Download TCDHA HISTOLOGY MIDTERM REVIEW TEST 2025- 2026 EXAMS FOR DENTISTRY and more Exams Dentistry in PDF only on Docsity!
2026 EXAMS FOR DENTISTRY
- histology study of microscopic structure and function of cells and tissues
- cell - smallest unit in the body
- interact w extracellular environment thru active processes (active transport - uses energy)
- pinocytosis cell DRINKING
- phagocytosis cell EATING
- cell membrane - "gate keeper" SURROUNDS the cell
- composed of phospholipid bilayer and proteins
- semipermeable (selective what goes in and out)
- phospholipids (in membrane)
- proteins (in membrane)
act as dittusion (passing of materials thru membrane) regulators
- structural reinforcements and receptors for certain hormones, neurotransmitters and immunoglobin (antibodies)
- cytoplasm aka cytosol
- clear liquid, includes organelles, inclusions and spaces/cavities called VACUOLES
- organelles - metabolically active specialized structures
- major: nucleus, mitochondria, ribosomes, endoplasmic reticulum, golgi appar- tus
- lysosomes
- cytoskeleton
2026 EXAMS FOR DENTISTRY
- nucleus - LARGEST, densest
- production of GENETIC material (DNA and RNA), site of synthesis for ribosomes
- usually single but can be binucleated or multinucleated
- binucleated cells cardiac muscle cells, parenchyma liver cells
- multinucleated cells
- components of a nucleus
- osteoclasts, skeletal muscle cells
- nucleolus,
- chromatin,
- nucleoplasm,
- nuclear envelope
- nucleolus produces RNA and nucleotides of 2 other types of RNA
- chromatin (form of DNA)
contains chromosomes
- nuclear envelope double layered membrane
2026 EXAMS FOR DENTISTRY
- ribosomes particles composed of protein and RNA which synthesize protein "PROTEIN FAC- TORIES"
- golgi apparatus - "CHEMICAL PROCESSING & PACKAGING centre"
- second largest organelle
- a stack of 3-20 flattened membranous sacs
- function: sorts, condenses, packages and delivers proteins from the RER
- attached to membrane and release via EXOCYTOSIS
- mitochondria "POWERHOUSE"
- 2 membranes (inner is folded to increase SA forming CRISTAE)
- most numerous
- releases energy from food molecules and transform energy into ATP (adenosine triphosphate)
2026 EXAMS FOR DENTISTRY
- lysosome - "SEWER SYSTEM" destroys worn cell parts
- membranous sacks produced by GOLGI APPARATUS
- contains hydrolysis (hyaluronidase) and digesting substances that enter cells
- cytoskeleton - microfilaments,
- intermediate filaments,
- microtubules
- microfilaments - delicate, threadlike, microscopic structures of specialized proteins arranged in bundles
- cause VARIOUS KINDS OF CELLULAR MOVEMENTS (such as in muscle cells as myofibrils)
- responsible for cell MOTILITY
2026 EXAMS FOR DENTISTRY
- tight junctions - closes intercellular space bw cells by FUSING cell membranes tg
- prevents MOVEMENT or LOSS of fluid
- location: small intestine
- desmosomes - BINDS CELLS tg by creating "SPOT WELDS" bw adjacent membranes
- location: outer skin and oral mucosa
- hemidesmo- somes
- attachment of CELL TO NON CELLular surface
- smaller attachment plaque from the cells side (half of desmosome)
- used in attachment of epithelium to connective tissue (ex. basement membrane in oral mucosa)
- ALLOWS GINGIVAL TISSUE TO ADHERE TO TOOTH SURFACE BY EPITHELIAL ATTACHMENT
- gap junctions - form TUBULAR CHANNELS bw cells that allow substance to be exchanged
- location: muscle cells of heart, digestive tube)
2026 EXAMS FOR DENTISTRY
- life cycle of a cell 1. interphase (dna replication)
- mitosis (cell division)
- cytokinesis (cytoplasmic division)
- ditterentiation
- interphase - cell GROWS and FORMS NEW organelles Consists of: G1, S, G2 phase
- G1 phase initial resting phase of cell growth
- S phase dna replication (chromatin and centrosome replication)
2026 EXAMS FOR DENTISTRY
- anaphase - centromeres split and each chromosome seperates into 2 chromatids
- chromatids migrate to opposite poles by the mitotic spindle
- spindle fibres shorten and pull individual chromosomes towards centrioles
- telophase - division into 2 daughter cells
- chromosome elongate and form chromatin threads
- nuclear membranes appear around each chromosome set
- NUCLEOLI APPEAR, MICROTUBULES DISAPPEAR
- cytokinesis (cyto- plasmic division)
- cell's divided into 2 identical daughter cells following mitosis
2026 EXAMS FOR DENTISTRY
- differentiation - process by which a less specialed cell becomes a more specialized cell type (ex. ovum+sperm = fetus)
- tissues structure formed by GROUPING OF CELLS w similar characteristics of form and function
- 4 basic types of tissue
epithelial, connective, muscle, nervous
- epithelial tissue - PROTECTIVE COVERING (from physical, chemical, pathogenic attacks, dehydra- tion, heat loss)
- SECRETION and SENSORY
- EXTERNAL and INTERNAL body surfaces, including vessels and small cavities
- can be derived from any of the 3 embryonic cell layers: ECTODERM, ENDODERM, MESODERM
- avascular (no blood vessels)
- connective tissue - supports, protects, framework, fill spaces, stores fat, produces blood cells, helps repair tissues
- BINDS STRUCTURES tg
- HIGHLY VASCULARIZED (provides its own source of nutrition)
2026 EXAMS FOR DENTISTRY
- endoderm respiratory, digestive tract
- mesoderm urinary tract
- epithelium - cells packed CLOSELY TG: surrounded by little or no intercellular substance or tissue fluid
- HIGHLY regenerative (its deeper cells reproduce by mitosis)
- AVASCULAR (no blood supply of its own)
- cellular nutrition (o2 and metabolites) obtained by DIFFUSION from connective tissue
- epithelial cells - tightly joined tg by DESMOSOMES
- joined to BASEMENT MEMBRANE by HEMIDESMOSOMES
- cell arrangement simple, stratified, pseudostratified
2026 EXAMS FOR DENTISTRY
- simple 1 layer, single of cells
- stratified 2 or more layers
- pseudostratified 1 layer but looks like 2
- cell shape squamous, cuboidal, columnar, transitional
- squamous flat
2026 EXAMS FOR DENTISTRY
- cilia hair like projections (propel other substances along, ex. fallopian tubes and egg)
- epithelium divi- sion
- simple squa- mous epithelium
simple, stratified, pseudostratified
- thin, FLAT cells, may vary
- 1 layer, NUCLEUS BULGES out (like fried egg)
- covers connective tissue w little intercellular matrix, attached by the basement membrane
- FILTERING FUNCTION on moist surfaces
- location: pulmonary alveoli (lungs), inner & middle ear, blood & lymphatic vessels, heart, serious cavities
2026 EXAMS FOR DENTISTRY
- endothelium simple squamous epithelium lining of vessels and serous cavities (surround organs)
- simple cuboidal epithelium
- simple columnar epithelium
- CUBES, top view: hexagon
- NUCLEUS in CENTRE of cell
- protection/covering for an organ, contributes to SECRETION
- location: line the ducts of various glands (ex. SALIVARY glands)
- RECTANGULAR, top view: hexagon
- NUCLEUS near BASE of cell
- PROTECTION, SECRETION/ABSORPTION due to GOBLET cells (secrete MUCIN)
- may/may not b CILIATED
- location: NONciliated- stomach, intestines, cervical cranial CILIATED- uterus, fallopian tubes, ductus deferents (male repro), small intra-pul- monary bronchi (lungs)
2026 EXAMS FOR DENTISTRY
- stratified squa- mous keratinized epithelium LAY- ERS
stratum
- basale
- spinosum
- granulosum
- lucidum (palms & soles, NOT in ORAL cavity
- stratum corneum (dead, non-nucleated)
- keratin - hard, tough, fibrous, opaque, waterproof protein
- resists friction
- impervious to bacteria and other invaders
- 1ST LINE OF DEFENCE
- nuclei are condensed and inactive
- transitional ep- ithelium
- ranges bw STRATIFIED SQUAMOUS NON-KERATINIZED and STRATIFIED COLUM- NAR EPITHELIUM
- ranges from polyhedral to dome shaped, flat cells
2026 EXAMS FOR DENTISTRY
- location: bladder cells are SOFT, PLIABLE and LOOSELY ARRANGED
- turnover time epithelial cells are capable of RAPID TURNOVER (time for newly divided cells to be replaced thruout tissue)
- SKIN is about 27 days
- ORAL CAVITY is about 14 days
- basement mem- brane
- 3 layers of base- ment membrane
- connective tissue cell types
- thin, ACELLULAR
- located bw epithelium and connective tissues
- 3 layers
- lamina lucida (clear, basal lamina)
- lamina densa (dense, basal lamina)
- reticular lamina (contains collagen and reticular fibres)
fibroblasts, macrophages, mast cells
