Organelles and cell function Flashcards
4 Types of organic molecules
- Carbs - Glycogen is a polysacharide
- Proteins
- Lipids
- Nuclei Acid
Carbohydrates
Function
Organisation
Example:
- Main source of Energy
- Mono, Di, Polyscaharides
- Glucose / Sucrose / Glycogen
Dehydration Sythesis forms bonds between sugars
Proteins(Amino acids)
Function
Organisation
Example:
- Major componet of most Tissues
- • Primary: Amino acid sequence • Secondary: Conformation (Alpha helices, B-sheets) • Tertiary: Folding to shapes (Ionic bonds) • Quaternary: 2 or more subunits
- Heamoglobin (Quaternary)
Lipids (Glycerol and fatty acids)
Function
Organisation
Example
- Cell Membranes / Energy reserves
- • Fatty Acids – Energy (glycerol backbone and hydrocarbon chain) • Phospholipids/Glycolipids – Cell membrane bilayer, hydrophobic= fluid and impermeable to polar substances (charged polar head, glycerol backbone, fatty acid chain) • Steroids – Hormones (4 bonded C rings)
- Fatty Acid→Triacylglycerol Phospholipids→Phosphatidylcholine Steroid→testosterone
Nucleic Acid (Nucleotides)
Function
Organisation
Example
- Carry genetic info
- • DNA Adenine←→Thymine Guanine←→ Cytosine • RNA Uracil instead of Thymine
- DNA RNA
Glycocalyx
Carb enriched coating covering outside of eukaryote cells
Found on apical portion of microvilli (BRUSH BORDER) in digestive tract
Cells
Charactaristics
All living things composed of cells
Basic structural and fuctional unit of life
All cells from pre-existing cells
Red blood cells only cells without nucleus
Cell membrane Functions
- Respond to stimuli via receptors
- Fluid Mosaic model of plasma membrane – Phospholipid bilayer – Made of phosphatidylcholine – Can fuse with other membranes – No movement of anything large or polar across membrane (except lipids) – Membrane proteins travel throughout surface
Cell membrane proteins:
Integral Proteins - Penetrate bi-layer or not completely
Peripheral Proteins - Inside or Outside cell
Lipid anchored proteins
Passive transport through Cell Membrane
Passive
Diffusion: High to low con gradient ( Non polar O2 / Co2)
↑speed = ↑ Temperature, ↑ energy state (gass), ↓ size, ↑ conc. gradient
Osmosis: H2o From high to low concentration (Hyper/Hypo/Iso)
Facilitated Diffusion: Much faster than simple diffusion Requires a membrane-bound carrier/ Reaches endpoint
Aqauporins: Integral proteins allow passive movement of water even through it is polar
Filtration: Only in the Kidney tubeoles
Active transport through cell membrane
Requires energy / against gradient /includes pumps / carrier proteins
PRIMARY
Maintains specific gradient ↑NA+ outside, ↑K+ intside – uses energy from ATP and Phosphorylation
SECONDARY
Energy stored in electrochemical gradient of another solute (usually sodium/potassium) – uses NA/K pump to go against gradient
Endocytosis
Pinocytosis
Phagocytosis
Pinocytosis: extracellular fluids, solutes Receptors not required
Endocytosis: requires membrane receptor to bind & internalize
Phagocytosis: Large molecules and foreign particles
Cytoskeleton function (4)
- Structure and Support
- Intracellular transport
- Contractility and Motility
- Spatial Organization
Microtubules
Size 24nm
Protein: TUBULIN
Hollow structure / MAP hold mictrotubles in place
Types of Microbubules
- Axonal transport: highway that motor proteins carry organelles on
- Cilia: Help transport fluid and materials / 9 - 2 cofiguration
- Basilar body Anchor cilia / 9 triples config
- Centrioles : Appear at poles during mitosis, attach to mitotic spindle separating DNA into daughter cells 9 triples config
Microfilaments + function
6nm
Protein: ACTIN
Functions: Wound healing
movement of axons
vesicles
phagocytosis
cytokinesis
Intermediate filaments
10nm
Most stable
Provide shape and structure to cell
Protein (various)
Cytokeratin - Epithelium
Rough Endoplasmic Reticulum
Synthesis/processing of secretory proteins
Continuous with nuclear envelope
Labyrinth of flattened sacs
Ribosomes on outside (Rough appearance)
Golgi Apparatus
Modifications of secretory proteins
• Adding sugars, folding etc.
− Stacks of flattened disklike membranous cisternae
− Usually less than 8 in a stack
− Vesicles bud from sides
Smooth endoplasmic Reticulum
Synthesis of lipids
o Liver: detoxification of drugs, toxins
o Liver: Release of glucose from glycogen when required
o Muscle cells: sequestering of Ca and regulated release
- Most remain membrane bound
- more “tubular” than the rough ER
- some like hormones secreted
Lysosomes
Fuses with vacuoles for digestion of cellular organelles, bacteria, macromolecules
− membrane-bound bags of enzymes
− Peroxisomes (special type) destroy peroxides
Nucleus
Contains genetic information (DNA)
− Pores in envelope allow for mRNA and protein movement
− Usually 1 per cell but some special cells can have 2
− Easiest structure to see under microscope
Nucleolus
rNA synthesis
(2 types of chromatin)
- Heterochromatin: (Inactive, clumps)
- Euchromatin: (dispersed) Active in RNA synthesis
Mitochondria
Energy production through cellular respiration
− 1 glucose = 36 ATP − Glycolysis (anaerobic) in cytoplasm, 2 pyruvic acid into mitochondria →2 ATP
− Oxidative phosphorylation in mitochondria matrix →34 ATP
Dimensions of the Eye
Globe diameter: 24-25 mm (1 inch)
Lens: 10mm x 4mm
Iris: 12 mm (wide) x 11 mm (tall) 37 mm circumference
Differentiate right vs left fundus images:
- side optic disc is on is which eye it is (right side right eye, left side left eye)
- optic disc is nasal to macula -blood vessels make L shape on left eye
Vitriad - -
Sclerad - -
Positioning Vocab:
Vitriad-closer to vitreous, more interior
Sclerad- closer to sclera, more exterior
Caruncle
Vascular nodule of modified skin (has hairs and accessory lacrimal glands)
Plica seminularis
“half moon” at nasal canthus allows eye to move the center of vision without stretching anything
Eyelids (Palpabrae)
+ FNX
Tarsal portion: part that closes over eye
Orbital portion: between brow and tarsal portion
Upper lid moves more than lower, on closing
Functions:
- covers globe when closed
- Protection
- Moves tears toward drainage
- Blinking spreads tear film over cornea
- Structures to produce tear film
Punctum
(2Puncta)
- Hole
- First part of tear drainage
- upper and lower
Meibomian Glands
Oil glands in lid margin that can be seen with the naked eye
Located at the posterior aspect of tarsal plate
Cilia
Eyelid Margin
Cilia eyelashes
Eyelid Margin: tissue between cilia and meibomian gland
Palpabral Fissure
Palpabral Sulci / Sulcus
Sulci “groove or fold” in the lid
Palpebral Fissure: opening
Canthi (plural of canthus):
x2
Lateral canthus: 5-7 mm medial to bony orbit
Lies on globe
Medial Canthus: Sit on medial margin of bone
Separated from globe by “Lacrimal Lake”
Lacrimal Lake: x triangular space at the medial angle of the eye, where the tears collect
Canaliculi (plural of canaliculus):
“tiny canal”
Upper and lower
Sits near medial canthus
Drain tears
Lacrimal glands
secretes portion of tear film
only superior
Extraocular Muscles
Name location
6 skeletal muscles
Meet at common tendinous ring before socket ends
Rectus “straight” Superior, inferior, lateral, medial
Oblique :Superior, inferior o Trochlea- “pully” for superior oblique
Chambers of the eye + Volume
Anterior chamber (200 µ)
Cornea= anterior boundary iris=posterior boundary
Posterior chamber (50 µl)
Posterior border=lens & zonules anterior border=iris
Vitreous Chamber (4.4 ml)
Contains vitreous that maintains eye shape
Fluids of the eye + Function
Aqueous
Function: nourishes + removes waste from lens + cornea (avascular) Maintains IOP (continuous production)
Vitreous
- Transparent viscoelastic gel: 2/3 eye volume
- 98% water
- refractive index 1.33
- sodium hyaluronate + collagen II makes it jelly/viscous
Describe the flow of Aqueous Homour
Flow:
Produced by Ciliary processes
percolates between ant. Lens and post. Iris
into anterior chamber
exits through trabecular meshwork in anterior angle
through canal of schlem into aqueous vein
Eye comprises of 3 TUNICS
+
Structures includes in each
Fibrous
Outermost , Cornea sclera with limbus as transion zone
Vascular
middle layer, highly vascularised Iris, cilliary body, Choroid
Neural
Inner layer RPE
*Ora Serrata Transition point for vascular and neural tunic Oral bay (give scalloped look) Dentate process (space in-between bays)
Functions of Cornea and Sclera
Cornea: (Transparent)
- Main refracting structure (80%)
- Protection
- Tear film
Sclera: Opaque
- Protection
- Withstand forces
- Imparts shape/size to eye
Iris
Colored part of eye
Pupil: opening in iris that allow light in
Collarette: physical structure on iris that separates Pupillary region and Ciliary region
Pupillary Margin/Ruff/Ring: highly pigmented, medial most aspect of iris
Ciliary Body
Pars plana: ciliary ring thin/flat but wider
Pars plicata: ciliary processes finger like projections thick but narrower
Ciliary Muscle: contract as part of accommodation
Ora Serata
ciliary body ——– choroid Transition Zone
Ora Serrata Transition point for vascular and neural tunic Oral bay (give scalloped look) Dentate process (space in-between bays)
Choroid + Functions
- Blood supply to outer retina appear to glow orange on retinal imaging (retinal blood vessels supply inner retina)
- Thermoregulation by inc./dec. blood flow
- Pigment absorbs light prevents reflect back through retina o Can affect IOP Due to blood flow regulation
- Possible role in eye growth regulation? By secretions
- Possible function as another means of accommodation? by thickening
Retina + Defined structures part of neural Tunic
Neuroretina: senses light and creates electrical impulses
Macula: center of retina o Fovea: area of highest acuity in center of macula
Optic nerve: transfers visual information from the retina to the brain Optic disc: point of exit ganglion cell axons that form the optic nerve and point of entry for major blood vessels (central retinal artery + vein)
Crystalline Lens:
Zonular fibers:
Crystalline Lens:
Focuses light on retina Connected to uveal tract by zonules
Zonular fibers: (Insert between ciliary processes)
Insert on anterior and posterior lens
Accommodation: Ciliary muscle contraction releases tension Increases curvature / Increases dioptric power
Epithelium to functional units
Requires membrane specializations
Lining tissue can line either a lumen (space) or the outside world (APICAL) aspect
Cells are closely bound into a functional unit
Function: move molecules and fluids, secret and absorb substance
Apical Spesializations of Epithelial cells
- Glycocalyx: proteins, sugars, lipids on plasma membrane
- Microvilli folds to increase surface area histological term = brush boarder
- Junctional complexes
Tight junction/Occluding Junctions (zonula occludens)
in Epithelial cells
Most apical
Proteins encircle cell perimeter on apical surface
Strands of globular proteins Proteins: occludin and claudin − both always present − Impermeability of skin epidermis due to claudin (Defect in gene would cause dehydration & death) − Maintains the blood-brain barrier − Certain signals open the junctions
- Plasma membranes of 2 neighboring cells stitched together
- Stop molecule movement along paracellular pathway
- Permeability depends on amount of proteins in a strand
Adhering junction (zonula adherens)
in Epithelium
Less tight, transmembrane proteins connect neighboring cells
- “belt” structure encircles cell inside membrane • Proteins: Cadherins and catenins
- − Catenins: transmembrane dimer
- − Cadherins: intercellular with 3 subunits
- − bind to actin cytoskeleton
- Calcium dependent linkages
- Connects external environment to cytoskeleton (domains in both)
- Signal transmission from outside to inside
Desmosomes (macula (spot) adherens)
in Epithelium
Found in tissues subject to mechanical stress (Cardiac muscle, skin epithelium) o Gives strength and rigidity
- “Spot” links to intermediate filaments (tonofilaments made in skin and epithelium)
- Transmembrane protein linkers make dense plaques
- Denser plaques on inside anchor to intermediate filaments as dark plaque • Protein: Cadherins
- − Different domain structure from those of belt adherens
- − Dimer protein with 2 subunits
Hemidesmosomes
in Epithelium
Lateral basement membrane
Integrins link plaque to keratin intermediate filaments
connect BM to underlying tissue
anchor basal domain to basal lamina
Gap junctions
in epithelium
Intercellular channels act as molecular pipelines between cells
• Integral protein: connexin (make connexons) Hydrophilic channel in the center forms path between cells
− 6 subunits
− Allows passage of water, and small ions and molecules
– Metabolites, coenzymes, amino acids
– Cardiac muscle electrical impulse from SA node
– Certain areas of brain have these, don’t require transmitters
Basement Membrane
in Epithelium
Extracellular to the epithelium BASAL aspect (between epitheliums and connective tissue) synthesized and secreted by the epithelium
Classification of Epithelial layer TYPE
(3)
- Simple: one cell layer thick
- Stratified: more than one layer
• Pseudostratified: (pseudo-fake) appears stratified, but all cells touch the basement membrane (only location we need to know is trachea)
Classification by Epithelial cell shape (5)
- Squamous: thin, fish-scale shaped
- Cuboidal: square
- Columnar: rectangular (higher than wider)
- Transitional: basal layers cuboidal or columnar, surface layers often squamous (in renal system, don’t need to ID because it looks different if bladder is full or not)
Simple SQUAMOUS Epithelium
Simple Squamous Epithelium skinny and appear irregular in en face view
**need to ID is cross sectional view
Endothelium Special term for squamous epithelium lining in blood vessels and cornea
Mesothelium Lines all cavities of the body
Stratified Sqaumous Epithelium (Non-keratinized)
Stratified Squamous epithelium (non-keratinized)
- non-keratinized = all cells are living (retain nuclei)
- j_unctional complexes_ on _lateral surface_s connecting cells
- cuboid on basement membrane and then become thinner and transition to squamous at apical level
- Lines wet cavities Mouth, esophagus, vagina
Corneal Epithelium
Layers and Function
5-7 layers of cells
Stratified, non- keratinized
Apical and basal only 1 cell layer Layers:
- Basal cells (1 layer of columnar/cuboid cells)
Sit on basement membrane, attached to Bowmans
Mitosis (stem cells) in limbus region
- Wing cells (2-3 layers)
Middle layer synthesizes and stores keratin tonofilaments
• Superficial cells (2-3 layers)
Barrier between tear film and inner cornea
In constant state of degeneration, slough off
Dense microvilli and glycocalyx have enzymes that interact with tear film
Junctional complexes prevent movement of water
Corneal Abrasion
Abrasion: quick to cover BM (6mm lesion closed in 48 hrs.)
- Cessation of mitosis
- Cells at edge retract, thicken, lose attachment to BM
- Cells enlarge, migrate to cover defect
- Mitosis resumes be able to ID layers ithelium b I a Stroma endothelium hexagonal shape
NORMAL
Constant mitosis and regeneration of cells 7d turnover time
Cells divide in limbal basal cell layer
New cells move centripetally (to center) and superficially
Sluff off after lifespan
Bowmans Layer
Special basement membrane
− 1 layer synthesized by overlaying epithelium like normal basement membranes
Basal Lamina: (Lamina lucida and lamina densa): made of collagen
- No regeneration of Bowmans if damaged (scar will form)
- Cells adhere via hemidesmosomes
- Collagen passes thru Bowmans to stroma
Endothelium
Simple Squamous
Hexagonal mosaic
- secreted by endothelium
- Lateral surfaces joined by junctional complexes
- Large # mitochondria
- active in pumping fluid
- Low regenerative capacity
Poly morphism / Megathism
3500/mm2 to 2500mm/2
Corneal Endothelium functions
Functions: − Na-K ATPase in basolateral membrane
Maintains hydration dt Constant evaporation
Prevents excessive hydration (pumps H2O out, too much water = opacity)
Barrier to pathogens
Decement’s Membrane
- Secreted by endothelium
- Increases in thickness throughout life (3x as think by age 50)
- Thicker in periphery o Ends at Schwalbe’ s line internal landmark of limbus thicker collagen
- No hemidesmosomes connect to endothelium! (different than epithelium)
- Regenerates if damaged o Continuously secreted for replacement
Simple Cuboidal Epithelium (Polygonal)
Retinal Pigment Epithelium (RPE)
Retinal pigment Epithelium - Simple Cuboidal
Define cell structures
- Apical microvilli (outer retina faces apical RPE)
- Lysosomes and phagosomes (degradation of photopigment material that is constantly regenerated)
- Nuclei line up
- Lots of mitochondria, rER and Golgi because lots of proteins are made
- Melanin absorbs excess light and UV radiation
In light adapted eye, moves into microvilli and protect outer segments of retina
In dark adapted eye, moves from microvilli back into the cell
Bruch’s membrane = basement membrane
Synthesized by cells making choriocapillaris
o Outer collagenous zone
o Elastic layer
o Inner collagenous zone
Structure features of the RPE
Simple Columner Epithelium
+
Example of where
Intestinal lining Medullary collecting ducts
+
Conjuctiva (But stratified 2 layers)
Conjunctival epithelial cells
Stratified columnar & cuboid ONLY 2 LAYERS (usually)!
Goblet cells secret mucin layer of tear film
Conjunctiva of eye
bulbar conjunctiva over sclera fornix transition point palpebral conjunctiva
How does epithelium change folowing the lids. Fron the skin of the lid to the cornea
Stratified Squamous Keratinized on skin of lids
→ Stratified columnar & cuboid on Conj (bulbar and palp.)
→ Simple Squamous on cornea Stratified squamous (lid margin) to str. columnar Palpebral Conjunctiva
Transitional Epithelium
Where and shape
Only found in the Urinary tract
Dome shaped apical cells.
Non-Ocular locations of Epithelium Types
Pseudostratified Ciliated Columnear Cells
Have Cillia & Goblet cells
On fase very irregular
TRACHEA
Non-Ocular locations of Epithelium Types
Simple columnar Epithelium
Intestinal lining / GI tract
Medullary collecting ducts
Non-Ocular locations of Epithelium Types
Transitional Epithelium:
Only located in renal system Appear hen when bladder is full
Glandular Epithelium
Endo & Exocrine differences
• Exocrine glands: secrete product into a duct system to go to target • Endocrine glands: Ductless. Secrete product into capillary network
***ALL EXOCRINE GLANDS _SECRATORY EPITHELIUM***_
Exocrine glands Structural classification
- Secretory:
- o acinar (round)
- o tubular (oval)
- o coiled
- Duct:
- o simple (unbranched)
- o compound (branched)
Functional classification of exocrine Glands
Merocrine
Merocrine:
o release by exocytosis
o secretory vesicles that fuse with plasma membrane
o protein products
o Most common
Functional classification of exocrine Glands
Holocrine
Holocrine:
o discharge entire breakdown of secretory cell
o sebaceous (oil) glands
Functional classification of exocrine Glands
Apocrine
Apocrine:
o discharge of membrane-bound vesicles
o some sweat glands o very rare
Identify Type and Location
Simple Unbranched Tubular:
o Entire intestine
o Goblet cells
o Secretes into lumen
Identify Type and Location
Compound Tubuloacinar
Sublingual, submandibular & lacrimal gland (main and accessory)
o Both tubular and round secretory portion
o Lacrimal gland : forms water (aqueous) part of tear film,
Lacrimal system
Label
Lacrimal structures important
Identify the structures of the lacrimal system
What glands are in the eyelids
What type of secretion
Meibomian glands:
- Oil
- Along lid margin
- Delays tear film evaporation Lubricates and protects cornea Glands of Zeis:
- Oil gland
- Attached to lash follicles
Glands of Moll:
- Special sweat gland
- Apocrine glands at lid margin
Accessory lacrimal glands
Same product and complex branched structure as main lacrimal gland
− Glands of Krause: o Fornix of conjunctiva
− Gland of Wolfring: o Above tarsal plate
Characteristics of connective tissue
Supporting Tissue
cells that live in an extracellular matrix not closely bound
Vascular (except cartilage)
Support, protection, binding, fat storage
Immune functions (“wandering” WBCs) Plasma calls, B lymphocytes, neutrophils, eosinophils, macrophages,
Components Of connective tissue:
3 Big groups
Cells
Ground Substance
Fibers
Cell components of Connective Tissue
Fibroblasts - Most common
Adipocytes
White (Wandering cells) RBC’s
Chondrocytes (cartilage)
Osteocytes / -blasts / -Clasts
Ground Substance in Connective tissue
GEL that withstands Stress
Composed of: – GAGs + proteins = Proteoglycans
– Extracellular fluid and ions Proteoglycan aggregates:
– Glycosaminoglycans (GAGs) Highly neg. charged, large, hydrophilic Link to proteins to form Proteoglycan
Fibers of connective tissue
Collagen: Main fiber
- most abundant protein
- Tensile strength
Elastic fibers:
- Elastic fibers=elastin protein
- Fibers or sheets (elastin)
- Give skin + vessels stretch and elastic recoil GAGS thin dark thicker lighter
Reticulin, laminin, fibrillin: o Small fibers o Delicate support framework for organs o Collagen III
Collagen Structure in Connective tissue
Pimary structure: amino acid sequence
− Secondary: 3 helixes wrapped around each other
− Secreted as Tropocollagen
− Stacked in specific staggered array forming banded structure
Collagen types
- Collagen I (90%)– Skin, bone, tendon, ligaments, sclera, corneal stroma
- Collagen II – Hyaline and elastic cartilage, vitreous
- Collagen III – Organs, smooth muscle, reticular lamina of BM – scaffolding giving structural support to basement membrane of epithelial tissue
- Collagen IV – Basal lamina of epithelium (basement membrane component) – Non-fibrillar
Specialized Connective tissue
Elastic Fibers
Reticular Fibers
Cross-linking of mature elastic fibers enable stretching and recoil
• Fibers stain black or dark blue
Reticular (Reticulin)- Secreted by reticular tissue in liver hepatocytes
• Very thin, branching
Simplist Connective tissue
Dense Regular connective tissue
?structures of the eye
Tendons and ligaments
SCLERA
CORNEAL STROMA
Fx Tensile strength and resistance to forces
Corneal Stroma
Tissue / Fx ? / Properties
Dense regular connective tissue
Cells are keratocytes (fibroblasts)
Fx: keeps IOP stable, resist force
48 D refractive power
Transparent due to size and arrangement of collagen fibers, smoothness of covering epithelium (5-7 layers) and being avascular Avascular unlike other connective tissue o flatter in periphery o Collagen Type I, V and VI
Basement Membrane and Bowmans Layer(Made by overlaying epithelium)
Tissue type?
Dense regular connective tissue
Basement membrane: Type IV collagen, laminin, fibronectin, perlecan
Bowmans layer beneathe it; only in primates
Collagen fibrils (type I)
Cells adhere via hemidesmosomes link to anchoring filaments of collagen VII squish nuclei linedup of o pass thru Bowmans into stroma Penetrate and branch among collagen fibers
Why is the cornea transparent?
Each layer called a lamella Collagen fibrils Embedded in proteoglycans that act as spacers arranged 90-degree angles (At limbus run circularly to maintain curvature)
Fibroblasts join one another connected by gap junctions Regular arrangement and spacing essential to maintenance of transparency
Sclera
Type of connective tissue and properties
Dense regular connective tissue
Posterior to choroid
Fibroblasts in ECM of collagen, elastin, PGs (not spacers in this tissue)
Structural integrity of eye (maintain size and shape)
70% water − Opaque due to water content higher than cornea
Avascular exept for superficial scleral vessels
Weakest part of sclera?
Lamina cribosa
− Scleral collagen fibers that cross where optic nerve leaves the eye − Weakest point
Dense Irregular connective tissue
Less dense
fewer collagen fibers Found in dermis of skin
Cell type of Epithelium above Dermis:
Keritinized stratified Sqaumous Epithelium
Loose (Areolar) Connective tissue
Found in IRIS STROMA
GI tract , Respitory, Urinary,
Surrounds vessels, nerves, and glands
Fx: Support, Elastisity
immune
ADIPOSE Tissue
Fx , Characteristics
Stores fat: energy, thermoregulation, cushioning, receptors hormones (insulin)
- fat droplets push nuclei to the side
- Vascular
- 2 types: o White (in adults)
o brown (only found in fetus, infant and hibernating animals)
Vitreous Chamber
Transparent Viscoelastic gel
– 98% water
- Refractive index 1.33
- Cells: hyalocytes
- Collagen II and hyaluronic acid main molecules that make it gel •
Vritreous Chamber
Name 4 Attachment sites
o Edge of disk
o Retinal attachment
Peripappillary attachment
Hyaloideo-capsular ligament (weigert)
Epidermis - Type of tissue
Dermis - Type of tissue
Epidermis = stratified squamous keratinized epithelium, provide water proofing, specialty cell location
Dermis = dense irregular connective tissue, (excepts around receptors, glans and BVs→ loose areolar) location of smooth muscle attachments, blood supply and hair follicles
Thick VS Thin Skin
Thick: •Palms and soles
•5 layers
•No hair, no oil glands Stratum Lucidum thicker
MANY layers of epidermis, tighter packed
Thin: •Rest of body
- Thin stratum corneum
- 4 layers FEW wispy layers of keratinized (dead) cells at the top
Identify the layer SC
Stratum corneum
Flattened dead keratinocytes provide water proofing (prevent dehydration)
Deeper layers, desmosomes intact
Upper layers, not intact = “desquamation”, call sluff off
Identify layer SL
Stratum Lucidum
Clear and thin
Larger in thick skin Protective shield
Identify Layer SG
Stratum Granulosum
2-4 cell layers thick
Keratohyaline granules
Stage in keratinization as cells move up to top layer (life of a cell basal to top is ~1 month)
Identify Layer SS
Stratum spinosum
Junctional complexes hold calls together
Tonofilaments, spines
desmosomes= “prickle cells” appear spiked and connect 1 cell to another
Tight binds make it resistant to abrasion
Identify Layer SB
Stratum basale (germinativum)
Mitosis (germinating layer)
Single layer Cuboid or low columnar keratinocytes Hemidesmosomes connect it to the BM
Many desmosomes bind adjacent cells
Melanocytes , Specialized functions
Melanocytes:
synthesize and secrete melanin tyrosinase + melanin = melanosome (mature melanin)
cytoplasmic extensions of melanocyte cells reach up into str. Spinosum and establish contact with keratinocytes,
granules containing melanin pinch off, phagocytized by cells and form protective barrier around nucleus
Melanin In Skin
types and what determines skin colour?
Degraded more rapidly by lysosomes in white skin:
color NOT form # of melanin, only due to degradation rate, production the same Types of melanin
Eumelanin → brown/black
Pheomelanin → reddish yellow
Albinism: no pigment, genetic defect, lacking enzyme (tyrosinase) to make mature melanin
Papilae and Receptors in DERMIS
Papillae: Invagination of dermis into epidermis
Contain BVs and receptors
− special receptors in papilla: Meissner’s Corpuscle → fine touch receptors, low frequency stimuli
− free nerve endings: temp and pain receptors
− Pacinian Corpuscles: Large collagen capsules surrounded by fluid with axon receptor
inside (look like onion) →Deep pressure/ vibration
Identify the Structures and function
Cell type: secretory epithelium
Sebaceous Gland(oil)
• Holocrine glands - Type
• Bag of cells
• attached to hair follicle
Sudoriferous Gland(sweat):
• Simple coiled tubular - type
• in Dermis + hypodermis
• Glands: simple cuboid epithelium
• Duct: stratified cuboid etothelium
Blood supply to skin
NO BVs in epidermis
Dermis: BV’s branch → cutaneous plexus subpapillary plexus→ loops of capillaries, sphincter to close off and regulate body temp Hypodermis: large BVs →Subcutaneous plexus
Eyelids
Skin / Tissue / Glands
Transition of tissue types: Lid skin (strat. squ. ker. ep.)→ Conj (strat. Cub/col ep.)→
cornea → (strat. sq. non ker. ep.)
0.5 mm thinnest skin in body
Protection, moves tears to drainage, spread tear film, Contains glands
Tarsal (Meibomian) glands: oil ducts lead upper lid 30-40 vs 20-30 in lower
Glands of Moll: sweat at edge of lid
Glands of Zeis: eyelash follicle oil gland
Identify Structure and Cell type
Conjunctiva
Mucin-secreting columnar epithelium
White goblet cells Inner eyelid (palpebral conj.)
Globe (bulbar conj.) Continuous w/ corneal epithelium
Clinical considerations for SKIN
cancers
Freckles
• Hyperpigmentation in spots (more melanin)
Basal cell carcinoma
• tumors in stratum basale cells
• usually due to excessive sun exposure
• Not usually malignant
Squamous cell carcinoma
• Keratinocytes in spinosum
• May metastasize (break through basement membrane)
Melanoma
• Melanocyte cancer
• Frequently breaks free and gets into blood/lymph system and spreads
Lens charactaristics
Thickens over time from ~3.5 to 5 mm (normal adult male 4 mm)
Diameter: 6.5-9 mm (infant to teen) (normal adult male 10 mm)
Cells = “fibers” not really fibers (also falsely named in muscle “fibers”)
Alters refractive index by ~15-20 D
Changes shape during accommodation
Behind iris, medial to ciliary body
Transparent
Avascular
Continues to grow throughout life 3.5 to 5 mm
Lens Capsule
Capsule
- • Transparent envelope
- • Encircles entire lens
- • produced by cuboidal epithelium at poles
- • Basement membrane
Anterior is thicker, mitosis continues so it continues to thicken with age
• Posterior is thinner and size is stable
• thinnest at poles
Has elastic properties
• Collagen fibers • Insertion of zonules at “zonular lamella”
Lens Modified epiithelium
Epithelium + Fibers
• Germinative zone →active mitosis
• Synthesizes and secretes capsule
• Cuboid only on anterior surface → become columnar by equator
• Terminates at lens bow (c shaped nuclei of new fibers)
New cells more equatorially → elongate into fibers and form sutures
• Nuclei move anteriorly as they age, and oldest cells become anuclear (no more mitosis)
• Central nucleus = harder material
• Fibers have hexagonal shape and are filled with crystalin
• High refractive index
Embryonic Lens Development
- • Starts as a hallow ball of epithelial cells with open center called lens cavity
- • Primary lens fibers (oldest fibers) elongate and take over the cavity
- • These fibers form the embryonic nucleus
- • Secondary lens fibers elongate anteriorly and posteriorly and meet neighbors from the other side to form anterior sutures
- • Primary fibers detach from the posterior basement membrane and nuclei degenerate
- • Because of this there are no longer any epithelial cells on posterior side to form capsule
Lens Divisions (Parts of the lens like onion)
Certer of lens ?
Embryonic nucleus:
made by primary lens fibers
Highest refractive index
Oldest proteins in the body
NB
All others are made by mitosis of secondary lens fibers at equator
Lens Divisions (Parts of the lens like onion)
2nd and 3rd 4th layer from center of lens ?
1)Fetal nucleus: Remember E comes before F
laid down before birth
2)Adult Nucleus
birth to sexual maturation
3)Cortex
after sexual maturity
Lowest refractive index
Lens sutures
GZ - germinal transision zone
- Lens fibers meet other fibers at poles
- Anterior suture – Overlapping apical aspects
- Posterior suture –Overlapping basal
- During development meet in 3 branches
- Eventually become too large to meet and sutures become more complex pattern
Identify structures
Image taken of posterior aspect of lens
Identify
Features of Zonular fibers
Zonules of Zinn (suspensory ligaments)
• Delicate protein similar to elastin
– Attach 2mm anterior and 1mm posterior - Arise from pars plana
– Fan out in V shape when they attach
• synthesized by epithelium in pars plana
– Blend with basal lamina of lens capsule
3 Types of zonules
Function and where they attach
3 types of zonules
- *Primary:** attach to lens
- *Tension Zonules:** anchor to basement membrane of ciliary muscle
- *Secondary:** connect a few primary together and attach to Tension Zonules
Identify the structure formed in the diagram
Canal of Cloquet:
fluid filled pipe
hyaloid artery that is needed in development for nutrients
breaks down
leaves collagen wall
Identify Structures Lettered
TM - trabicular Meshwork
PC - Posterior Chamber
C - Cornea
CP - Cilliary Process
AC - Anterior Chamber
CM - Cilliary Muscle
LZ - Lens Zonule
PM - Pupil Margin / Rough
Identify the structures
Anterior iris Structures
+ epithelial changes
Epithelial bilayer continuous over iris and ciliary body
Pupillary margin/rough is continuation of bilayer In iris both layers are pigmented, on ciliary processes the posterior layer becomes nonpigmented and anterior stays pigmented
Lens has pupillary region that sits on lens and root at angle Thinnest in the center and thicker at pupillary region and root
The anterior portion of iris less pigmented in lighter colored eyes
Collarette separates ciliary zone and pupillary zone of iris
4 Layers of the IRIS
1) Anterior border
- Denser CT than underlying stroma
- Dense fibroblasts with holes between them called “crypts of Fuchs” that aqueous flows through
- Melanocytes underneath
- Collagen
•2) Stroma
- o Loose CT w/ fibroblasts, melanocytes, collagen
- o Very vascular
- o Fluid movement in and out of stroma through crypts
- o Mast cells, macrophages (“clump cells”)
- o Sphincter smooth muscle 1 mm width
4 layers of IRIS
Bottom 2 (Specialized Epithelium)
3-4 Bilayer Epithelium
o Anterior layer:
o basilar processes, myoepithelium = pupillary dilator muscle
o Posterior layer:
o more cuboidal, pigmented epithelium, junctional complexes between cells
o ridges (folds and furrows)
2 layers sit apex to apex
The Ciliary Body
• 5-6 mm (width) ring from scleral spur (ant) to ora serrata (post)
• Anterior pars plicata
• 2 mm wide; 70 radial folds = ciliary processes
o Minor ones interspersed with major ones
• Posterior pars plana
o 4 mm stretch to ora serrata (limit of retina)
• Lined by bilayer ciliary epithelium – Bilayer continuous with iris epithelium
o Inner non-pigmented; outer pigmented
o Inner: aqueous, zonules, vitreous
Identify structures and cell in diagram.
Histological divisions
Epithelium of Ciliary Body
**Cells sit apex to apex
Posterior layer nonpigmented
Zonules
Pars plicata 70-80 processes
Pars plana: thin bilayer epithelium
Ciliary Muscle fibers
Ciliary Muscle
- Circular fibers
- Radial fibers
- Longitudinal fibers
Each layer defined by their orientation
Identify these structures and cell types
Anterior + Posterior Chamber
FLOW of Aqeous
Anterior Chamber
– Cornea and anterior surface of iris and lens
– Lateral recess is iridocorneal angle w/trabecular mesh
– 250 μl aqueous humor
TRONSPORT Metabolites to lens and cornea; production of IOP
Posterior Chamber
– Bound by lens & zonules, Iris
– Production of aqueous
Traditional Aqueous flow:
- *Ciliary processes** → between posterior iris and anterior lens→ into anterior chamber→ into
- *angle** →through trabecular meshwork → out canal of Schlemm
Type of Tissue
Cells and metabolism
Cartilage
Cells surrounded by matrix they secrete
Cells live in lacunae (Hollow cavity)
Limited mitosis ( Unable to regenerate)
Cells contain:
Lipids
Glycogen
Lots of RER and Golgi (to constantly secret matrix)
Surrounded by perichondrium
Identify
TYPE
Location Function
Hyaline Cartilage (Most Common)
• Fetus skeleton template • Adult articular surfaces of joints
• Respiratory tract
(Tracheal rings, Bronchi, Larynx,Nose)
• costal (rib) cartilage
- Enables movement of bones with synovial fluid
- Support and framework for airways
Features of Hyaline Cartilage
• Type II collagen
• resilience • pliability • fibrous
• cells bunched together in isogenous groups
• lipid droplets in cells
• surrounded by vascular adipose
tissue (blood supply for cartilage)
Identify
TYPE
Locations and function
Elastic Cartilage
- External ear • Auditory canal • Epiglottis
- Prevents food in airway
- Support and framework of ear
Elastic Cartilage
Features
• Type II collagen
• resilience
• pliability
• elasticity
NB • elastic fibers and sheets (purple or black
stain)
• cells bunched together in isogenous groups
• lipid droplets in cells
Fibro Cartilage
(Lacks perichondrium)
• Intervertebral discs • Symphysis pubis • Mandible • Joint capsules • Menisci and tendon attachments
Functions • Cushions spine. • Joint movements
• Skeletal system connections
mainly type II collage, some type I • Lacks Perichondrium • Small chondrocytes in clusters • Less rigid matrix • Minimal PGs and water • Lots of matrix
Growth of Cartilage
2 types
Growth:
Appositional (early)
Developing cells in the perichondrium (chondroblasts/fibroblasts) lay down matrix at surface
Interstitial (later)
Mature cells divide and remain in the same lacuna (form isogenous group)
Cells secret territorial matrix and push away from one another
Types of Lamellar Bone
identify
Woven - featus and bone repair
Parts of Lamellar Bone:
– Compact (outside)
– Cancellous/spongy (interior)
Trabeculae (spiky structure that makes up meshwork of spongy bone)
Histology of Bone:
- *Osteons/ Haversian systems:**
- Functional unit of compact bone
- Gives very regulated organization
- Concentric arrays of lamellae with osteocytes (mature cells) in lacuna between them
- Haversian/Central Canal: at center, bring BVs, nerves and lymphatics to bone
- Canaliculi: radiate from lacuna and connect cells to outside osteons
- *- Volkmann’s**/Perforating Canal: connect central canals of different osteons
Identify the cells
Osteocytes:
Mature cells in lacunae
Trapped in the matrix they synthesize and secrete
Live in lacunae (fluid filled spaces)
Long processes in canaliculi that connect neighboring cells
Gap junctions at contact points of processes (share waste, nutrients, oxygen between cells)
Minimal protein synthesis (low energy required, small amount of RER, condensed
heterochromatin)
Identify the cell Marked and its functions
Osteoblasts: Blasts Build
- Large cells on surface of developing bone
- Cuboid or polygonal
- Lays down osteoid (nonmineralized organic matrix)
- Polarized
- Can revert to osteoprogenitors or become osteocytes if enzymes are released and mineralize matrix, trapping cells
Identify and describe function
Multinucleated Lie in depressions (Howship’s lacunae/ruffled border)
Osteoclasts: Clasts Crush
Resorbtion (digestion) and remodeling
Dissolve mineral with organic acids
Dissolve organic matrix with lysosomes
Lysosomes from golgi release enzymes & H+
Causes CaPO4 to break down
Products transferred to blood
- *Regulation:**
- Parathormone** *increases blood Ca→stimulates resorbtion and delays mineralization
- Calcitonin** *decreases blood Ca→inhibits resorbtion
- *sealing zone stops** from digesting the wrong part
Which hormones are responsible for Bone remodeling
in OSTEOCLASTS
Regulation:
Parathormone increases blood Ca→stimulates resorbtion and delays mineralization
Calcitonin decreases blood Ca→inhibits resorbtion
sealing zone stops from digesting the wrong part
Identify the structures of a single Osteon
Blood
Function:
Tissue Type?
Special connective tissue
Functions:
Transport of gasses, nutrients, waste, hormones (mainly oxygen and carbon dioxide)
Body temperature regulation: sphincter muscles control blood brough to the surface of skin
Composition of Blood
Extracellular matrix (liquid cells are suspended in)
− Plasma: 55% total volume
• Water
• protein (fibrogens, albumen, globulins)
• solutes (ions)
Cells (formed elements)
45 % total vol.
− Red Blood Cells (erythrocytes)
− White Blood Cells (leukocytes)
• Granulocytes
o Neutrophils, basophils, eosinophils
• Agranulocytes
o Lymphocytes, Monocytes
− Platelets (thrombocytes)
Hematocrit
<35 Ameamia
Hematocrit: %RBCs/volume
Serum w/o fibrinogen = plasma
When centrifuged you can see blood is:
35-55% RBCs (packs to bottom)
1% WBC’s and platelets (Buffy coat)
44-64% plasma
RBC’s
Erythrocytes
Oxygenated in lungs (Bright red color)
Deoxygenated in tissue capillaries (Dark red)
- Transports O2 for delivery, CO2 for removal
- Only anucleate cell in humans
- No organelles / Biconcave disc / most abundant element.
- Smallest cell in the body (7-8 μm x 2.6 μm) • Elastic
- Aged ones destroyed in liver, spleen, marrow
• Contains hemoglobin = Quaternary structure
o 4 polypeptide chains w/ iron group (heme) in the center of each
o Each binds an O2 (RBS can carry 4 oxygen molecules)
Diseases Affecting RBC’s
o Sickle Cell Anemia:
Caused by one aa substitution in B chain
Deoxygenated become insoluble in RBC making them inflexible and fragile
Blood is more viscous, and RBCs get trapped in capillaries
o Thalassemia “anemias”:
Defective alpha or beta chains causes hemolysis of RBCs
Platelets
Thrombocytes
Platelets (Not cells)
• Derive from megakaryocytes in marrow
• Microtubules and microfilaments give them size and shape
• 4 types of granules, 2 “true” (lysosomal and “very dense”)
Function:
• Aggregate into clot at vessel rupture
o Release serotonin (from dense core) = vasoconstriction
o Release thromboplastin = fibrin clot
Megakaryocytes
• Large
• Sit in bone marrow
• Polyploid
• Multilobed nucleus
• Extensive cytoplasm
Function:
• Form platelets through disaggregating (breaking into small pieces)
WBC’s
Neutrophils
Neutrophils (Polymorphonucleocytes=PMNs):
• 10-12 μm; 60-70% WBCs
• Lifespan of ~7 hrs
• Multilobular nucleus
• Phagocytic
– 2 types fine granules( Lysosomes + Azurophilic)
Function:
Responds to inflammation
1st line Defense against bacteria + fungus - Ligands bind and bacteria recognized
- Can used cytoplasmic processes to bring bacteria closer to it - Phagocytizes and neutralizes - Apoptosis (dies)
Function of Neutrophils
WBC’s
Basophils
o Small
o Least common in normal blood
o Bilobed nucleus difficult to see
o Dark blue granules
Function:
- *Allergic reactions**
- Vasodilation
- Inflammation
- Histamine
- Anaphylactic shock
- slow-reacting substance of anaphylaxis
Leukocytes = WBCs
Granulocytes– Contain primary and secondary granules
• Neutrophils, basophils, acidophils
- Agranulocytes – Contain only primary granules (smaller)
- Monocytes, lymphocytes
- All may leave bloodstream in response to stimulus – “Diapedesis”
Eosinophils/Acidophils:
• 12-15 μm, 3% WBCs
o Slightly larger than basophils
o Bilobed nucleus (easy to see)
o Numerous large pink stained granules (Peroxidase,histaminase)
Function:
Parasitic infections
- Phagocytic
- Limits inflammation
- Triggers asthma
- In gut mucosa / In lamina propria – GALT
Monocytes
o Largest WBC
o Large nucleus takes us ~1/2 cell
Function:
Macrophage
Phagocytosis of cells, debris, bacteria
- Chemotaxis calls to area needed
- In tissues, differentiate to:
o Osteoclasts (bone)
o Kupffer cells (liver)
o Alveolar macrophages (lung)
o Langerhans cells (skin)
Lymphocytes
o Quite prevalent
o Small about the same size as RBC
o Large round nucleus takes up most of the cell
- *o 2 types:**
- Small: Tcells (Killer cells) - Most common
- Large: Bcells - Rarer
Function:
Immune responses
- recognize foreign Abs
Identify All the cells
3 types of muscle tissue
Skeletal
-Striated / Voluntary Control / Multinucleated
Smooth (visceral)
-Not striated, Involuntary, One nucleus
Cardiac (Heart only)
- -Striated, 1-2 Nuclei
- -Cells branch at end
- -Involuntary
Skeletal / Striated Muscle
o Striated (striped)
o Voluntary control
o Multinucleated, pushed to the side of cell
o Uniform size and rectangular shape but vary in length
o Motor end plates synapse with motor axons
o Fine and “course” control
− depends on location
− Smaller number of cells controlled by 1 motor neuron=finer control
o Post-mitotic
− Increase in size due to hypertrophy
ex. going to the gym
Cell number stays the same, but cells get thicker
Increase in cell volume
Increase in # of proteins (myofibrils)
Striated Muscle cell structure
• Plasma membrane = Sarcolemma
– Nuclei beneathe membrane
• Specialized smooth ER = sarcoplasmic reticulum, surrounds myofibrils
– Reservoir and regulator of Ca++
• Sarcoplasm = cytoplasm
Structure of Skeletal muscle
Sarco- means muscle
Sarcomere:
functional unit of muscle
I band: only actin, no overlap
H band: only myosin, no overlap
A band: end to end of myosin, overlap
Z Disk/Line: ends of sarcomere
M Line: center connecting myosin proteins
Z disks move apart→ M and A stay the same size, H and I increase in size
Structural componets of Muscle fibers
Identify and describe
Sarcolemma:
plasma membrane
Sarcoplasmic reticulum: (top label)
specialized smooth ER
surrounds myofibrils
Next to T tubules
Reservoir of Ca+
Sarcoplasm: Bottom label
cytoplasm
Transverse tubules (T-tubules):
Indent into cell at A/I junction
2 per sarcomere
Identify the structure and describe
bundle of muscle cells
Muscle fiber:
cell (misnamed fiber)
Myofibril:
Many in each cell
Myofilaments:
Proteins
Actin (Smaller)
Myosin (Larger)
Sliding filament model of contraction
Tropomyosin: forms cross bridge with head of myosin
Troponin: connected to tropomyosin
o Action potential occurs
o Ca+ released from lumen of SR into cytoplasm of muscle cells
o Ca+ binds troponin
o Causes conformational change of tropomyosin to unblock site on actin
o Myosin head binds actin
o Change of head from a 90 degree→ more acute angle cases it to move actin forward
o (Requires 3 ATP)
Muscle connective tissue components
Epimysium:
− Surrounds entire muscle
Perimysium:
− Thinner, more delicate
− Surrounds fascicles
− Contains vessels and nerves
Endomysium:
− Thick
− Collagenous fibers
− Wraps single muscle cell
− Brings in nerves and blood supply
Label and Identify
Label and Identify
Label and identify
EOM’s
Smooth Muscle Locations
Locations
• Vessels (surround blood vessels)
• Respiratory tract
• Hollow organs (bladder, stomach)
• Iris sphinctor
• Ciliary body: ciliary muscle
• Arrector pili in skin. (Makes hairs stand up when cold)
Smooth Muscle in disease
• Asthma
– Constriction of bronchi
– Overactivity of smooth muscle cells
• Smooth muscle retains mitotic ability
(Can form New cells)
Cardiac Muscle tissue
o Involuntary - only in Heart
o 1-2 centrally located nuclei
o Cells branch at end + Lots of CT between cells
o More extracellular matrix between cells
o Vast blood supply
o Gap junctions between cells
− Contracts as a unit, “syncytium”
o Has SER and T-tubule system similar to striated
o Huge mitochondria tremendous energy requirement
o Post-mitotic
o Intercalated disk − Zonula adherens anchors cells together
− Desmosomes give structural integrity
Cardiac Muscle disease
o Clinical correlations
− Heart attack
Cells die Incapable of regenerating
Fibroblasts invade and make scar tissue
Cells become longer & larger and have to work harder
The CHOROID
• Posterior part of uvea
• Thin, pigmented, vascular, conn tissue
– Nourishment, conduit to other parts of eye, light absorption
- From optic nerve margins to ciliary body
- 220 μm thickness in posterior, 100 μm anterior
• Inner surface = part of Bruchs membrane
• Outer = suprachoroid
– lamina fusca: outermost choroidal layer
Functions of the choroid
- Blood supply to outer retina
- Thermoregulation by increasing and decreasing blood flow
- Pigment can absorb light, prevent reflect back through retina
- Choroid blood flow regulation can affect IOP
- Resilient tissue: protects sclera from increases in IOP
- Possible role in eye growth regulation
• Possible function as another means of accommodation
o changing thickness by filling lacunae with fluid
Structure of Choroid
- Thin • Pigmented • vascular • connective tissue
- Continuous with anterior parts of uvea
- From optic nerve margins to ciliary body
- Thicker in posterior, thins anteriorly as it reaches the ora serrata
- Separated from RPE by Bruch’s membrane
- Vortex vein: large vein that drains choroid
Histological Layers
• Bruch’smembrane
• Choriocapillaris
Stroma
• Sattlers layer– Medium vessels
• Hallers layer – Large vessels
• Suprachoroid
• Laminafusca
Anterior Border (Vitread) of Choroid
• Inner surface
o outer most part of Bruch’s membrane is part of choroid
Choriocapillaris
(2nd layer of Choroid)
o Bed of fenestrated capillaries
o Density greatest near fovea
o Extends to ora serrata
o Is a “vascular net” with very regular structure
o Fed from arterioles in Sattler’s layer
Form hexagonal patches from one feeder
o Output through venioles
Stromal Layer of Choroid
- *o Sattler’s layer** - Medium vessels
- *o Haller’s layer** - Large vessels
− Random collagen I, elastic fibers, fibroblasts, melanocytes
− Pigmentation greater in darker skinned people
− Immune cells: Mast, macrophages, lymphocytes
Suprachoroid
Lamina Fusca
• Suprachoroid
o outermost choroidal layer
o transition zone
o fluid filled AVASCULAR space between choroid and sclera
o Continuous with supraciliary space of anterior eye
• Lamina fusca
o sometimes called its own layer but also can be used interchangeably with suprachoroid
LABEL
Label
Clinical inplications : Choroid
Clinical Implications:
Lipofuscin: lipid-rich waste
Builds up
Stops water movement
Forms barrier between Bruch’s and RPE
Blood circulation system
+
Exeptions
• Veins:
− bring blood toward the heart
• Arteries:
− bring blood away from the heart
• Exception to rule:
− Portal systems
− Vein or arteriole interposed between 2 capillary networks
− Occurs in the liver, kidneys and endocrine system
Layers of Blood Vessels:
Arteries and Veins similar excepts the walls of veins are thinner
Innermost layer of the bloodvessels
Tunica Intima
• Endothelial cells:
o simple squamous cells that line the lumen, apical on lumen side, basal forms BM
• Subendothelial layer
• Internal elastic lamina (IEL):
o thicker and wavier in medium arteries
Tunica Media
Different in medium vs large arteries
• Circular Smooth muscle in medium/muscular arteries
o layers of muscle decrease as arteries become small (single layer in smallest
arteriole)
• Sheets of elastic and collagen in large/elastic arteries
o acellular
• External elastic lamina (EEL) layer at edge
Tunica Aventitia
Tunica Adventitia:
- Loose connective tissue with fibroblasts
- Has its own blood and nerve supply
- Thinner in large, thicker in medium
Blood vessels
Microvascular bed
• Arterioles
• Capillaries
• Postcapillary venules
− Precapillary sphincter: shunts blood, responds to local environment, “autoregulation”
Capillaries
o Site exchange gas, fluid, ions, metabolites, wastes
o RBC’s fold to fit through smallest ones
o single layer endothelium & basement membrane
o 1-3 cells joined by tight junctions
o Some w/ specialized cells that wrap around them: pericytes
Continuous capillary
- Most predominant
- Always have BM with tight junctions
- In CNS, muscle, lung, retina, iris
Fenestrated
cappilaries
- Pores bridged by diaphragm
- Molecules can move through
- Sometimes have a BM
- In endocrine, GI tract, kidney, choroid
Discontinuous Capillaries
• Rare
• Huge holes
• Never have a BM
• In liver, spleen, marrow
Blood Supply to the eye
Types of vessels Choroid
Layers of Choroid:
• Choriocapillaris:
o thin layer of capillaries closest to RPE
• Sattler’s:
o stromal layer with medium BV’s
• Haller’s:
o suprachoroid with large BV’s
Blood vessels of the eye
Pathology:
− High cholesterol can cause fatty plaque deposits
− Lumen becomes more narrows
− Increased risk for clots
Nervous system cell types:
− Neurons→communicator cells
− Glial Cells→ support cells
Structure of a NEURON
Axon: electrical impulses travel down, only 1 per cell but can branch
Terminal: end of axon
*Synapse** can occur on c**ell body, axon, spine** or **dendrite** of next cell
*post synaptic vs presynaptic is relative** to the other cells
Transmitter: released at terminals to transmit chemical signal
Dendrite: site of contact from other cells
Soma/Perikaryon: special name for cell body of neuron
Nucleus: light stained nucleus with dark stained nucleolus, lots of euchromatin due to high
protein production
Nissl Bodies: special name for neuron Rough ER, site of protein production
Myelin Sheathe: made my glial cells wrapping around axon and squeezing out cytoplasm (lipid),
insulation/ saltatory conduction
Nodes of Ranvier: gaps in myelin (only in vertebrates), impulse jumps from node to node to
increase speed
Neurofilaments: special name for intermediate filaments of neuron
Types of Neurons
• Motor
o largest neurons with the largest cell bodies
o motor end-plates at neuromuscular junction
o any of 3 muscle types
o junctional folds increase surface area of receptor region
o synaptic cleft between terminal and junctional folds
• Pyramidal Cell
o In cerebral cortex
o Including visual cortex
o Triangular shape
• Purkinje cells
o In cerebellum
Types of Glial Cells
PNS
Types of Glial Cells
PNS
• Schwann cells
o Myelin
o Unmyelinated cells also associated with Schwann cells
o Wraps only 1 axon
• Satellite cells
o In ganglia
o Surrounds soma
o Local environment control
Cells of the CNS
CNS
• Astrocytes
o Most numerous support cells in brain
o Fill spaces between neurons
o Regulate extracellular matrix Protoplasmic astrocytes help blood brain barrier
o Contact Ependymal cells Line ventricles of CNS Cuboid epithelial cells
• Oligodendrocytes
o Myelin
o Not all axons are myelinated
o Wraps several axons
Muller Cells
• Support cells in retina
• Extend from one end of retina to the other
Microglia
• Microglia
o Phagocytes
o Cleans debris
o Helps with disease and injury repair
o Immune cells in brain and spinal cord
o Migrate to sites of dead neurons, proliferate and phagocytose
Neurotransmitters
Neurotransmitters
- Exocytosis with vesicles
- Most binds a receptor
- Lipid soluble (hormones) act on genes instead of receptor
- Open channels or activate second messenger
- Inhibit or excite action potential
- Enzymes destroy neurotransmitters left in cleft or reuptake system recycles
2 TYPES of neurotransmitter
2 types
o Low molecular weight
Synthesized in axon terminal
Dopamine
− Circadian rhythm daytime mediator in retina
GABA
− Inhibitory retinal transmitter
Glutamate
− Photoreceptor transmitter
o Peptide (high MW)
Synthesized in cell body (soma)
− VIP in retina amacrine and ganglion
− Glucagon in retina amacrines
Nicotinic Acetylcholine Receptors
• Nicotinic Acetylcholine Receptors
o Acetylcholine binds receptor
o Opens channel for sodium to flow through
o Flips membrane potential
o Causes calcium release in muscle cells
Nervous system
Clinical corelations
• Multiple sclerosis
− Demyelination of motor neurons in CNS
− replaced by fibrous tissue
− impulse conduction loss
− Limb weakness, swallowing & speech affected
• Lateral sclerosis (ALS-Lou Gehrig’s)
− Motor neuron degeneration in brain motor centers
− Limb weakness
• Alzheimer’s (senile dementia)
− Loss of neurons in cortex
− Protein “plaques” form outside neuro n
− tangles form in neurons
Spinal chord Sensory to Motor pathway
Protection of the CNS
Brain and Spinal Chord
o Surrounded by protective CT (meninges)
− Dura
• outer most layer
• Fibroelastic
• Tough dense CT
• Merges with periosteum
• Small subdural space underneath
− Arachnoid
• Fibrous
• Less dense
• Lined by simple squamous epithelium cells
• CSF and vessels in large subarachnoid space
− Pia
• Collagen, elastin, fibroblasts
• Very delicate
Blood Brain Barrier
Blood-brain barrier
o Perivascular space in brain
o surrounded by basement membrane from endothelium and end feet of glial cells
o Non-fenestrated endothelial cells with occluding junctions prevent diffusion
from blood
o Glucose passes freeing but most others are blocked
NERVES
GREY Matter & WHITE Matter
Nerves
o Afferent (sensory)
o Motor
o Mixed
Gray matter
o Neuron cell bodies
o Central in spinal cord
o As spinal cord descends ratio of grey matter increases
o Outside in brain
White matter
o Axons
o Outside in spinal cord
o central in brain
PNS (Peripheral nervous system)
Connective tissue of nerves
Peripheral Nervous System (PNS)
o Peripheral nerves
o 31 spinal roots
– 12 cranial nerves
– Fascicles of axons
o Connective Tissue
Endoneurium
– Surround axons around myelin
Perineurium
– Surrounds fascicle of axons
Epineurium
– Surrounds nerves
– Thickest
Retina and Optic Nerve
- Extension of the brain
- Site of phototransduction (PRs)
- Local circuit processing
IMPULSE travel
• Ganglion cell axons to LGN(1st relay), to cortex
– EXIT at OPTIC DISC
Identify and explain cause
DRUSEN
RPE digests old photopigment.
If RPE can’t do this it dumps partially digested materials beneath RPE cells into or on Bruch’s membrane
Identify the layers
Layers of the retina
- RPE
- Photoreceptor
- Outer limiting membrane
- Cell bodies rod and cones
- Outer plexiform
- Inner Nuclear
- Inner Plexiform
- Ganglion cell layer
- Optic nerve fibers
- Inner Limmeting membrane
Photoreceptor Layer:
− Inner and outer segments of rods and cones
− Nuclei in cell bodies
− organelles in inner segments
− Disks in outer segments
− Cilia connect inner and outer segments
− project through fenestrated external limiting membrane into subretinal space
Layers of the retina
RPE
Photoreceptor
Outer limiting membrane
Cell bodies rod and cones
Outer plexiform
Inner Nuclear
Inner Plexiform
Ganglion cell layer
Optic nerve fibers
Inner Limmeting membrane
Synapse area made by Mueller cells
Contain specialized structures (synaptic ribbon and vesicles)
called the Pedicle in cones
o 2-3 indentations each holding the dendrite of 1 bipolar cell and 2 horizontal cells
called the Spherule in rods
o only 1 set of 1 bipolar and 2 horizontals are attached
Layers of the retina
RPE
Photoreceptor
Outer limiting membrane
Cell bodies rod and cones
Outer plexiform
Inner Nuclear
Inner Plexiform
Ganglion cell layer
Optic nerve fibers
Inner Limmeting membrane
− Rods:
smaller in enface view disks are separate/free-floating density highest at 20 degrees from fovea −
Layers of the retina
RPE
Photoreceptor
Outer limiting membrane
Cell bodies rod and cones
Outer plexiform
Inner Nuclear
Inner Plexiform
Ganglion cell layer
Optic nerve fibers
Inner Limmeting membrane
− Cones:
larger in enface view
disks are continuous invaginations not surrounded by plasma membrane
connected to one side
density highest at fovea
Layers of the retina
RPE
Photoreceptor
Outer limiting membrane
Cell bodies rod and cones
Outer plexiform
Inner Nuclear
Inner Plexiform
Ganglion cell layer
Optic nerve fibers
Inner Limmeting membrane
Outer Plexiform Layer:
− white matter
− synapses between photoreceptors and bipolar/horizonal cells
Layers of the retina
RPE
Photoreceptor
Outer limiting membrane
Cell bodies rod and cones
Outer plexiform
Inner Nuclear
Inner Plexiform
Ganglion cell layer
Optic nerve fibers
Inner Limmeting membrane
Inner Nuclear Layer:
− horizontal cells
o lateral circuit neurons
o closets to synaptic impute
− bipolar cells
o in the middle
− amacrine cells
o local circuit neurons
o closer inner plexiform layer
Layers of the retina
RPE
Photoreceptor
Outer limiting membrane
Cell bodies rod and cones
Outer plexiform
Inner Nuclear
Inner Plexiform
Ganglion cell layer
Optic nerve fibers
Inner Limmeting membrane
Inner Plexiform Layer:
− synapses between bipolar/amacrine cells and ganglion cells
Layers of the retina
RPE
Photoreceptor
Outer limiting membrane
Cell bodies rod and cones
Outer plexiform
Inner Nuclear
Inner Plexiform
Ganglion cell layer
Optic nerve fibers
Inner Limmeting membrane
Ganglion cell axons: course to disc
Papillomacular bundle
From macula to disc
Shorter fibers and deeper (closer to cell bodies)
Superior & inferior arch around macula Make arcuate patterns
Temporal fibers don’t cross raphe
Nasal “radiating” go directly to disc
Long ones from peripheral retina more vitread Farther from cell bodies
5 Cell types of the Retina
Amacrine:
− make synaptic connections between bipolar and ganglion cells
Horizontal:
− make synaptic connection between bipolar and photoreceptor cells
Bipolar:
− connect photoreceptors to ganglion cells
Mueller:
− glial cells
− special oligodendrocytes
− Attachment point for collagen II of vitreous
− Polarized
− Microvilli project into subretinal space
− True basement membrane end feet synthesize ILM
− OLM not BM: Zonula adherens between Mueller’s, rod & cone, fenestrated
(Permeable to fluid; does not form a barrier)
Interplexiform:
− synapse in both inner and outer plexiform layer
Central retina
• Macula
• 5.5mm diameter
• Temporal to optic disc
• Distinguishing feature= presence of xanthophylls pigment in plexiform layers
• Macula lutea:
– located 3.5mm lateral to edge of disk
– Darkened region
– Lutein & zeaxanthin pigments
– Darker & taller RPE cells
Foveola→fovea →parafovea→perifovea→ (end of macula) peripheral retina
Foveola
o Foveola:
− in the very center
− edge marked by sloped wall called clivus
− avascular
− densest population of cones with smallest diameter
Peripheral Retina
o Peripheral Retina:
− thins out
− Rods and cones disappear
− nuclear & plexiform layers merge
− Becomes nonpigmented epithelium of pars plana (single layer of
cuboid/columnar cells)
− Only a few blood vessels
ILM spined
− Retina attached to vitreous posterior to the ora serrata
Optic Nerve
Optic nerve:
o Extension of the brain (CNS)
o Composed of ganglion cell axons
exits through lamina cribrosa→LGN→visual cortex
o Papillo macular bundle: fibers that takes the shortest path from the macula to
the disc, deepest (closer to cell bodies)
o Further from the disk, fibers are more superficial
o Fibers radiate superiorly and inferiorly making an arcuate pattern
o Raphe: horizontal line superior and inferior fibers do not cross on the temporal
side
o Nasals side they go directly to the disk since fovea is not in the way
• Myelinated optic nerve and central retinal artery surrounded by meninges CT
(Pia, arachnoid, dura)
Optic nerve head
Nerve head (optic disc)
• Elongated vertically
• Physiologic Cup
o Difference in cup to disk ratio in glaucoma
• Paler in color; no RPE
o Lamina cribrosa and capillaries give yellow color
• Physiologic blind spot
• Site of entry of central retinal artery, exit retinal vein
Liver Functions
second largest organ in body
Functions:
• Nutrients (except lipids) are absorbed in intestine
• go via portal vein to liver
• processed and glycogen stored
o Glycogen storage makes cells eosinophilic
• Neutralizes and eliminates toxins
• Bile is exocrine secretion
• Makes plasma proteins such as albumin
Main cell type making up Liver
Hepatocyte
microvilli
Polyhedral shape in units called lobules
Extensive rough and smooth ER for detox
Basolateral surface in contact with space of disse
Apical side in contact with surface of other hepatocytes
o form plates
o make boundary of tubular space = bile canaliculus
o gap junction and tight junctions
Kupffer Cells
Ito Cells
Kupffer cells
In sinusoids on lumen surface
15% of surface
Special monocytes (macrophages)
o Metabolize aged RBCs
o Digest hemoglobin
o Secrete immuno proteins
o Destroy bacteria
Ito (stellate) cells
In space of Disse
Fat storage
retinoid synthesis
release (vit A metabolism)
GallBladder
Gallbladder
• Stores, concentrates and releases bile
• Connected to cyctic duct, which connects to the common hepatic duct into duodenum
o liver gallbladder and pancreas release products together
• Pear-shaped
Cells of the Gallbladder
• Mucosa
o Columnar
o many microvilli absorb water from bile concentrate
o Branching folds
• Muscularis
o Interlacing smooth muscle
o Contraction moves bile into cystic duct
o “spiral valve of Heister” controls opening into gallbladder
• Serosa
o outer layer; continuous with mesothelium lining liver
