Download The cardiovascular system

Systems in the body
1. The cardiovascular system
2. The lymphatic system
3. The nervous system
4. The endocrine system
5. The respiratory system
6. The digestive system
7. The urinary system
8. The musculoskeletal system
9. The reproductive system
10. The special senses
 Eye
 Ear
 Nose
 Skin
 Tongue
The cardiovascular system:
The cardiovascular system in humans consists of a four-chambered heart to pump blood
and a series of vessels needed to transport blood in the body. Blood is a connective tissue used to
deliver oxygen, nutrients, water, hormones, and ions to all the cells of the body. It is also used to
pick up the carbon dioxide and wastes produced by cells and to move these to the appropriate
areas for elimination. Further, it assists in thermoregulation in the body as well as fighting
infectious agents.
The critical functions of the cardiovascular system are achieved by blood transported
through the system. For this reason, the composition of blood needs to be examined more
closely.
The lymphatic system:
The lymphatic system consists of a series of vessels running throughout the body, lymph,
and lymphoid tissue. The system serves to return fluids that were unclaimed at the capillary beds
to the circulatory system, picks up chylomicrons from the digestive tract and returns them to
circulation, and fights infection via leukocytes.
The nervous system:
The nervous system has the daunting task of coordinating all of the body’s activities. The
central nervous system (CNS) is composed of the brain and spinal cord. The peripheral nervous
system (PNS) is composed of any nervous tissue located outside of the brain and spinal cord.
Nerves are the primary structures within the PNS. In order to understand the functioning of the
CNS and PNS, it is necessary to look at the detailed function of neurons.
The endocrine system:
The endocrine system is composed of endocrine glands located throughout the body.
Hormones are generally secreted from an endocrine gland into the bloodstream. In order to
maintain homeostasis in the body, it is necessary to regulate the functioning of specific targets
within the body. Hormones achieve this regulation. Hormones are chemical messengers secreted
into the bloodstream that travel to a specific target in the body and change the functioning of that
target. The target can be individual cells, tissues, or entire organs.
The respiratory system:
The respiratory system has the primary jobs of providing the body with oxygen and
eliminating carbon dioxide. Pulmonary arteries, coming off the right side of the heart, carry
deoxygenated blood, which is low in oxygen and high in carbon dioxide, to the lungs. Oxygen
that enters the lungs will be distributed to hemoglobin in the erythrocytes within the capillaries
that branch off the pulmonary arteries that surround the alveoli. Carbon dioxide will diffuse into
the alveoli from the pulmonary arteries to be exhaled. Now blood is oxygenated and will travel
back to the left side of the heart via pulmonary veins. In addition to oxygenating blood, the
respiratory structures are responsible for pH regulation, vocal communication, the sense of smell,
and protection from infectious agents and particles.
The digestive system:
The digestive system is designed to extract nutrients from food and eliminate wastes. The
system is set up as a series of modified tubes to keep food and digestive enzymes sequestered
from the body. It is also known as the gastrointestinal (GI) tract. In addition to the GI tract, there
are several accessory structures (the liver, gallbladder, and pancreas) which perform functions
vital to the digestive system. The three primary components of the diet that require digestion are
carbohydrates, proteins, and fats. The digestive system has the following functions: mechanical
digestion of food achieved by chewing, chemical digestion of food achieved by assorted
digestive enzymes, absorption of nutrients into the bloodstream, and elimination of waste
products.
The urinary system:
The urinary system consists of the kidneys, which produce urine, and supporting tubing
to store and eliminate urine from the body. The kidneys are the main excretory organ of the
body: however, the skin can also act as an excretory organ. In addition to producing urine as a
means of eliminating nitrogenous cellular waste products, the urinary system also regulates
blood pressure by means of blood volume, adjusts blood pH, and regulates the osmotic
concentrations of the blood.
The musculoskeletal system:
Muscles provide structural support, help maintain body posture, regulate openings into
the body, assist in thermoregulation via contractions (shivering) that generate heat, and contract
to help move blood in veins towards the heart, assisting in peripheral circulation. Skeletal and
cardiac muscle is striated, while smooth muscle is not. Cardiac and smooth muscles are
involuntary, while skeletal muscle is under voluntary control.
The reproductive system:
The female and male reproductive systems have the common function of producing
gametes for sexual reproduction. Egg cells in females and sperm cells in males are produced by
the gonads. In addition, the female reproductive system has to be structured to accept sperm from
the male system and to allow for embryonic and fetal development.
Special senses:
The senses have specialized sensory receptors that is present outside the brain. The
special senses are meant for smell, sight, hearing, and taste: these are found in eye, nose, ear and
tongue and one of the special senses is skin that is useful as protecting and for survival to the
body.
Eye: It is the organ of sight. This is situated in the orbital cavity and it is supplied by the optic
nerve. The optic nerve is located at the second cranial nerve. It is spherical in shape with the
diameter of 2.5 cm. The space between the orbital cavity and eye is occupied by adipose tissue.
The eye consists of 3 layers of tissue in the wall.

The outer layer( fibrous) layer: sclera and cornea

The middle layer(vascular layer):choroid, ciliary body and iris

The inner layer(nervous): retina
Ear: It is the organ of hearing and it is supplied by the cochlear part of the vestibulocochlear
nerve that is present in the 8th cranial nerve. The ear is divided into 3 parts.

The outer ear: auricle(pinna), external acoustic meatus(auditory canal)

The middle ear (tympanic cavity): auditory ossicles(malleus, incus, stapes)

The inner ear: bony labyrinth and membranous labyrinth.
Nose: It is the sense of smell, or olfaction, which is also act as passageway for respiration. It is
originated in the nasal cavity. The olfactory nerves present in the first cranial nerves.
Inflammation of the nasal mucosa prevents odorous substances from reaching the olfactory area
of nose causes loss of the sense of smell.
Skin: The skin is the largest organ of the body and it covers the whole body with the surface area
of about 1.5-2 m2 in adults and it contains hair, nails and glands.
The skin consists of two layers i.e, epidermis and dermis. The functions of skin are

Regulation of body temperature

Sensation of pain, touch and temperature due to the presence of somatic nerve endings

Protection of underlying organs from microbes and injury
Tongue: The sense of gestation or taste, it is closely linked to the sense of smell and it also
involved in the stimulation of chemo-receptors by dissolved chemicals.
The fundamental sensations of taste are salt, sweet (at the tip), sour (at the sides) and
bitter (at the back). The trigger of the sense of taste is salivation and the secretion of gastric juice.