Tissues Flashcards
What’s a tissue?
Group of cells that have a common origin and function together to carry-out specialized activities
What are the 4 types of tissues?
- Epithelial
- Connective
- Muscle
- Nervous
What are the 2 types of epithelia?
- Covering and lining
- Forms outer covering of skin
- Lines inside of respiratory, digestive, urinary and reproductive systems - Glandular
- Secreting portion of glands
Name some general characteristic of epithelial tissue?
- Closely packed cells
- Cells form sheets and attach to a basement membrane
- Single or multiple cells
- Nerve supply
- Avascular
What are some functions of epithelial tissue?
- Protection
- Lubrication
- Secretion
- Absorption
What are the 2 characteristics that classify epithelial tissue?
- Arrangement of cells into layers
2. Shape of cells
What are the 3 different arrangements of layers?
- Simple
- Pseudostratified
- Stratified
Describe the simple cell arrangement
- Single layer
Functions in:
- Diffusion
- Osmosis
- Secretion
- Absorption
- Filtration
Found in:
- Lining of alveoli (air sacs)
- Kidneys
- Blood vessels
Describe the pseudo stratified cell arrangement
- Appears to have multiple layers of cells
- In reality, it’s a simple/single layer epithelium because all cells rest on a basement membrane
Describe the stratified cell arrangement
- 2 or more layers of cells
- Protect underlying tissue
- Present in areas of considerable wear and tear
Found in:
- Salivary glands
- Gums
- Back of tongue
- Hard palate
- Esophagus
What are the 3 cell shapes?
- Squamous
- Cuboidal
- Columnar
Describe the squamous cell shape
- Flat, thin
- Allows for rapid passage of substances through them
Found in:
- Mouth
- On lips
- On cervix
- Skin
Describe the cuboidal cell shape
- As tall as wide
- May have microvilli
- Function in secretion and absorption
Found in:
- Ovary
- Kidney
Describe the columnar cell shape
- Taller than they are wide
- Protect underlying tissues
May have microvilli or cilia
Found in:
- Digestive tract
- Female reproductive
- Respiratory (nasal passage)
- Line ears and buccal cavity
- Eyes
Describe the transitional cell shape
- Change shape from cuboidal to squamous and back
Found in:
- Organs that stretch, such as the urinary bladder
What is the glandular epithelium?
- Function is secretion
- Glands composed of specialized epithelial cells that secrete substances
- Secrete into ducts, onto a surface or into blood
What’s an endocrine gland?
Secrete into fluid then diffuse into blood
Ex: Pituitary, thyroid, adrenal
What’s an exocrine gland?
Secrete into ducts that empty on surface of covering/lining epithelium
Ex: Sweat, salivary, earwax
What are the 3 glands that are both exocrine and endocrine
Pancreas
Ovaries
Testes
What are some general characteristics of connective tissue?
- Nerve supply present, except in cartilage
- Blood supply present, except in cartilage
- Most abundant tissue in body
2 basic elements: cells and extracellular matrix
What is the function of connective tissue?
- Bind together, support, and strengthen other body tissues
- Protect and insulate internal organs
- Compartmentalizes structures
- Transport system for blood (transport system)
- Stored energy reserves (adipose tissue)
- Site for immune responses
Describe the 2 components of connective tissue: extracellular matrix and cells
Extracellular matrix:
- Material located between its widely spaced cells
- Made of protein fibres and ground substance
- Extracellular fluid located in this matrix (contains plasma and interstitial fluid)
Cells:
- Embryonic cells called mesenchymal cells give rise to the cells of the connective tissues
What’s a ground substance of connective tissue?
- Within the extracellular matrix
- Component between the cells and fibres
- Can be fluid, semifluid, gelatinous or calcified
- Supports and binds cells, stores water provides a medium for movement
- Active role in how tissues develop and carry out metabolic functions
Ex: Hyaluronic acid (slippery and lubricates joints) Chondroitin sulfate (supports bones and cartilage)
Name the 6 types of cells of connective tissue and their functions
- Fibroblasts:
- Common in connective tissues - Macrophages:
- Type of WBC that eats bacteria and debris - Plasma cells
- Secrete antibodies - Mast cells
- Produce histamine, which is a chemical that dilates mood vessels and kills bacteria - Adipocytes
- Fat cells found deep to the skin and around organs such as the heart and the kidneys - WBCs
- Not commonly found in connective tissue except during infection
What are the 3 types of fibres of connective tissue?
- Collagen fibres
- Strong, but flexible
- Most abundant fibre - Elastic fibres
- Smaller in diameter than collagen fibres
- Branch together to form network
- Highly elastic - Reticular fibres
- Provide support in wall of blood vessels
- Form network of cells around tissue
What are the 2 types of connective tissue?
- Embryonic
2. Mature
Describe the classification of 5 types of mature connective tissue
- Loosely arranged cells
- Areolar (mostly interstitial fluid providing strength)
- Adipose (insulation, energy storage)
- Reticular (support) - Densely packed tissue contains more fibres, making them thicker
- Dense regular (tendons, ligaments)
- Dense irregular (skin)
- Elastic (lung tissue) - Cartilage (dense network of collagen and elastic fibres)
- Hyaline (ribs, nose, trachea, ends of long bones)
- Fibrocartilage (meniscus in knees)
- Elastic (external ear) - Bone (spongy, compact)
- Osteon (base unit of structure in compact bone)
- Haversian system (contains blood vessels, found in centre of osteon) - Liquid
- Blood tissue (connective tissue with liquid extracellular matrix and transports blood, provides O2/CO2 exchange
- Lymph (liquid in lymph vessels)
Describe the 3 types of fibres
Collagen
- Strong but have some flexibility
- Must abundant fibre in the body
Example: Bone, cartilage, tendons
Elastic
- Smaller in diameter to collagen fibres
- Branch together to form a fibrous network
- Highly elastic up to 150%
Example: Skin, blood vessels, lung tissue
Reticular
- Support in wall of blood vessels
- Form network of cells around tissue
Example: Supporting network for spleen and lymph nodes
What are the 2 types of cells in nervous tissue?
Neurons
- Convert stimuli into electrical signal (action potential) to other neutrons)
Neuroglia
- Support neurons
What are the 3 parts of a neuron?
- Cell body
- Dendrites
- Axons
Describe the functions of the 3 parts of a neuron
Cell body:
- Contains nucleus and other organelles
Dendrites:
- Tapering, highly branched, and short cell processes
- Major receiving or input portion of a neuron
Axon:
- Single, thin, cylindrical process that can be very long
- Conducts nerve impulses toward another neuron or to another tissue
What are the 3 main types of neurons?
Sensory (afferent)
- Conduct impulses from the sensory organs to the CNS
Motor (efferent)
- Conduct impulses from the CNS to the effector organs (muscles and glands)
Interneurons (connector neutrons or association neutrons)
- Only in CNS
- Connect sensory neurons to motor neurons
What is the function of neuroglia?
- Helper cells in the nervous system
- Produce products that provide structural support and protect the neurons
- Don’t generate or conduct any nerve impulses
What are the 3 types of muscle tissues?
- Skeletal
- Cardiac
- Smooth
Describe skeletal muscle tissue
- Long, cylindrical shaped, striated fibres
- Vary in length
- Limited capacity for rejuvenation due to small number of cells that can undergo cell division
- Voluntary muscles
- Usually attached to bones by tendons
Functions:
- Motion
- Posture
- Protection
Describe cardiac muscle tissue
- Striated fibres with only 1 centrally located nucleus
- Attached to one another by transverse thickening of plasma membrane called intercalated discs
- Found in heart wall
- Involuntary control
Function:
- Pumps blood to all parts of the body
Describe smooth muscle tissue
- No striations
- Spindle shaped cell
- Thickest in the middle tapering at each end
- Single centrally located nucleus
- Found in iris of eyes, hollow internal structures (blood vessels, airways to lungs, intestines)
Function:
- Motion by producing powerful contractions
What are the 4 main functions of muscular tissues?
- Produce body movement
- Storing and moving substances within the body
- Electrical excitability
- Elasticity
What is Multiple Sclerosis?
- Abnormal immune system response produces inflammation in the CNS
- This damages/destroys myelin and oligodendrocytes
- Causes damage to underlying nerve fibre
- Slows or halts nerve conduction
