Basic tissues Flashcards
what tissues does oral histology include
- the lining of the mouth
- the tissues of the tongue
- the periodontium
- the tooth
- the salivary glands
- also includes the study of the process of facial and tooth development (embryology)
the practice of dentistry and dental hygiene is based on knowledge of:
- structure
- arrangement
- reactions
of all oral tissues
why is it important that we know the basics of how cells are gathered in tissues
- to understand how oral tissues react to prevent or produce disease
how can we understand diseases caused by oral biofilm
- study of tissue structure
- study of tissue reaction
- study of tissue repair (from removal of calculus)
what is histology
- the science and study of tissues
- from a cellular to tissue level
what is a tissue
- a group of similar cells surrounded by intercellular (between cells) substance (IS)and tissue fluid
- a group of cells combined in a specialized manner to perform a particular function
types of tissues:
- hard
- sturdy/elastic
- delicate
- secretory
- nutritive
- hard: bone
- sturdy/elastic: skin
- delicate: lining
- secretory: salivary glands
- nutritive: blood
how do we study tissues
- microscopically using stains
how do we prepare microscopic slides
- small piece of tissue removed from body
- fixative placed (preservation) and sent to lab
- specimen dehydrated in alcohol
- placed into melted paraffin wax
- paraffin block thinly sliced with a microtome
- arranged on slides
- wax removed with xylene
- stained
components of a tissue
- cells
- intercellular substances (IS)
- tissue fluid (interstitial fluid) (IF)
structure of cells
- rbc: no nucleus
- wbc: one or several nuclei
- muscle cells: contract
- fat: displaced nucleus (pushed against cell walls)
what is intercellular substance
- in between cells; colourless and transparent
- is a product of cells, holds them together
- provides medium for passing nutrients and removing wastes to and from capillaries
- serves as a physical barrier to prevent the penetration of foreign substances into tissue
- IS occurs in 2 main forms: fibrous; amorphous - shapeless, gel-like known as ground substance (serves as the barrier mentioned above)
- differs in different tissues: bone - mostly IS, little cells; skin - mostly cells, limited IS (dryer)
tissue fluid
= interstitial fluid
- very similar to blood plasma
- part of blood which can diffuse through walls of capillaries and then drains back into blood through osmosis
- in tissues, nutrients are carried out through capillary walls to surrounding IS and then to the cells; waste products of the cells are returned from IS to the capillaries
- different tissues have different amounts of TF
- blood vs skin
4 types of primary tissues
- epithelial tissue
- connective tissue
- muscle tissue
- nerve tissue
divided based on shape, type and amount of; cells, intercellular substance, tissue fluid
epithelial tissue groups and subgroups
surface cells of covering and lining membranes
A - simple: squamous, cuboidal, columnar
B - pseudostratified columnar
C - stratified: squamous, cuboidal, columnar, transitional
epithelial tissue
- very little or no IS or IF, many cells
- avascular (has no blood supply of its own) -> O2/nutrients obtained by diffusion from highly vascularized underlying CT
what is a basement membrane
- composed of 2 layers - made up of fibers and ground substance
- basal lamina: secreted by ep. cells and is mostly ground substance
what does epithelial tissue give rise to
- liver, pancreas as well as salivary glands, thyroid gland and
- enamel organ: produces enamel of developing teeth
2 major groups of epithelial tissue
- covering and lining epithelium: covers body surfaces, lines body cavities, hollow organs and vessels
- glandular tissue: forms glands
what is glandular tissue (2nd type of glands)
- specialized epithelial cells secrete substances mucus, hormones
- 2 major types glands: exocrine glands (duct glands, secretions lead to external surfaces of body), endocrine glands (ductless glands, secretions, such as hormones, enter the blood)
3rd type of glands
exocrine and endocrine glands
- pancreas: endocrine function: secretes insulin and glucagon; exocrine: excretes enzymes to break down proteins
- liver: endocrine function: secretes IGF-1 (has insulin like effects and stimulates growth in the body); exocrine: secretes bile into intestine
- sex glands
3 epithelial groups
- covering and lining epithelium
- glandular tissue
- mixed endocrine and exocrine
connective tissue
- fibrous connective tissue
- areolar connective tissue
- adipose (fat) tissue
- hemopoietic (blood) tissue
- cartilage
- bone
- mesenchyme (gives rise to connective tissue)
fibrous regular connective tissues
- arranged in parallel bundles
fibrous irregular connective tissues
- not parallel bundles
what is the dermis made up of
- mostly fibres, less rigid than the dense regular
what was the fibres of fibrous connective tissues produced by
- cells called fibroblasts: predominant cells in fibrous connective tissue
areolar connective tissue
- loose connective tissue
- attaches skin to muscles; organs to body membranes
- subcutaneous layer
- think of when you remove skin from meat and there’s little strings between the skin and the muscle – that’s areolar tissue
adipose (fat) tissue
- store fat: displace nucleus and cytoplasm
- located in soft tissue and yellow bone marrow
hemopoietic (hemo=blood; poietic=to make)
- tissues that produce blood cells (rbc and wbc) to remove worn out blood cells from the bloodstream
- occurs as rbm and lymphatic tissue (tonsils, nodes where cells differentiate into wbc)
cartilage
- cells are called chondrocytes
- most skeletal fetus first made of cartilage which resorbs as bone tissue - replaces it
- in adults it comprises parts of the nose, trachea, larynx, ear
bone
- is mineralized connective tissue
- cells are called osteocytes
mesenchyme
- embryonic or young connective tissue
- undifferentiated cells that will form connective tissue of the body and blood
- tissue that has not been differentiated
nerve tissue
- forms nervous system
- nerve cells are called neurons
- highly specialized cell = react to stimuli (excitable) and conduct nerve impulses
2 main divisions
- CNS: brain and spinal cord
- PNS: nerves leaving CNS, nerves associated with other organs
muscle tissue
- muscle cells are much longer than wide -> each muscle cell is called a muscle fibre
3 divisions of muscle tissue
based on appearance and muscle control
- non-striated (smooth) involuntary
- striated voluntary
- striated involuntary
what do the tissues of the oral cavity originate from (basic tissues)
- epithelial tissue: gives rise to mucous membranes and salivary glands
- connective tissue: gives rise to jaw bone, fibres of periodontal ligament
- muscle tissue: give rise to muscles attached to mandible and form tongue
- nervous tissue: give rise to nerves that supply oral cavity
what are the tissues of the tooth
- anatomical crown: covered by enamel (epithelial cells)
- anatomical root: covered by cementum (CT cells)
- cervix: neck of the tooth b/w root and crown
- dentin: bulk of tooth in crown and root (CT)
- pulp: in crown and root (CT)
- in crown - pulp chamber
- in root - pulp canals
