Flashcards in Histology 1: Histology of Basic Tissues Deck (33):
What is a tissue?
A tissue is a group of similar cells that perform a common function
What is matrix?
non-living intercellular material
What are the four principal types of tissues?
1. Epithelial tissue
2. Connective tissue
3. Muscle tissue
What is epithelium?
The tissue that covers the external surface of the body and lines hollow structures (except blood and lymphatic vessels). It forms continuous layers of cells that cover surfaces (skin) and line cavities of the body.
What is mesothelium?
Found in closed peritoneal, pleural and pericardial cavities, mesothelium is a single layer of cells lining serous membranes, which release serum that is like syrupy plasma without the clotting ingredients
What is endothelium?
Epithelium lining the cardiovascular (blood) and lymph vessels
What are some generalisations about epithelial tissue?
1. Limited amount of matrix material
2. Membranous type attached to a basement membrane
4. Cells are in close proximity (20 nm), with many desmosomes and tight junctions
5.Capable of reproduction
What are 'junctional complexes'?
Epithelial attachment points found between neighbouring epithelial cells to hold cell membranes in close apposition. They are anchoring sites for the filaments of the cytoskeleton, to stabilise the cell shape
What is the basement membrane?
A thin, delicate membrane lying at the base of epithelial cells made from specialised intercellular matrix, separating them from connective tissue. It supports the cell and prevents bacteria from entering
Epithelium is avascular. What is the consequence of this?
it depends upon the diffusion of substances across the basement membrane, and receives blood from surrounding tissue through diffusion
What are the three structural characteristics of epithelium?
1. The number of cell layers
2. The shape of the cells
3. The presence of surface specialisations ( cilia, microvilli and keratin etc.)
There are two classifications for the number of cell layers. What are they?
1. Single layer- 'simple' epithelium
2. Multiple layers- 'stratified' epithelium
There are three classifications for epithelial cell shapes. List them.
What are the main functions of epithelium?
1. Protection (preventing injury, dehydration or bacterial invasion)
3. Lubrication (Glandular epithelia cells secrete mucus)
4. Excretion (of waste products from the blood)
5. Diffusion of gases
7. Detection of sensations
8. Secretion by glandular epithelial cells
What is connective tissue?
The supporting framework for tissues and organs of the body. They anchor and bind organs and the packing tissue between them
What are the components/composition of connective tissue?
Consists of fluid, gel, or solid matrix, with or without extracellular fibres (collagenous, reticular, and elastic) and proteoglycans or other compounds that thicken and hold together the tissue
What are the function of connective tissue?
1. Transport (blood)
2. Support (L,T,B,C)
3. Repair (Scar tissue)
4. Defence (Blood and lymph)
5. Storage (Fats and bones)
What are muscle cells, and what do they permit?
Fibres where the cell is longer than wide. It allows for locomotion, constriction and pumping by changing their length and developing tension
What are the contractile elements of muscles cells (myofibril) composed of?
Specific arrays of myofilaments. The proteins (actin and myosin) are responsible for the contractile capability of the cell
What are the three types of muscle?
1. Skeletal (striated, voluntary)
2. Cardiac (striated, involuntary)
3. Smooth (non-striated, involuntary)
What are the features of skeletal muscle?
1. They are long, cylindrical and multinucleated.
3.Actin and myosin is responsible for the contraction and relaxation
4. Tend to be attached to other bones or the skin
What are the features of cardiac muscle?
1. Only found in the heart walls and muscular tissue (septa/myocardium)
2. Has inherent rhythmicity, contracting simultaneously
3. Each cell has a single oval-shaped centrally placed nucleus (although occasionally two are present)
4. Contain intercalated disks, that are strong and allow the muscles to function as one large unit
What are the features of smooth muscle?
1. Cells are fusiform (tapered at each end)
2. Elongated (20-200um)
3. Contain a single central nucleus with two or more nucleoli.
4. No cross striations
5. Located in the walls of blood vessels, hollow organs and the dermis of the skin
What are the two types of epithelium?
Covers the body and some of its parts and lines the serous cavities; blood and lymphatic vessels; and respiratory, digestive, and genitourinary tracts
Secretory units of endocrine and exocrine glands
What comprises the CNS and PNS?
The brain and spinal cord make up the central nervous system, while the nerves that emerge from the spinal cord and brain to pass to parts of the body make up the peripheral nervous system
What is the purpose of nervous tissue?
Form a system of neuronal communication within the body and is specialised for detecting stimuli, integrating functions, controlling effectors and for other higher functions
What does nervous tissue consist of?
1. Cell bodies
2. Cell processes (nerves)
3. neuroglia (connective tissue cells)
What are neurons?
The structural and functional units of the nervous system, responsible for the receptive, integrative and motor functions. They can generate nerve impulse and transmit these along their processes.
What are the parts of a neuron?
1. Cell body (soma, perikaryon):
Contains a centrally-located nucleus with a nucleolus
RECIEVE (afferent) stimuli from sensory cells, axons and other neurons, which are passed on to the cell body (soma)
Axons SEND synapses to other cells. They arise as a single process extending a longer distance from the cell body than the dendrite. They come close to another cell and form a synapse
What are peripheral nerves?
Bundles (fascicles, bundles of structures) of nerve fibres (axons) surrounded by several CT sheaths
What are myelinated fibres?
Myelin (rich in lipid) is the plasma membrane of the Shwann cell organised into a sheath that is wrapped several times around the axon. Myelinated fibres are capable of rapid transfer of impulses, and acts as an insulator of the axons, allowing them to conduct impulses more rapidly
Nerve fibres convey impulses to and from non-nervous structures, such as the skin and muscle, where they terminate in peripheral nerve endings. What might these be?
1. Sensory receptors responding to the sensation of touch (Meissner, Pacinian corpuscles), pain, temperature etc.
2. Motor endings such as a complex ending (motor end plate or neuromuscular junction) which lies at the junction between the motor nerve fibre and the skeletal muscle fibre