Introduction to Human Body Tissues and Their Functions Study Notes
Introduction To Human Body Tissues: Study Notes
Cambridge International College (CIC)
The Human Body Tissues
We explain what the tissues of the human body are and the characteristics of the epithelial,
muscular, connective and nervous tissues.
The cells of the tissues are firmly connected to each other.
What are the tissues of the human body?
With the term “tissue”, in biology and medicine, we normally refer to organic materials made
up of a huge set of regularly distributed cells , which together fulfill the same specific purpose
and have a common embryonic origin. Put more simply, tissues are the types of flesh or pulp in
the body, made up of cells of different types but with the same physiological role .
The body’s tissue organization is typical of the most complex living species. It differs from those
that are gathered in cell colonies, such as sponges, in that it is capable of reorganizing and
regaining its structure on the other side of a sieve through which it is separated. This does not
happen with tissue cells, which are tightly bound together and in a mutually dependent
The human body, like that of animals and other multicellular life forms, is made up of various
types of tissues, each with its own set of functions and characteristics, and histology is the
study of these tissues. The four major forms of tissue found in the human and animal bodies
are described in detail below.
The squamous cells are more external and under them are the cuboidal ones .
This is the name given to the tissue made up of multiple densely packed cells that constitute
the skin , that is, the limits of the body itself.
Its name comes from how we call this type of cortex: the epithelium, and although in other
animals it fulfills clearer defensive functions (for example, by means of scales), in the case of
mammals they are stratified cell groups of two types :
Squamous cells: They are the most external, flattened.
Cuboidal cells: They are located deeper in the epithelium, the shape of which resembles
One of its functions is to protect internal tissues from the action of environmental elements,
infections and aggression from competitors (as far as possible). In addition, it has the ability to
lubricate and protect itself, and it is also found lining the small intestine, where it helps absorb
nutrients, and also the internal glands, where they secrete some enzymes and hormones.
Each subtype of muscle tissue performs specific function
Muscle tissue is the tissue that gives our body solidity, structure, and definite shape, and that
also gives the body its complex range of voluntary and involuntary movements. It is made up of
elastic cells capable of deforming and recovering their shape, called myocytes, and can be
classified into three subtypes of tissue, which are:
Skeletal muscle tissue. One that is subject to the will of the mind, such as that of our
arms and legs, or facial muscles, and that is composed of cylindrical and multinucleated
cells, up to 30 cm long, endowed with a large number of mitochondria to manage the
energy needed for body movements. Together, they make up striated muscles, attached
by a tendon to the bones of the body.
Cardiac muscle tissue. As its name indicates, we refer to the musculature of the heart,
made up of cardiomyocytes, elongated and branched cells, endowed with a central
nucleus , and capable of forming terminal junctions with a high level of specialization,
which facilitate the transmission of nerve impulses. Its function is to operate as a
hydraulic pump to keep blood circulating throughout the body. For that reason, it does
not obey our mind at all.
Mooth muscle tissue. Composed of leimocytes, spindle-shaped mononuclear cells,
without striations or tubule systems, it is found in the walls of hollow viscera (stomach,
bladder, uterus, intestine, etc.) and most blood vessels. Your contractions do not obey
the mind, but operate automatically.
Connective or connective tissue
Connective tissue can be of various types, depending on its functions in the body.
A heterogeneous range of organic tissues developed from embryonic mesoderm and
responding to the fundamental purpose of giving support and systemic integration to the
human body are gathered together under the same label in this situation. That is, it maintains
everything organized and in its proper position.
Depending on its function in the body, connective tissue can be of numerous forms. To begin,
we can distinguish between specialized connective tissues that perform unique and specific
duties (such as bone, cartilage, blood, or lymphatic tissue) and non-specialized connective
tissues that only give support and physical structure (such as adipose or fibrous tissue).
On the other hand, we must also differentiate between:
dense or fibrous connective tissue . Composed of collagen, it holds things in place in a
specialized way, whether it’s muscles attached to bones (tendons and ligaments), or
certain tissues separate from others (such as the capsules of certain internal organs
loose connective tissue . Endowed with abundant extracellular content, it fulfills specific
roles depending on its type: the mucosal connective tissue, endowed with defensive and
structural roles; the reticular connective tissue, composed of collagen and which makes
up many lymph nodes and lymphoid organs; and mesenchymal connective tissue, which
makes up the embryonic mesenchyme and provides specialized cells to all tissues.
Nervous tissue is made up of neurons and glial cells
It is made up of nerve cells, such as neurons and glial cells, and makes up the brain, spinal cord,
and the enormous network of nerve endings that make up our body’s nervous system.
These are highly sensitive cells that may respond to both exterior and internal stimuli and send
information through their connections. As a result, it effectively and quickly connects the entire
body to the brain.
The somatic system, which connects nerves to skeletal muscles and performs conscious orders,
or the autonomic system, which acts automatically and controls smooth and cardiac muscles, is
responsible for processing our motions.