Exam 1 Flashcards
What tissue are serous membranes composed of?
Simple squamous epithelial tissue
Components of cytoplasm
Cytosol, cytoskeleton, inclusions, organelles
Marker molecules
Outside of cell: cell to cell recognition
Inform immune system of “self” cell or cell type
Glycoproteins or glycolipids
Attachment proteins
Attach cells to other cells, extracellular molecules or intracellular
Basis of forming tissue (cell-cell adhesion)
Channel proteins
Involved with transportation of substances in and out of a cell
Transporter proteins
move substances (ions or molecules) from one side of the plasma membrane to the other
Channels vs transporters
Channels - proteins that form a hydrophilic pore through membrane, molecules passively diffuse
Transporters - transfer only those molecules or ions that fit into specific binding sites on the protein, can move against concentration gradient
Receptor proteins
contain binding sites that can attach to specific substances
external signals effect internal cell function
What does tissue begin as?
As pluripotent stem cells
Wandering cells
Some cells that temporarily appear in tissue
Phagocytes/other immune cells, embryonic cells involved in differentiation/growth
3 functions of junctions
Form fluid-tight seals between cells
Anchor cells together or to the matrix
Act as channels, which allow ions and molecules to pass from cell to cell in a tissue
Tight Junctions
Watertight seal between cells, plasma membrane fused with a strip of proteins
Common in cells that line GI and bladder
Adherens junctions
Hold epithelial cells together
Structural components: plaque (dense layer of proteins inside cell membrane), plaque contains microfilaments that extend into cytoplasm, cadherin proteins that connect membrane of other cell
Gap junctions
Forms tiny connection between plasma membranes of 2 cells, made of protein channels called connexons - fluid filled tunnels, cytoplasm is shared between cells
Rapid instant communication between cells
Muscle/nerve impulses, heart, smooth muscle of gut
Desmosomes
Cellular rivet - resists separation and cell disruption, similar structure to adherens junction except intermediate filaments enter cytoplasm of cell which is connected to the cytoskeleton
Cellular support of cardiac muscle
Hemidesmosome
Half a desmosome, connect cells to extracellular basement membrane
The basal lamina
Part of BM, from epithelial cells and collagen fibers
The reticular lamina
Part of BM, secreted by connective tissue cells and reticular fibers
Function of BM
Guide for cell migration during development, may become thickened due to increased collagen and laminin production
2 types of epithelium
1) Covering and lining epithelium - epidermis of skin, lining blood vessels and ducts, respiratory, reproductive, urinary, GI tract
2) Glandular epithelium -
secreting portion of glands, thyroid, adrenal, and sweat glands
Endothelium
Lines the heart and blood vessels
Mesothelium
Lines the thoracic and abdominopelvic cavities and covers the organs within them
Keratinized vs non-keratinized
Non-keratinized: stays moist, found in other mucous membranes
Keratinized: skin (epidermis), hardened protein layer is protective, prevents infection, and moisture loss
Gland
A single cell or a mass of epithelial cells adapted for secretion
Derived from epithelial cells that sank below the surface during development
2 types of exocrine glands
Unicellular glands - goblet cells
Multicellular glands - shape and structure
2 ways to classify multicellular glands
Secretory unit - determine if gland shape is tubular or aciner/alveolar
Epithelial duct - determine if gland structure is simple or compound (branches)
Merocrine glands
Secretory products discharged by exocytosis
Examples - watery (sudoriferous) sweat, salivary glands, digestive enzymes
Apocrine glands
Accumulate secretory products at the apical surface of the secreting cell
Portion of cell pinches off to form the secretion
Examples - mammary and cerumen glands
Holocrine glands
Accumulate the secretory products in the cytosol
Cell dies and its products are discharged
Examples - sebaceous and meibomian glands
What is connective tissue derived from?
Mesenchyme (embryonic connective tissue)
Macrophages
engulf bacteria and debris by phagocytosis
Plasma cells
produce antibodies that fight against foreign substances
mast cells
produce histamine that dilate small BV
components of extracellular matrix
Glycosamine glycans - slick sugary molecules
Hyaluronic acid - thick, viscous, slippery
Chondroitin sulfate - jellylike substance providing support
adhesion proteins (fibronectin) - holds collagen fibers to ground substance
Collagen fibers
Parallel bundles, the body’s main structural protein
Great tensile strength, flexible, only slightly elastic
Found in bone, cartilage, ligaments, tendons
Elastic fibers
Spring-like, some branching
Not as strong as collagen fibers, can stretch and return to original shape
Found in vocal cords, respiratory air passages, skin, blood vessels
Reticular fibers
Thin, branching, web-like fibers of collagen
Form delicate, supporting networks
Found in spleen, liver, support in the blood vessels and in lymph nodes
Areolar connective tissue
Found in the subcutaneous layer of the integument
Makes of BM of epithelial tissue
All 3 types of fibers present
Adipose connective tissue
Consists of adipocytes, deeper skin, surrounding organs, yellow marrow
Cushions and insulates, serves as energy reserve
Generates considerable heart to help maintain proper body temp
Reticular connective tissue
Contains fine interlacing reticular fibers and reticular cells
Forms the stroma (framework) of certain organs
Helps to bind together the cells of smooth muscle
Chondrocytes
Secrete matrix - ground substance and embedded fibers
What tissue provides nutrients to cartilage?
Dense irregular connective tissue
Hyaline cartilage
Fine collagen fibers - transparent
Glassy ECM
Covers ends of long bones at joint: articular cartilage
Spongy pad to absorb compression
Elastic cartilage
More flexible, due to elastic fibers in the matrix
Fibrocartilage
Very tough, due to many collagenous fibers
Shock absorber
Alternating rows of chondrocytes and cartilage fibers
Osteoblasts
(immature) deposit matrix in lamellae (layers), which occur in rings around central canals - capillaries
Red and yellow marrow
Red marrow produces blood
Yellow marrow reduces weight
Neuroglia
Support and nourish neurons: remove waste
Epidermis is composed of
Stratified squamous keratinized epithelial tissue
Keratinocytes
Majority of cells: produce keratin
Fibrous = tough, water-resistant
Melanocytes
Produce melanin, which is absorbed by keratinocytes
Melanin protects nucleus of cells from UV radiation/cancerous mutations
Tactile cells
Merkel cells (Pacinian corpuscles)
Compressed, released NTs on sensory neuron dendrites
Immune cells
Epidermal Dendritic cells, phagocytes
Stratum basale
Deepest layer, one layer thick, mitosis occurs here
All 3 cell types but most immature keratinocytes
Stratum spinosum
Several layers thick, contains cells pushed up from S. basale
Spines = non-dividing keratinocytes
Lots of desmosomes and keratin fibers, give cells “spine” shape
Also epidermal dendritic cells
Stratum granulosum
2-5 cell layer thick
Contains kerato-hyaline granules and lamellated bodies
Cells produce mature keratin (intermediate filaments)
Cells flatten and membrane thickens/less permeable - organelles disintegrate
Kerato-hyaline granules
give the epidermis its strength (granules that are visible)
Lamellar granules
secrete lipids which give the epidermis its waterproofing (granules not visible)
Stratum lucidum
Clear layer, only found in thick skin
Thick vs thin skin
Thick skin contains all 5 epidermal layers, found on palms of hands, finger tips, soles of feet
Thin skin: lacks S. lucidum, found everywhere else
Stratum corneum
20-30 cells thick, hornlike, provides protection from external environment, dead cells
Thicker in thick skin
More keratin in keratinized epithelium
The connective tissue layer of skin in the dermis
Areolar and Dense irregular - 3 types of fibers present
2 layers of dermis
Papillary layer (superficial) and reticular layer (deep)
Papillary layer
Projections called dermal papillae, extend into the deep epidermis
Composed of loose connective tissue (areolar)
Dermal papillae and epidermal ridges form interlocking layer, increase SA between 2 layers
Blister
Separation of the papillary layer of the dermis from the epidermis
Reticular layer
Composed of dense irregular connective tissue (not reticular)
Network of collagen fibers, no clear boundary between the reticular and papillary layer
Dermal blood supply
Temperature regulation
Dermis - extensive innervation and blood supply
largest vessels = near hypodermis
Blood flow to skin dissipates heat
core temp increases - skin vessel vasodilate
Sebaceous glands
Found all over body except palms of hands and soles of feet
Secrete oily secretion called sebum
Lubricates hair and skin, bactericidal
Sweat glands
Distributed over the entire skin surface except for nipples and parts of external genitalia
two types - merocrine and apocrine
Merocrine sweat glands
Secretes sweat via duct onto epidermis
Farm more numerous, on palms of hands, soles of feed, forehead
Prevents overheating of the body - in combination with dermal blood flow
Apocrine sweat glands
Found in axillary and anogenital areas, begin to function at puberty
Sweat secretion is odorless, body odor caused by bacteria
Release secretions into hair follicles
Ceruminous glands
Modified apocrine glands found lining the external ear canal, secrete cerumen, traps dirt/debris, contains lysozymes
Bone Tissue
Calcified bone tissue, skeletal cartilage, coating of dense irregular connective tissue, blood and nervous tissue, ligaments and tendons (dense regular connective tissue)
Bone classification by shape
Long bones (long and narrow, longitudinal axis), expanded ends
Short bones (cube-like, length = wide)
Flat bones (platelike, with broad surfaces)
Irregular bones (variety of shapes, most are connected to other bones)
Bone classification by location
Sutural - located within the sutures of the skull (not always present)
Sesamoid - shaped like a sesame seed, bone surrounded by a tendon
Outermost layer of bone
Compact bone
Consists of cylindrical units called osteons
Run longitudinally down axis of bone
Strong and solid bone for weight bearing
Resists compression
Inner layer of bone
Spongy bone
Fine honeycomb of bone called trabeculae
Small cavities for blood (red marrow) and fat (yellow marrow)
Structure of short, irregular, and flat bone
Thin plate of spongy bone covered by compact bone
Compact bone covered by connective tissue (dense irregular)
Outside - periosteum
Inside - endosteum
Marrow within trabeculae - no large cavity
When forming moveable joint surfaces: hyaline cartilage (articular cartilage)
Structure of long bone
Outer cover of compact bone with spongy bone inside
Epiphysis
Expanded end
Articulates with another bone
Articular cartilage (hyaline)
Epiphyseal plates
Growth plates
Bone growth = cartilage becomes calcified
Diaphysis
Bone shaft
Between diaphysis and epiphysis is metaphysis (widening part)
Medullary cavity
Chamber lined with spongy bone and blood vessels
Contains yellow marrow (in adults)
Periosteum
Encloses bone; dense irregular connective tissue (except joints surfaces)
Waxy and vascular
Well innervated
Endosteum
Lines inside surface of compact and trabeculae of spongy bone
Projections
Site of muscle/ligament attachment
Rough/raised surface
Examples: tubercle - lesser tubercle insertion for back and shoulder muscles
Surfaces
Gliding points between joints
Examples: fact - flat and smooth articulation points between bones
Depressions and openings
Blood vessels and nerves to nourish bones
Examples: foramen or foramina
Osteoprogenitor cells
Form of stem cell - can divide
Found in periosteum and endosteum
Can differentiate into osteoblast or remain stem cell
Osteoblast
Similar to chondroblast - secrete collagen matrix for bone growth
Becomes calcified later
When cell is completely surrounded by matrix, it becomes an osteocyte
Osteocyte
Found in lacunae in bone tissue
Monitor and maintain bone matrix
Communicate mechanical strain information to osteoblast and osteoclast
Osteoclast
Enzymatically breaks down bone
Decreased mechanical strain and normal bone maintenance
What cell types reabsorb and deposit bone?
All 4 cell types constantly reabsorb and deposit bone
Bone remodeling
Maintain microscopic structure
Basic structural unit of compact bone
Osteon
Osteons
Long cylinders which run length of bone
Cemented together to form bone tissue
Central canal
Blood vessels and nerves from medullary cavity to nourish bone tissue
Central canals connected via…
A perforating canal
Rings of bone matrix surrounding central canal
Lamellae - osteocytes within lacunae
Canaliculi
Osteocytes with each lacunae are connected via tiny passages called canaliculi
Osteocytes send extension through canaliculi to maintain contact between cells
Osteocytes connected via…
Gap junctions
Involved in cell-cell communication
Exchange of nutrients and waste
Spongy bone (cancellous bone)
Has osteocytes and ECM, no organized osteons
Web-like cavities called trabeculae
Trabeculae
Collect nutrients from endosteum blood vessels, sent to osteocytes via canaliculi
Trabeculae look disorganized
- carefully positioned along stress lines - structural reinforcement
Constantly remodeled as a result of mechanical stress
Bone anatomy reflects…
Stress it has encountered
Chemical composition of Bones - organic
Soft; able to withstand tension (stretch or twist) - equal strength of steel
All cells and osteoid 1/3 of matrix
Ground substance and collagen fibers secreted by osteoblasts
Collagen fibers bonded together by…
Sacrificial bonds
Break easily on impact - dissipate energy to prevent injury
Reform quickly
Chemical composition of bone - inorganic
harder; able to withstand compression - half strength of steel
Remaining 66% bone is inorganic components -
Calcium phosphate crystals in and around collagen fibers
Exceptional hardness
