ANAT2011 Histology Notes

Module 1: How to Speak Histology

• Histology Ultrastrucutre of cells .............................................................................. 2

Module 2: Nervous System

• Epithelial Tissue ..................................................................................................... 7

• Neural Tissue ....................................................................................................... 13

Module 3: Sniff, swallow, speak!

• Histology of Nose, Mouth and Salivary Glands ........................................................ 22

Module 4: Just Breathe

• Histology of Heart and Vessels .............................................................................. 35

Module 5: Who are the Great 8?

• Histology of Respiratory System ............................................................................ 45

Module 6: No Guts, No Glory

• Histology of Upper GIT ......................................................................................... 52

• Histology of Lower GIT .......................................................................................... 64

Module 7: Toilet Break

• Histology of Renal System ...................................................................................... 72

Module 8: Sex and Multiplication

• Histology of Male Reproductive System ................................................................. 86

• Histology of Female Reproductive System .............................................................. 97

Module 9: Muscoskeletal System

• Histology of Smooth Muscle and Connective Tissue .............................................. 111

• Histology of Bone Cartilage and Joints.................................................................. 118

Module 1 Histology Ultrastructure of cells Cytoplasm

• Contains organelles (membrane and non-membrane bound ones), inclusions (small, insoluble particles such as glycogen, lipid droplets) and cytosol (water, salts, organic molecules, soluble proteins)

Plasma membrane

• Lipid bilayer structure • 9nm wide • selectively permeable • contains pumps, channels, receptors • hydrophilic heads face outside and hydrophobic tails face each other on inside

Nucleus

• nucleus of non-dividing cells contain chromatin, and dividing cells have chromosomes • chromatin=DNA + histones (proteins) packaged together, their main function is to

package DNA into a compact form • 2 types of chromatin

o euchromatin-more active, less compact, lighter o heterochromatin-less active, more compact, darker

• Cytoskeleton

• cytoskeleton is the cells internal framework of filaments and tubules • its function is structural support and is important for intracellular movement of

organelles • 2 main components (that we need to know)-microtubules, microfilaments, • microtubules

o function ▪ intracellular transport ▪ maintain cell shape ▪ cilia movement ▪ chromosome arrangement

o they continually form and disassemble o structure

▪ tubulin protein ▪ hollow cylinders ▪ 22nm diameter

▪ 5nm thick walls o things that disrupt them are drugs, reduced temperature and increased

hydrostatic temperature

o o

o • Microfilaments

o Structure ▪ Made up of actin ▪ Flexible ▪ 6nm diameter

o much thinner than microtubules o function

▪ microvilli structure ▪ extension of cell processes ▪ provide support to cells

o Mitochondria

• generate ATP via oxidative phosphorylation, citric acid cycle, ß-oxidation of fatty acids • initiate apoptosis (controlled cell death)

• Rough endoplasmic reticulum (RER)

• function is protein synthesis via transcription and translation thus has many ribosomes present

• often next to golgi apparatus

• o made up of cisterna (flat sheets of membrane) which have ribosomes on them

Smooth ER

• function is lipid and steroid metabolism, synthesis of steroids, detoxification, membrane formation, calcium isolation

• also have cisternae but lack ribosomes • often glycogen surrounding

• Golgi apparatus

• stacked, flattened membrane bound cisternae with small vesicles budding off terminal cisternae

• function is to package and modify proteins from RER, receives proteins via incoming transport vesicles at cis face

• trans face is output of secretory vesicle end

• Lysosomes

• membrane bound • formed from golgi • contain digestive/hydrolytic enzymes such as protease (breaks down proteins) and

lipase (breaks down fat) • components to be digested are in endosome, hydrolytic enzymes are synthesised in RER,

pass to golgi via transport vesicles and then are added to endosomes to form lysosomes • digested material can be re-used by cell • undigested material forms residual body

Module 2 Histology-Epithelial tissue General

• covers inner and outer surfaces of body • cells connected via junctions • no blood vessels • attached to a basement membrane • usually has ability to constantly shed and replace

Types of epithelium

• squamous→ width>height

o ▪ these show stratified squamous epithelium

• cuboidal→ width=height

o • columnar→ height>width

o • pseudostratified (pseudostra)→ appears stratified but all cells rest on basement

membrane

o • transitional→ability to expand and contract

o usually dome shaped cells at apical surface o line urinary organs→bladder and ureter

o Mucosa

• consists of epithelial cells overlying connective tissue (CT) • covers internal surfaces of organs and vessels

Serosa

• consists of mesothelium (simple squamous epithelium) overlying CT • covers outer surfaces of organs and lines body cavities • mesothelium lines major body cavities like lung and heart cavity

Endothelium • simple squamous epithelium that lines blood vessels

• Apical surface specialisations

• microvilli o shortest of specialisations o contain actin filaments o increase surface area for absorption

o • cilia

o made up of microtubule doublets plus dynein protein o arranged in 9+2 pattern known as axoneme

▪ o longest of specialisations o often are motile and are to move substance along in lumen

o

• stereocilia o didn’t mention much, medium sized o basically longer microvilli

Lateral specialisations

• only really seen in electron micrograph • lateral specialisations referred to as terminal bar or junctional complex and run along

lateral surface of epithelial cells but only really towards apical region i.e. don’t run down that deep

• junctional complex always includes zonula occludens and adherens and may include the others but not always

• components of junctional complex (photos below) usually from superior to inferior are: o zonula occludens/tight junction

▪ provides adhesion and allows selective movement of ions and water through intercellular space

▪ • yellow are proteins which have actin filaments attached, these

proteins give it a fuzzy dark appearance in electron microscope • also note that the two cell membranes don’t fuse, they just get

very close o zonula adherens/ adherens junction/ intermediate junction

▪ much stronger adhesion than occludens, but don’t appear as dark in electron microscope

▪ doesn’t allow any substances through ▪ reinforces against mechanical stress

▪ ▪ again plasma membranes of cells don’t fuse and leave an intercellular

space o desmosomes aka macula adherens

▪ like zipper, very hard to rip apart ▪ very similar to adherens ▪ have intermediate filaments coming off protein zipper, can often see

filaments in electron microscope

▪ black region running down centre is protein zipper, proteins are intercollating here

▪ o gap junctions/communicating junctions

▪ 6 specific proteins channels which run through intracellular space and can open or close to allow stuff through

▪ hard to recognise, probably wont be asked to identify

▪

• also have lateral interdigitations

o run all the way down lateral wall and are like puzzles interlocking, offer further adherence to adjacent cells

Basement membrane

• epithelium is anchored to basement membrane • produced by fibroblasts • can influence differentiation, regeneration, shape of epithelial cells • filtration barrier via ionic charge e.g. if epithelial cells were absorbing a substance,

basement membrane can selectively transport it to vessels • allows underlying immune cells to migrate across it towards lumen for immune

response • epithelial cells are attached to basement membrane via hemi desmosomes

o • also compartmentalises underlying CT and overlying epithelial tissue