Introduction to Cells, Tissues, Organs and Body Systems PDF

Introduction to Cells, Tissues, Organs and Body Systems Powerpoint: https://drive.google.com/drive/u/1/folders/1DwowhpEEfAAqoSxkYkZyA4h1pMNb6OiR https://drive.google.com/drive/u/1/folders/1DwowhpEEfAAqoSxkYkZyA4h1pMNb6OiR There are o...

Introduction to Cells, Tissues, Organs and Body Systems Powerpoint: https://drive.google.com/drive/u/1/folders/1DwowhpEEfAAqoSxkYkZyA4h1pMNb6OiR https://drive.google.com/drive/u/1/folders/1DwowhpEEfAAqoSxkYkZyA4h1pMNb6OiR There are over 100 types of cells, which group together to perform specific functions There are four types of tissues Connective Epithelial Muscle Nerve Tissues regulate together to perform particular tasks Organs are linked to look after inter-related functions Body systems are collection of organs sharing a common function Introduction to Cells, Tissues, Organs and Body Systems 1  Image of a nucleated cell Introduction to Cells, Tissues, Organs and Body Systems 2  Diagram of the cell The plasma membrane is the outer layer of the cell and encloses the cytosol within it It is a phospholipid bilayer (contains 2 layers of phospholipids) Phospholipids have hydrophilic heads and hydrophobic tails Sugars and proteins are embedded within the layer It controls the entry and exit of substances into cells The nucleus is the largest organelle, surrounded by a nuclear envelope. It contains the genetic material of the cell in the form of chromosomes and contains a nucleolus (involved in the synthesis of ribosomes) Skeletal muscles are multinucleated Red blood cells are anuclear Introduction to Cells, Tissues, Organs and Body Systems 3  Nervous system Introduction to Cells, Tissues, Organs and Body Systems 4  Immune & Lymphatic system Introduction to Cells, Tissues, Organs and Body Systems 5  Endocrine system Cytoskeleton The cytoskeleton is a network of protein fibres that give the cell shape and allow it to move Composed of Microfilaments Small fibres that provide structural support Allow contractions Microtubules Larger fibres also involved in movement Centrosome Directs organisation of microtubules Introduction to Cells, Tissues, Organs and Body Systems 6  Pair of centrioles Important in cell division Cell extensions Projections of the plasma membrane Important for movement Mitochondria are the powerhouse of the cells They produce energy for the cell through aerobic respiration Double-walled with cristae High abundance in cell types with a high energy demand eg muscle, liver Introduction to Cells, Tissues, Organs and Body Systems 7  Electron microscopy of a mitochondrion There are two types of endoplasmic reticulums: Smooth & Rough Smooth Responsible for synthesising lipids and steroid hormones Drug detoxification Rough Studded with ribosomes Responsible for protein synthesis to be exported from the cell E.g. enzymes Ribosomes are made up of RNA and protein Introduction to Cells, Tissues, Organs and Body Systems 8  Important in protein synthesis Synthesise proteins from amino acids using RNA as the template Can be found in the cytoplasm and on the RER Cytoplasmic ribosomes make proteins for use in the cell RER ribosomes make proteins for export Golgi apparatus is a stack of membrane-bound sacs (cisternae) Important for the export of proteins from the cell Proteins are received from the ER where they are packaged into vesicles and stored until needed To exit the cell, vesicles move to the plasma membrane and fuse with it Contents of vesicles are expelled from the cell by exocytosis Golgi also produces lysosomes image of a golgi apparatus Lysosomes Spherical vesicles that have been ‘pinched off’ the Golgi apparatus Introduction to Cells, Tissues, Organs and Body Systems 9  Contain enzymes that are used to breakdown large molecules within the cell Eg. DNA, RNA, proteins, carbohydrates etc. Internal acidic pH (pH 5) Once broken down, the smaller fragments can then be extruded from the cell or recycled Cytosol Cytosol is the watery fluid that houses the organelles (pH 7) Cytoplasm is the name given to the cell contents, excluding the nucleus E.g. cytosol and organelles Examples of Microscopy techniques Light microscopy (LM) Fluorescence microscopy (FM) Scanning electron microscopy (SEM) Transmission electron microscopy (TEM) Tissues Tissues are large groups of similar cells grouped together to perform a particular function. Tissues are classified according to the size, shape and function of their constituent cells. Epithelial tissue Lines surfaces of body cavities, tubes Role in transport diffusion secretion Muscle tissue Introduction to Cells, Tissues, Organs and Body Systems 10  Generate motile forces through contraction Skeletal muscle Smooth muscle Cardiac muscle Nervous tissue Communication Interconnected networks that allow communication from the brain and spinal cord to other parts of the body Connective tissue Basic type of supportive tissue Structural role Insulator role Protective role All tissues are composed of CELLS and EXTRACELLULAR MATRIX (ECM) ECM is made by the cells and exported to fill the extracellular space Scaffolding Introduction to Cells, Tissues, Organs and Body Systems 11  Extracellular matrix (ECM) Differs between tissue types e.g. epithelial tissue is formed from sheets of cells with little ECM present. Connective tissue has a high amount of ECM and comparatively few cells present Roles of the ECM: Scaffolding Form junctions with cells Regulate migration Influence development and growth Change morphology / function of cells Epithelial tissue Covers the body, lines body cavities and found in glands Structure is closely related to functions of Protection Secretion Absorption Epithelial tissue can be simple (a single layer of cells) or stratified (multiple cell layers). Simple Stratified Introduction to Cells, Tissues, Organs and Body Systems 12  Simple epithelial tissue Simple Squamous Epithelium Flattened cells attached to a basement membrane Lines the heart, blood vessels, lymph vessels, lung alveoli and collecting ducts of the kidney nephron Cuboidal Cube-shaped cells attached to a basement membrane Introduction to Cells, Tissues, Organs and Body Systems 13  Forms kidney tubules and some glands Important role in secretion, absorption and/or excretion Columnar Rectangular-shaped cells attached to a basement membrane Found in stomach, small intestine, trachea, fallopian tubes Can be ciliated Introduction to Cells, Tissues, Organs and Body Systems 14  Stratified Epithelial Tissue Stratified Epithelium Several layers of cells Continual cell division in the basal layers Main role is in protection from wear and tear Introduction to Cells, Tissues, Organs and Body Systems 15  Stratified epithelium can be Squamous epithelium Transitional epithelium Stratified Squamous Epithelium Keratinised stratified epithelium Dry surfaces Skin, hair and nails Top layer of cells have no nuclei and contain keratin Non-Keratinised stratified epithelium Moist surfaces, protects them from drying out Introduction to Cells, Tissues, Organs and Body Systems 16  Mouth, pharynx, oesophagus and vagina Transitional Epithelium Pear-shaped cells Only found within the urinary tract Pseudostratified Epithelial tissue Pseudostratified Epithelium Introduction to Cells, Tissues, Organs and Body Systems 17  Gives the impression of multiple cell layers but each cell is attached to a basement membrane Pseudostratified columnar ciliated epithelium is found within the respiratory tract “Mucociliary escalator” In image, C = cilia and G= goblet cells Connective Tissue Most abundant tissue in the body Consists of cells embedded within a surrounding jelly – extracellular-matrix (ECM) ECM contains fibres to provide a support structure for the cells Main functions of connective tissue are Binding/structural support Protection Transport Insulation Types of connective tissue Introduction to Cells, Tissues, Organs and Body Systems 18  Loose (areolar) connective tissue Adipose tissue Reticular tissue Dense connective tissue Cartilage Bone (Blood) Loose (areolar) connective tissue Most abundant connective tissue type Semi-solid matrix of collagen and elastin fibres containing fibroblasts, adipocytes, mast cells and macrophages Connects and supports other tissues Eg. Under skin, between muscles Adipose tissue Areolar tissue matrix containing adipocytes Adipocytes contain large fat globules 2 types: 1. White adipose tissue About 20-25% BMI in normal, healthy adults Acts as a thermal insulator and energy store Introduction to Cells, Tissues, Organs and Body Systems 19  2. Brown adipose tissue Found in the new-born Highly vascularised Reticular Tissue Found in lymph nodes and organs of the lymphatic system Matrix consists of reticular fibres Cells present are reticular cells and white blood cells Dense Connective Tissue Low cell numbers but high in fibre content Can be FIBROUS TISSUE or ELASTIC TISSUE Fibrous tissue Collagen fibres in closely-packed bundles Fibroblast cells sit between fibres Eg. Tendon, ligament, periosteum Introduction to Cells, Tissues, Organs and Body Systems 20  Elastic tissue Elastin fibres secreted by fibroblast cells Tissue has high degree of recoil Found in organs where change of shape is common Eg. Blood vessels, lungs Cartilage Chondrocytes (cartilage cells) embedded in a collagen and proteoglycan matrix Three types of cartilage in the body Hyaline – ends of long bones (articulating cartilage). Acts as a shock absorber Fibrocartilage – intervertebral discs Elastic fibrocartilage – outer ear Introduction to Cells, Tissues, Organs and Body Systems 21  (black is elastin) Bone Bone is a connective tissue Bone cells (osteocytes) embedded within a mineralised collagen matrix. Osteoblasts – lay down new bone matrix Osteoclasts – remove bone matrix Osteocytes – mature bone cells that reside within the matrix Two types of bones Compact Spongy/cancellous Bone heals really well because it has a huge blood supply Bone is constantly re-growing Introduction to Cells, Tissues, Organs and Body Systems 22  Muscle tissue Muscle tissue is able to contract and relax Provides movement Three types of specialised muscle Skeletal Smooth Cardiac Skeletal muscle Striated (striped), multinucleated muscle fibres Under voluntary control Moves bones of the skeleton Introduction to Cells, Tissues, Organs and Body Systems 23 Introduction to Cells, Tissues, Organs and Body Systems 24  Smooth muscle Non-striated Under involuntary control Useful in propelling contents along tubes by peristalsis (rhythmic contractions) Found in gut tube, ureter etc. Cardiac muscle Striated Introduction to Cells, Tissues, Organs and Body Systems 25  Under involuntary control Mononucleated Makes up the walls of the heart Intercalated discs between cells help propagate wave of contraction A big difference between skeletal and smooth is that skeletal is striped while smooth is not. Furthermore, smooth muscle is involuntary control while skeletal muscle is voluntary control Nervous tissue Two types of cells within the nervous system Neurones Excitable cells Initiate, receive and transmit information Glial cells Non-excitable cells Support the neurones Introduction to Cells, Tissues, Organs and Body Systems 26  More numerous than neurones Astrocytes, oligodendrocytes, ependymal cells and microglia Neurones Cell bodies are found within the Central Nervous System (CNS, Brain and spinal cord) Axons are found within the Peripheral Nervous System (PNS) How do cells attach and communicate with each other? Functional classification of junctions Occluding junctions Introduction to Cells, Tissues, Organs and Body Systems 27  Anchoring junctions Communicating junctions Occluding Junctions 1. tight junctions (vertebrates only) 2. septate junctions (invertebrates mainly) Main role is to seal cells together to prevent molecules from leaking either to another cell or across a boundary Anchoring Junctions Actin filament attachment sites 1. cell-cell junctions (adherens junctions) 2. cell-matrix junctions (focal adhesions) Intermediate filament attachment sites 1. cell-cell junctions (desmosomes) 2. cell-matrix junctions (hemidesmosomes) Main role is to mechanically attach cells (and their cytoskeletons) to adjacent cells or to the extracellular matrix. Communicating Junctions 1. gap junctions 2. chemical synapses 3. plasmodesmata (plants only) Main role is to control the passage of signals (chemical or electrical) from one cell to the other. Introduction to Cells, Tissues, Organs and Body Systems 28  Most cells are linked to their neighbours via gap junctions Good examples are cardiac and smooth muscle cells Visualising tissue Tissue samples need to be processed to study them by microscopy Technique known as histology Tissue is sliced into thin sections and stained Introduction to Cells, Tissues, Organs and Body Systems 29 Introduction to Cells, Tissues, Organs and Body Systems 30