Types of Joints

 

Types of Joints
                        A joint is the location at which two or more bones make contact. They allow movement and provide mechanical support. Joints can be classified on the basis of the degree of movement they allow.
Immoveable (fixed) joints: Such joints allow no movement e.g. the joints between the skull bones.
Slightly moveable joints: Such joints allow slightly movement e.g. the joints between vertebrae.
Moveable joints: They allow a variety of movements e.g. shoulder, hip, elbow and knee joint etc.there are many types of moveable joints in body. The main types are hinge joints and ball-and-socket joints. Hinge joints move back and forth like the hinge on door and allow movements in one plane only. The knee and elbow are hinge joints. Ball-and-socket joints allow movement in all direction. The hip and shoulder joints are ball-and-socket joints.

Role tendons and ligaments:
                                                         Tendons and ligaments are bands of connective tissue. Tendons are tough bands and attach muscles to bones. When a muscle contract tendon exerts pulling force on the attached bone, which moves as a result. Ligaments are strong but flexible bands and join one another at joints. They prevent dislocation of bones at joint.

Read more

SUPPORT AND MOVEMENT

       SUPPORT AND MOVEMENT

In this chapter, we study human skeleton system (skeleton) which is primarily responsible for support and movement.
Human Skeleton
Skeleton system or skeleton is defined as the framework of hard, articulated structures that provide physical support, attachment for skeleton muscles, and protection for the bodies of animals.
Skeleton are of two types which are following:
1. Endoskeleton
2. Exoskeleton
Endoskeleton:
                     Like other vertebrates, the human skeleton is on the inside of body and is called endoskeleton.
Exoskeleton:
                    The skeleton system of some invertebrates e.g. arthropods, is on the outside of body, and is called exoskeleton.
Role of Skeleton System:
                                      The big function of skeleton system is protection, support and movements. In our body, skeleton work very closely with the muscular system to help us move. Similarly, skeleton provides protection to many internal organs e.g. skull protects brain, vertebral column protects spinal cord and ribs protects most of other internal organs. Vertebral column also provides the main support to our body mass.
Bone and Cartilage:
                              Overall, the human skeleton is made of bony framework but in certain parts, this framework is supplemented by cartilage.
a. Cartilage:
                        Cartilage is dense, clear blue-white firm connective tissue. The cells of cartilage are called chondrocytes. Each chondrocyte lies in a fluid space called lacuna present in the matrix of cartilage. The matrix of cartilage contains also collagen fibers.
Blood vessels do not enter cartilage. There are three types of cartilage.
Hyaline Cartilage is strong yet flexible. It is found covering the ends of the long bones, in the nose, larynx, trachea and bronchial tubes.
Elastic Cartilage is similar in structure to hyaline cartilage. It is also quite strong but has elasticity due to a network of elastic fibers in addition to collagen fibers. It is found in epiglottis, pinna etc.
Fibrous Cartilage is very tough and less flexible due to large number of thick collagen fibers present in knitted form. It is found in intervertebral discs.
b. Bone:
                  Bone is the hardest connective tissue in body. Bone not only moves, support and protect the various parts of body but also produce red and white blood cells and store minerals. The hard outer layer of bone is called compact bone.
While the interior of bone is soft and porous. It is called spongy bone. Spongy bone consists of blood vessel and marrow.
The mature bone cells are called osteocytes.

Read more

Homeostasis in Human:

 The following are the main organs which work for homeostasis.
Lungs remove excess carbon dioxide and keep it in balance.
Skin performs role in the maintenance of body temperature and also removes excess water and salts.
The kidney filter excess water, salts, urea, uric acid etc. from the blood and forms urine.
Skin:
        We know that our skin consist of two layers. Epidermis is the outer protective layer without blood vessels while dermis is the layer containing blood vessels, sensory nerve endings, sweat and oil glands, hairs and fat cells.
Skin performs important role in the regulation of body temperature. The thin layer of fat cells in the dermis insulates the body. Contraction of small muscles attached to hairs form ‘Goosebumps’. It creates an insulating blanket of warm air.
Similarly, skin helps in providing cooling effect when sweat is produced by sweat glands and excess body heat escapes through evaporation. Metabolic wastes such as excess water, salts, urea, and uric acid are also removed in sweat.
Lungs:
            In the previous chapter we learned how lungs maintained the concentration of carbon dioxide in blood. Our cells produced the carbon dioxide when they perform respiration. From cells, carbon dioxide is diffused into tissue fluid and form there into blood. Blood carries carbon dioxide to lungs from where it is removed in air.

Read more

Homeostasis in Plants:

 

Homeostasis in Plants

                                   Plants respond to environmental changes and keep to their internal conditions constant i.e. homeostasis. They apply different mechanisms for the homeostasis of water and other chemicals (oxygen, carbon dioxide, nitrogenous material etc).

Removal of Extra Carbon dioxide and Oxygen:

In daytime, the carbon dioxide produce during cellular respiration is utilized in photosynthesis and hence it is not a waste product. At night, it is surplus because there is no utilization of carbon dioxide. It is removed from the tissue cells by diffusion. In leaves and young stems, carbon dioxide escapes out through stomata. In young roots, carbon dioxide diffuses through the general root surface, especially through root hairs.

Removal of Extra Water

                                    We know that plants obtain water from soil and it is also produced in the body during cellular respiration. Plants store large amount of water in their cells for turgidity. Extra water is removed from plant body by transpiration.
At night, transpiration usually does not occur because most plants have their stomata closed. If there is a high water content in soil, water enters the roots and is accumulated in xylem vessels. Some plants such as grasses force this water through special pores, present at leaf tips or edges, and form drops. The appearance of drops of water on tips or edges of leaves is called guttation.

Removal of Other Metabolic Wastes
                                                         Plants deposit many metabolic wastes in their bodies as harmless insoluble materials. For example, calcium oxalate is deposited in the form of crystals in the leaves and stems of many plants e.g. in tomato.
In trees which shed their leaves yearly, the excretory products are removed from body during leaf fall. Other waste materials that are removed by some plants are resins (by coniferous trees), gums (by keeker), latex (by rubber plant) and mucilage (by carnivorous plants and ladyfinger) etc.
Osmotic Adjustments in Plants:
                                        On the basis of the available of water and salt, plants are divided into three groups. 

Hydrophytes: are the plants which live completely or partially submerged in freshwater. Such plants do not face the problem of water shortage. They have developed the mechanisms for the removal of extra water from their cells. Hydrophytes have broad leaves with a large number of stomata on their upper surfaces. This characteristic helps them to remove the extra amount of water. The most common example of such plants is water lily.
 Xerophytes: live in dry environments. They possess thick, waxy cuticle over their epidermis to reduce water loss from internal tissue. They have less number of stomata to reduce the rate of transpiration. Such plants have deep root to absorb maximum water from soil. Some Xerophytes have special parenchyma cells in stems or roots in which they store large quantities of water. This makes their stems or roots wet and juicy, called succulent organs.

 Halophytes: lives in sea waters and are adapted to salty environments. Salts enter in the bodies of such plants due to their higher concentration in sea water. On the other hand, water tends to move out their cells into the hypertonic sea water. When salts enter into cells, plants carry out active transport to move out of their cells into the hypertonic sea water. When salts enter into the cells, plants carry out active transport to move and hold large amount of salts in vacuoles. Salts are not allowed to move out through the semi-permeable membranes of vacuoles. So the sap of vacuoles even more hypertonic than sea water. In this way, water does not move out of cells. Many sea grasses are included in this group of plants.

Read more

Homeostasis

                     The tendency of an organism or a cell to regulate its internal conditions, usually by a system of feedback controls, so as to stabilize health and functioning, regardless of the outside changing conditions.
 Examples:       
        Body Temperature Homeostasis

In warm-blooded animals such as humans, body temperature must be maintained by various negative feedback reflex responses within the body.
Heat in the body is generated by the cellular respiration reaction, combining oxygen and ATP (a product of glucose) and creating heat, carbon dioxide and water.
The hypothalamus of the brain monitors body temperature and regulates that temperature by either increasing the rate of cellular respiration reactions, or decreasing the rate and otherwise causing heat loss from the skin.
If the body becomes cold, and more heat is needed, more ATP / glucose are “burned” to generate that heat.
If the body becomes too hot, the blood vessels near the skin dilate (open up) to allow more heat loss from the blood to the skin to the air, and perspiration from the skin causes evaporative cooling.
The body temperature must be maintained within a few degrees of the normal 98.6o F. If the core temperature falls below 90o or above 110o, death can result.

Glucose Level in Blood

 
Another example is glucose levels in blood. Glucose is the form of sugar that is found in blood and that provides energy for cellular respiration.
When glucose levels are too high in the blood, a hormone called insulin is secreted by the pancreas. Insulin stimulates the absorption of glucose by cells and the liver’s conversion of glucose into glycogen. Glycogen is a sugar that can be stored in the liver and blood cells.
As glucose levels decrease, less insulin is produced. When glucose levels are too low, another hormone called glucagons is produced, which in turn causes the liver to convert glycogen back to glucose

Read more

Bad Effects of Smoking

 

1. Coughing

Smokers coughing that is. After a not predetermined time of being a smoker, you will begin to experience smokers cough, because your body uses this as a way to try and get rid of the toxins you inhale while smoking.

2. Yellow teeth

many smokers when they realize the state of their smile, that has gone from bright white to almost yellow stop smiling all that much, or try to hide their teeth while smiling.

3. Trouble with blood circulation

After contaminating your blood for a period of time with the smoke you inhale and that therefore gets into your blood stream, your blood will not circulate as freely in your body as it used to, and your arteries will begin to clog. The Ares furthest away from the heart, (hands and feet) will be first to get lowered their blood flow, and you will begin to experience cold hands and feet.

4. Lessened glowing of your skin

A healthy skin have a natural glow about, but with the clogged arteries, the lessened blood flow, will slowly make your skin greyer, and more pale than it used to be.

5. Ugly yellow fingertips

The smoke that several times daily gets in contact with your skin at the fingertips, is slowly going to make the fingers on the hand you hold the cigarette with into ugly looking yellow fingers.

6. Lower Energy

When you smoke, your immune system never relaxes for very long. Immediately when smoke gets in your body, the immune system start fighting it, and is therefore working on overdrive so to speak. That extra use of energy has to come from somewhere, and it does. The energy used is taken from your overall energy levels, Along with that; the lesser lung capacity reduces your bodies’ oxygen intake, which again reduces your energy levels. So you can expect a lower energy level overall from smoking.

7. Less oxygen for your brain: 

Lower oxygen in your causes the brain to get lesser oxygen then it needs to function optimally. This may cause you to have a worse than average ability to focus on things, and it may also cause dizzy spells.
These are just some of the more obvious negative effects of smoking that your body suffers under being a smoker, in the long term your risk of severe blood clogs, lung cancer and heart diseases will dramatically increase the longer you are a smoker.
 

Read more

Respiratory Disorders

 

 Respiratory Disorders
There are a number of respiratory disorders which affect people. The percentage of such disorders is particularly in Pakistan. It is due to the more concentration of air pollutants not only in the urban but also in rural atmosphere. Some of the important respiratory disorders are described next.

 

 Bronchitis

Bronchitis is the inflammation of the bronchi or bronchioles. It results in excessive secretions of mucus into the tubes, leading to the swelling of tubular walls and narrowing of tubes. It is caused by viruses, bacteria or exposure to chemical irritants (e.g. tobacco smoke).
The symptoms of   bronchitis include a cough, mild wheezling, and fever, chilis and shortness breathe (especially when doing hard jobs).

Emphysema

Emphysema is the destruction of the walls of alveoli. It results in larger sacs but with less surface area for gaseous exchange. As lung tissue breaks down, the lung does not come back to its original shape after exhalation. So air cannot be pushed out and is trapped in the lungs.
Symptoms of Emphysema include shortness of breath, fatigue, recurrent respiratory infection and weight loss. By the time the symptoms of emphysema appear, the patient has usually lost 50% to 70% of his/her lung tissue. The level of oxygen in blood may get so low that it causes serious complication.

Pneumonia

Pneumonia is an infection of lungs. If this infection affects both lungs, it is called double pneumonia. The most common cause of pneumonia is a bacterium, Streptococcus pneumoniae.Some viral and fungal infection may also lead to pneumonia.
The symptoms of pneumonia include a cold that is followed by a high fever, shivering and a cough with sputum production. Patient may become short of breath. The patient’s skin color may change and become dusky or purplish. It is due poor oxygenation of blood.                       
Vaccines are available to prevent pneumonia caused by S.pneumoniae.Antibiotics are used in the treatment of this type of pneumonia.

 

Asthma

Asthma is a form of allergy, in which there is inflammation of the bronchi, more mucous production and narrowing of the airways. All those factors which causes allergy is called allergens
The symptom of asthma is varying from person to person. The major symptoms include the shortness of breath, wheezing, cough and chest tightness.
The chemical with ability to dilate the bronchi and bronchioles are used in the treatment of asthma. Such medicines are given in the form of inhalers.

 

Lung cancer

                                Lung cancer is a disease of uncontrolled cell division in the tissue of lungs. The cell continue ton divide without any control and form tumors. The cellular growth may also invade adjacent tissues beyond the lungs.
The most common symptoms are shortness of breath, coughing and weight loss.

 

 

 

 

Read more

Gaseous Exchange in Human

 

Gaseous Exchange in Human

In humans and other higher animals the exchange of gases is carried out by the respiratory System.

  The respiratory system is divided into two parts.

(A) Air passage way      (B) The lungs 

(A)  Air passage way:
The air passage way consist of the parts through which the outside air comes in the lungs
And after the exchange of gases it goes out. This passage way of air consists of following parts.

1- The nasal cavity:
The nose encloses the nasal cavity. It opens to the outside through the openings called the
Nostrils.
2-Pharynx:
The nasal cavity opens into the pharynx by means of two small openings called internal
Nostrills.Pharynx is a muscular passage and is common to both food and air. It extends to the
Opening of the esophagus and the larynx. The air goes from the pharynx into the larynx.   
3-Larynx:
The larynx is a box, made of cartilage. It is present between pharynx and trachea. It is also called the voice box.
4- Trachea:
Larynx continues to the trachea, which is also called the wind pipe. It is about 12 cm long tube
This lies in the front of esophagus.
5- Bronchi:
On entering the chest cavity, the tracheas divided into two smaller tubes called bronchi.
6- Bronchioles:
The bronchi continue dividing in the lungs until they make several fine tubes called bronchioles.
7- Alveolar duct:
The bronchioles progressively lose the cartilages as the become narrower. The bronchioles end as fine tubes called the alveolar duct.
8-Alveoli:
Each alveolar duct opens into a cluster of pouches called alveoli.


 

Read more

Gaseous Exchange In Plants

 

Gaseous Exchange In Plants

Plants have no organ or system for the exchange of gase with the enviroment every
cell of the plant body exchanges gases with the enviroment by its own.

 

Stomata

These are small opening in the walls of the leaves.the leaves and young stems have stomata
in their epidermis.The gaseous exchange occurs through these stomata.

 

The machanism of gaseous exchange in leaves

The inner cells of leaves and stem also have air spaces among them which helps in the
exchange of gases.

 

Gaseous Exchange in stem

In woody stem and mature roots,the entire surface is covered by bark which is imprevious
to gases or water.However,there are certain pores in the layer of bark.These are called
lenticels.

 

Gaseous Exchange in roots

Gases diffuse in and out of the general surface of young roots the gases are found in soil
surrounding the roots.

 

Read more

Gaseous Exchange

 

Taking in oxygen and giving out of carbon dioxide is termed as gaseous exchange.

Cellular respiration:   
Cellular respiration is the process through which animal take air in which the C-H bonds
in food are broken by oxidation reduction reaction and the energy is transformed into ATP.
Importance in breathing:
The term breathing is used for the process throgh which animal take in air in their bodies
to get oxygen from it and then give out the air for getting rid of carbon dioxide.

Read more