Unit 2 Flashcards
groups of cells similar in structure and function
-types: epithelial, connective, muscle, and nerve
tissues
covers external/internal surfaces
covering and lining epithelia (epithelial tissue)
covers secretory tissues in glands
grandular epithelia (epithelial tissue)
two main types: covering and lining/grandular
functions:
-physical protection: protects from dehydration, abrasion, destruction
-selective permeability: allows passage of some substances while preventing passage of others
-secretions: some cells are specialized to secrete
-sensations: supply information to nervous system
characteristics:
-cells have polarity: apical (upper, free) and basal (lower, attached) surfaces
-composed of closely packed cells
-supported by connective tissue reticular lamina
-avascular but innervated
-high rate of regeneration
classifications: 1. how many layers? 2. what type of cell
epithelial tissue
one layer
simple
multiple layers
stratified
squished cell
squamous
square or cubed cells
cuboidal
column or cylinder-shaped cells
columnar
single layer of flattened cells with disc-shaped central nuclei, the simplest of the epithelia
function: allows passage of materials by diffusion and filtration in sites where protection is not important; secretes lubricating substances in serosae
location: kidney glomeruli, air sacs of lungs, lining of heart, blood vessels, lymphatic vessels, lining of ventral body cavity
simple squamous epithelium
single layer of tall cells with round to oval nuclei, some cells bear cilia, may contain mucus-secreting glands (goblet cells)
function: absorption, secretion of mucus/enzymes/other substances, ciliated type propels mucus by ciliary action
location: nonciliated type lines most of digestive tract/gallbladder/excretory ducts of some glands, ciliated variety lines small bronchi/uterine tubes/ some regions of uterus
simple columnar epithelium
thick membrane composed of several cell layers, basal cells are cuboidal or columnar and metabolically active, surface cells are flattended
function: protects underlying tissues in areas subjected to abrasion
location: nonkeratinized type forms the moist linings of the esophagus/mouth/vagina, keratinized variety forms the epidermis of skin/dry membrane
stratified squamous epithelium
embryonic connective tissue
-gives rise to all other connective tissues
-gel like ground substance with fibers and star-shaped cells
mesenchyme
structural elements: cells, fibers, ground substance
functions:
-binding and support: ligaments and tendons
-protection: bones of cranium, fat for kidneys
-storage: fat for energy, bone for calcium
-transport: blood
connective tissue
contains:
-macrophage: engulfs debris or dead tissues
-fibroblast: secretes resources that give fiber types
-mast: immune cells that secrete histamine
-neutrophil: “wondering cells”, destroying bacterial cells
cell types of connective tissue
strongest and most abundant type, 25% of body’s protein, provides high tensile strength
collagen (white fibers) (fiber type of connective tissue)
network of long, thin elastic fibers that allow for stretch (skin, arteries)
elastic (fiber type of connective tissue)
short, fine, mesh, highly branched collagenous fibers; abundant in the stroma of lymph nodes and liver
reticular (fiber type of connective tissue)
non living material
-medium through which solutes diffuse between blood capillaries and cells
-solid/semisolid
-viscous
-components: interstitial fluid, proteoglycans, cell adhesion proteins
ground substance
gel like matrix with all three fiber types; cells: fibroblasts, macrophages, mast cells, and some white blood cells
*fewer fibers, more ground substance
function: wraps and cushions organs; its macrophages phagocytize bacteria; plays important role in inflammation; holds and conveys tissue fluid
location: widely distributed under epithelia of body i.e. forms lamina propria of mucous membranes, packages organs, surrounds capillaries
loose connective tissue; areolar
primarily irregularly arranged collagen fibers; some elastic fibers; major cell type is the fibroblast
*more fibers, less ground substance
function: able to withstand tension exerted in many directions; provides structural strength
location: fibrous capsules of organs and of joints; dermis of the skin; submucosa of digestive tract
dense connective tissue; dense irregular
types of cartilage
hyaline, elastic, fibro
amorphous but firm matrix; collagen fibers from an imperceptible network; chondroblasts produce the matrix and when mature (chondrocytes) lie in lacunae
function: supports and reinforces; has resilient cushioning properties; resists compressive stress
location: forms most of embryonic skeleton; covers the ends of long bones in joint cavities; forms costal cartilages of the ribs; cartilages of the nose, trachea, and larynx
hyaline cartilage
matrix similar to but less firm than that in hyaline cartilage; thick collagen fibers predominate
function: tensile strength with the ability to absorb compressive shock
location: intervertebral discs; pubic symphysis; discs of knee joint
fibrocartilage
closely packed chondrocytes in lacunae; abundant elastic fibers that form weblike mesh; limited ground substance
function: maintains shape while permitting extensive flexibility
location: external ear, epiglottis of larynx
elastic cartilage
functions of the skin
- resistance to trauma and infection (protection)
- immune defense
- vitamin D3 synthesis (metabolic regulation)
- sensations: heat, cold, pressure, vibration
- thermoregulation
- nonverbal communication
covers front of hands and bottoms of feet
-epidermis is 0.5mm thick
thick skin
covers rest of the body
-epidermis is 0.1mm thick
thin skin
most superficial
layers (superficial to deep):
-stratum corneum
-stratum lucidum (only in thick skin)
-stratum spinosum
-stratum basale
epidermis
under epidermis/middle layer
dermis
energy reservoir and thermal insulation
subcutaneous tissue (fat)
only found in thick skin, serves as padding
stratum lucidum
stem cells divide to create keratinocytes (most abundant cell)
stratum basale
cells create spikes when stained
stratum spinosum
filled with granulocytes that help form protective barrier, depositing of kertain takes place (thick protein that kills cells to create keratinized layer)
stratum granulosum
living- doesn’t contain keratin
dead- contains keratin
keratyinocytes
detects sensations
tactile cells
produces melanin, protects nucleus from UV lightening
melanocytes
0.2mm to 4mm thick; blood supply and nerve endings; facial muscles attach for expressions; contains hair follicles; arrector pili muscles
-contains papillary and reticular layers
dermis
superficial layer of dermis with extensive nerve fibers, sensory nerve fibers that detect pressure/vibration/cold, motor nerve fibers that controls blood flow and gland secretions; forms dermal papillae and composed of areolar connective tissue
papillary dermal layer
80% thickness, deepest layer, contains: pressure receptors, blood vessels, collagen fibers, phagocytes
reticular dermal layer
subcutaneous tissue, has more areolar and adipose than dermis has
hypodermis
most superficial layer of epidermis; 20-30 layers of dead, flattened, keratin filled keratinocytes
stratum corneum
functions of the skeleton
- protection
- movement
- reservoir for minerals
- red blood cell production
composed of bones, cartilages, and ligaments
skeletal system
rigid organ
bone
forerunner of most bones; covers many joint surfaces of mature bone
cartilage
holds bones together at joints (bone to bone)
ligaments
attach muscle to bone
tendons
dense or cortical bone; 80% of bone mass
-provides strength and rigidity
compact bone
cancellous or trabecular bone; 20% of bone mass
-provides stress relief throughout the bone
spongy bone
semirigid connective tissue; more flexible than bone
cartilage
longer than they are wide
examples: arm/leg bones
long bones
wider than they are long
examples: hand/foot bones
short bones
flat
examples: skull bones
flat bones
have no designed shape
examples: vertebra
irregular bones
ends of bones
epiphysis
middle shaft
diaphysis
contains growth plate (epiphyseal line), separates epiphysis from diaphysis
metaphysis
continuous with tendons, where regenerator cells are found, provides support for blood vessels
periosteum
soft tissue occupying marrow cavities of long bones and small spaces of spongy bones
bone marrow
contains hemopoietic tissue which produces blood cells
red marrow (myeloid tissue)
fatty marrow that does not produces blood, found in adults
yellow marrow
contains ground substance, fibers, and cells; soft organic substances that undergoes mineralization (calcifies)
osseous tissue
found in periosteum; mitotically active (can divide)
osteogenic cell
lays down bone
under endosteum/periosteum; synthesize organic matter of bone matrix; nonmitotic
osteoblasts
building
former osteoblasts in matrix that now resides in lacunae; cytoplasmic process that reaches into canaliculi; connect to osteoblasts; importance of canals
osteocytes
breaking down
ruffled border; increases cell surface area; reside in pits: resorption bays
osteoclasts
osteoid produced by osteoblasts; collagen protein; semisolid ground substance of proteoglycans and glycooproteins
organic components
salt crystals and calcium phosphate; interacts with calcium hydroxide (forms crystals: hydroxyapatite); crystals deposit around collagen fibers; harden matrix and account for rigidity of bones
inorganic components
growth in length
occurs within internal regions of cartilage; dependent upon growth of cartilage within the epiphyseal plate
interstitial growth
produce cartilage matrix
chondroblasts
chondoblasts encased within the matrix; occupy small spaces: lacunae; maintain the matrix
chondrocytes
growth in width
occurs on cartilage’s outside edge; occurs within the periosteum
-osteoblasts build bone at the circumferential lamellae and osteoclasts widen the medullary cavity
appositional growth
formation and development of bone/connective tissue; begins in the embryo; continues through childhood and adolescence
ossification or osteogenesis
bone growth within a membrane
produces:
-flat bones of skull
-some facial bones
-mandible
-central part of clavicle
intramembranous ossification
steps of intramembranous ossification
- ossification centers from within thickened regions of mesenchyme
- osteoid undergoes calcification
- woven bone and surrounding periosteum form
- lamellar bone replaces woven bone, as compact and spongy bone form
embryonic development; produces most bones of skeleton; mesenchyme develops into body of hyaline cartilage
endochondral ossification
steps of endochondral ossification
- fetal hyaline cartilage model develops: chondroblasts secrete cartilage matrix during 8th to 12th week of development
- cartilage calcifies, a periosteal bone collar forms: chondrocytes in the cartilage model produce holes in the matrix, matrix calcifies and chondrocytes die- produces calcified cartilage shaft with large holes
- primary ossification center forms in diaphysis: periosteal bud extends from periosteum into cartilage shaft, growth of capillaries and osteoblasts; osteoblasts produce osteoid on calcified cartilage template; bone development extends in both directions towards epiphyses
- secondary ossification centers form in epiphyses: hyaline cartilage calcifies and degenerates; blood vessels and osteoprogenitor cells enter; secondary ossification centers form
- bone replaces cartilage, except articular cartilage and epiphyseal plates
- lengthwise growth continues until epiphyseal plates ossify and form epiphyseal lines: growth continues until epiphyseal plate is covered to epiphyseal line indicates bones has reached adult length
continues throughout adulthood; occurs at different rates; 20% of skeleton are replaced yearly; dependent upon the coordinated activities of osteoblasts, osteocytes, and osteoclasts; influenced by hormones and mechanical stress
bone remodeling
dwell constitutively in tissues and organs
examples: fibroblasts
resident cells
cells that wander due to a signal
examples: macrophages, lymphocytes
wandering cells
