Introduction to human structure & function

by Suria Shahid

Introduction
to Human

Structure &
Function

In this book:
1.Human organizational level
2. Homeostasis
3. Directional term
4. Body planes
5. Body cavities
6. Abdominopelvic region

Human organizational level

Atom are the smallest unit
of matter that combine to
form a molecule.

Molecules combine to each
other to finally create a
functional living unit called
cell.

The cells combine together
to form a type of tissue. A
combination of epithelial
cells form an epithelial
tissue. Connective tissue
made up of several types
of connective cells. There
are 4 types of tissues:
epithelial, connective,
muscles and nervous
tissue.

The different tissues
combine together to form
an organ. For example:
epithelial, connective,
muscles and nervous
tissue fused together to
form an organ like
stomach, intestine, uterus
and so on.

The different organs work
together in a system. In a
human body, there are
eleven systems:
integumentary, skeletal,
muscular, lymphatic,
respiratory, digestive,
nervous, endocrine,
cardiovascular, urinary, and
reproductive systems.

Homeostasis

Homeostasis is a balanced
condition of human's
internal environment.
There are a lot of elements
that must always be in
homeostasis: blood sugar
level, body temperature,
blood pressure, oksigen
level, Co2 level, calcium level
and even each hormones in
our body need to be in
balanced condition.

There are feedback
mechanisms to ensure
homeostasis always
achievable.

In feedback mechanism,
there are 4 components:
1.Stimulus: the changes
2.Receptor: to detect the
changes
3.Control centre: to
translate the changes and
plan the response
4. Effector: to do the
response needed

Everyone knows a normal
body temperature is 36.7 °
C. Let’s say, you are
outdoors and the weather
is very hot (this is a
stimulus). External
temperature can affect the
internal temperature of the
body. Skin receptors detect
heat and send information
to the brain (control
center). The brain instructs
the skin (effector) to
sweat. Sweat helps get rid
of excess heat from the
skin, then the body
temperature returns to
normal.

Hot environment = stimulus
Skin thermoreceptor = receptor
Brain = control centre
Sweat gland = effector

There are 2 types of
feedback mechanisms:

Positive feedback
&

Negative feedback

When we have fever,
homeostasis of body
temperature is disturbed and
ends up becoming very high.
This condition is optimal to
slow down the virus and give
the immune system a chance

to eliminate it.

However, the uncontrolled high
temperature can damage enzymes,
hormones, and tissues which can

eventually fail organ functions.

The same goes when a human
already develops high blood
pressure, homeostasis can not

happen at a normal pace
anymore. Every time they are
having a trigger factor that
may raise the blood pressure,
they need medication to make

sure the blood pressure
reduces back to normal.

No matter what position the
human body is in at one time,
we always refer every direction
to the ANATOMICAL POSITION

ANATOMY DIRECTIONAL TERM

When it comes to anatomy,
there are some uncommon
terminologies are being used

to refer to directions.
We use anterior to refer to in

front.

The dog is sitting anterior to a dog house.

We use posterior to refer to
behind.

The boy is standing posterior to the chair.

We use superior to refer to
above and inferior to refer to

below.

The cloud and rainbow are located superior
to the tree.

While the boy is standing inferior to the
tree.

We use medial to refer to the
location near the midline of the

body and lateral vice versa.

The eyes are medial, and the ears are
lateral.

We have four limb attachment
points.

Any structure located near to
the point is called proximal,
and anything away from the
points is called distal.

The fingers are distal, and the elbows are
proximal.

Superficial refers to nearer to
surface, and the opposite is

deep.

The epidermis is superficial, and the muscle
tissue is deep.

BODY PLANES

Sagittal plane

The sagittal plane or sagittal section gives
us a vertical image perspective.

This picture shows a vertical image of the
trachea.

There are two types of
sagittal planes; midsagittal and

parasagittal.

Midsagittal is the plane on the midline,
while parasagittal is not on the midline.

Transverse plane

The horizontal plane gives us a horizontal
image perspective.

This picture shows a horizontal image of
the trachea.

Frontal plane

The frontal plane gives us a vertical image
from the anterior view.

This picture shows a vertical image of the
lung from the anterior view.

BODY CAVITIES:

Cranial cavity
Spinal cavity
Thoracic cavity
Abdominal cavity
Pelvic cavity

Cranial cavity contains brain.

The spinal cavity contains the
spinal cord.

The thoracic cavity contains the
lung, heart, trachea, esophagus

and vena cava..

The abdominal cavity contains
the stomach, intestine, liver,
pancreas, kidney and spleen.

The pelvic cavity contains the
rectum, uterus (in women),
ovary (in women), prostate (in
men), urinary bladder, and

ureter.

ABDOMINOPELVIC REGION

ABDOMINOPELVIC REGION
The nine regions at the

abdominopelvic cavity that
divided by 2 parasagittal lines
cross through the mid-clavicle

and two transverse lines.

These are the organs in each of
the region.

Thanks for reading...