Tissues Flashcards
1
Q
Define Tissue
A
Tissue: A group of cells performing similar functions
-vary in structure, function & content of their extracellular matrix (can contain protein fibres, salts, H20 & dissolved macromolcules)
2
Q
4 Types of Tissues
A
- Epithelial Tissue
- Connective Tissue
- Muscle Tissue
- Nervous Tissue
3
Q
Epithelial Tissue - 6 General characteristics
A
- Lines every body surface and all body cavities (organs lined on the outside and inside & majority of glands are derived from epithelial tissue)
1. Cellularity: composed almost entirely of cells - little extracellular matrix w/ cells bound together w/ intercellular junctions
2. Polarity - have apical suface & basal surface (i.e. lots of channels - one side of cell exposed, other not)
3. Attachment - Basal surface attached to thin basement membrane
4. Avascularity - lack blood vessels (nutrients via diffusion from underlying tissue)
5. Innervation - Richly innverated to detect changes in enviro
6. Regeneration - apical surface in constant contact w/ enviro (freq. damaged/die)- replaced quickly
4
Q
4 Functions of Epithelial Tissue
A
- Physical Protection: From dehydration & abrasion (phys. chem. bio.)
- Selective Permeability: needs to absorb certain things from enviro.
- Secretions: exocrine cells produce secretions such as sweat & oil (may be scattered amount other cell types in epithelium or may form a gland)
- Sensations: possess nerve endings that can detect light, taste, sound, smell & hearing
5
Q
Basement Membrane
A
- is a specialised structure of epithelium
- found between epithelium & underlying connective tissue
- provides physical support and anchoring of epithelial tissue
- acts as barrier to regulate passage of large molecules between epithelium & underlying connective tissue
*is actually composed of 3 layers that all strengthen attachment & form a selective barrier
6
Q
Intercellular Junctions - 4 types
A
*Epithelial cells strongly bound to each other by sharing membrane specialisations 4 types; 1. Tight junctions 2. Adhering Junctions 3. Desmosomes (or hemidesmosomes) 4. Gap junctions
7
Q
Tight Junctions
A
- Encircle cells near apical surface
- Prevents molecules from travelling between - must go through epithelial cells to reach basal membrane (are therefore gatekeepers)
- provides structure & support at apical surface.
-in small intestine, prevent digestive enzymes that degrade molecules from moving between epithelial & connective tissue
8
Q
Adhering Junctions
A
- Formed completely around the cell deep to tight junctions
- microfilaments act like a purse string to stabilise the apical surface (is a strengthening belt of the cell)
- provide a small space between neighbouring cells in direction of basal surface = passage between cells for materials that have already passed through epithelial cell
9
Q
Desmosomes
A
- Doesn’t totally encircle cell
- Like a button or snap between adjacent cells - joins cells together
- At places of mechanical stress between cells
- Have thickened protein plaque on each of apposed cell membranes w/ fine network of proteins spanning intercellular space
- On cytoplasmic side, intermediate filaments attach to plaques & provide suppot and stability
10
Q
Gap Junctions
A
- Fluid filled channels that directly connect the cytoplasms of apposed cells sharing these structures
- allow adjacent cells to communicate w/ each other by flow of ions & other small molecular messengers (i.e. glucose, a.a.)
i.e. muscle cells for contraction along muscle - might need communication along.
11
Q
Epithelia Classification
A
*classified based on shape of cells (at most superficial surface) & no. of cell layers
12
Q
Epithelial Cell Shapes (3)
A
- Squamous: flattened, wide, irregular w/ large nucleus (like a fried egg)
- Cuboidal: about same size on all sides - nucleus centrally located (but do NOT have edges)
- Columnar - taller than they are wide (nucleus is oval & located in basal region)
13
Q
Epithelium Cell Layers (3)
A
- Simple Epithelium: single layer of cells w/ all cells having apical surface & attached to basement membrane (apical often covered by thin layer of fluid or mucus for protection)
- found where stress minimal & absorption, filtration or secretion is primary function
- Stratified epithelium - 2+ layers (not all have apical surface or attach to basal membrane)
- areas subject to abrasive or mechanical stresses
- Pseudostratified epithelium - single layer - not all cells reach apical surface
- Nuclei give appearance of multilayered, stratified epithelium (those that do reach often have cilia to help move fluid along)
14
Q
Types of Epithelium & Location (Simple)
A
- Simple Squamous Epithelium: single layer of flat cells (allows rapid diffusion: lungs, blood vessels & membranes that cover body cavities)
- Endothelium (lines lumen of blood & lymphatic vessels & heart & its chambers
- Mesothelium (serous membrane that lines internal walls of pericardial, pleural & peritoneal cavities) - Simple Cuboidal: forms ducts of exocrine glands (gen. involved in absorption & secretion)
- Simple columnar: I.e. small intestine (involved in absorption & secretion
- Simple Columnar Ciliated - Possess cilia on apical surface such as in respiratory and reproductive systems
15
Q
Types of Epithelium & Location/function (Stratified)
A
- Stratified Squamous Cells - in areas w/ lots of stress as provide protection for underlying tissue
- either exists as nonkeratinized (remains alive w/ mucous or saliva) or keratin (apical = cells that are deal & lack a nucleus - such as outer layer of skin)
- Stratified Cuboidal Epithelium: Generally found in glandular tissue (i.e. sweat or semen), although function is mainly protective (serves to strengthen wall of gland ducts)
- Stratified Columnar - quite rare to fine (e.g. male urethra)
- Psuedostratified Columnar - not really stratified as all cells in contact w/ basement membrane - looks stratified as not all cells reach apical surface.
- often covered w/ cilia, generally involved in protection
- found in respiratory tract, naval cavity
16
Q
Transitional Epithelium - what it is, where found & distinct Feature
A
- Found in the lining of the urinary bladder
- Changes shape between squamous and cuboidal depending on whether bladder if full or empty (walls stretched or contracted)
- when stretched: resemble squamous cells
- When relaxed: polyhedral (many sided) - Distinct feature: presence of few binucleated cells
- Cells aren’t uniform - are bunched up
17
Q
Glands - Function
-2 Categories
Definition of Duct
A
- Perform secretory function
- produce mucin, hormones, enzymes & waste products
2 categories;
- Exocrine glands: possess ducts that cells secrete products into - almost all derived from epithelial tissue
- i.e. milk, sweat, mucous, saliva glands
- Endocrine Glands: do not possess ducts - cells secrete products into interstitial fluid or bloodstream - derived from multiple tissue
- i.e. hormones
Duct: epithelium lined tube through which secretions of glands are discharged to epithelial surface
18
Q
Connective Tissue - Overview
A
- Is most diverse, abundant, widely distributed and structurally varied of all tissue types
- serves to connect structures together
- Is the glue AND filler of the body
- designed to support, protect & bind organs`
e.g. tendons, ligaments, body fat, bones & cartilage
19
Q
3 structural components of Connective Tissue
A
- Cells: differ between types of connective tissue (CT)
- i.e. fibroblasts produce fibres, adipocytes = fat, chondrocytes = cartilage
- Protein Fibres: elastic fibres (flexibility), collagen (strength), reticular fibres (interwoven framework)
- Ground Substance: mix of proteins & carbs w/ variable amounts of salts and H2O
- Protein fibers and ground substance comprise extracellular matrix - produced by CT cells
- Most CT = mainly extracellular matrix w/ small portion of cells (relative to epithelial)).
*Different connective tissues vary in these components
20
Q
Protein fibres in CT (3)
A
- Elastic fibres
- collagen fibres
- Reticular fibres
21
Q
6 Functions of connective tissues
A
PBS-STI
- Physical protection - fat can protect kidneys, axial cavity can protect brain, heart, lungs
- Binding of structures - e.g. ligaments, tendons
- Support and structural frameworks - bones allow soft tissue to connect
- Storage - fat for energy, Bone for Ca & P
- Transport - blood transports nutrients
- Immune Protection - WBC can ward off infection/disease
- extracellular matrix is viscous material that interferes w/ movement and spread of disease-causing organisms
22
Q
3 Broad classifications of Connective Tissues
A
- CT Proper
- Supporting CT
- Fluid CT
23
Q
Connective Tissue Proper - 2 Categories (3 types within each category)
A
- Loose CT: fewer protein fibres & more ground subs.
- serves as body’s packing material - found in spaces around organs- 3 types: areolar, adipose, reticular
- Dense CT: More proteins & less ground subs.
- 3 types: dense regular, dense irregular, elastic
24
Q
Loose CT; Areolar
A
- contains fibroblasts, collagen & elastic fibres
- Can be distorted w/out damage
- provides shock absorption
- found subcutaneous to skin
- found nearly everywhere: surrounds nerves, blood vessels & individual muscle cells
25
Q
Loose CT; Adipose
A
- known as “fat”
- comprised mainly of adipocytes (fat cells) and little else (nuclei pushed to peripheral of cells
- serves to pack around structures & provide padding, cushion shocks & acts as an insulator
- if adipose cells increase fat stores = lipogenesis
- if decrease fat stores = lipolysis
*Fat cells can NOT divide - mesenchymal cells provide extra fat cells if body has excess nutrients
26
Q
Loose CT; Reticular
A
- contains reticular fibres, fibroblasts & leukocytes
- found in spleen, lymph node & bone marrow
- Provides structural support
27
Q
Dense Connective Tissue - characteristics
A
- Is strong, has fibres (mostly collagen) packed tightly together
- less ground substance than loose connective tissue
28
Q
3 types of dense connective tissue
A
- Dense regular CT
- Dense irregular CT
- Elastic CT
29
Q
Dense CT; Dense Regular
A
- collagen fibres aligned parallel to applied force
- found in tendons (muscle to bone) and ligaments (bone to bone)
- few blood vessels - takes long time to heal following injury (rich blood supply necessary for good healing)
30
Q
Dense CT; Dense Irregular
A
- bundles of collagen fibres extending in different directions
- found in deep portions of skin (dermis) & capsules around organs such as liver, kidney & spleen
- forms supporting layer around cartilage & bone (except in joints)
- In places where you’d need to deal with forces from different directions.
31
Q
Dense CT; Elastic CT
A
- predominantly elastic fibres that provide ability to stretch and recoil
- found in voal cords & large/medium arteries & suspensory ligament of penis
32
Q
Two cell groups in CT proper
-examples (4 in each)
A
- Resident cells (permanently in CT)
- Fibroblasts: most abundant in CT proper; produces fibres & ground sub. components of ECM
- Adipocytes - small clusters or as adipose tissue (if large cluster)
- Fixed macrophages - large irregular cells which phagocytose dead cells or pathogens - release chem. which stimulate immune response
- Mesenchymal cells - embryonic stem cell - differentiates into required CT cell - Wandering Cells - primarily Leukocyte type (WBC) [no. at particular moment depends on local conditions]
- mast cells: usu found close to blood vessels - involved in clotting and dilation of vessels
- plasma cells: synthesises disease fighting proteins called antibodies - usu found in intestinal walls, spleen & lymph node
- free macrophages: mobile phagocytic cells that are formed from monocytes; engulf and destroy and bacteria, foreign particles or damaged cell/debris
- Other leukocytes migrate through blood vessel - majority = neutrophils (seeks out bacteria)
33
Q
Fibres of Connective Tissue Proper (3)
A
- produced by CT cells and secreted in ECM
1. Collagen Fibres: long, unbranching, strong, flexible and resistant to stretching; make up 25% of all protein; found in ligaments & tendons - parallel struct. allows them to withstand enormous force in that direction
2. Elastic Fibres: thinner than collagen, stretch easily (due to coiled struct.), branch & then rejoin; allow structures (blood vessels, skin, lungs, arteries) to stretch & relax
3. Reticular Fibres: thinner than collagen, form a meshwork-like configuration; act as packing material & provide structural support for certain organs. Found in organs w/ abundant spaces: liver, lymph nodes & spleen
34
Q
Ground substance of Connective Tissue Proper
A
- Is a colourless, featureless, viscous solution that has a gelatinous, rubbery consistency
- Is a combo of proteins and carbs
- additional content such as H2O & salts can result in texture that is semi-fluid to hard
35
Q
Two Types of supporting Connective Tissue (identify only)
A
- Cartliage
2. Bone
36
Q
4 Components of Fluid Connective Tissue
A
- Plasma: watery ground subs. containing protein fibres
- Erythrocytes: red blood cells
- Leukocytes: White blood cells
- Platelets: Fragments of blood cells involved in blood clotting
37
Q
Muscle tissue - composition & basic outline as to function
A
- Comprised of cells called fibres
- When stimulated by nervous system, fibres shorten or contract - resulting in movement
38
Q
3 Types of Muscle
A
- Skeletal: multinucelated, long cylindrical, striated fibres
- moves skeleton
- Responsible for voluntary body movement
- attaches to bone or skin - found in voluntary sphincters
- Cardiac: one/two nuclei, short bifurcated and striated fibres w/ intercalated discs
- involuntary contractions & relation pump blood in heart (heart wall - myocardium
- Smooth: non sriated, spindle shaped (fusiform) w/ central nucleus
- involuntary movements and motion
- found in walls of internal organs - vessels, airways, bladder, stomach, uterus
- helps propel & control movement of material through these organs
39
Q
2 types of Cell in Nervous Tissue
-function of nervous tissue
A
- Neurons: nerve cells that are capable of initiating and conducting electrical activity throughout body
- are the longest cell in the body
- Neuroglia: cells that support the neurons (are a supportive network)
*Function: communication and control of body function
40
Q
Body Membranes - where they are
-4 Types
A
-Found in major body cavities that line the internal and external cavity surfaces.
Types;
- Mucous
- Serous
- Cutaneous
- Synovial
41
Q
Mucous Membranes (Mucosa)
- where
- roles
A
- Lines body passageways
- connective tissue - lamina propria
- Has absorptive, secretory and protective roles
- mucous cells prevent drying out - lubricate and trap foreign substances
- Found: digestive, respiratory, reproductive and urinary tracts
42
Q
Serous Membranes (Serosa)
- composed of
- where found
A
- simple squamous epithelium - mesothelium
- Parietal and visceral serous layers
- Found; pleura (around lungs), pericardium (around heart) & peritoneium (around abdomin)
43
Q
Cutaneous membranes (skin)
A
- largest membrane in body
- keratinised stratified squamous epithelium
- connective tissue - dermis (also w/ epidermis)
- protects body from external enviro & prevents water loss
44
Q
Synovial membranes - joint lining
A
- composed of well-vascularised areolar, fibrous or adipose connective tissue
- secretes synovial fluid that reduces joint friction and provides nutrients to the joint surfaces
