Glossary of Histology II
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- Layers of epidermis from inside out
- Stratum Basale
- Stratum Basale characteristics
- Single layer of basophilic cells
Rests on Basement membrane
Bound to BM by desmosomes
Contains stem cells
Has intense mitotic activity
responsible in part for renewal of epidermal cells (along with first part of spinosum)
Contain intermediate keratin filaments
- Stratum spinosum characteristics
- cubpodal or slightly flattened cells
has processes filled with keratin filament bundles
Cells bound together by filament filled cytoplasmic spines and desmosomes
Part of the spinosum is mitotic
- Stratum granulosum charactersitics
- 3-5 layers of flattened polygonal cells
Cytoplasm has coarse basophilic granules (keratohyalin)
Has lamellar granules (seen in EM) that discharge lipid layers into granulosum
- What is the basophilic granule content of stratum granulsom cells made of?
- What are the 2 types of granules in stratum granulosum?
- keratohyalin granules
- What do you call the keratin bundles visible in stratum spinosum cells?
- Stratum lucidum characteristics
- More apparent in thick skin
translucent, thin layer
extremely flattened eosinophilic cells
mainly dense packed keratin in matrix
- Stratum corneum characteristics
- 15-20 layers of flattened nonnucleated keratinized cells
cytoplasm filled with keratin
- What is the major cell type of the epidermis?
- Where are melanocytes derived from?
- Neural crest
- Appearance of melanocytes in LM
- clear/pale staining
small, dark nucleus
wedged in between basal layer keratinocytes
- What to melanocytes do?
- Inject keratinocytes with melanosomes
- Appearance of langerhans cells
- Apear as pale staining in suprabasal epidermal layers
- Appearance of langerhans cells II
- pale staining in suprabasal layers
by EM, heve indented nucleus and tennis racket structures in cytoplasm
- what are birbek's granules?
- tennis racket-like (as seen by EM) inclusions in cytoplasm of langerhans cells
- What do langerhans cells do?
- macrophages of the epidermis
associated with immune response/antigen presentation to T cells
stimulate keratinocytes to make an epidermal thymocyte-activating factor
- What do merkel's cells look like?
- Pale staining
located in basal layer
primarily in thick epidermis
have small dense granules in cytoplasm
frequently close to nerve endings
- structure of the dermal-epidermal junction
- 1) basal cell PM
2) basal lamina
3) underlying fibrous zone (with anchoring fibers, type III collagen, etc)
- What do you call the projections of dermis that interdigitate with projections of the epidermis?
- Dermap papillae
- What is underneath the basal lamina underneath the epidermis?
- lamina reticularis (net of reticular fibers)
- Contents of dermis
- Rich blood/lymph supply
some arteriovenous shunts for T reg
sweat and sebaceous glands
NO PARASYMATHETIC INNERVATION
- 2 layers of dermis
- papillary dermis (thin, loosely packed collagen/elastin fibers)
reticular dermis (coarse elastin fibers and thick collagen bundles)
[underneath this is hypodermis (subcutaneous layer))--usually just fat
- Describe the vasculature of the skin
- there is a vascular plexus on each side of the hypodermis
Another vascular plexus supplies capillaries in dermal papillae
Each papilla has one ascending arterial branch and one decending venous branch
These arteriovenous anastomoses in the papillae can shut off and shunt blood to underlying capillary beds
Sympathetic stimulation turns off the shunt, allowing blood to bypass the capillary beds, thus conserving heat.
This was all kind of unclear.
- Where is hair follicle found?
- deep in hypodermis
- How is hair follicle formed?
- invagination of epidermis
- what is the pilosebaceous unit?
- Hair follicle
attached smooth muscle
- describe the structure of exposed hair
- Similar to stratum corneum tissue:
anucleate cells filled with keratin filaments in a matrix
- Describe hair differentiation
- the growth of hair is discontinous.
Undergoes active growth period followed by decline and then inactivity
- Fine structure of har follicle
- Terminal dilation: hair bulb
dermal papilla: little thing that contains capillary network for follicle, at end of bulb
medulla: moderately keratinized
cortex: heavily keratinized
cuticle: farther toward periphery of the hair
Internal root sheath: surrounds hair, but dissapears above level of sebaceous glands
external root sheath: continuous with the epidermis
glassy membrane: separates follicye from the dermis; noncellular hyaline layer
arector pili muscles: connects glassy membrane to the dermis; smooth muscle
- What is the malphigian layer?
- Where all mitoses in the epidermis are confined to. Namely, the stratum basale and the first bit of the stratum spinosum.
- Where are sebaceuos glands found?
- embedded in the dermis over most of the body
- structure and fxn of sebaceous glands:
- several acini open into short duct
duct usually opens into upper portion of a hair follicle
Epithelium of acini dproliferate and differentiate, filling the acini with rounded cell with a lot of fat in cytoplasm
Nucleii shrink, cells fill with fat and burst
Product of this is sebum, which gradually moves to skin surface
- what is a holocrine gland? Give an example.
- Product of secretion is released with remnants of dead cells.
Ex: sebaceous gland, which releases lipids, waxes, cholesterol, etc
- Where does the sebaceous gland arise from?
- from differentiating epithelium in proliferative area adjacent to basement membrane.
- Are sebaceous glands innervated?
- no, but it seems they are responsive to the sex hormones.
- what are the 2 types of sweat glands?
- General structure and location of sweat glands
- Simple, coiled tubular glands
contain myoepithelial cells for discharging contents
Secretory portion is a convoluted tube in hypodermis
Conducting portion is a spiralling duct through dermis and epidermis
- Details of merocrine/eccrine sweat glands
- simplle, coiled tubular
secretory part embedded in dermis; surrounded by myoepithelial cells which contract to help discharge secretion
2 kinds of cells in secretory portion : dark and clear
Dark: pyramidal cells. Line most of the lumen. Have secretory granules in apical cytoplasm.
Clear: no secretory ranules. Basal plasmalemma has numerous invaginations.
- Sweat contents
- Water, NaCL, urea, ammonia, and uric acid
- Apocrine sweat gland detainls
- Present in axillary, areolar, and anal regions
Much larger in diameter (3-5 mm)
Embedded in dermis and hypodermis
Open into hair follicles
Produce viscous secretion that is initially odorless but may aquire odor due to bacterial decomposition.
Innervated by adrenergic nerve endings (eccrine get cholinergic fibers)
- Meisnerrs Corpuscles details:
- Small, encapsulated receptors sensitive to light touch
Found in papillary layer of dermis
Comprised of flattened, transversely arranged Schwann cell-type cells and helically arranged unmyelinated nerve fiber
- Pacinian corpuscle details
- Larger than Meisner's
Found in the dermis and hypodermis
concentric layers of flattened Schwann cells with collagen layers. Oniony.
Sensitive to pressure, course touch.
- Thickness of the 2 skin layers:
- Epidermis: 75-150 um (thin), 400-600 (thk)
Dermis: varies: up to 4 mm (on back)
- vascularity of the 2 skin layers:
- epidermis: none?
dermis: plexus between papillary and rticular layers, and between dermis and subcutaneous dissue.
- Embyronic layer of origin of the 2 skin layers:
- Epidermis: ectoderm
Dermis: paraxial mesoderm
- Opaque, white posterior five sixthes of tehe external layer of the eye is the
- What is the external layer of the eye?
- Tunica fibrosa
- What is the sclera made of?
- Dense CT
- What is the anterior one sixth of the tunica fibrosa?
- What is the structure of the cornea?
- 5 layers:
- What is the structure of the corneal epithelium?
- 5-6 layers of stratified squamous.
Mitotic figures in the basal part of the epithelium
One of the richest sensory nerve supplies of any eye tissue
- What is the structure of bowmans' membrane?
- Homogenous layer
Collagen fibers crossing ot random
contributes to stability of cornea
- What is the structure of the stroma?
- Many layers of paralell collagen bundles, crossing at apx. right angles
Between the layers, extensions of fibroblasts are flattened like butterfly wings
cells and fibers immersed in glycoprteins and chondroitin
Avascular, but may be some lymphoid cells
- Descemet's membrane structure:
- Thick homogenous structure
Fine collagenous filaments in 3d network
- Corneal endothelium structure
- simple squamous epithelium
Helps with ion transport ot keep the stroma relatively dehydrated
- What is the limbus?
- The corneoscleral junction.
Highly vascularized, compared to the avascular cornea
Contain's Schlemm's canal, which drains fluid from the anterior chamber to the venous system.
- Name the 3 parts of the middle layer of the eye
- What is the choroid?
- A highly vascularized coat
With loose CT high in fibrobalasts, macrophages, lymphocytes, collagen, elastic, melanocytes.
Has inner latyer called choriocapillary layer; separated from retina by Bruch's membrane (hyaline)
- What is the choriocapillary layer?
- Inner layer of the choroid that is richer in small vessels
Provides nutrients to retina
- What is Bruch's membrane?
- A thin hyaline membrane separating choriocapillary layer from the retina
- What is the optic papilla?
- Region where the optic nerve enters the eyeball
- Structure of the ciliary body?
- Anterior expansion of the choroid at the level of the lens
Continuous thickened ring lying in the inner surface of the anterior portion of the sclera
Forms a triangle in transverse section (facing vitreous body, sclera, and lens/posterior chamber)
Mainly loose CT surrounding ciliary muscle
- Ciliary muscle structure
- 2 bundles of smooth muscle fibers
Insert on sclera anteriorly, different ciliary body regioons posteriorly.
Bundle placement allows for one bundle to stretch choroid and other to relax lens tension when contracted
- Function of ciliary body
- Produces aqueous humor
Stromal portion helps to focus lins via suspensory ligaments of the lens
- Epithelium of iris is continuous with...
- epithelium that lines the iris.
- Structure of iris
- Extension of the chorioid that partially covers lens
Anterior surface is irregular, formed by layer of pigment cells and fibroblasts
Posterior surface is covered by 2 layers of epithelium that also cover ciliary body/process
Surface layer of this epithelium is heavily pigmented
- Dilator pupillae muscle
- Overlapping myofilaments in the other epithelial cells of the posterior surface of the iris
- What can be found in the strom a oof the iris?
- Sphincter pupillae muscle
- Smooth muscle bundoles dispose din circles concentric with pupillary margin
constricts pupillary opening
- 3 components of the lens
- Lens capsule
- Lens capsule structure
- Thick, carb rich capsule
Thick Basement membrane
Mainly Collagen IV and glcoprotein outside of surfasce epithelial cells
- Subcapsular epithelium structure
- Single layerof cuboidal epithelial cells on the ANTERIOR suruface of the lens,
The cells interdigitate with the lens fibers
Proliferation/elongation of these cells at the lens equator causese formation of more lens/lens fibers
- Lens fiber structure
- Elongated, thin flat structures
Highly differentiated cells derived from subcapsular epithelium
Eventually lose nuclei and other organelles and become elongated and filled with <b>crystallins</b>
- What is the zonule?
- Radially oriented fibers that connect lens capsule and ciliary body
Sililar to elastic fibrils
When ciliary muscles contract, there is forward displacement of choroid and ciliary body, reieving tensoun on zonule and allowing lens to become thicker
- Content of vitreous body
- 99% waer
hyaluronic acid molecules
- 2 portions of the retina:
- Posterior portion (photosensitive)
anterior portion (not photosensitive, forms interior/psterior lining of ciliary body and iris)
- Describe pigment epithelium of retina
- columnar cells with a basal nucleus
Basal regions adhere firmly to Bruch's membrane
Lateral cell membranes have lots of zonulae occludens and adherens at their apexes; also gap junctions and desmosomes
Apices have microvillia as well as sheaths that envelpo tps of photoreceptors
- Layers of the optical part of retina
- Outer layer: rods and cones
intermediate layer: bipolar neurons
internal layer: ganglion cells
- What is between layer of rods and cones and teh bipolar cells? What happens there?
- External plexiform layer
Synapses between rods/cones and bipolar cels occur
- Where is tehe internal plexiform layer and what happens there?
- Synapses between bipolar and ganglion cells occur there
It is between the ganglioin cell layter and the layer of bipolar cells
- What is the origin of the outer segments of rods and cones?
- They are modified cilia
- What is the external limitin membrane
- A series of junctional complexes between the photoreceptors and glial cells of the retina (Muller cells)
Both rod and cone cells pass through this
Nuclei of cones are near the ELM, whereas nucleus of rods lie near center of inner segment
- Rod cell details
- Thin, elongated cells
1) external photosensitive rod shaped portion, made mainly of flattened intermembranous disks (not continuous with PM) that contain rhodopsin
Low light sensitive, color insensitive
- Cone cell detains
- Elongated neurons
Similar to rods (outer/inner segments, basal body w/cilium, lots of mitochondria and ribosomes)
contain one of three kinds of iodopsin (for 3 colors of light)
- Bipolar cell layer
1) diffuse bipolar cells (synapse with >1 photoreceptors), and
2) monosynaptic bipolar cells
- Horizontal cells
- establish contact between photoreceptors
- Amacrine cells
- establish contact between ganglion cells
- Muller cells
- extensively ramified
Processes bind neural cells of retina and extend from internal to external limiting membranes (where they bind to photoreceptors)
Analogous to neuroglia
- What type of collagen is found in vitreous body?
- type 2
- Do retinal pigment epithelial cells form jucntions when they interdigitate with outer segmennts of rods and cones?
- What is the point of highest visual acuity? What does it contain?
Contains only cones
- What forms the external limiting membrane?
- Muller cells attaching to photoreceptor cells via zonula adherens
- What forms the internal limiting membrane?
- Bases of muller cells and their basal lamina
- What is in the external plexiform layer?
- synapses of bipolar neurons and photoreceprors
- What is in the inner nuclear layer?
- cell bodies of bipolar neurons
- what is in inner plexiform layer?
- processes and synaptic regions of bipolar neurons, ganglion cells, and amacrine cells
- what is in ganglion cell layer?
- ganglia cells
- Signal transduction in the retina: overview
- 1) rhodopsin exposed to light
2) this causes the 11-cis-retinal in rhodopsin to convert to all-trans-retinal
3) this causes conformational change in rhodopsin
4) this causes rhodopsin to activate G protein TRANSDUCIN
5) Transducin activates a cGMP phosphodiesterase
6) cGMP levels in outer segment fall
7) cGMP-sensitive ca/na channels in PM now close
8) PM befcomes hyperpolarized
9) glutamate (a neurotransmitter) now no longer is released
10) Bipolar cells detect lack of gluatmate and send signal
11) this leads to stimultaion of ganglion cells, which transmit signal to optic nerve and then to the brain
- This is a <b>test</b>
- What is a cause of glaucoma
- Blockage in the canal of Schlemm-->poor drainage of aqueous humor-->increase intraocular pressure-->pressure on optic nerve
- describe macular degeneration
- Age related loss of central vision
Can be due to increased vascularizatoin of retina, leading to blood leakage and scar formation
- Describe retinitis pigmentosa
- Inherited condition
Causess degeneration of rods, then cones
Initially causes night vision and tunnel vision (due to rod degeneration, which give low light vision and are acentrally concentrated)
- What is presbyopia?
- Age related decrease in the elasticity of the lens, resulting in difficulty focusigngg on close objects (acommodation)
- What is astigmatism:
- abnormal curvature of the cornea, leading to more than one focal point
- Four principal layers of GI tract
- components of GI mucosa
- 1) epithelial lining
2) lamina propria (loose CT+vessels+some smoothe muscle)
3) muscularis mucosae (usually inner circular layer and outer liongitudinal layer...separates mucosa from submucosa)
- GI submucosa componenets
- Dense CT with blood and lymph vessels
Submucosay (meissner's) nerve plexus
- GI muscularis components
- smooth muscle cells that are spirally oriented and divided into 2 sublayers according to the direction the muscle cells follow
Internal sublayer: generally circular
External sublayer: generally longitudinal
Myenteric (auerbach's) plexus lies between the two sublayers
- GI seros structure
- Thin layer of loose CT
Simple squamous covering epithelium
In the abdominal cavity, serosa is continous with the mesenteries that support the intestines, and with the peritoneum
- Where in GI tract layers are lymphoid nodules abundant?
- Lamina propra (in mucosa) and submucosal layer
- What is most of the conducting portion of the respiratory systme lined with?
- respiratory epithelium
- Describe respiratory epitelium
- Ciliated, pseuudostratified columnar epithelium
lots of goblet cells
Typically 5 cell types:
1) ciliated columnar
2) mucous goblet
3) brush cells (microvili)
4) basal (short) cells: do not extend to lumen. Likely regenerative stem cells.
5) small granule cells: like basal, but with granules
- What are the thick short hairs that filter large particles from inspired air?
- what covers the three conchae?
- Bottom two: respiratory epithelium
Superior: a specialized OLFACTORY epithelium
- What are swell bodies?
- Large venous plexuses in the lamina propria of the conchae
Every 20-30 min, swell bodies on one side become engorged, distending conchal mucosa and decreasing air flow. Gives that side's epithelium a chance to recover from dessication.
- Structure of the olfactory epithelium
- Pseudostrativied columnar epithelium
3 types of cells:
1) supporting cells: broad apex, narrow base, micvilli in fluid
2) basal cells: fomr single layer at epithelial base
3) olfactory cells: bipolar neurons
In lamina propria: glands of Bowman that secretes fluid to flood olfactory cilia
- What are vocal ligaments made of?
- large bundles of parallel elastic fibers
- Structure of trachea
- Lined with respiratory muchosa
In lamina propria are 16-20 C shaped rings of hyaline cartilage, with opening posteriorly
Fibroelastic ligament + smooth muscle joins open ends of C
- what is the pulmonary root?
- structure at hilum where artieries enter and veins + lymphatics leave. Surrounded by dense CT.
- How many times does each primary bronchus divide?
- Histological differences between bronchi and trachea
- bronchial cartilage: at first, cartilage rings completely encircle bronchus. Then they become more irregular. Eventually rings are replaced by isolated plates/islands of hyaline cartilage.
Bneath epithelium is a smooth muscle layers of crisscrossing bundles of spirally arrange SM. Becomes mor ebrominent near respiratory zone.
- Changes in bronchiolar epithelium
- Starts out as ciliated pseudostratified columnar
Becomes ciliated simple (and lower) columnar or even cuboidal epithelium
- Histo differences between bronchi and bronchioles
- Bronchioles (unlike bronchi) have no cartilage and no glands in mucosa. They have only scattered goblet cells, and only initially.
Terminal bronchiolar epithelium also have CLARA CELLS, which have no cilia and have secretory granules in apex.
Bronchioles also have neuroepithelial bodies (80-100 cells with sec granules that receive cholinergic nerve endings)
- Gross organization of ovary
- 1) simple squamous/cuboidal epithelium (GERMINAL EPITHELIUM)
2) tunica albuginea
3) cortical region (where follicles are)
4) medullary region (rich vascular bed)
- Oocyte development
- 1) primordial germ cells migrate to gonads
2) divide -->oogonia (600K)
3) oogonia enter prophase of M1
- Oogenesis 2
- 1) primordial germ cell migrate to gonad primordia
2) divide --> oogonia
3) enter prophase of M1 --> primary oocytes
4) --> become surrounded by follicular cells
5) many primary oocytes lost thru atresia
- ovarian follicle structure
- Oocyte surrounded by one or more layers of follicular cells (granulosa cells)
Oocytre has large nucleus and nucleolus
Basal lamina underlieds follicular ecslls and marks boundary between follicle and stroma
- Describe the epithelium of the Trachea
- pseudostratified ciliated columnar
contains goblet cells
- What is Kategener's syndrome
- Chronic respiratory infections due to immotile cilia in tracheal epithelium
- What do ligaments in the trachea do?
- prevent overdistention of the trachea
- Describe the general histology of the brochi
- similar to trachea (cartilage, glands, goblet cells, pseudostratified ciliated epi)
But more smooth muscle (spiral bundles)
Cartilage rings gradually replaced by irregular cartilage plates
- What are bronchioles
- Intralobular airways with diameters of 5 mm or less
- Structure of bronchioles
- 1) no cartilage, No glands in mucosa
2) scattered goblets initially
3) ciliated pseudostratified columnar at first
4) becomes ciliates simple columnar or cuboidal
5) terminal bronhcioles have Clara cells
6) have specialized neuroepithelial bodies
- What are Clara cells
- In epithelium of terminal bronchioles
Devoid of cilia
Sec granules in apex
Secrete proteins to protect the bronchiolar lining gainst oxidative pollutants and inflammation
- What are neuoepithelial bodies?
- Specialized regions in bronchioles
contain sec granules
Receive cholinergic nerve endings
function poorly understood; probably has to do with gas composition chemoreceptors
- Bronchiolar lamina propria
- Composed mainly of smooth muscle and elastic fibers.
Under control of vagus and the SNS
- Effects of neural stimulation of bronchiolar SM
- 1) Vagal: decreases diameter
2) SNS: increases diameter
- What is a respiratory bronchiole
- Terminal bronchiole divides into 2 or more respiratory bnronchioles
Serves as regions of tranision between conducting and respiratory portions of the respiratory system
- Structure of respiratory bronchioles
- 1) mucosa just like terminal bronchioles, except there are interruptions of walls with saclike alveoli
2) ciliated cuboidal epithelial cells and Clara cells
3) EXCEPT at rim of alvolar openings where it becomes coninuous with the Type I alveolar cells
4) cilia absent in more distal bronchioles
5) smooth muscle and elastic CT beneath epithelium
- Alveolar ducts
- 1) when respiratory bronchiole wall becomes entirely openings to alveoli
2) lined with extremely attenuated squamous alveolar cells
3) network of smooth muscle surrounds rim of the alveolus
4) open into ATRIA that communicate with the alvveolar sacs.
- 1) saclike evaginations of rep broncioles, alveolar ducts, and alveolar sacs
2) small pockets open on one side
3) separated by interalveolar septa
- Structure of interalvolar septum
- 1) 2 thin squamous epithelial layers
2) layer of capillaries, elastic/reticular fibers, and CT matrix in between (this is the INTERSTITIUM--where the richest cap bed in the body is found)
- Name the 3 components of the blood air barrier
- 1) surface lining and cytoplasmof alveolar cells
2) fused basal laminae of teh closely apposed alveolar and endothelial cells
3) cytoplasm of endothelial cells
- What does carbonic anhydrase do?
- Liberates CO2 from H2CO3 that is in the RBC
(enzyme is in the RBC)
- Describe capillary endothelial cells
- Vey thin
Look like type I alveolars
NUMEROUS PINOCYTOTIC VESICLES
- Type I alveolar cells
- "Squamous alveolar cells"
97% of the surface
Numerous pinocytotic vescicles that help with turnover of surfactant
Joined by desmosomes and occluding junctions to keep fluid out of airspace
- Type II alveolar cells
- 1) interspersed among type 1's
2) occluding and desmosome junctions with type 1s
3) ROUNDED cells
4) grops of 2 or 3 along alvolar surface at junctions between type I cells
5) some stem cell function
6) contain lamellar bodies
- What is the characteristic histology of type 2 cells?
- Vescicular or foamy cytoplasm
- What causes the foamy vescicular cytoplasm of type 2 cells?
- Lamellar bodies
Contain concentric/parallel lamellae limited by a unit membrane
Contain: pospholipids, GAGs, proteins
Give rise to: pulmonary surfactant, that lowers alveolar surface tension
- Describe the surfactant layer contents and function
- Contents: aqueous proteinaceous hypophase covered with a monomolecular PL film
Fxn: reduces surface tension, meining less inspiratory force needed to inflate the alveoli, keeps alveoli from collapsing on expiration
Constantly being recycled via pinocytic activity
Also removed via ciliary activity: passing up thru the airways, combining with bronchial mucus to form bronchoalveolar fluid
- What are dust cells
- Lung macrophages
Where : in interor of interalvolar septom and surface of alveolus
Function: dust is pinocytosed into interstitium, phages scavenge outer surface of epitelium within the surfactant layer, eventually coughed up and swallowed
- What are alveolar pores?
- Pores in the interalveolar septom that connect alvoli, equalizing pressure in the alveoli and promoting collateral circulation, if necessary
- Describe pulmonary blood flow
- 1) pulmonary arteries come in along with branches of the bronchial tree.
2) from cab bed in interalveolar septua
3) venules originate from this bed, but are a little removed from the airways
4) they enter the interLOBULAR septa until they leave the lobule
5) then they follow the tree back toward teh hilum.
1) folow the bronchial tree up to respiratory bronchilole level
2) then they anastomose with small branches of PULMONARY ARTERY
- Lymphatic flow in lung
- DEEP NETWORK:
1) Follow the bronchi and pulmonary vessels
2) also found in interlobular septum with veins
3) drain into hilar lymph nodes
4) NOT FOUND in termianl portions of bronchial tree (beyond alveolar ducts)
Vessels in the visceral pleura. Also drain toward hulum
- What is the pleura
- Serous membrane covering the lung
Parietal and visceral; continuous tat hilum
Mesothelial cells resting on a fine CT layer.
- What does gas have to cross from airway to blood?
- 1) surfactant layer
2) alveolar cell PM/cytoplasm
3) fused BM with endothelial cell
4) cap endothelial cell
5) lumen of Cap
6) RBM PM
- What distinguishes trachea and bronchus
- Short answer: the organization of cartilage and SM
Bronchial cartilage: more irregular in shape. At first, it forms rings that can encircle lumen (compared to C-shaped rings). Gradually, rings are replaced with isolated plates
SM: Bronchus has crisscrossing bundles of SM in spirals, becming more prominent distally
- What lines the oral cavity
- Stratified squamous epithelium (may be keratinized, may not be)
- What covers the soft palate, llips, cheeks, and floor of mouth?
- Nonkeratinized squamous epithelium
- General structure of digestive mucosa
- 1) epithelial lining
2) loose CT lamina propria
3) Muscularis mucosa--a SM layer (inner circular, outer longitudinal)
- General structure of GI tract, inside out
- 1) mucosa
3) Muscularis externa
5) adventitia (upper and lower ends)
- Where are esophageal glands located?
- submucosal layer
- What kind of glands are in the lamina propria of the region near the stomach? What do they do?
- esophageal cardiac glands
- Describe muscularity of esophagus
- Distal: only smooth muscle
Mid: mixture of striated and smooth
Proximal: only striated
- What enzyme promotes the initial digestion of proteins?
- 4 regions of the stomach
- structure of stomach mucosa
- 1) surface epithelium
2) epithelial invaginations forming gastric pits
3) Branched, tubular glands empty into gastric pits
4) lamina propria=loose CT + SM and lymphoid cells
5) muscularis mucosae eparates mucosa and submucosa
- what epithelium covers surface and lining of gastic pits? (What does it do?)
- simple columnar (secrete alkaline mucus that protects stomach from acid)
- Describe cardia mucosa
- Contains simple or branched tubular cardiac glands. Terminatl portions are frequently coiled with large lumens.
A few parietal cells that make HCl
- Stem cells: info
- 1) Where: in neck region of glands
2) Shape: low columnar with oval nuclei
3) high mitotic rate
4) differentiate into pit and surface mucous cells, mucous neck cells, aparietal, chief, and enteroendocrine cells.
- Mucous neck cells
- 1) Found in clusters or singleets between parietal cells in neck region
2) secrete mucous that is different from epithelial mucous cells
4) secretory granules near the apical surface
- Parietal cells
- AKA oxyntic cells
1) mainly in upper half of gastric glands
2) scarce at base
3) rounded or pyramidal
4) inensely eosinophiilic
5) EM features: many mitos, intracellular canaliculus
6) Secretes HCl
- What do parietal cells secrete
- Why do parietal cells have so many mitochondria?
- To pump out KCL, to pump in H+
- Name a mechanism that stimulates parietal cell secretion
- 1) cholinergic nerves/sympathetic
2) histamine and gastrin
- Chief cell facts
- 1) predominate in lower region of tubulalr glands
2) Basophilic (due to lots of RER)
3) pepsinogen granules
- What is pepsinogen?
- IOnactive form of pepsin that is secreted by chief cells.
Pepsin is a highly active proteolytic enzyme
- Where are enteroendocrinne cells foound?
- near bases of gastric glands.
- Compare cardiac glands ad pyloric glands
- Pylori glands have longer pits and shorter coild secretory portions
Both secrete mucus and lysozme
- What are G cells
- Intercalated among mucous cells of pyloric glands.
Relese gastrin, whcih stimulates secretion of acid by parietal cells; has trophic effect on gastic mucosa.
Releas Inhibited by somoatostatin (Releasaed by G cells)
- Stomach muscluaris
- Smooth muscle fibers oriented in 3 directions:
- What are the permanent folds in the lining of the small intestine?
- Plicae circulares
- In what segment are the plicae circulares most developed?
- What are intestinal glands?
- AKA "crypts"
1) Location: between intestinal vili
2) simple tubular glands
3) epithelium is continuous with epithelium of villi
4) contain: stem ccells, absorptive cells, goblet cells, paneth's cells, and enteroendcrine cells
- What are absorptive cells (intestine)
- 1) tall columnar with nucleus in basal half
2) striated bruch border at apex, made of dense microvillus
3) FXN: absorb nutrient molecules, secrete peptidases and dissacharideases
- What are intestinal goblet cells?
- 1) Where: interspersed between absorptive cells
2) less abundant in duodenum; increase toward ileum
3) Produce ACID GLYCOPRITEINS that help form mucus
- What are Paneth's cells?
- 1) found in basal portion of intestinal glands
2) eosinophilic secretory granules in apical portions
3) granules contain lysozyme (antibacterial)
- What are M cells?
- 1) Micrfold cells.
2) Specialized epithelial cells overlying lymphoid follicles of peyer's patches
3) numerous basal membrane invaginations that form pits containing lymphocytes and macrophaes
4) work to endocytose antigen and transport them to underlying phages and lymph cells
5) discontinuous basal lamina
- What is the diffuse neuroendocrine system?
- Widely distributed cells
Release secretory granules by exocytosis
May be "open type" or "closed type" depending on if they secrete into the lumen
- Describe the small intestine lamina propria
- 1) loose CT with blood and lymph vessels, nerves, SM cells
2) penetrates core of intestinal villi
- What are Brunner's glands
- Duodenal glands
Alkaline ucous secreters
- where are brunner's glands located?
- submucosa of initial portion of duodenum
- Structure of brunner's glands?
Ramified, coiled, tubular glands that OPEN into intestinal glands
- What are lacteals?
- Capillaries thar are the beginning of lymph vessels
Found in the middle of villi
Larger than blood cappilaries
- What forms the innerevation of the intestines?
- Intrinsic component
- What makes up the intrinsic componenet of intestinal innervation?
- Myenteric plexis (auerbach's), betwen the outer longitudinal and inner circular layers of the muscularis
Submocosal plexus in the submucosa
- What makes up the extrinsic innervation?
- Parasympatetic cholinergic nerve fibers that stumulate the activity of the intestinal smooth muscel
Sympathetic nerve fibers that depress intestinal smooth muscle activity
- Gross structural differences in large intestine
- 1) mucosal membrane has no folds (except in distal portion)
2) no vili are present
- Describe intestinal glands in the large intestine
- 1) long2) characterized by a great abundance of goblet cells and absorptive cells
2) small number of enteroendocrine cells
- Characterize the lympoid tissue in large intestine
- It is rich--a lot of GALT
- Describe the muscularis in the large intestine
- Two layers: inner circular, and outer longitudinal. The outer layer is in arrangged in 3 thick bands called teniae coli.
- Differences between appendix and large intestine
- 1) fewer and shorter intestinal glands
2) no teniae coli
- What do absorptive cells absorb?
- How do goblet cell granules stain?
- PAS positive
Basophilic (if preserved)
- What do goblet cells secrete?
- Acid proteoglycans
- What all does paneth cell secrete?
- What does enteroendcrine EC cell do? Where is it?
- 1) secrete serotonin and motilin peptide
2) effects sm contraction and peristalsis
3) Where: stomach and intestines
- What is enteroendocrine G cell? What does it do?
- 1) secrete gastrin polypeptides
2) this stimulates acid secretion by parietal cells and pepsinogen secretion by chief cells
3) where: pyloric stomach and duodenum
- What do S ee cells do? where?
- 1) secretes secretin polypeptide
2) this effects bicarbonate secretion from bile ducts and pancreatic ducts
3) in the intestine
- What do I ee cells do? where?
- 1) secretes cholecystokinin
2) effects pancreas zymogen secretion and gall bladder contractoin
3) in small intestine
- Mucous cells of salivary glands
- Usualyly cuboidal to columnar
Most often organized as tubules
- Submandibular gland organization:
- Mucous cells form tubules, but their ends are capped by serous cells (the serous deilunes)
- What are the serous demilunes?
- Serous cells that cap a mucous cell tube in the submandibular glands
- What are intercalated ducts?
- What secretory endpieces empty into.
Lined by cuboidal epithelial cells
Join to form striated ducts
- What are striated ducts?
- What intercalated ducts empty into.
Striated due ti infloldings of basal plasma membrane with numerous elongated mitos aligned paralel to it.
- Where do striated ducts drain?
- Into ducts in septa separating lobules, where they become interlobular/exretory ducts
- Parotid gland structure
- 1) branched acinar gland
2) exclusively serouc cells with granules (no mucous cells)
3) secretions acount for hydrolysis of most carbs
- Submandibular gland structure
- 1) branched tubuloacinar
2) secretory portion has mucus and serous cells
3) Mainly serous (basophilic cytoplasm)
4) serous cells secrete lysozyme (antbacterial)
- Sublingual gland structure
- 1) branched tubuloacinar gland
2) serous and mucous, but mostly mucous, unlike submandubular
- Pancreas, generally
- Mixed exocrine/endocrine gland
Produces digestive enzymes and hormones
- Exocrine portion of pancreas: structure
- Compound acinar gland, similar to the parotid.
- Distinguishhing the parotid from the exocrine portion of the pancreas:
- Pancreas: no striated ducts. Has "centroacinar cells"
Parotid: no islets of langerhands
- What are centroacinar cells?
- INtercalated duct cell that sticks into the acinar lumen. Found only in pancreatic acini.
- What all does the exocrine pancrease secrete?
- What are the main secretory products fo the exocrine pancreas/
- Digestive enzymes
- Where does pancreatic bicarbonate come from?
- Ductule cells
- What is the main function of the liver?
- It is the organ where nutrients absorbed in the digestive tract ar processed and stored for use by other parts of the body.
IOW, the interface between the digestive system and the blood
- Where does liver get its blood?
- 75% portal vein
25% hepatic artery
- What is a liver lobule?
- Formed of a polyganal mass of tissue .7 x .2 mm.
no defined separation between them.
Portal spaces at the corter (3-6 per lobule)
- Portal spaces
- Regions demarcating liver lobules
Contani bile ducts, lymphatics, nerves, BV
- More structure of liver lobule
- 1) hepatocytes radially dispossed, arranged like bricks
2) cellular plates form a spongelike structure
3) structure between plates = liver sinusoids, which contain capillaries
- What separates hepatocyte plates from sinusoid endothelium?
- SPace of Disse
- Structure of liver sinusoids
- Irregularly dilated vesels--all fenestrated endothelial cells.
- What else do sinusoids contain besides blood and endothelium?
- Kupffer cells: macrophages
- Outline facts on kupffer cells
- monocyte derive phagocyte
- What cells are found in the space of Disse?
- Ito's cells (Stellate, fat-storing cells)
have vitamin A rich lipid inclusions
- Blood flow thru liver lobule
- Branch of portal vein sends branches radially toward center of lobule as sinusoids.
Sinusoids converge cetreally on central vein.
Vein takes all the sinuosoid blood and empties into the sublobar vein, which empties into hepatic vein.
Arterial blood flows also radially toward center of lobule.
- What are canals of hering?
- What the bile canaliculi empty into at the periphery of the liver lobule
- What does the liver synthesize?
- plasma proteins
- What endocrine functions does liver mediate?
- glucose release and uptak
- How many mitos do hepatocytes have?
- 2000. Up to 25% by volume.
- Where is ilrubin formed?
- In the mononuclear phagocyte system (including kupffer cells).
It is transported to the haptocytes, where it is conjugated in their SER to glucuonic acid.
Conjugated bilirubin then excreted in bile.
- Where does gluconeogenesis occur?
- What is hepatic, cystic, and common bile duct lined with?
- Simple columnar epithelium
- Describe epithelium of gall bladder
- simple columnar (like duct)
no goblet cells
Intercellular spaces at or near base of cells
- What is the capsule of Glisson?
- Thin connective tissue capsule surrounding liver
- What is the functional unit of the kidney?
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