Download Body Systems

Overview of the Human Body
Introduction to the Organs and Body Systems
Cell  Tissue  Organ  Organ System
1. Integumentary System
a. This system consists of the skin and numerous
accessory organs. It helps maintain homeostasis.
i. Skin has 2 layers – epidermis (superficial) and
dermis (deep layer). The epidermis has a waxy
coat and is composed of dead cells. The dermis
consists of connective tissue, fat and areolar
tissue (hypodermis), and blood vessels,
receptors, and glands.
ii. Functions – protections, prevention of fluid loss,
maintenance of internal body temperature.
2. Skeletal System
a. This system consists of bones, joints, and associated
connective tissues. Its supportive nature makes body
movement possible.
b. The skeletal system consists of bones, joints between
opposing bones, and the connective tissue that holds it
all together. The bones, joints, and tissues form the
skeleton. The skeleton has 206 bones. Each bone
falls into 1 of 2 categories – axial skeleton or
appendicular skeleton.
i. Axial – bones closest to the vertical axis
1. Skull, vertebral column, and thoracic
cage.
ii. Appendicular – bones that are lateral to the
vertical axis
1. Shoulder (pectoral) girdle, upper limbs,
pelvic girdle, and lower limbs.
c. Functions – supporting soft tissues and organs,
protection of organs, storage of mineral salts,
attachments for muscles, and red blood cell
production.
3. Muscular System
a. This system contains the muscles that attach to
bones. Contraction of muscles provides body
movement.
b. It consists of skeletal muscle tissue (attached to bone)
and associated connective tissue. There are more than
500 muscles in the body. A single muscle consists of
cells packaged into bundles, which are highly
specialized to contract. The connective tissue that is
associated with the muscle envelops the muscle’s
individual cells, the bundles, and the muscle itself. It
also extends beyond the muscle to form tendons.
Within the connective tissues are blood vessels and
nerves, which provide the muscle with nourishment
and energy, remove wastes, and nerve stimulation so
that the muscle can contract.
c. Functions – skeletal movement, maintenance of
form, posture, support, and maintenance of body
temperature.
4. Nervous System
a. This system consists of the brain, spinal chord,
nerves, and special sense organs, and is classified on
the basis of structure and function. It maintains
homeostasis by way of rapid impulses. It provides a
way of communication between the body and the
external world. The organs of the nervous system are
structurally classified into 2 categories: the CNS or
the PNS.
i. CNS – central nervous system: brain and
spinal chord
ii. PNS – peripheral nervous system – nerves that
extend between the CNS and the structure in
which they terminate or originate.
b. The nervous system can also be classified on the basis
of functional differences, such as the direction
information is traveling. It consists of afferent or
efferent information.
i. Afferent – info is carried toward the CNS
ii. Efferent – info is carried away from the CNS
1. The efferent portion is composed of the
somatic and autonomic nervous systems.
a. Somatic – stimulates skeletal muscle
contraction and is under conscious
control.
b. Autonomic – receives commands
from the CNS and is not under your
control.
c. Functions – maintain stability (homeostasis).
5. Endocrine System
a. This system consists of endocrine glands. It
maintains homeostasis by the relatively slow action
of hormones that are released by the glands. The
organs in this system do not contain ducts. They
consist of glandular epithelium that is associated
with connective tissue, through which travel blood
vessels and nerves.
b. The primary organs are the pituitary gland, the
thyroid gland, four or five small parathyroid glands,
two adrenal glands, certain regions of the pancreas,
the gonads, the thymus, the pineal gland, the
stomach, and the kidneys. The products secreted by
these glands are collectively called hormones. The
cells affected by the hormones are called targets.
6. Cardiovascular System
a. The organs of the cardiovascular system include the
heart and blood vessels. This system provides
transportation for the various substances carried by
the blood. The blood vessels that carry blood away
from the heart are called arteries and the blood vessels
that carry blood toward the heart are called veins.
Capillaries are the smallest type of arteries and they
are the site of the exchange of materials between the
bloodstream and the internal fluid.
b. The heart provides the propulsion system to move the
blood. It consists of four chambers, two upper atria
(collect blood) and two lower ventricles (pumps).
c. Blood – the liquid portion is called plasma. The solid
portion consists of erythrocytes (RBCs), WBCs, and
thrombocytes (platelets – blood clotting factors).
7. Lymphatic System
a. The lymphatic system contains lymphatic vessels,
lymph modes, the spleen, the thymus, and the tonsils.
It provides immunological protection from foreign
bodies. It transports lymph fluid toward the heart.
b. The lymph nodes, spleen, thymus, and tonsils, are
composed of lymphatic tissue, which manufactures
two types of WBCs – monocytes and lymphocytes.
c. The primary function of the lymphatic system is to
protect the body from the harmful effects of
microorganisms, toxins, and dead or diseased body
cells.
8. Respiratory System
a. The respiratory system consists of the lungs and the
tubes that transport air to and from them. It provides
for the exchange of gases between the exterior and the
bloodstream.
b. The respiratory system is functionally divided into
two components: a conducting zone and a respiratory
zone. The conducting zone brings in the oxygen and
consists of nose, the pharynx (throat), the larynx
(voicebox), the trachea (windpipe), and two bronchi,
which lead into the lungs. The respiratory zone
consists of the lungs and is where gas exchange
occurs. The gas exchange happens in the alveoli
(sacs) of the lungs.
9. Digestive System
a. The organs of the digestive system include the
mouth, salivary glands, esophagus, stomach, small
intestine, pancreas, liver, gallbladder, and the large
intestine. This system prepares particles for their
entry into the bloodstream. The breakdown of food
particles into useable energy is called digestion.
b. The digestive system is a long, continuous tube,
composed of numerous organs that extend from the
mouth to the anus.
i. Mouth – break apart food.
ii. Salivary glands – secrete enzymes to break
down carbohydrates.
iii. Food passes the pharynx and enters the
esophagus which brings the food down to the
stomach. The stomach further digests the food
until it’s a liquid.
iv. The liquid passes to the small intestine where
digestion proceeds and is completed. The liver
and the gallbladder provide the small intestine
with bile, which digests fats. The pancreas
provides the small intestine with enzymes to
further digest proteins, carbs, and fats.
v. Any material that is not absorbed into the
bloodstream via the small intestine is passed
into the large intestine, where water is removed
and returned to the bloodstream. The solid waste
is then removed from the body via the anus.
10.
Urinary System
a. The urinary system contains the kidneys, ureters,
urinary bladder, and urethra and maintains
homeostasis by regulating fluid content and volumes
in the body. Water, salts, acids and bases are
removed from the bloodstream and then secreted from
the body in the form of urine.
11.
Reproductive System
a. The reproductive system contains organs that differ
between males and females. It provides a continuing
of the species.
b. In males, the reproductive organs are the testes. The
other organs transport and maintain sperm.
c. The female organs that produce eggs are called the
ovaries. Once a month an egg is released into the
fallopian tubes where it can become fertilized. A
fertilized egg is swept to the uterus where the embryo
will develop. Inferior to the uterus is the vagina,
which opens to the external environment. The external
genitalia is called the vulva.