TBL 2 (Phase I) Flashcards
What are the two categories of embryonic connective tissue?
Mesenchyme and mucous
What are the two types of adult connective tissue?
Connective tissue proper, specialized connective tissue
What are the three types of connective tissue proper?
Loose (areolar) connective tissue, dense irregular connective tissue, dense regular connective tissue
What is loose connective tissue called in the digestive tract?
Lamina propria
What is lamina propria?
Loose (areolar) connective tissue of the digestive tract
What type of connective tissue is found in the tendon?
Dense regular connective tissue
What types of tissue are classified as specialized connective tissue?
Reticular connective tissue, adipose tissue, bone, cartilage, blood
What are the two types of “wandering” connective tissue?
Immigrant and transient
From what cells does resident connective tissue originate?
Mesenchymal cells
From what cells do immigrant and transient connective tissue originate?
Hematopoietic stem cells
Fibroblasts are derived from what type of connective tissue?
Resident cells
What is the function of fibroblasts (generally)?
Synthesize fibers (collagen, elastic fibers) and secrete “ground substance” (proteoglycans, glycoproteins)
What cells are classified as immigrant connective tissue cells?
Macrophages, mast cells, plasma cells
What cells are classified as transient connective tissue cells?
Leukocytes (lymphocytes, eosinophils, basophils and neutrophils)
What type(s) of collagen form fibrils?
Collagen I, II and III
What type(s) of collagen form network(s)?
Collagen IV
Where is type I collagen found?
Skin, dentin, bone, tendon
Is type II collagen thinner or thicker than type I collagen?
Thinner
Where is type II collagen found?
Elastic cartilage and hyaline
What type of collagen is recognizable as a “silver stain”?
Type III collagen
What type of collagen forms first in wound healing?
Type III collagen (then replaced by type I)
Where is type III collagen found?
Reticular lamina, also “stroma” of bone marrow and lymphoid organs
What type of collagen is found in elastic cartilage and hyaline?
Type II collagen
What type of collagen is found in skin, dentin, bone and tendon?
Type I collagen
What type of collagen is found in the reticular lamina?
Type III collagen
What does type IV collagen bind to?
[Collagen IV-binding site of] laminin
Where is type IV collagen found?
Basal lamina (lamina densa along with glycoproteins)
Where can both collagen I and II be synthesized (in what cells)?
Smooth muscle cells
Where can smooth muscle cells be found?
Walls of arteries, uterus, respiratory bronchial tree, intestine
What is the ECM comprised of?
Fibers and “ground substance”
What (3) types of fibers comprise the ECM?
Collagen, reticular, elastic
What (3) types of “ground substance” comprise the ECM?
Glycosaminoglycans, proteoglycans, glycoproteins
Define glycosaminoglycans
Large unbranched polysaccharide chains (ex. Hyaluronic acid, chondroitin sulfate)
Define glycoproteins
Globular proteins with short branched carbohydrates (laminin, fibronectin)
What are reticular cells?
A type of fibroblast that synthesizes type III collagen
What are fibroblasts called in bone?
Osteoblasts
What are fibroblasts called in cartilage?
Chondroblasts
What are fibroblasts called in teeth?
Odontoblasts
What does “FACIT” stand for?
Fibril-associated-collagen-[with] interrupted-triple helices
Where does the intracellular portion of collagen synthesis occur?
Collagen is made in RER (proline and lysine hydroxylated, which requires ascorbic acid), then goes to Golgi apparatus for packaging
Describe the extracellular portion of collagen synthesis
Peptidase cuts off pro- end of collagen to for tropocollagen, which self-aggregates into fibrils (aided by lysyl oxidase), which then links to form fibers
What are the symptoms and cause of scurvy?
Inadequate wound healing d/t poor collagen formation s/t vitamin C deficiency
What are the symptoms and cause of Ehler-Danlos syndrome?
Hyperelasticity of skin and hyper mobility of joints d/t defect in synthesis or structure of collagen (if defects extend to visceral collagen, results in tissue rupture)
Where are elastic fibers synthesized in skin and tendons?
Fibroblasts
Where are elastic fibers synthesized in cartilage of auricle of the ear, epiglottis, larynx, and auditory tubes?
Chondroblasts
Where are elastic fibers synthesized in large blood vessels like the aorta and respiratory tree?
Smooth muscle cells
What is the cause of Marfan syndrome?
Elastic fiber disease d/t defect in gene encoding for fibrillin-1
What are the symptoms of Marfan syndrome?
Tall, long limbs and digits, can die from aortic dissection, dilation of root of the aorta or mitral valve prolapse (elastic fiber disease)
What are Kupffer cells?
Macrophages in the liver
What are osteoclasts?
Macrophages in the bone
What are microglial cells?
Macrophages in CNS
Define histiocytes
Phagocytic cells that migrate into a certain tissue and stay there
What type of mast cells are T-cell independent?
Connective tissue mast cells (CTMCs)
What type of mast cells are T-cell dependent?
Mucosa mast cells (MMCs), predominantly in lamina propria of intestine and the lungs
What type of immigrant cell will have abundant lysosomes (and residual bodies) on microscopy?
Macrophages
What type of immigrant cell produces cytokines?
Macrophages
What are the 3 functions of macrophages?
(1) turn over senescent fibers and ECM materials (2) present antigens to lymphocytes as part of inflammatory and immune response (3) produce cytokines
What type of immigrant cell secretes immunoglobulin?
Plasma cells
What are plasma cells derived from?
B lymphocytes
What type of immigrant cell has a high affinity [receptor] for IgE?
Mast cells
What type of immigrant cell releases vasoactive mediators to herald transient cells?
Mast cells
What type of immigrant cell is associated with allergic hypersensitivity (i.e. Hay fever, asthma)
Mast cells (release mediators like histamine)
Describe the effects of metachromasia
After “blue” stain, the [basophilic cytoplasmic] granules of mast cells might appear purple-red, but nucleus will still be blue
What type of transient cell contains defensins?
Neutrophils
What is the function of defensins?
Aid in phagocytosis of bacteria
What transient cells are associated with acute infection?
Neutrophils
What transient cells are associated with parasitic infection?
Eosinophils
What transient cells are associated with allergic reactions?
Eosinophils (inactivate histamine and heparin)
What is loose (areolar) connective tissue called in bone marrow?
Reticular tissue
What are the five functions of integument
Protection, sensory, thermoregulatory, endocrine (metabolic), water maintenance
What are the five layer of epidermis (from deep to superficial)
Stratum basale, stratum spinosum, stratum granulosum, stratum corneum, stratum lucidum
What two layers (of epidermis) are only present in thick skin?
Stratum corneum and stratum lucidum
What gives stratum lucidum its characteristic “light” appearance on LM
Eleidin
In what layer of epidermis are melanocytes found?
Stratum basale
What are the symptoms and underlying cause of epidermolysis bullosa?
Defect in anchoring fibrils cause separation and fluid build up between epidermis and dermis, resulting in blistering and skin erosion. Ultimately, scarring, chronic infection and dehydration can result.
In what layer of epidermis are keratin tonofibrils found?
Stratum spinosum
In what layer of epidermis are keratohyalin granules found?
Stratum granulosum (gives characteristic basophilic appearance)
What layer of epidermis is primarily responsible for water protection (as a means of maintaining internal environment)?
Stratum granulosum
What is the embryologic origin of melanocytes?
Neural crest cells
Describe the process of melanin production (in melanocytes)
Tyrosinase converts tyrosine into DOPA, which then forms melanin (latter reaction carried out in premelanosomes)
What are Langerhans cells?
Antigen-presenting cells of the epidermis (“the macrophage of the skin”)
Where can Merkel cells be found?
Stratum basale (“sit” on basal lamina)
Describe the function of Merkel cells
Release neurosecretory granules in response to influx of calcium (triggered by keratinocytes pooling on cell surface). Important for tactile discrimination (underlying afferent nerves).
What is the embryological origin of dermis?
Para-axial mesoderm
What are the two layers of dermis?
Dermal papillae (superficial), and deeper reticular layer
Which layer of dermis possesses more elastic fibers?
Deeper reticular layer
What type(s) of collagen are found in the dermal papillae layer?
Type I & III collagen
What type(s) of collagen are found in the deeper reticular layer (of the dermis)?
Type I collagen
What type of connective tissue is present in the dermal papillae layer?
Loose (areolar) connective tissue
What type of connective tissue is present in the deeper reticular layer (of the dermis)?
Irregular dense connective tissue
What layer of skin is primarily associated with drug absorption?
Hypodermis (fat cells and numerous blood vessels)
What is the panniculus carnasus?
Striated muscle deep to subcutaneous fascia that contributes to facial expression
Where are mast cells most common?
Skin, gastrointestinal lining, the serosal lining of the peritoneal and pleural cavities and around blood vessels
What (specifically) is ascorbic acid responsible for in collagen synthesis?
Hydroxylation of proline to hydroxyproline (non-hydroxylated collagen cannot form triple helix)
What are some of the symptoms of scurvy?
Hemorrhages into the skin, joints, and muscles and loosening of the teeth
What are the four differentiating characteristics of thick skin (as compared to thin)?
(1) grooves and ridges (2) abundance of sweat glands (3) no hairs (4) no sebaceous glands
What are Pacinian corpuscles? What do they do?
Schwann cells wrapped around nerve fibers. Important in sensing coarse touch, pressure and vibration.
What are Meissner corpuscles? What do they do?
Schwann cells arranged horizontally, important for sensing light touch or low frequency vibrations.
Describe free nerve endings
Unencapsulated receptors that respond to noxious stimuli
What do Ruffini corpuscles do?
Sense stretch or torque
What are Krause end bulbs?
Thin collagenous capsules penetrated by nerve fibers, only found in penis and clitoris, respond to low frequency vibrations
What is the function of Merkel cells?
Sense texture (and light touch)
What do arrector pili muscles do?
Cause hair to stand up in order to retain warmth
What type of glands are sebaceous glands (i.e. how do they release secretion products)?
Holocrine (release by disintegration)
What causes acne?
Retention of sebum in hair follicle
What are the two types of sweat glands?
Eccrine and apocrine
What are the four stages of skin repair?
(1) Cut blood vessels bleed into the wound, (2) blood clot forms and leukocytes clean the wound, (3) blood vessels then regrow + granulation tissue forms, (4) epithelium regenerated and connective tissue fibrosis occurs
Which type of sweat gland is coiled?
Eccrine
What type of sweat gland is innervated by adrenergic fibers?
Apocrine
What type of sweat gland is innervated by cholinergic fibers?
Eccrine
What do clear cells (of sweat glands) produce?
Sweat
What do dark cells (of sweat glands) produce?
Proteinaceous secretion
In which tissues are reticular cells present?
Liver, spleen, lymphoid and bone marrow
What type of collagen predominates in tunica adventitia?
Type I collagen
What type of collagen is produced by tunica media?
Type III collagen
