Histology - Post Mid-term Flashcards
What are the 2 major divisions of the lymphatic system?
- Tissues [no capsule]
- Diffuse (loose/dense)
- Nodular (primary-neonate/secondary) - Organs [capsule]
- Primary: bone marrow, thymus
- Secondary: lymph nodes, spleen, tonsils
What are the 2 types of diffuse lymphoid tissue?
- Loose - Lamina propria (first response)
2. Dense - Walls of GI tract, along mucous membrane
What are 2 major differences (histologically) between the thymus and a lymph node?
Thymus: no afferent lymph vessel, no reticular fibers
Lymph node: PALS cover the central arteriole
The difference between loose & dense lymphoid tissue…
Loose: few lymphocytes
Dense: many lymphocytes, supported by reticular fibers
A germinal center indicates…
A response to antigen
What are the 2 divisions of nodular lymphoid tissue
- B cells w/in germinal center [maturing]
2. Corona/mantle on the outside with T cells
What are differentiating characteristics of the thymus?
- NO afferent lymphatic vessels
- ERC’s
- Cortex is divided; medulla is continuous
- Capsule: dense irreg. C/T
What is the origin of the thymus?
3rd pharyngeal pouch
What syndrome results in lack of a thymus?
DiGeorge Syndrome
What is the difference between the cortex & the medulla of the thymus?
Cortex: immature thymocytes & ERC’s
Medulla: mature T lymphocytes
What type of capillaries are in the thymus?
Continuous
How are ERC’s held together?
Desmosomes
What is the function of the ERC’s?
Blood-thymus barrier
Where are Hassall’s corpuscles found?
ONLY in the medulla
When does the thymus undergo involution?
After puberty
What is the function of the lymph node?
Filter lymph fluid
What area 2 distinguishing characteristics of lymph nodes?
- Afferent lymphatic vessels
2. Reticular fibers
Where are lymphatic nodules in a lymph node?
Cortex (w/ B lymphocytes)
Medulla: T, B, plasma cells
What lymph organ is associated with cancer metastasis?
Lymph node
What are the functional divisions of the lymph node?
- Capsule
- Cortex
- Paracortex
- Medulla
- Hilum
Beneath the capsule of a lymph node is…
Subscapular sinus
What type of epithelium lines the afferent vessel?
Flat epithelial cells
Trace the flow of lymph in a lymph node.
Afferent lymphatic –> subscapular sinuses –> radial/trabecular sinuses –> medullary sinus –> efferent lymphatics
Differentiate between the outer cortex & paracortex of a lymph node.
Outer cortex: mainly B cells
Paracortex: mainly T cells
Where are HEV’s?
Deep cortex of a lymph node; allow for the transition of lymphocytes from the blood stream to the lymph tissue
What are the 2 components of a lymph node’s medulla?
- Cords - B lymphocytes, plasma cells, reticular cells – branched extension of dense lymphoid tissue
- Sinuses - Dilated spaces w/ lymph, few macrophages
What type of collagen is found in lymph nodes?
Collagen III (Can stain w/ PAS & Silver)
What is the embryologic origin of the spleen?
Mesoderm
What is the function of the spleen?
- Filter blood
2. Immune response to antigens
The outer spleen is covered by:
Simple squamous epithelium`
The blood vessels penetrate the parenchyma of the spleen through
Trabeculae
The parenchyma of the spleen consists of:
- Red pulp (Cords of Billroth & sinusoids)
2. White pup (central a.)
What are the divisions of the splenic artery?
- Branches along capsular artery –> trabeculae –> central arteries
Who surrounds vessels in the spleen?
PALS (periarteriolar lymphatic sheath)
What is found around the layer of PALS?
B lymphocytes
What is the rim of lymphocytes + APC’s referred to in the spleen?
Marginal zone – this is where lymphocytes come into contact with antigens
What differentiates the spleen from a lymph node?
The eccentric central artery
What composes the splenic cords of Billroth?
RBC’s, lymphocytes, plasma cells, macrophages, granulocytes (immune cells draped on reticular fibers)
What are Littoral cells?
Splenic sinusoids are lined by elongated endothelial cells, called Littoral cells
What happens to healthy RBC’s in the spleen?
Healthy RBC’s – flexible – enough to squeeze between the endothelial cells to enter the cords; older ones are trapped and degraded by macrophages (found right outside the sinusoids)
What is the function of the tonsil?
Process antigens that enter the body through the oral cavity
What is the term for the annular arrangement of lymphoid tissue in the oral cavity?
Waldeyer’s ring
In general, all tonsils are lined by …
Epithelium
Palatine tonsils are lined by
Stratified squamous NK epithelium
* Deep crypts w/ dead bacteria, etc.
An enlarged pharyngeal tonsil is called …
Adenoid (in posterior pharyngeal wall / nasopharynx)
How do we differentiate pharyngeal tonsils from palatine tonsils?
Pharyngeal – Respiratory pseudostratified epi + St. sq. NK epi
Lingual tonsils are associated with…
Mucus glands
3 characteristics of endocrine organs
- Cords of cells invested in RETICULAR fibers
- FENESTRATED capillaries
- Produce hormones into B/S or C/T
Who controls the pituitary gland?
Hypothalamus
What is another name for the pituitary gland?
Hypophysis
How do hormones get from the hypothalamus to the pituitary gland?
Hypothalmo-hypophyseal portal system
The pituitary is divided into… (mention embryologic origin)
Anterior- cells + reticular fibers – Rathke’s pouch (oroectoderm)
Posterior- nervous tissue (neuroectoderm)
Pars intermedia: remnants of Rathke’s Pouch
What is the posterior pituitary?
Herring bodies store hormones produced in hypothalmus
Supraoptic- ADH/Vasopressin
Paraventricular- oxtytocin
What are Herring’s bodies?
Storage units in the posterior pituitary?
What are glial cells called in the posterior pituitary?
Pituicytes
Pars intermedia of the pituitary produces…
MSH (melanocyte stimulating hormone)
What types (major) of cells do we see in the anterior pituitary?
- Chromophobes (stem cells/degranulated/support/unknown fx)
2. Chromophils – acidophils/basophils
What are the different types of chromophils of the anterior pituitary?
Acidophils - Somatotrophs (GH) / Mamotrophs (prolactin)
Basophils - Gonadotrophs (FSH, LH), Corticotrophs (ACTH), Thyrotrophs (TSH)
Describe the embryology of the adrenal gland.
Cortex: mesoderm
Medulla: neural crest cells
Describe the 3 zones of the adrenal cortex (and their products).
- Zona glomerulosa - aldosterone (mineralcorticoid)
- Zona fasciulata
- Zona reticularsia
(2 & 3: cortisol (glucocorticoid) & androgens/DHEA
Describe the regulation of the adrenal cortex
Zona glomerulosa - angiotensin 2
Zona fas & Zona retic - ACTH
Briefly describe the renin-angiotensin-aldosterone cascade.
Angiotensinogen –> (renin) AT1 –> (ACE) AT2 –> aldosterone (reuptake Na/H20 – inc. BP)
Describe the products of the adrenal medulla
Catecholamines (adrenaline/noradrenaline)
Describe the blood supply of the adrenal gland
- Subcapsular plexus (capsule/cortex/medulla)
2. Central vein (supra-renal vein)
The endocrine pancreas cells are located within:
Islets of Langerhans
The endocrine pancreas cells are:
Alpha - periphery - glucagon
Beta - central - insulin
Delta - somatastatin (paracrine) & gastrin
F/PP - pancreatic polypeptide
The parathyroid glands… (fx)
PTH (chief cells)
Stimulate osteoclastic activity
Increase serum calcium
Decrease serum phosphate
The 2 types of parathyroid cells are:
- Chief (PTH) - smaller/basophilic
2. Oxyphil - acidophilic (unknown fx)
The pineal gland is responsible for secreting…
Melatonin (Pinealocytes)
The thyroid gland is divided into…
Follicles w/ colloid – lined by simple squamous
Stroma – C/T with fenestrated vessels + C cells
The thyroid secretes…
Calcitonin (reduce serum Ca)
T3/T4 (from thyroglobin w/in the colloid) – metabolism
Calcitonin promotes
Osteoblastic activity
Thyroid hormones store
Iodine
Endocrine stomach
Gastrin
Endocrine duodenum
Gastrin, secretin, CCK
Endocrine heart
ANF (atrial natiuretic peptide)
Endocrine kidneys
EPO (active vitamin D)
Endocrine adipose
Leptid, Resistin
Endocrine placenta
HCG, lactogen, relaxin
What cells release renin in the kidney?
JG cells
* In response to decreased extracellular fluid volume (detected by macula densa)
What is the distinguishing histological feature of the PCT of the kidney?
Brush border
Which cells of the renal corpuscle are phagocytic?
Mesangial cells
Mesengial cells have receptors for..
- Angiotensin 2
2. ANP
Vascular endothelium of the renal corpuscle are…
Fenestrated capillaries w/o diaphragms
Modified simple squamous epithelium lining the glomerulus/Bowman’s capsule…
Podocytes
The renal corpuscle consists of:
- Glomerulus
2. Bowman’s capsule
The uriniferous tubule consists of:
- Nephron (metanephric intermed. mesoderm)
2. Collecting duct (uteric bud)
Bowman’s space has 2 poles
- Vascular pole (aff/eff vessels)
2. Urinary pole (PCT)
A renal lobe is:
Medullary pyramid + cortical tissue
The renal cortex appears … (histologically)
Granulated
What comprises the renal cortex?
Renal corpuscle & convoluted tubules
What comprises the renal medulla?
Several pyramids
What is a renal column?
Cortical tissue that extends between medullary pyramids
Trace the ureter through the kidney
Ureter –> pelvis –> major calyx –> minor calyx –> papilla
The apex of a medullary pyramid is called
Renal papilla (tip: area cribrosa)
What is the renal pelvis?
Expansion of upper ureter
The function of the kidney:
- Electrolyte/pH balance
2. Filter waste
Endocrine kidney
- EPO
2. Renin (JG cells)
A nephron is comprised of:
- Renal corpuscle
- P/D CT
- LOH
The enzyme renin…
Angiotensinogen –> angiotensin 1 (plasma)
A1 -ACE-> A2 [lung caps] –> aldosterone (zonula glomerulosa of the adrenal cortex)
Aldosterone stimulates
Na retention in the DCT
* H2O follows Na and thus the extracellular space fluid volume is increased
Angiotensin 2
Potent vasoconstrictor
The collecting tubules in the cortex/medulla respond to…
ADH/Vasopressin
Who empties into the area cribrosa?
Papillary collecting tubule (apex of papilla)
Who travels along the corticomedullary junction at the base?
Arcuate arteries (Renal –> Interlobar –> arcuate)
Trace the blood flow to the glomerulus
- Renal a.
- Interlobar a.
- Arcuate a. (cortico-medullary jx)
- Interlobular a.
- Afferent/glomeular artery
Trace the blood flow from the glomerulus
- Efferent artery –> peritubular network supplies convoluted tubules
- Vasa recta (into the medullary pyramids)
- Hairpin loops into the medulla
- Arcuate vein
- Interlobar veins –> Renal vein
Who drains the outer cortex of the kidney vs. the inner cortex?
Outer: Superficial cortical veins –> Interlobular –> Arcuate
The renal interstitium is a connective tissue compartment within the kidney. What types of cells are in the cortical and medullary layers?
Cortex: Fibroblasts + Mononuclear
Medulla: Pericytes (along descending vasa recta)
Within the medullary ray, the two cell types in the collecting tubule are:
- Principal (light cells) - simple cuboidal; central nucleus
- Intercalated (dark) - microplicae folds; apical cytoplasm
The medullary collecting cells consist of:
Similar to cortical collecting tubule
- Dark cells in outer medulla
- Light cells in inner medulla
The papillary collecting tubule is where
The collecting tubulus converge
* Only principal cells!
The layers of tissue in the ureter:
differentiate upper 2/3 from lower 1/3
- Mucosa (transitional epithelium / urothelium)
- Submucosa (richly vascularized C/T)
- Inner longitudinal / outer circular (lower 1/3 with additional outer circular layer 4 peristalsis)
- Adventitia
Who has thicker epithelium: ureter or calcyx?
Ureter
The urinary bladder epithelium is:
Transitional
The male & female urethera have sub-epithelial glands of…
Littre
The distal end of the male urethra is called…
Fossa ovalis (st. sq)
The function of the respiratory system:
- Provide O2 to tissues in exchange for CO2
The 2 major divisions of the respiratory system
- Conducting – deliver warm, moist air to lungs
2. Respiratory – gaseous exchange
The components of the conducting respiratory system:
- Nose
- Pharynx
- Larynx
- Trachea/Primary bronchus
- Secondary bronchus
- Bronchioles + terminal bronchi
The components of the respiratory pathway of the respiratory system:
- Respiratory bronchioles
- Alveolar ducts
- Alveolar sacs
- Alveoli
The 3 main divisions of the nose:
- Vestibule - intraepithelial glands + vibrissae
- Respiratory - pseudostratified
- Olfactory - olfactory (bi-polar nerves), supporting cells, basal stem cells
The 2 main divisions of the pharynx:
- Nasal - pseudostratified – pharyngeal tonsil, eustean tube
- Oral - st. sq. NK – pallatine tonsil
The 3 parts of the larynx:
- Superior false vocal cord (vestibular fold - pseudostrat)
- Inferior true vocal cord (st. sq.)
- Epiglottis (pseudostratified)
What types of glands are present in the olfactory region of the nose?
Bowman’s glands
What are several features of the trachea/primary bronchi?
- Elastic lamina separates LP from submucosa
2. C-rings of hyaline cartilage
What are the effects of dopamine & serotonin on cila?
Dopamine: inhibit cilia
Serotonin: excite cilia
The intrapulmonary bronchioles are characterized by…
2: plates of hyaline cartilage
Bronchioles/terminal: Clara (macrophage) cells, smooth muscle
The cell types within the respiratory conduit of the respiratory system:
- Type I pneumocytes (gas exchange)
- Type II pneumocytes (surfactant / Lamellar bodies)
- Dust cells (alveolar macrophages)
Alveoli contain these types of pores:
Pores of Kahn
- Communication between alveoli
- Expand/recoil w/ elastic + reticular
Who secretes renin in the kidney?
JG cells
In the kidney, aldosterone receptors are located…
DCT
The 4 major categories of renal pathology:
- Glomerular injury
- Tubular injury
- Interstitial injury
- Vascular injury
Nephritic syndrome vs. Nephrotic
Nephritic – hematuria, edema, hypertension, oliguria (acute proliferative glomerulonephritis)
Nephrotic - proteinuria (IgA nephropathy)
2 examples of renal tubular injury
- Congenital PKD (recessive-fibrocystin; dominant-polycistin)
- Acute tubular necrosis (acute ischemia)
Example of interstitial kidney injury
- Acute pyelonephritis (BPH/pregnancy) –> neutrophils in the intersitium + tubules
How does hypertension affect the kidney?
Thickened vessels, increased pressure
HTN/Hyperglycemia –> microalbuminuria (hyperperfusion)
How does diabetes affect the kidney?
Kimmelstiel - Wilson nodules
- Thickened basement membrane, (can lead to glomerulosclerosis) decreased permeability of capillaries
- Increased mesengial matrix deposition associated with diabetic nephropathy / reduced surface area for filtration
Renal cell carcinoma generally affects:
Renal tubular epithelial cells
What type of carcinoma do you see in the larynx?
Squamous cell (characteristic keratin pearls)
A mutation in the genes for tubulin/dyenin can lead to…
Primary ciliary dyskinesia / Kartenger’s syndrome (with situs inversus)
The 2 broad classes of COPD
- Chronic bronchitis (clinical dx)
2. Emphysema
What protein normally restores elastin broken down by cigarette smoke?
Alpha-1-antitrypsin
- Presistent smoking can lead to increase of neoutrophils and elastase activity
- This can lead to permanent dilation (difficulty expiring air b/c recoil activity is halted)
Cystic fibrosis is a mutation on what chromosome?
7
What molecule is unable to pass through the defective CFTR in CF?
Choloride
What is hyaline membrane disease?
Infant respiratory distress syndrome
- Collaped alveoli (atelectatic)
- No surfactant, high surface tension
- Vascular congestion
Where does squamous cell carcinoma of the lung generally arise?
Bronchi (metaplasia of respiratory epithelium to stratified squamous epithelium b/c of chronic irritation)
What is the difference between chronic bronchitis & emphysema?
Chronic bronchitis – inflammation of bronchioles – thick mucous buildup ** mucus-filled cough **
Emphysema – overinflated alveoli (unnatural retention of air within the lungs) ** SOB **
Do we see cartilage in the bronchioles?
No
What is the difference between the terminal bronchiole and the respiratory bronchiole?
Respiratory: beginning of the respiratory portion of the resp. system
What type of epithelial changes do we see in the bronchioles?
Simple columnar –> simple squamous
What is the difference between the trachea and bronchus?
Trachea – C rings of cartilage; bronchus – full cartilage; secondary bronchus – cartilaginous plates
What two basal lamina are fused in the alveoli?
Alveolar basal lamina + capillary endothelial basal lamina
What do we see in the terminal bronchioles?
CCC – cuboidal, clara, cilia
The last time we see smooth muscle in the lung is…
alveolar duct
The interalveolar septum is characterized by:
Pneumocytes type I – blood-gas-barrier
What are type II pneumocytes called?
Great alveolar/septal/granular
* Produce surfactant
What is the difference between the superior and inferior parts of the larynx?
Superior – vestibular fold (respiratory epi)
Inferior – vocal fold (stratified sq.)
Asthma is characterized by…
Dilation of smooth muscles of the bronchioles
- Decrease in diameter of bronchiole
- Albuterol (smooth muscle relaxer)
The 3 components of the JG apparatus in the kidney:
- JG cells (release renin)
- EC matrix
- Macula densa
When all the collecting ducts condense, we form…
Duct of Ballini
ADH acts on…
Collecting tubules
The 2 types of nephrons
- JG (long LOH) – vasa recta
2. Cortical (short LOH) – peritubular network
The difference between the PCT/thick descending limb & DCT/thick ascending limb
- PCT – dirty lumen, large internuc spaces
The LOH appears (histologically)
Simple squamous, bulging lumen
Mesengial cells have receptors for:
- Angiotensin 2
2. ANF
Function of skin
- Barrier
- Immunologic
- Homeostasis (temperature/H2O loss)
- Sensory, endocrine, excretion
Layers of epidermis
Stratum corneum Stratum lucidum Stratum granulosum (keratin granules) Stratum spinosum (Langerhan cells) Stratum basale (single layer -- melanocytes + Merkels)
Where are Langerhan’s cells in the skin?
Stratum spinosum
* Antigen presenting cells
Where are melanocytes & Merkel’s cells?
Stratum basale
The 2 major divisions of the dermis
Papillary layer
Reticular layer
Function of dermis
Protection, shock absorption, nourish the epidermis
Which layer of the epidermis is limited to thick skin?
Stratum lucidum
T/F Black people have more melanocytes
False – we have a constant number of melanocytes – relates to amount of melanin produced
What are Merkel’s cells?
Mechanoreceptors (dense neurosecretory granules)
Encapsulated sensory receptors of the skin include:
- Pacinian (deep pressure – deep dermis/hypodermis)
2. Mesiners (touch – dermal papilla)
What is the function of a sebaceous gland?
Secrete sebum (oily coat) * Associated with acne
What is the difference between eccrine and apocrine sweat glands?
Eccrine – everywhere
Apocrine – adults / axilla, areola, genitoanal
Who stimulates cells of Leydig to secrete? What do they produce/secrete? Where are they located?
LH
- Testosterone
- Located in the interstitum
What are the 2 cell populations that make up the seminiferous epithelium?
- Spermatogenic cells
2. Sertoli cells
What are the functions of Sertoli cells?
- Support, protect, nourish maturing sperm
- Phagocytes
- FSH receptors (synthesis of androgen-binding protein)
- Secrete inhibin (negative feedback for FSH)
What hormone inhibits FSH release? Who produces it?
Inhibin
* Sertoli cells
LH stimulates… (male)
Testosterone production (Leydig cells)
FSH stimulates… (male)
Synthesis of ABP (androgen-binding protein – binds to testosterone concentrating it to permit sperm maturation)
What progenitor cell in the testes undergoes mitosis?
Spermatagonia
Which cells in the testes under go meiosis?
Primary & secondary spermatocytes
What is spermeogenesis?
Spermatid –> spermatozoa
How long does spermatogenesis take?
74 days
What is unique about spermatogenesis?
Daughter cells are connected by intra-cellular bridges
* The synctium is disrupted at the end when the individual spermatozoa are released into the lumen
Who sits on the basal lamina of a seminiferous tubule epithelium?
Spermatagoina (Type A-pale/dark; B)
Flagella are made from what type of microtubule?
Centrioles
Describe the order:
Spermatocyte, spermatid, spermatazoa, spermatoagonia
Spermatagonia (basal)
Spermatocyte (1/2)
Spermatid (centroles)
Spermatazoa (released into lumen)
Trace the path of sperm after the seminiferous tubules
- Tubuli recti
- Reti testis
- Ductus efferents
- Epidymis
- Vas deferens
- Ampulla –> ejaculatory duct
Name the 2 types of erectile tissue in the penis
- Corpus spongiosum
2. Corpus cavernosum(2)
What does the prostate gland secrete?
Whitish, thin fluid-containing substance w/ proteolytic enzymes, citric acid, acid phosphatase, lipids
What are corpora amylacea?
Concretions (calcified) of the prostate
* Can increase with age
Who governs the prostate’s secretions?
Dihydrotestosterone
What does the seminal vesicle secrete?
Fructose (70% of ejaculate)
What is characteristic of the seminal vesicle?
False lumens!
What is the ejaculatory duct?
Where the vas deferens meets the seminal vesicle (in/around the prostate)
Hyperkeratosis
Hyperplasia of stratum corneum
Parakeratosis
Retention of nuclei in stratum corneum
Acantholysis
Loss of cohesion between keratinocytes (stratum spinosum)
Acanthosis
Hyperplasia of stratum spinosum
Transdermal patches
Lipid soluble
Psoriasis
Acanthosis (hyperplasia of stratum spinosum); cells ascend very quickly and leads to scaling
Bullous pemphigoid
Autoimmune hemidesmosome destruction (skin)
Pemphis vulgaris
Autoimmune desmosome destruction (skin)
Albinism
Melanocytes
- Inability to take up tyrosine
- Dysfunctional tyrosinase enzyme
Vitiligo
No melanocytes
Burns (first, second, third)
1: epidermis (partial thickness) – red
2: epidermis & dermis (partial thickness) – blister
3: hypodermis – charring – full thickness
Differentiate between sq. cell carcinoma, basal cell carcinoma & melanoma (skin)
Squamous: keratin pearls (keratinocytes)
Basal: Basal layer
Melanoma: Melanocytes
Von Recklinghausen Disease
Neurofibromatosis * Not a skin lesion
* Disease of PNS (Schwann cells)
Acne
Elevated sebum production can clog the pores
Warts
Excessive epidermis production
Fungal infections
Can take 2-4 weeks for the bottom-most cells to ascend – thus treatment course is 2-4 weeks and shouldn’t be stopped early
Cellular response to injury consists of:
- Cloudy swelling (early evidence of injury, loss of normal staining intensity)
- Hydropic degeneration (Continued swelling of organelles)
- Fatty change (steatosis – accumulation of TAG’s in the cytoplasm – most common in liver)
Differentiate between atrophy & hypertrophy
Decrease/Increase in size
Differentiate between hyperplasia, metaplasia, dysplasia, neoplasia
Hyperplasia: increase in number of cells
Metaplasia: Change in differentiation of cells
Dysplasia: Failure of differentiation & maturation (rapid multiplication of cells)
Neoplasia: Abnormal mass of cells (benign–localized/malignant–spread widely)