Tissue Types and Their Functions Summary Notes PDF

Tissue Types and Their Functions Summary Notes 1. Epithelial Tissue Structure: i. Epithelial tissue consists of tightly packed cells arranged in continuous sheets, either as a single layer (simple) or multiple layers (stratified). ii. Cells have little i...

Tissue Types and Their Functions Summary Notes 1. Epithelial Tissue Structure: i. Epithelial tissue consists of tightly packed cells arranged in continuous sheets, either as a single layer (simple) or multiple layers (stratified). ii. Cells have little intercellular material and are supported by a basement membrane that separates them from underlying tissues. iii. Epithelial cells have different shapes: squamous (flat), cuboidal (cube- shaped), or columnar (tall and rectangular). Function: i. Protection: Forms protective barriers against physical damage, pathogens, and chemical exposure. For example, the outer layer of skin (epidermis) protects underlying tissues. ii. Absorption: Specialised for absorbing substances; for instance, the lining of the intestines absorbs nutrients. iii. Secretion: Glandular epithelia produce and release substances such as hormones, mucus, and digestive enzymes. iv. Excretion: Plays a role in removing waste products, like the lining of the kidney tubules involved in infiltration. v. Sensory Reception: Certain epithelial cells are involved in sensory perception, such as taste buds and olfactory cells. Examples: i. Simple squamous epithelium: Found in the alveoli of the lungs, where it allows for gas exchange. ii. Stratified squamous epithelium: Found in the skin, mouth, and oesophagus, providing protection. iii. Simple columnar epithelium: Lines the stomach and intestines, facilitating absorption and secretion. 2. Connective Tissue Structure: i. Connective tissue is composed of scattered cells within an extracellular matrix, which can be fluid, gel-like, or solid. The matrix includes fibres (collagen, elastin, and reticular) that give connective tissue its strength and elasticity. ii. Types of cells include fibroblasts (produce fibres), macrophages (involved in immune response), and adipocytes (fat storage cells). Function:  i. Support and Protection: Bone tissue supports and protects body structures, while cartilage provides flexible support. ii. Binding of Organs: Tendons (connect muscles to bones) and ligaments (connect bones to bones) are connective tissues that bind different structures together. iii. Storage: Adipose tissue stores fat as a source of energy and insulation. iv. Transport: Blood, a type of connective tissue, transports oxygen, nutrients, and waste products throughout the body. v. Immune defence: Lymphatic tissue is involved in immune responses, helping to defend the body against pathogens. Examples: i. Loose connective tissue: Found beneath the skin, supporting and cushioning organs. ii. Dense connective tissue: Found in tendons and ligaments, providing strong connections between tissues. iii. Cartilage: Found in joints, the nose, and ears, providing flexibility and support. iv. Bone: Provides structural support and protection for the body. v. Blood: Functions in transportation of gases, nutrients, and waste products. 3. Muscle Tissue Structure: i. Muscle tissue is made up of elongated cells called muscle fibres that are capable of contracting in response to stimulation. Muscle fibres contain actin and myosin proteins, which are responsible for contraction. ii. There are three types of muscle tissue: skeletal, cardiac, and smooth. Function: i. Movement: Muscle tissue is responsible for voluntary and involuntary movements of the body. ii. Posture and Support: Skeletal muscles maintain posture and stabilize joints. iii. Heat Production: Muscle contractions generate heat, helping to maintain body temperature. Types and Examples: i. Skeletal Muscle: Voluntary muscle attached to bones; responsible for body movement. For example, the biceps muscle helps move the arm. ii. Cardiac Muscle: Involuntary muscle found only in the heart; responsible for pumping blood throughout the body. It has striations and is connected by intercalated discs for synchronized contraction. iii. Smooth Muscle: Involuntary muscle found in the walls of hollow organs (e.g., intestines, blood vessels), controlling the movement of substances through these structures. 4. Nervous Tissue Structure: i. Nervous tissue consists of two main types of cells: neurons and neuroglia. Neurons are the primary signalling cells, while neuroglia support and protect neurons. ii. Neurons have three main parts: the cell body (soma), dendrites (receive signals), and axons (transmit signals). Function: i. Communication: Neurons transmit electrical impulses throughout the body, allowing for rapid communication between different body parts. ii. Control and Coordination: Nervous tissue helps regulate and control bodily functions by processing sensory input, making decisions, and transmitting motor output. iii. Reflexes and Responses: Neurons coordinate quick reflexive responses to stimuli, such as pulling your hand away from a hot surface. Examples: i. Central Nervous System (CNS): Brain and spinal cord, responsible for processing information and controlling most body functions. ii. Peripheral Nervous System (PNS): Nerves extending from the CNS, transmitting signals to and from muscles, glands, and sensory organs. Summary of Tissue Functions: