Respiratory System

The respiratory system helps to breathe – which is inhaling oxygen so that it can be distributed to each cell in the body and collect the waste product carbon dioxide from the cells and expel it back to the atmosphere.

The human respiratory system consists of:

The nasal passages

Pharynx

Larynx

Windpipe

Lungs

The exchange of the gases – replenishing the blood with oxygen and removing carbon dioxide from it – happens in the lungs. We breathe about 6 liters of air every minute. The adult lungs have the capacity to hold about 3 liters of air.

When we breathe, the air first enters the body through the nose or the mouth and enters the trachea. The trachea splits into two bronchi – one going to each lung. Each bronchus continues to divide into narrower and narrower bronchi ending up as microscopic alveoli. The walls of alveoli are single celled through which the blood can exchanges the carbon dioxide with oxygen from the fresh air in the lungs.

What makes us breathe?

The breathing action is as a matter of fact is not initiated by the lungs. They are like bags which get compressed and expanded due to a dome shaped muscle that attaches to both the lungs. This muscle is called the diaphragm. The diaphragm is an involuntary muscle that keeps contracting and flattening. When the diaphragm contracts, it pushes the ribs upward and out. This makes the lungs expand. When the lungs expand, the pressure in the lungs in less than the atmospheric pressure, due to which the air from the outside rushes in. This action of pulling in the outside air into the lungs through the nose and or mouth is called the inhaling.

When the diaphragm returns to its normal shape, the ribs move downward and in thereby squeezing the lungs which therefore force the air out of the body. This is called exhaling.

What are the diseases of the respiratory system found in humans?

The common diseases that affect the respiratory system are:

Bronchitis

Pneumonia

Asthma

Lung Cancer

Emphysema

As obvious, any infection or disease associated with the respiratory system makes breathing difficult. When the body is not able to get sufficient oxygen, the heart tries to work faster to circulate more blood so that enough oxygen can be supplied to the parts of the body. The lack of oxygen due to difficulty in breathing can make the body feel tired. A severe lack of oxygen can also prove to be fatal.

How can we keep the respiratory system healthy?

The respiratory system can keep healthy if we breathe fresh air. Inflammation of the bronchi or the lungs may not be easy to prevent but trying to keep away from infections or infected people can help you stay healthy. The tumors in the may not be preventable.

However, smoking is one major activity that is extremely harmful and that many adults and youth indulge in.

Skeletal System

Skeletal System

Skeletal system is the biological system providing support in living organisms.

Skin, muscle and bones allow movement. Skin - pliable covering. Muscles do actual moving. Bones give anchor to move against.

The skeleton functions not only as the support for the body but also in haematopoiesis, the manufacture of blood cells that takes place in bone marrow. This is why people who have cancer of the bone marrow almost always die. It is also necessary for protection of vital organs and is needed by the muscles for movement.

Introduction To Skeletal System

Bones

A. Functions of Bones

1. Support. Provide a hard framework.

2. Protection of many vital organs.

3. Movement. Act as levers with skeletal muscles moving them. Joints control possible movements.

4. Mineral storage. Especially calcium and phosphate, critical minerals for cellular function. Continuous deposition and withdrawal. Exquisite control of Ca++ (calcium ions) levels necessary for function of nerves, muscles, blood coagulation and other functions. Most of Ca++ in body in bones. Osteoclasts & osteoblasts controlled by hormones which regulate blood levels of Ca++.

5. Blood cell formation. Certain bones have active marrow.

B. Structure

1. Compact-Dense outer layer, looks smooth and solid. Contains cylinder of concentric layers with central canals.
a. Haversian system = circles of bone (lamella) with central canal (Haversian canal)
b. Central canal contain blood vessels & nerves. Connected at right angles to network.
c. Perforating small canals - blood vessels & nerves go through lamellar bone to supply osteocytes. Connect to periosteum.
d. Osteocytes live in bone, maintain it. Live in holes called lacunae. Connect to each other and central canal via canaliculi, little canals. Pass nutrients, waste products

2. Spongy- honeycombed, open spaces. Same structure as compact but less regular.

Withstand maximum stress with least weight. In bone interiors & weird weight bearing bones like head of femur. Not organized in lamella. Trabeculae are arranged along lines of stress. Osteocytes interconnected by canaliculi. Nutrients reach osteocytes by diffusing through the canaliculi from capillaries. Osteoporosis - More bone resorption than deposition, very weak bone.

Skeletal System

A. Axial skeleton

Principal supportive structure of the body includes skull, vertebrae, sternum & ribs. Central column of the skeleton from which arms and legs & bones that help them hang.

B. Appendicular skeleton

Provides fairly freely movable frame for upper & lower limbs. Includes pectoral (shoulder) & pelvic (hip) girdles, arms, forearms, wrists, hands, thighs, legs & feet.

Joints

Bones -> framework; muscles -> power; joints provide mechanism that allows body to move

A joint is where 2 adjacent bones or cartilages or combination thereof meet.

Most joints movable, some not.

General Structure

1. Articular cartilage

2. Joint (synovial) cavity

3. Articular capsule - external layer = fibrous capsule, inner layer is a synovial membrane

4. Synovial fluid-occupies all free spaces within the joint capsule, fluid derived by filtration from blood flowing thorough the capillaries in the synovial membrane

5. Reinforcing ligaments

Divisions of the sceletal system

The skeleton is divided into the axial skeleton and the appendicular skeleton. The axial skeleton includes the bones of the skull, the hyoid bone, the bones of the middle ear, the vertebral column, and the bony thorax.
The appendicular skeleton includes the bones of the extremities and the bones of the hip and shoulder girdles.
• Axial skeleton •
• Facial bones •
• Vertebral column •
• Curvatures •