cellular and matrix arrangements.
4. Muscle Tissues
Muscle 3ssue is composed of cells that contract and move the body. There are three types of muscle 3ssue (1) smooth
muscle, (2) skeletal muscle, and (3) cardiac muscle.
,(1) Smooth muscle consists of elongated cells with a central nucleus and is located in the walls of blood vessels, airways
to the lungs, and the diges3ve tract. It facilitates changes in blood vessel size and aids in the movement of food and
fluids. Notably, the contrac3on of smooth muscle fibers occurs involuntarily, without conscious control. (2) Skeletal
muscle, also known as striated, striped, or voluntary muscle, exhibits striped fibers with alterna3ng light and dark
bands. A;ached to bones, skeletal muscles are under the conscious control of the animal, allowing for voluntary
movements. (3) Cardiac muscle, found exclusively in the heart walls, is responsible for genera3ng the heartbeat. The
cells of cardiac muscle are branched cylinders with central nuclei and faint stripes. While each fiber contracts
automa3cally, the overall coordina3on of the heartbeat is regulated by the pacemaker and the involuntary autonomic
nervous system.
5. Nervous Tissues
Nervous 3ssue is responsible for the forma3on of the nerves, spinal
cord, and brain. Neurons, the building blocks of the nervous system,
are comprised of a cell body and a long axon, which serves to transmit
nerve impulses. Typically, the axon is enveloped by an insula3ng
sheath of fa;y material known as myelin.
6. The 11 Body Systems
Organs do not operate in isola3on; rather, they collaborate with other organs and body structures to collec3vely fulfill
the essen3al MRS GREN* func3ons required to sustain the life of an organism.
* Movement, Respira/on, Sensi/vity, Growth, Reproduc/on, Excre/on, and Nutri/on
6.1 Skin
The skin covering the body consists of two layers, the epidermis and dermis. Associated with these layers are hairs,
feathers, claws, hoofs, glands, and sense organs of the skin.
6.2 Skeletal System
This can be divided into the bones of the skeleton and the joints where the bones move over each other.
6.3 Muscular System
The muscles, in conjunc3on with the skeleton and joints, give the body the ability to move.
6.4 Cardiovascular System
This is also known as the circulatory system. It consists of the heart, the blood vessels, and the blood. It transports
substances around the body.
6.5 Lympha+c System
This system is responsible for collec3ng and “cleaning” the fluid that leaks out of the blood vessels. This fluid is then
returned to the blood system. The lympha3c system also makes an3bodies that protect the body from invasion by
bacteria etc. It consists of lympha3c vessels, lymph nodes, the spleen and thymus glands.
, 6.6 Respiratory System
This is the system involved with bringing oxygen in the air into the body and geing rid of carbon dioxide, which is a
waste product of processes that occur in the cell. It is made up of the trachea, bronchi, bronchioles, lungs, diaphragm,
ribs, and muscles that move the ribs in breathing.
6.7 Diges+ve System
This is also known as the gastrointes3nal system, alimentary system, or gut. It consists of the diges3ve tube and glands
like the liver and pancreas that produce diges3ve secre3ons. It is concerned with breaking down the large molecules
in foods into smaller ones that can be absorbed into the blood and lymph. Waste material is also eliminated by the
diges3ve system.
6.8 Urinary System
This is also known as the renal system. It removes waste products from the blood and is made up of the kidneys,
ureters, and bladder.
6.9 Reproduc+ve System
This is the system that keeps the species going by making new individuals. It is made up of the ovaries, uterus, vagina
and fallopian tubes in the female and the testes with associated glands and ducts in the male.
6.10 Nervous System
This system coordinates the ac3vi3es of the body and responses to the environment. It consists of the sense organs
(eye, ear, semicircular canals, and organs of taste and smell), the nerves, brain, and spinal cord.
6.11 Endocrine System
This is the system that produces chemical messengers or hormones. It consists of various endocrine glands (ductless
glands) that include the pituitary, adrenal, thyroid, and pineal glands as well as the testes and ovary.
7. Direc+onal Terms
To describe structures in the body of an animal it is necessary to have a system for describing the posi3on of parts of
the body in rela3on to other parts. The terminology used for this purpose is known as direc3onal terms.
7.1 The 3 Anatomical Body Planes
Some3mes it is useful to imagine ‘geing inside’ the animal (so to speak) to check
which side is which. The other common and useful direc3onal terms are (1)
transverse, (2) sagi;al, and (3) coronal.
• Transverse (horizontal) plane = divides the body or an organ into upper
(superior) and lower (inferior) portions.
• Sagittal (longitudinal) plane = divides the body or an organ into right and
left sides.
• Coronal (frontal) plane = divides the body or an organ into front (anterior)
and back (posterior) portions.
7.2 Direc+onal terms
Term Defini+on Example
Dorsal Nearer the back of the animal than The backbone is dorsal to the belly
