BIOL10811 Body Systems Study Notes

BIOL10811 Body Systems Notes

Instructor Information

  • Name: Jenny Metcalfe

  • Email: jenefer.metcalfe@manchester.ac.uk

Course Overview

Topics Covered

  • Robust and delicate surface tissues

  • Types of muscle:

    • Skeletal

    • Cardiac

    • Smooth

  • Intercellular junctions

  • Overview of connective tissues

Reading and Additional Support

  • Textbook: Frederic Martini, J.N. (2020) Fundamentals of Anatomy and Physiology, Pages 143-172

  • Videos on Canvas:

    • The four tissue types

    • What is epithelial tissue?

    • Epithelia cell histology

Organisation of the Body

  • Cell: Fundamental structural and functional unit of the body

  • Tissue: A collection of cells that perform a particular function

  • Organ: Multiple tissues that perform a function by working together

  • System: A group of organs with a collective function

  • Organism: One complete individual

Basic Tissues

  • Types of Basic Tissues:

    • Epithelia

    • Connective Tissue

    • Muscle

    • Nervous

Epithelial Tissues

General Characteristics

  • Location:

    • Covers surfaces

    • Lines cavities and tubes

    • Forms glands

  • Important Characteristics:

    • Attachment

    • Avascularity (lack of blood vessels)

    • Regeneration (ability to rapidly reproduce)

    • Polarity (apical and basal surfaces)

    • Basement membrane connects to underlying connective tissue

Classification of Epithelia

  • Formation Based on:

    • Number of cell layers

    • Shape of the cells in the most superficial layer

Number of Cell Layers

  • Simple: One layer

  • Stratified: Two or more layers

Shape of Cells

  • Squamous: Flat

  • Cuboidal: Cube-shaped

  • Columnar: Rectangle-shaped

Main Types of Epithelia

  1. Simple Squamous Epithelium

    • Description: Flat cells with oval-shaped nuclei, one layer

    • Major Function: Exchange of nutrients and gases

    • Location: Blood vessels, alveoli

  2. Keratinised Stratified Squamous Epithelium

    • Description: Flat surface cells with oval-shaped nuclei, many layers with keratin

    • Major Function: Protection, barrier (waterproof)

    • Location: Skin

  3. Non-Keratinised Stratified Squamous Epithelium

    • Description: Similar to keratinised but without keratin

    • Major Function: Protection, barrier

    • Location: Oral cavity, oesophagus

  4. Simple Cuboidal Epithelium

    • Description: Square cells with round nuclei, one layer

    • Major Function: Secretion and absorption

    • Location: Glands, kidney tubules

  5. Simple Columnar Epithelium

    • Description: Tall cells with oval, basally located nuclei, one layer

    • Major Function: Absorption and secretion

    • Location: Gastrointestinal tract

    • Surface Modifications: Microvilli present to increase surface area

  6. Pseudostratified Ciliated Columnar Epithelium with Goblet Cells

    • Description: Tall cells appearing stratified as some cells don’t reach free surface; all cells touch the basement membrane

    • Modifications: Cilia and goblet cells

    • Functions: Mucociliary escalator to trap and move particles out of respiratory tract

    • Location: Trachea and large respiratory airways

Intercellular Junctions

General Description

  • Definition: Specialised areas of cell membrane that bind one cell to another

  • Examples of Junctions:

    • Desmosomes

    • Hemidesmosomes

    • Tight junctions

    • Gap junctions

Types of Intercellular Junctions

  1. Desmosomes

    • Very strong connections between adjacent cells

    • Function: Resist stretching and twisting

  2. Hemidesmosomes

    • Attaches cells to the basement membrane

    • Stabilises the position and anchors cells to the underlying tissue

  3. Tight Junctions

    • Interlocking proteins tightly bind cells together near the apical edge

    • Prevent passage of water and solutes between cells, important in the digestive tract

  4. Gap Junctions

    • Cells are held together by interlocking membrane proteins containing a central pore

    • Allows movement of small molecules and ions between cells; commonly found in cardiac muscle

Connective Tissue

Functions

  • Forms a structural framework for the body

  • Supports, surrounds, and interconnects other tissue types

  • Protects delicate organs

  • Transports fluids and dissolved materials

  • Stores energy reserves

  • Defends body from microorganisms

Composition

  • Cells:

    • Fibroblasts: The main cell type that synthesizes the extracellular matrix

    • Other cell types include adipocytes, macrophages, and mast cells

  • Extracellular Matrix Components:

    • Ground substance consisting of tissue (extracellular) fluid

    • Fibres, including collagen, reticular, and elastic fibres

Classification of Connective Tissue

  1. Specialised Connective Tissue:

    • Blood

    • Bone

    • Cartilage

  2. Connective Tissue Proper:

    • Classified according to the type, arrangement, and abundance of fibres, cells, and ground substance

Types of Connective Tissue Proper

  1. Loose (Areolar) Connective Tissue

    • Contains a lot of ground substance and few fibres (collagen & elastic)

    • Variety of cells including fibroblasts, adipocytes, macrophages (transient)

    • Location: Found under the epithelium that covers and lines body surfaces

  2. Dense Irregular Connective Tissue

    • Contains little ground substance, many collagen fibre bundles arranged haphazardly, few cells (mainly fibroblasts)

    • Function: Resists excessive stretching and distension

    • Location: Found in the dermis

  3. Dense Regular Connective Tissue

    • Contains little ground substance, many densely packed bundles of collagen fibres arranged in parallel rows, few cells (mainly fibroblasts)

    • Location: Found in tendons and ligaments

Muscle Tissue

General Description

  • Function: Produces movement and is specialised for contraction

  • Types of Muscle Tissue:

    • Skeletal

    • Smooth

    • Cardiac

Similarities Among Muscle Types

  • All muscle types are elongated and aligned parallel to their axis of contraction

  • Contains numerous mitochondria

  • Contains contractile elements

Types of Muscle Tissue

  1. Skeletal Muscle

    • Function: Moves and stabilises the skeleton; forms sphincters in digestive and urinary tracts; involved in respiration (Moore et. al., 2018)

    • Cell Description: Long, cylindrical cells that are striated (striped); multinucleated; innervated by the somatic nervous system

  2. Smooth Muscle

    • Function: Located in the walls of organs, blood vessels; facilitates gastrointestinal movement; alters diameter of airways and blood vessels (Moore & Dalley, 2010)

    • Cell Description: Short, fusiform cells that are non-striated; have a single, centrally located nucleus; innervated by the autonomic nervous system

  3. Cardiac Muscle

    • Function: Found in the heart wall; helps to circulate blood and maintain blood pressure (Moore & Dalley, 2010)

    • Cell Description: Branched muscle fibres; striated; contain 1-2 central nuclei; has intercalated discs;

    • Innervated by the autonomic nervous system (Moore et. al., 2018)