Tissues In The Human Body Essay

Task 1- tissues Tissues are groups of similar cells which have a similar structure and function. All of these cells work together to complete various tasks. There are four different types of tissues in the human body that I am going to give examples of. These include the epithelial tissue, connective tissue, collagenous tissue and the nerve tissue. The first time of tissue is the epithelium tissue which has the function of helping to protect the body. There are four main types of epithelium tissues; squamous epithelial cells, Cuboidal epithelial cells, columnar epithelial cells and ciliated columnar cells.

The squamous epithelium protects the linings in the body such as blood vessels and air sacs in the lungs. The cuboidal epithelium protects things such as the kidneys and glands as they can secrete and absorb substances. Columnar epithelium can also secrete which protects the body from being damaged. There is also ciliated epithelium which covers surfaces with cilia to protect the body from harm. Examples of the epithelial tissues: Squamous epithelium- This type of epithelial tissue is very thin and also very flat. It is usually one cell thick and is therefore in contact with the basement membrane.

Because it is so thin, it is brilliant at diffusion and filtration, and it is also found in locations where these functions are essential. Squamous epithelial cells also have an egg-shaped nucleus. Columnar epithelium- These cells are elongated and column-shaped. They occur in one or more layers. The nucleus is also elongated and are normally located near the base of the cells. Columnar epithelium makes up the lining of the stomach and also the lining of the intestines. Some of which are specialised for sensory reception, for example the nose, ears and taste buds. Unicellular glands are found between the columnar epithelium nd the duodenum.

They secrete mucus, lubricating the surface of cells. Cuboidal epithelium- These cells are a cuboidal shape, and each have a circular nucleus in the middle of them. This type of epithelium tissue is found in the glands and in the lining of kidney tubules as well as in the glands ducts. Its main function is to absorb and secrete. They actively pump molecules in and out of the lumen, in which some of them are lined with microvilli, especially the kidney tubules. The next type of tissue is the connective tissue. Its function is to support and protect the body.

This tissue can secrete different fibres, for example collagen fibres. These fibres add support to many body parts as they have a high tensile strength. Examples of connective tissue: Adipose tissue- Adipose tissue is a type of loose connective tissue which is basically body fat made up of adipocytes. Adipose tissue is located beneath the skin, also known as subcutaneous fat, around internal organs, in bone marrow and also in breast tissue. Adipose tissue is derived from lipoblasts. Its main function is to store energy in the form of lipids, yet is also cushions and insulates the body.

It is a major endocrine organ, producing hormones such as estrogen, resistin and leptin. There are two types of adipose tissues which are white adipose tissue and brown adipose tissue. Cartilage-Cartilage is a flexible connective tissue that is located in the bodies of humans including the joints between bones, the rib cage, the ear, the nose, the elbow, the knee, the ankle, the bronchial tubes, and the intervertebral discs. It is made up of specialised cells called chondroblasts which make a large amount of extracellular matrix.

Cartilage is split into three different types: elastic cartilage, hyaline cartilage, and fibrocartilage, which vary in the relative amounts of these three main components. Unlike other connective tissues, cartilage does not contain blood vessels. Bone tissue-Bone tissue is a type of dense connective tissue. Bones can be found in a variety of shapes and they also have a complex internal and external structure. Bone tissue are lightweight, however they are also strong and hard also serving numerous functions. It has moderately high compressive strength, but poor tensile strength as well as a low shear stress strength.

Reticular- Reticular connective tissue is called for the reticular fibres which are the key structural part of the tissue. The cells that produce the reticular fibres are fibroblasts called reticular cells. Reticular connective tissue forms a framework for other cells in several organs, such as lymph nodes and bone marrow. The function of the nervous tissue is to send signals from one part of the body to the other. It does this due to the cells present in nervous tissues. One cell present is neurons which transmit nerve impulses and the second cell present is neuroglial cells which are support cells.

Examples of nervous tissue: Spinal cord- The nervous tissue of the spinal cord receives information from the skin and muscle sensory receptors and then sends out movement instructions. It rules the autonomic nervous system, and is responsible for sending out sympathetic signals, though some parasympathetic neurons originate in the lower part of the spinal cord. The spinal cord, about 43-45 cm long is hollow. The channel going through its centre is called the central canal. Like the ventricles of the brain, cerebrospinal fluid circulates through the central canal, providing the spinal cord with nutrients, hormones and leukocytes.

Brain- The brain is the main control centre of the central nervous system that is located in the skull. It is responsible for perception, cognition, attention memory, emotion, and action. The brain is made up of many specialized areas that work together, one of which is the cortex. This is the outermost layer of brain cells. The brain stem is between the spinal cord and the rest of the brain. Simple functions like breathing and sleep are controlled here. The basal ganglia are a cluster of structures in the center of the brain. The basal ganglia arrange messages between numerous other brain areas.

The cerebellum is at the base and the back of the brain. The cerebellum is responsible for balance and coordination. Peripheral nerve- Peripheral nerve is a term used to describe the peripheral nervous system. This is a network of 43 pairs of motor and sensory nerves that connect the brain and spinal cord to the entire human body. Its main function is to relay information to and from your central nervous system. Your peripheral nerves transmit voluntary and involuntary actions. Your peripheral nervous system contains 12 pairs of cranial nerves, which emerge from your brain and mostly serve your head and neck.

It also has 31 pairs of spinal nerves, which branch off from your spinal cord and source the rest of your body. The last type of tissue is the collagenous tissue. This type of tissue is the rubbery protein constituent of bone, cartilage, tendon, and other connective tissue. It is transformed into gelatin by boiling. Collagen is a protein composed of aminoacids, which are in built of carbon, oxygen and hydrogen. Examples of collagenous tissue: Tendons- A tendon is made up of dense fibrous connective tissue composed primarily of collagenous fibers.

Primary collagen fibers, which contain bunches of collagen fibrils, are the basic units of a tendon. They attach muscles to other body parts, usually bones. The primary cell types of tendons are the spindleshaped tenocytes and tenoblasts. Fibroblasts are typical cells that are known to reproduce the collagen fibers. The main function of tendons is to allow free and flexible movement in the bo body. Ligaments- Ligaments are tough fibrous bands of connective tissue that has a function to support the internal organs and hold bones together. A ligament is made up of dense fibrous bundles of collagenous fibers.

They are spindleshaped cells known as fibrocytes. Ligaments may be of two major types: yellow ligament is rich in elastic fibers, which are quite tough even though they allow elastic movement and white ligament is rich in collagenous fibers, which are robust and inelastic. Skin- The skin is the largest organ in the body. It separates the body’s internal environment from the external environment. The skin has many varied roles. It acts as a network of communication with the outside world. It also protects the body from water loss, as well as using specialized pigment cells known as melanocytes to protect the body from ultraviolet radiation.

The skin also takes part in calcium homeostasis by contributing to the body’s supply of vitamin D. It also helps regulate metabolism and body temperature. Skin has three layers. The first one is the epidermis. This is the outermost layer of skin that provides a waterproof barrier and creates our skin tone. The next layer of the skin is the dermis which is beneath the epidermis and contains tough connective tissue, hair follicles, and sweat glands. The last layer is the deeper subcutaneous tissue, also known as the hypodermis and is made of fat and connective tissue.