4. Basic Tissues Flashcards
What are the 4 Basic Tissues
- Epithelia
- Connective Tissue
- Muscle
- Nervous
Epithelium location
- Cover surfaces
- Line cavities and tubes
- Form glands
Function of epithelial tissue
- Provide physical protection.
- Control permeability
- Provide sensation
- Produce specialised secretions
Important characteristics of Epihelium
- Attachment - held onto basement membrane
- Avascularity - no blood vessels with the cells
- Regeneration - lost cells are quickly replaced by mitosis
- Polarity (apical and basal)
- Cellularity - cells separated by minimal amounts of ECM
6 main types of epithelium
- Simple squamous
- Keratinised stratified squamous
- Non keratinised stratified squamous
- Simple cuboidal
- Simple columnar
- Pseudostratified stratified columnar with goblet cells
Describe Simple Squamous Epithelium
- Flat cells - oval shaped nuclei
- One layer of cells
Major function - exchange of nutrients and gases
Location – blood vessels, alveoli
Describe Simple Cuboidal Epithelium
- Square cells with round nuclei
- One layer
Major function – secretion and absorption
Location – glands, kidney tubules
Describe Simple Columnar Epithelium
- Tall cells with oval, basally located nuclei
- One layer
Major function – absorption and secretion
Location – gastrointestinal tract
Surface modifications - microvilli
Describe Keratinised Stratified Squamous Epithelium
- Flat surface cells with oval shaped nuclei
- Many layers
- Keratin
Major function – protection, barrier (waterproof)
Location – skin, gums
Describe Non-Keratinised Stratified Squamous Epithelium
- Flat surface cells with oval shaped nuclei
- Many layers
Major function – protection, barrier
Location – oral cavity, oesophagus
Describe Pseudostratified Ciliated Columnar Epithelium with Goblet Cells
- Tall cells
- Appears stratified as some cells don’t reach free surface.
- All cells touch basement membrane
Modifications – cilia & goblet cells
Functions – mucociliary escalator
Location - trachea and large respiratory airways
What is an Intracellular junction?
Specialised area of cell membrane that bind one cell to another.
Describe the 4 Intracellular Junctions. What are their functions?
Tight Junctions
- Interlocking proteins tightly bind cells together near apical edge - Prevent passage of water and solutes between cells – (e.g. in digestive tract)
Desmosomes
- Very strong connections between adjacent cells - Proteoglycan arranged on the side of epithelial cells to bind them together - Resist stretching and twisting
Gap Junctions
- Cells held together by an interlocking membrane proteins containing a central pore - Connexons - Proteins that link two epithelial cells in a gap junction - Allows movement of small molecules and ions between cells - found in cardiac muscle
Hemidesmosomes
- Attach cells to the basement membrane - Stabilise the position and anchor cell to the underlying tissue
Define Connective Tissue
Consists of cells suspended within a uniform extracellular matrix.
Fills internal spaces, provides structural support for other tissues, transports materials within the body, and stores energy
Functions of Connective Tissue
- 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
3 specialised connective tissues
Blood, Bone, Cartilage
What is Connective Tissue Proper?
Protective ‘packaging’ between tissues/organs.
Classified according to the type, arrangement and abundance of fibres, cells and ground substance.
3 Types of Connective Tissue Proper
Loose (Areolar) Connective Tissue
Dense Irregular Connective Tissue
Dense Regular Connective Tissue
What is Loose (Areolar) Connective Tissue
Found under the epithelium that covers and lines the body surfaces
Connects epithelial tissue to underlying tissues.
Hold some internal organs in place in the body cavity
Contains - Lots of ground substance - few fibres (collagen & elastic) - Variety of cells; ○ Fibroblasts ○ Adipocytes ○ Macrophages (transient)
What is Dense Irregular Connective Tissue
Found in the dermis
Resists excessive stretching and distension
Fat tissue - energy stockpile for the body
Contains
- little ground substance - many collagen fibre bundles arranged haphazardly - few cells (mainly fibroblasts)
What is Dense Regular Connective Tissue
Found in tendons and ligaments
Attaches muscles to bone in the form of tendons. And attached bone to bone in the form of ligaments.
Contains
- little ground substance - many densely packed bundles of collagen fibres arranged in parallel rows - few cells (mainly fibroblasts)
3 Types of Muscle Tissue
Skeletal
Smooth
Cardiac
Similarities between all muscle tissues
- Elongated parallel to axis of contraction
- Numerous mitochondria
- Contractile elements
Describe Skeletal Muscle and its function
- Long, Linear, cylindrical cells Striated (striped)
- Multinucleated
- Innervated by somatic nervous system
Function - Moves and stabilises the skeleton - Forms sphincters in digestive and urinary tracts - Involved in respiration Attached to bone by tendons
Describe Smooth Muscle and its function
- Short, fusiform cells
- Non-striated
- Single, centrally located nucleus
- Innervated by autonomic nervous system
- Located in the walls of organs, blood vessels and airways
Function
- Gastrointestinal movement
- Alters diameter of airways and blood vessels
Describe Cardiac Muscle and its function
- Found in the heart wall
- Branched muscle fibres Striated
- 1-2 central nuclei
- Intercalated discs
- Innervated by the autonomic nervous system
Function
- Helps to circulate blood & to maintain blood pressure
Describe Nervous Tissue
carries information from one part of the body to another in the form of electrical impulses.
