Primary Tissues Flashcards
What are the 4 basic types of body tissue?
+ Epithelia
+ Connective tissues
+ Muscle
+ Neural tissue
What do epithelial tissues function in?
\+ Secretion \+ Absorption \+ Transport \+ Barrier/protection \+ Barrier/selective \+ Strength/support
Describe the features of epithelial cells
+ Cover surfaces
- varied shape and arrangement (flat to columnar; single or multilayered)
+ Show surface modifications or adaptions
+ Bound to each other by specialised junctions and adhesion molecules
- not only found in epithelial tissues
+ Sit on the basement membrane, a specialised layer of extracellular matrix material
What shape/formation can epithelial cells take?
+ Simple squamous
+ Cuboidal
+ Columnar
+ Stratified types
What are some surface modifications of epithelial cells?
+ Microvilli
+ Absorption/sensing
+ Cilia
+ Movement/lateral transport
What type of junctions might be expressed between cells?
+ Tight junctions
+ Desmosomes
+ Gap junctions
+ Adherens junctions
What is the role of tight junctions?
Sealing
What is the role of desmosomes?
To strengthen cell links
What is the role of gap junctions?
To connect cytosols of adjacent cells for very small molecules
What is the function of adherens junctions?
To form spots of connection linking movement proteins (actin)
What are features of the basement membrane?
+ Contains proteins that link to the surface of the epithelial cells
+ Contains filamentous proteins that provide strength
What is the role of nervous tissue?
Collects, processes/integrates and sends information (cells are adapted for local and distant cellular communication)
What are the two main systems associated with the nervous system?
+ CNS (central nervous system)
+ PNS ( peripheral nervous system)
What is the defining characteristic of neurons?
The cell process
What are neurons?
Neurons are separate cells that communicate by releasing chemicals by secretion at the ends of cell processes, therefore a neuron is essentially an elongated secretory cell
What forms the apex of a neuron?
An axon
What forms the base of a neuron?
Dendrites
What do axons do?
Direct stimulus away from the cell
What do dendrites do?
Direct stimulus towards the cell
Where does secretion occur in a neuron?
+ At the end of axons
+ Into specialised intercellular gaps called synapses
What occurs at the axon end bulb?
It is the site of chemical neurotransmitter release
What are the features of the myelin “fatty” sheath?
+ Enhances conduction
+ Discontinuous with periodic gaps
What is the myelinating cell found in the peripheral nervous system?
Schwann cells - one builds one internode
What is the myelinating cell found in the central nervous system?
Oligodendrocyte - build a number of internodes
How many times more numerous are glial cells of the CNS than neurons?
10 times
What types of glial cells reside in the CNS?
+ Oligodenrocytes (myelination)
+ Astrocytes
+ Microglia
+ Ependyma (lining cells of the CNS cavities)
What types of glial cells reside in the PNS?
+ Schwann cells (myelination)
+ Satellite cells (support cells in ganglia)
What is the role of astrocytes?
They provide metabolic and mechanical support (in CNS scar tissue also)
+ Nervous system repair: Upon injury to nerve cells within CNS, astrocytes fill up the space to form a glial scar, repairing the area by transformation into neurons and replacing the CNS cells that cannot regenerate
What is the function of microglial cells?
+ First and main form of active immune defence (macrophages) in the CNS
What are the three types of muscle tissue?
+ Skeletal
+ Cardiac
+ Smooth
What are the features of skeletal muscle?
+ Striated, coordinated contraction under direct voluntary reflexes (can be involuntary)
What are the features of cardiac muscle?
+ Striated, coordinated contraction
+ Involuntary control of the blood pump
+ Ionice/structural linkages via specialised junctions - intercalated discs
What are the features of smooth muscle?
+ Non-striated, produces coordinated contraction
+ Involuntary
+ Cells are spindle shaped but cell borders rarely seen clearly
+ No striking ordered arrays of myosin and actin
+ E.g responsible for peristalsis in the gut
What are the 4 types of connective tissues?
+ Fibrocollagenous tissues
+ Cartilage, bone and teeth
+ Adipose tissue (white fat)
+ Blood
What is a major feature of connective tissues?
+ Mix of different cells
+ Extracellular matrix (ECM)
What does the ECM contain?
+ Fibrous proteins
+ Structural carbohydrates and proteins
+ Mineral deposits
What are the different types of fibrocollagenous tissues?
+ Loose
+ Dense
+ Reticular
Where can loose connective tissue be found?
+Around epithelia and organs
+ Type I collagen, cells ++)
Where can dense connective tissue be found?
+Tendons
+ Ligaments
+ Type I collagen, cells +/-
Where can reticular tissue be found?
+ Liver
+ Lymph nodes
+ Type III collagen
What cells form fibrocollagenous tissue?
\+ Fibroblasts \+ Macrophages \+ Mast cells \+ Plasma cells \+ Stem cells \+ Blood cells and adipocytes
What is the function of fibroblasts?
+ To synthesise fibrous proteins such as collagens, elastins
+ To synthesise extracellular matrix components - proteoglycans
What is the function of macrophages?
+ To phagocytise foreign bodies/organisms
+ Present antigens to stimulate immune cells
What is the function of mast cells?
To synthesise histamine and other mediators of inflammation
What is the role of plasma cells?
To synthesise antibodies (mature B cells)
What is the role of cartilage?
To bring flexibility, smooth joint movement and strength
What types of cartilage are there?
+ Elastic
+ Hyaline
+ Fibrocartilage
What are the properties of elastic cartilage, and where can it be found?
+ Flexible (elastin++)
+ Found in the inner ear
What are the properties of hyaline cartilage, and where can it be found?
+ Impact resistant
+ Durable
+ Low friction
+ Found at join surfaces and the trachea
What are the properties of fibrocartilage, and where can it be found?
+ Strong (collagen I ++)
+ Found in the intervertebral discs and at knee joint menisci
What cells are found in hyaline cartilage?
Chondrocytes
What does the ECM of cartilage consist of?
+ Proteoglycans
+ Collagen (mainly type II)
+ High water content (60-80% by weight)
+ No blood vessels; an avascular tissue
What is the function of bone?
+ Skeletal support
+ Protection
+ Miner (calcium) store
+ Blood formation
What are the two types of bone?
+ Trabecular
+ Compact
What are the cells involved in maintaining bone?
Osteocytes (embedded in the bone structure)
What does the ECM of bone consist of?
+ Framework of collagen fibres mineralised with calcium salts
+ Proteoglycans
+ Blood vessels; vascular tissue
How is compact bone arranged?
Cylindrically in Haversian systems
What are osteoclasts?
Large macrophage-like cells that digest bone
What are osteoblasts?
Cells that lay down the framework in bone formation - become trapped as osteocytes
What types of adipose tissue are there and what is the function of each?
+ White fat
- energy storage
- insulation
- protection
+ Brown fat
- heat production
White fat produces adipokines, what do these do?
Send signals to regulate nutritional balance and other systems
What is an example of an adipokine?
Leptin
What does leptin do?
It signals to the brain that the body has had enough to eat
How does brown fat make heat?
By uncoupling oxidative phosphorylation in mitochondria
