The Body Tissues PDF

The BODY TISSUE Course: biology ESP001  Learning objectives ❖ Understanding the different types of tissues. ❖ Epithelial tissue ❖ Connective tissue: types and functions ❖ Muscles tissue: types, organization of skeletal muscles and how it works ❖ Nervous tissue  Tis...

The BODY TISSUE Course: biology ESP001  Learning objectives ❖ Understanding the different types of tissues. ❖ Epithelial tissue ❖ Connective tissue: types and functions ❖ Muscles tissue: types, organization of skeletal muscles and how it works ❖ Nervous tissue  Tissues: Tissues: are groups of cells that perform the same or very similar functions. There are 4 types of tissues: 1) Epithelial tissue: These are sheets of closely packed cells; they cover our body and line our internal organs. - Their main function is to act as a barrier of protection. - In some cases, they provide a surface area for the exchange of fluids and gases.  Cont.: Epithelial Tissues : There are several types of epithelial tissues that are named based on: number of layers: ▪ Simple : single ▪ Stratified : multiple ▪ Pseudostratified : a single layer but looks multiple because they are long) The shape of cells: ▪ Squamous: flat like floors ▪ Cuboidal: cubes like a dice ▪ Columnar: long and wide like bricks. Other characteristics: - Ciliated: with hair-like projections -Transitional: the different layers have different shapes - Glandular: cells have secretions. Connective Tissues: Components of connective tissue Connective tissues differ widely but still made up of three fundamental components ❑ Cells ( apart from each other) ❑ Protein fibres ❑ Ground substance Protein fibres and ground substance are collectively called as extracellular matrix. The composition and structure of extracellular matrix determine function and characteristic of connective tissue Ground Substance: Non-cellular component of a connective tissue between the cells and fibres. The ground substance may be viscous (as in blood), semisolid (as in cartilage), or solid (as in bone). Supports cells, binds them together, stores water, and provides a medium for exchange of substances between the blood and cells. Plays an active role in how tissues develop, migrate, proliferate, and change shape Functions of connective tissues Enclosing and separating organs Connecting tissues to one another (ligaments and tendons) Supporting and moving ( Joints and cartilage) Storing (adipose tissue and bones) Cushioning and insulating (adipose tissues) Transport and protection (blood) Protection ( Bones: cranium and sternum)  Loos connective tissue 1. areolar connective tissues: ▪ Viscous ground substance ▪ Collagen and Elastin fibers ▪ Highly Vascularized ▪ Location: Surrounding organs + blood vessels + under the skin 2. Adipose tissue: - Little matrix - these are closely packed adipose cells, that act as insulation (surround organs), at areas that have a lot of fat cells, under the skin  Dense connective tissue 1. Regular: ▪ Densely packed parallel bundles of collagen. ▪ Withstand a lot of stress ▪ They form tendons + ligaments 2. Irregular: Irregular pattern of collagen Vascularized + more GS Withstand stress Found in skin + cover bones Cont.: Dense connective tissue 3. Elastic: - Dense Elastic Fibers - Provide elasticity - Found in Trachea + walls of arteries  Supportive connective tissue: ▪ Cartilage: ▪ Semi-soloid matrix , high collagen , strong and flexible skeletal material and is made of collagen. It is found at the end of bones and supports ears and noses. Hyaline Provide framework End of bone, nose Fibrocartilage Resist compression Spinal column + knee Elastic Provide flexible framework (elastic Ear + part of larynx fiber) Cont. Supportive tissue: 2. Bone: collagen fibers that are embedded in hard mineral substances like calcium, magnesium, and phosphate. ▪ Forming Compact and Spongy bones Fluid connective tissue ▪ Blood and lymph are considered fluid connective tissues, with their cells circulating in a fluid extracellular matrix. ▪ Plasma is Ground Substance ▪ it is a liquid tissue that transports nutrients through the body. 3) Muscle tissue: Cont. Tissues The most abundant tissue in our bodies. - They are made up of long cells called muscle fibers. - The cells are connected forming strip-like lines known as striations. There are three types of muscle tissue: ▪ Skeletal muscles: these are attached to our bones with the help of tendons. Their function is to voluntary movement.  Cont. Tissues ▪ Cardiac muscle: this forms the contractive part of our hearts; it provides involuntary contraction of the heart. ▪ Smooth muscle: these are called smooth because they don’t have striations. They are found in the walls of internal organs like the stomach, brain, and intestines as well as in our blood vessels. Muscle Type Location Characteristics Control Skeletal Attached to the bones Long, cylindrical Voluntary for movement cells; multinucleated, striated Cardiac Muscle of the Heart Short, branching Involuntary cells, Single nucleus, faintly striated. Presence of intercalated disk. Smooth walls of internal Small spindle shaped Involuntary Muscle organs :GI, cells, Respiratory, & Single nucleus, Genitourinary tract mucous membranes, muscle in blood vessel walls.  The organization of the skeletal muscles ❑ These are the muscles that provide us with movements. ❑ They are arranged in bundles (all grouped together).  The organization of the skeletal muscles ❑ The different parts of the skeletal muscles: - Fiber: this is the smallest part of the skeletal muscle (the cell). - Each fiber is made of smaller bundles called myofibrils (myo= muscles/ fibrils=small fibers). - Then each myofibril is further made of more bundles called myofilaments (filaments= threads). - Finally, the myofilaments are made of two proteins “actin” and “myosin” - Many fibers together are arranged in bundles called fascicles. - The overall muscles are made of many fascicles connected with connective tissues (creating the muscle tissue).  How does the skeletal muscles work? ❖ We can control when and in which way we want to move our skeletal muscles. ❖ How? (example of moving hand to pick up a cup). 1. When you have decided to pick up a cup with your hand (you have used your brain). 2. The brain will send messages to the muscles on your hand, through specific nerves known as the “motor neurons”. 3. Without this message from the brain, you will not be able to move your skeletal muscles. The message from the brain to the muscle The message that is sent from the brain is known as a “neurotransmitter”. - neuro: nerve - transmit: send or carry. There are many different neurotransmitters, each is made of different molecules and has a specific function. The neurotransmitter that is responsible for the movement of muscles is called “acetylcholine (ACh)”. Cont. The message from the brain to the muscle ❖ How does ACh effect the muscles? 1. The brain will send electrical impulses throughout the motor neuron until they reach the muscle. 2. At the area between the end of the neuron “synapse” and the beginning of the muscle, ACh will be secreted. 3. It will reach the muscle and cause electrical signals that will allow the proteins of the myofilaments to move (actin and myosin) with help of Ca ions. 4. Finally, when actin and myosin move, they will cause the entire muscle to move.  Cont. Tissues 4) Nervous tissue: - They are a collection of nerve cells (neurons). - Their function is to sense stimuli and rapidly transmit the information. - They are found in the brain and spinal cord. - Neurons are made up of 3 main parts: axon, Cell body, and dendrites.