Tissue Flashcards
What are tissues
A group of similar cells that work together to perform a common function
What are the 4 types of tissue
- Epithelial tissue
- Connective tissue
- Muscle tissue
- Nervous tissue
What is epithelium?
- epithelium is a tissue consisting of closely packed cels
- they cover the surfaces of the body and line its cavities
- soem forms of epithelium are modified to perform specialised functions
- such as secretion, absorption, protection, transport
Characteristics of epithelium?
- cells are closely packed with little intercellular material (matrix material)
- cells rest on a basement membrane
- they’re avascular (have no blood supply)
How to classify epithelium types?
Number of layers:
- 1 layer: simple epithelium
- 2 or more: stratified epithelium
- looks like multiple but it’s only 1: pseudostratified epithelium
Shape:
- squamous: flat cells
- cuboidal: height and width of the cell are the same
- columnar: height of the cell is greater than the width
Modifications of epithelium
Ciliated epithelium: exposed surface has cilia
Microvilli: membrane is folded to increase surface area
What is muscle tissue?
- tissue made of cells that contain contractive proteins (actin, myosin) that enable cells to shorten and produce movement
- highly cellular and vascular
Skeletal muscle
- cells of skeletal muscle are elongated and have many peripheral nuclei
- they’re striated in appearance
- most skeletal muscle is under voluntary control
- most skeletal muscles are atached to and move bones of the skeleton
Cardiac muscle
- only occurs in the heart
- cells are striated and their movement is involuntary
- they form a network of interconnected cells that join together at intercalated disks
- cells have a single nucleus and are branched
Smooth muscle
- smooth muscles are spindle shaped and contain a single central nucleus
- they’re non striated
- they’re involuntary and form sheets
- occurs in the walls of amny internal organs
- e.g., gut, uterus, blood vessels
What is connective tissue
- provide the body with its supporting framework and help bind various body structures together
What are the characteristics of connective tissue?
- cells are typically separated by intercellular fluid
- the matrix consists of fibres and ground substance, which determines the mechanical properties of tissue
- connective tissue usually has a good supply of blood, but some don’t
Components for the matrix of connective tissue
-fibres: collagen fibres are the most abundant and give the most tensile strength, elastic and reticular fibres give the tissue flexibility
- ground substance - complex carbohydrates that make the substance viscous
Classifying connective tissue
Loose: relatively few fibres
Dense: many fibres
- dense regular: fibres are parallel (tendons and ligaments)
- dense irregular: fibres are arranged randomly (dermis of the skin)
Cartilage (connective tissue)
- tought white elastic tissue
- avascular (when it’s damaged, it doesn’t repair easily)
- the embryo’s skeleton is made entirely of cartilage and gets replaced over time
- in adults, cartilage covers the ends of joint in bones
Bone (connective tissue)
- made of a brittle, calcified matrix with many collagen fibres
- has a rich blood supply
Blood (connective tissue)
- a connective tissue with a fluid matrix (plasma) and no fibres
- cells found in blood are red blood cells (transport oxygen) and white blood cells (pasrt of the immune system
- platelets are fragments that help blood clot
Cells of connective tissue
- fibrocytes: secrete ground substance
- adipocytes: store fat
- mast cells: secrete histamine
- macrophages and lymphocytes: protective immune cells
Nervous Tissue
- transmits electrochemical signals
- made of:
- neurones- highly specialised cells that generate and transmit nerve impulses
- glial cells- support, insulate and protect
- vary in size and shape
