Learning Objectives-Exam 1 Flashcards
describe the physiologic functions of the epidermis (4)
primary protection/physical barrier against microbes, chemicals, toxins, and impacts via formation of the cornified envelope. production of antimicrobial substances, and permanent shedding of corneocytes; is also the primary envelope to contain water, electrolytes, and macromolecules
describe the physiologic functions of the dermis (3)
blood supply, immune protection, anchors epidermis
describe the physiologic functions of the hypodermis/subcutis
anchors the dermis to underlying muscle and bone
describe basic anatomy of the ear and how ear canal, middle, and inner ear relate to each other
- pinna: outer shell, can palpate
- ventral canal connects pinna to horizontal canal (palpation and otoscopy)
- tympanic membrane leads to bony septum leads to inner ear (ventral to middle ear); need to sedate to look at
- middle ear leads to auditory tube
(can only evaluate inner ear and middle ear via CT and MRI)
contrast feline ear to canine ear
In felines, septum bulla (felines have not dogs) almost completely separates tympanic cavity into two compartments (ventromedial and dorsolateral) but this separation is incomplete and not as prominent in canines
describe how the ear canal, middle ear, ad inner ear relate to each other
- pinna: visible from outside and can palpate; elastic cartilage; sweat and sebaceous glands
- vertical canal: should feel pliable and not painful upon palpation
- typmanum: pars tensa, pars flaccida, manubrium of malleus
- pars tensa= thin shiny sheet on ear drum
-manubrium= give conical shape
-pars flaccida= not taut like tensa and hold up membrane - inner ear is embedded in bones, contains
-vestibular organ: semi-circular ducts, balance
-cochlea: hearing
-both above communicate with middle ear through membrane-covered windows - middle ear: boney hollow structure; holds the air-filled tympanic cavity
define the healthy ear and skin microbiome (5)
- the collection of microbes that naturally live on our bodies
- in a constant state of flux
- composition varies based on species, between individuals of the same species, and depending on body site of the same individual
- influenced by many factors
- shifts in our natural microbiome can be caused by inflammation
if a dog’s natural ear microbiome is chronically shifted, what can result?
they can have chronic otitis due to persistent inflammation; allergic dogs have a tendency to develop bacterial otitis; body responds to allergens with inflammation, making a more suitable environment for infection
what are internal impacts to the skin? (2) what can they result in?
- malnutrition
- lack of essential fatty acids
these can cause epidermal lipid deficiency/disturbance and lead to scaling and poor barrier function
what are external impacts to the skin? (3) what can they result in?
- excessive washing
- chemicals
- wet/dry environment
can weaken epidermal barrier, leading to increased scaling and increased transepidermal water loss
describe the process of keratinization (4)
- proliferation/adhesion
- production of additional keratin filaments; beginning of synthesis of lipid-containing lamellar bodies
- progressive flattening of cells, keratin filaments get progressively packed into large, insoluble polymers with the help of filaggrin
- keratinocytes are terminally differentiated, coated by lipids, separated by proteases, and constantly shed
list the phases of the hair follicle cycle (go to hair follicle brainscape and study further too!)
- anagen (growth phase)
- catagen (regression phase)
- telogen (resting phase)
- exogen + anagen
explain the basic anatomy of hooves
keratinized portion of hoof is composed of wall, sole, frog
wall: stratum externum (tubular and intertubular horn), stratum medium (tubular and intertubular horn), stratum internum (lamella), laminar corium (dermis, where primary and secondary epidermal and dermal laminae interdigitate)
sole: similar to tubular and intertubular regions of wall, but softer than wall, has white line
frog: similar to sole but underlying papillae are shorter and frog is softer than sole
contrast integument anatomy of nails, hooves, and horns across species
horses: hoof; wall, sole, frog
ruminants and swine: claws; wall, sole, bulbs (no frog); walls only have primary epidermal and dermal laminae, no secondary
carnivores: claws; wall and sole
explain basic anatomy of horns and nails
- horn is keratinized portion (hard keratin; doesn’t slough off)
- underlying dermis (corium)
- hypodermis may or may not be present; modified to form digital cushion and digital pad
- bones and associated structures of bones
Name, list, and identify the bones related to forelimb (small and large animals).
Name, list, identify, and recognize the bones that make up specific joints of the forelimb (small and large animals).
see other brainscapes for this
Define cutis and subcutis and relate to gross anatomy
cutis: superficial dermis + underlying dermis
subcutis: hypodermis (where sub Q fluids are deposited)
both are outermost layers of the skin
Distinguish between the strata of the epidermis and the layers of the dermis. Describe their interdigitation.
epidermis:
1. stratum corneum: outermost; layers of flat cornified/keratinized. cells lacking a nucleus and organelles; varies in thickness based on abrasion
2. stratum lucidum: clear layer, inconsistent and rare squamous cell layer; found only in very thick epidermal regions
3. stratum granulosum: flattened cells that contain keratohyalin granules (present in soft keratin but NOT in hard keratin)
4. stratum spinosum: prickle cell layer; thick in regions with no hair, thin in regions with hair
5. stratum basale: proliferation and attachment layer; adjacent to dermis; cell division occurs here
dermis/corium: network of collagen, elastic, reticular fibers
1. papillary layer: loose irregular CT; most superficial layers; interdigitates with s. basale via dermal papillae
2. reticular layer: dense irregular CT; deepest and thickest layer; many large bundles of collagenous fibers
Distinguish between keratinocytes and non-keratinocytes
keratinocytes: most numerous cell type of epidermis; maturation process is kertinization
non-keratinocytes: include melanocytes (produce pigment, cytocrine secretion), intraepidermal macrophages/Langerhan’s cells (dendritic cells in upper stratum spinosum), and tactile epithelioid cells/Merkel cells (sensory mechanoreceptors in basement membrane of s. basale)
Distinguish between the layers of the hair
hair is subdivided into shaft, root, and hair bulb; shaft has 3 layers
1. cuticle: outermost single layer of overlapping (shingle-like) keratinized cells
2. cortex: densely packed keratinized cells that contain pigment granules
3. medulla: center of hair, loosely arranged cuboidal or flattened cells
distinguish between the layers of the hair follicle (6)
- internal epithelial root sheath: innermost layer next to hair root/stratum corneum of hair follicle
- external epithelial root sheath: strata basale and spinosum of hair follicle
- glassy membrane: basement membrane of follicle epithelium
- dermal root sheath and dermal papilla: CT enclosure of hair follicle; root sheath continuous with papilla that projects into underside/base of bulb; made of collagen and elastic fibers, blood vessels, nerves
- hair matrix: dividing cells (s. basale) overlying dermal papilla, product the hard keratin = hair
- arrector pili muscle: smooth muscle, innervated by ANS; spans dermal root sheath of follicle and papillary layer of dermis; elevates hair and expresses sebaceous glands located between follicle and muscle mass
Distinguish between sebaceous and sudoriferous glands and know their modes of secretion/what they produce
sebaceous glands: alveolar, holocrine secretion, secrete sebum; secrete product into hair follicle or directly onto skin surface
sweat glands/sudoriferous glands: produce sudor/sweat; vary greatly in appearance and secretory product; utilize merocrine and apocrine secretion; include mammary glands, anal glands
Determine the type of cartilage that supports the pinna
elastic cartilage
Define cerumen and list the glands that contribute to its formation
cerumen: the combo of sebaceous and ceruminous gland secretions known as ear wax; ceruminous glands are simple coiled tubular apocrine sweat glands of inner surface of ear pinna and external auditory canal
what are the 3 glands of the eyelids? name the products of each
Miebomian/tarsal glands: meibum (polar and nonpolar lipids)
Zeiss: sebaceous glamds
Moll: aprocrine sweat glands
Determine why Meibomian glands are also called tarsal glands
located in the tarsal palate
Define anal sacs and relate to gross anatomy
- paired cutaneous diverticula that open into anal canal at anocutaneous junction
- ducts and sacs are lined by stratified squamous epithelium
- cats have both apocrine and sebaceous but dogs only have apocrine glands
List the basic integumentary glands that empty into the anal sacs of dogs v. cats
cats have both apocrine and sebaceous but dogs only have apocrine glands
Determine which basic integumentary gland that circumanal glands are derived from, and whether they are present in both the dog and the cat
circumanal glands are modified sebaceous glands located circumferentially around anus; frequent site of canine tumors in intact males and females; not present in felines
What type of glands are mammary glands?
modified sweat glands; compound tubuloalveolar
What type of epithelium lines mammary gland ducts?
varies from simple cuboidal epithelium in the smaller ducts to stratified cuboidal epithelium surrounded by increasing amounts of CT as ducts become progressively larger
What are the exocrine modes of secretion of mammary glands?
lipids are released via apocrine
proteins are released via merocrine
so milk is released by both apocrine and merocrine secretion
How do mammary glands respond to hormonal stimulation for milk letdown?
myoepithelial cells contract in response to oxytocin to force milk into the duct system = milk letdown
Distinguish between the different types of adult CT proper
- loose/areolar CT: always irregular; cells are fibroblasts; contain all 3 collagen fibers but type I is most visible
- dense CT: irregular and regular;
-dense irregular: cells are fibroblasts, contain all 3 fibers, but Type I most visible and large bundles than loose
-dense regular: collagenous and elastic; cells are fibroblasts; all 3 fibers; type I most visible in collagenous and elastic most dominant in elastic - reticular CT: reticular cells and their fibers concentrated to a mesh-like framework for soft organs like bone marrow, spleen, liver, endocrine glands; cells are reticular cells; fibers are reticular fibers
- adipose tissue: cells are adipocytes; fibers are a delicate network of collagen and reticular fibers
-white adipose: white fat; found throughout body and varies in abundance based on BCS; single chamber (unilocular)
-brown adipose: multi-chambered (multi-locular); less abundant; location is regional
what is embryonic CT? describe
also called mesenchyme; the CT of the developing embryo; cells are mesenchymal cells and are pluripotent; all three fibers present but are fine and not highly visible
Distinguish between the different types of cartilage
- hyaline cartilage: found in most bone-forming sites, articular surfaces, resp airways, larynx and nose; cells are chondrocytes inside lacunae which can revert back to condroblasts to divide and form cells nests; type II collagen; territorial (more basophilic) and interterritorial matrix organization (less basophilic); HAS perichondrium EXCEPT at articular surfaces (articular cartilage)
- elastic cartilage: external ear and external auditory canal, auditory tube, portions of laryngeal and epiglottic cartilages; cells are condrocytes within frequent isogenous groups; matrix is identical to hyaline but also has elastic fibers; HAS PERICHONDRIUM
- fibrocartilage/fibrous cartilage: in intervertebral discs and attachments of certain tendons and ligaments; joint menisci; pubic symphysis, plus regions of transition between fibrous CT and hyaline cartilage; cells are small chondrocytes in lacunae; matrix has type I collagen fibers in herringbone pattern; NO PERICHONDRIUM
list the growth patterns of cartilage
chondroblasts divide and synth matrix in response to hormones or bone repair; 2 types of growth
1. interstitial growth: growth within inside; chondroblasts divide and secrete matrix around and between daughter cells
2. appositional growth: growth upon outside; chondroblasts within perichondrium secrete matrix onto cartilage surface
Define intramembranous and endochondral bone formation and relate these to the formation of the diaphysis and epiphyses
intramembranous: mesenchymal cells differentiate into osteoblasts, which produce pre-bone matrix (osteoid) that becomes calcified; common method for flat bone formation (marrow space but not marrow cavity)
endochondral: mesenchymal cells differentiate into chondrocytes that form a hyaline cartilage model of future bone; cartilage model is digested and replaced with bone tissue; common method for long bone formation (have a marrow cavity);
diaphysis is primary center of ossification; like a turtle neck/bony collar at diaphysis; bone around outside cuts off cartilage inside so it dies and calcifies, sending signals for repair to bring in vessels and osteoblasts, which lay down bone and grow towards metaphysis
Understand how bone grows in width
growth in width occurs by simple appositional growth on outer bone surface as diaphyseal diameter increases and so does diameter of marrow cavity via existing bone resorption
Demonstrate an understanding of how long bones grow in length by labeling the zones of the epiphyseal cartilage
this all occurs at the epiphyseal cartilage (physis or epiphyseal plate)
1. zone of resting cartilage/reserve zone: anchors growth plate to epiphysis; cells appear inactive
2. zone of proliferation: cells arranged in rows or columns (pancakes); actively dividing chondrocytes
3. zone of hypertrophy/maturation: maturing chondrocytes are increasing in size
4. zone of calcification/ossification: cartilage “walls” around hypertrophied chondrocytes calcify; cartilage “floors and ceilings” between chondrocytes are resorbed by incoming osteoclasts, brought in by invading capillaries
Know the location of the metaphysis
the wide portion of long bones; located between diaphysis and epiphysis (where the funnel/angle of epiphysis stops)