whats the extracellular matrix (ECM)?
complex structural tissue component surrounding and supporting cells of the mammalian tissues
what does the ECM control?
Gesticulation and tissue differentiation
what is the purpose of gesticulation?
- Is to position the 3 embryonic germ layers:
- 1. Ectoderm
- 2. Endoderm
- 3. Mesoderm
what is the ectoderm?
brain, skin, nails, epithelium of the nose and teeth
what is the endoderm?
inner linings of the digestive and respiratory tract
what is the mesoderm?
muscles, circulatory and excretory systems of the body
what are he components of the ECM?
- Proteins (collagen, elastin, fibronectin and laminins)
what is the role of collagen?
Strong, flexible protein fiber
what is the role of elastin?
Elastic protein fibers
what is the role of fibronectin and laminins?
Help connect the ECM components to the cells by binding with integrins in plasma membranes
what are proteoglycans?
- mostly carbohydrates (sugars)
- EX. heparin
what is the role of proteoglycans?
- Absorb water
- Provides lubrication and resiliency
- Acts as a shock absorber for joints
what is the role of epithelial cells?
@ lumen aspect of organs
what do fibroblast do?
- Cells responsible for the synthesis of ECM components
- Found in large number of connective tissue
- Involved in wound healing
what is the role of capillaries?
Feed the cells
what is the role of glycosaminoglycans (GAGs)?
Major components of joint cartilage, joint fluid and other soft connective tissue
what is the role of the macrophage?
Removal of cell debris
What are the principal types of tissue?
- 1. Epithelial tissue
- 2. Connective tissue
- 3. Muscle tissue
- 4. Nervous tissue
what is the role of epithelial tissue?
outer layer of skin, lining of respiratory, digestive tract
what is the role of connective tissue?
bones, joints, cartilage, tendons
what is the role of muscle tissue?
heart, skeletal, smooth (walls of hallow organs)
what is the role of the nervous tissue?
brain, spinal cord, sensory organs
What are the 2 types of epithelial tissue?
- 1. Covering and lining: organized sheets of cells forming a barrier (ex. epidermis)
- 2. Glandular epithelium: makes up most of the glands in the body
what are the locations of epithelium tissue?
1. Lining epithelium: covers the body and some of its parts line the serous cavities (thoracic and abdominal), blood and lymphatic vessels, respiratory, digestive and genitouitary tracts
2. Glandular epithelium: secretory units of endocrine and exocrine glands
what are the functions covering/lining epithelium?
- Protects against underlaying tissues against physical damage, drying out, chemical injury and infection
- Allows and regulates the passage of materials (diffusion, absorption, filtration, section, excretion) into or out of tissues of the body which they cover or line
- Oxygen, food and waste pass through one or more epithelial layer
- Specialized epithelia form sensory parts of organs such as the eye, ear, mouth (taste buds) and nose (olfactory)
what are the functions of the glandular epithelium?
- Specialized for producing secretions that are watery-fluid containing salts, enzymes, hormones, mucus, fats
- oTHERS: milk, insulin, sweat, saliva, calcitonin, tears and bile
what are the general functions of epithelial cells?
- Sensory function
- Secretion - glandular epithelium
what are the characteristics of epithelial tissue?
- Extremely limited amounts of intracellular matrix material
- Appear as continuous sheet cells packed tightly together
- Epithelial layer attaches to an underlying layer of connective tissue by the basement membrane and is AVASCULAR (no blood supply/there are no blood vessels)
what is the apical surface?
All epithelia have 1 free surface which is exposed at the body surface or at the lumen (space) of the body cavity, duct, tube or vessel
what are the characteristics of covering/lining epithelia based on?
- # of cell layers
- Cell shape
- Specialization of their cell surface
what are the 2 different cell layers?
1 layer: simple epithelium
Several layers: stratified epithelium.
what happens when 2 or more layers are present?
Most cells do not reach the basement membrane, the epithelium is classified as stratified
what are the different shapes of cells?
- Flat: squamous epithelium (in lungs),
- Square: cuboidal epithelium (tubules),
- Rectangular: columnar epithelium (mucus membranes),
- Transitional epithelium: if the shape changes depending of the degree of stretching of the tissue (respiratory system/cilia)
how do you figure out what type of cells you are dealing with?
By looking at the shape and the position of the nuclei
Squamous epithelium: if the nuclei are flat and parallel to the free surface
Columnar epithelium: if the nuclei are oval and parallel to the axis of the cell and situated at its base
Cuboidal epithelium: if the nuclei are round and situated in the middle of the cell
what are the 2 types of epithelia?
- 1. The simple epithelia:
- Being composed of 1 layer of cells only,
- they are very thin.
- They are found in areas of minimum wear and tear.
- Main function:to allow passage of substances between the lumen and the surrounding tissues.
- 2. The stratified epithelia:
- Being composed of several layers of cells, they are very thick.
- Main function: is to protect the tissues that they cover.
- The shape of the cells closest to the basement membrane is quite different from that of the cells at the top, near the lumen.
- Thus, the problem is: how can you further classify the stratified epithelia? By convention, stratified epithelia are further classified according to the shape of the cells at the free surface.
what are the simple squamous epithelium?
- 1 layer of flat cells (having 1 flat nucleus).
- Found in: alveoli in lungs, kidney in glomeruli, lining of the heart, blood vessels in the lymphatic system
- Well adapted for diffusion, filtration and secretion
what are simple cuboidal epithelium?
- 1 layer of cuboidal cells with 1 round nucleus
- Found in : small glands, kidney tubules and ovary surface
- Adapted for secretion and absorption of surfaces
what are simple columnar epithelium?
Composed of 1 layer of the columnar cells with 1 oval nucleus
- 1) Non ciliated:
- Contain microvili on apical surface
in the digestive lining
and is involved in absorption
and secretion of mucus
- 2) Ciliated:
- Has cilia on apical surface
- Found :
in the small bronchi, uterine tubes and part of the uterus
what are simple pseudo stratified epithelium?
- 1 layer of cells
- All cells rest on basement membrane
- Cells are different heights
- Nuclei are at different levels
- Can be ciliated or non-ciliated on apical surface
- 1) Non ciliated
- Found: in lining of male urethra and ducts of large glands
- 2) Ciliated
- Found: in trachea, primary bronchi and in the most upper respiratory tract
- Involved in secretion and propulsion of mucus
what are stratified squamous cells?
- thickest of all epithelia
- has several layers
- may or may not contain keratin
- 1) keratinized
- forms the epidermis of the skin
- 2) non keratinized
- lines wet surfaces subject to abrasion like lining of the mouth, tongue, esophagus, part of the epiglottis
what are stratified cuboidal cells?
- has several layers
- surface is composed of cuboidal cells
- Role = proetction
- Found in = largest ducts of sweat glands, mammary glands, and
what are stratified columnar cells?
- Composed of columnar cells
- Vary rare
- Lines part of the urethra, large ducts of some glands, portion of the eye
- Role = protection and secretion
what are transitional epithelium?
- Found in = lining of surfaces of organs subjected to stretch such as the bladder, the ureters and part of the urethra
- If stretched, looks like a stratified squamous epithelium
- If unstretched, looks like a stratified cuboidal epithelium
what is the glandular epithelium?
Specialized cells that secrete exocrine or endocrine substances
what are exocrine glands?
- Release their products into the free surface of the skin or of the open cavities of the body
- Discharge secretions into ducts
- ex. salivary of sweat gland
what are endocrine glands?
- "ductless" glands
- discharge secretions directly into the blood or interstitial fluid
what are the different types of glandular epithelium?
what are apocrine epitehlium?
- Product pinches off and is released form Apex
- Ex. mammory glands, hair follicle, goblet cells in the duodenum
what are holocrine epithelium?
Product collect in the cell, then when product is released the plasma membrane ruptures
what are merocrine (eccrine) cells?
- Most common type
- Secrete through the plasma membrane
- Ex. salivary glands, gastric glands, sweat glands in body acting in cooling system (different from apocrine sweat gland)
what are sebaceous gland?
Produce sebum and lubricate skin and hair
what is connective tissue?
Most abundant tissues
where do you find connective tissue?
Everywhere in the body
what is the function of connective tissue?
connects, supports, transports, insulates, repairs (scar tissues) and protects
how does connective tissue work in insulation?
Fat cells or adipose tissue is a connective tissue that cushions organs and insulates them and provides reserve energy fuel
how does connective tissue work in transportation?
Blood is a connective tissue and it carries and delivers oxygen and nutrients to tissues
what are histological characteristics of connective tissues?
what are the 4 main types of connective tissue?
- 1. Fibrous
- 2. Cartilage
- 3. Bone
- 4. Blood
what are different types of fibrous connective tissue?
- a. LOOSE (Aerolar ex. fascia, fat (protection and insulation)
- b. Dense regular ex. tendons and ligaments (flexible but strong)
- c. Dense irregular ex. symphysis pubis joint (very strong, little flexibility)
what are different types of cartilage tissue?
- Gives firm but flexible support
- Elastic: ear, epiglottis, nose
- Hyaline: trachea rings, joint surface of bone, larynx
- Fibrocartillage: symphysis pubis bone (connection of bones together)
what are different types of bone tissue?
- 1. Compact bone
- 2. Spongy bone - mineralized ECM
classification of connective tissue
2. what is cartilage?
- composed of specialized cells called chondroblasts
- produce a large ECM composed of collagen fibres, abundant ground substance rich in proteoglycan and elastin fibres
how does cartilage differ from other tissue?
The only cell type present is chondrocyte
what are lacunae house cells?
Lacuna hole or pit is a small space containing a chondrocyte in cartilage or an osteocyte in bone
why would cartilage heal slowly?****
- Its has no direct blood supply
- Chondrocytes are supplied by diffusion
what are chondroblasts?
They secrete the ECM (composed of fibres) of cartillage
where are chrondroblast found?
- In the outer layer of cartilage
- As chondroblasts secrete matrix and fiber, the become trapped inside it and mature into cells called chondrocytes
Chondroblast, chondrocyte, lacuna
what is fibrocartilage?
the strong dense fibres that fill the matrix convey shock absorbing qualities
3. what is bone tissue?
- Highly specialized connective tissue
- Cells (osteocytes) = embedded in a calcified matrix
what are the functions of bone tissue?
- Point of attachment for muscles
- Reservoir for minerals
- Supports blood forming tissue
what is compact bone?
Found forming most of the hard shell of a bone
what is the Haversian Canal?
Blood vessels, connective tissue, nerves
what is the Canaliculi?
Small canal allowing for nutrients to travel between lacunae
what is the Lamellae?
Concentric rings - form the bone matrix
what is the Lacunae?
Spaces in the bone (holes) where the osteocytes are located
what is the osteon?
Basic structural unit of compact bone
what is spongy (cancellous) bone?
Forms a network of hard beams of bone tissue inside many bones
what is blood tissue?
- Most unsual connective tissue
- Exits in liquid state
what is the composition of whole blood?
- Plasma = 55%
- Formed elements (RBC, WBC, Platelets) = 45%
what are the functions of blood?
- Regulation of body temperature
- Regulation of body pH
- WBC destroy bacteria
- Circulating blood tissue is formed in the red bone marrow by a process called hematopoiesis
Summary of connective tissue type
what is muscle tissue?
- cells specialized in contraction
- Are elongated and can change their shape by becoming shorter and thicker
what are some histological characteristics common to ALL MUSCLE TISSUES?
- They're made of many cells together
- They are well vascularized (lots of blood vessels)
- They're elongated
- They contain microfilaments
what are the 3 kinds of muscle tissue?
- 1. Skeletal muscle
- 2. Smooth muscle
- 3. Cardiac muscle
what is skeletal muscle?
- Striated voluntary
- Thread like cells with many cross striations
- Very long rod shaped cells
- Multinucleated (normal)
what is smooth muscle?
- No striations
- Fusiform shaped cells
- 1 nucleus per cell
what is cardiac muscle?
- Branching cells with intercalated disks (formed by meeting of plasma membranes of 2 cells)
- 1 or 2 nuclei present (in the centre)Are only found in the heart
what type of muscle lines arteries and veins?
- Smooth musclesYou can see the difference in wall thickness
what is the purpose of having artery and veins lining the smooth muscle?***
Arteries : It relaxes to allow more blood to flow to an area, and contracts to restrict the local blood flow
Veins: smooth muscle that gently pumps blood back to the heart.
what is the function of nervous tissue?
- Rapid regulation and integration of body activitiesIts Ectodermal
what are some specialized characteristics of nervous tissue?
what are some organs containing nervous tissue?
what is a neuron?
Conducting unit of a system
what is the structure of a nervous tissue?
Basic function of the nervous tissue is to rapidly regulate and integrate actions from the body
Has well developed excitability and conductivity characteristics
what is the cell body?
- Aka the soma
- Spherical part of the neuron that contains the nucleus and most of the organelles
what is an axon?
Transmits nerve impulse away from cell body and axon
what are dendrites?
Transmits nerve impulse towards cell body and axon
what is myelin?
- Substance rich in lipids and proteins that forms layers around the nerve fibres
- Acts as insulation
how does a neutron look like?
what are glial cells?
Support, protect and bind neurons
what are the histological characteristics of the nervous tissue?
- 1. Made of many cells close together
- 2. Most of the cells are strongly branching