UNIT 2 -BIO120

epithelial tissue

lines the outer surface of many internal organs, the corresponding inner surfaces of body cavities, and the inner surfaces of blood vessels

connective tissue

provides support, protection, and connection to other tissue and organs, acts as “cellular glue”

muscle tissue

composed of cells that have the special ability to shorten or contract in order to produce movement of the body parts

nervous tissue

specialized tissue composed of two main types of cells, neurons and glia

neurons

responsible for generating and conducting electrical nerve impulses

• the main cell type in nervous tissue

glia

provides support, insulation, and nutrients for neurons

gap junctions

channels that connect two cells

hemidesmosome

a junction that connects a cell to a basement membrane

desmosomes

connect cells to adjacent cells

squamous

cuboidal

columnar

simple cell layer

a single layer of cells

stratified cell layer

made up of more than one layer of cells

ciliated pseudostratified columnar epithelium

goblet cells

connective tissue

composed of living cells in an extracellular matrix that contains protein fibers called collagen and elastin

loose connective tissue

serves as a soft, elastic, and cushioning padding withing the body, filling space between organs and tissues and protecting them

• includes areolar, adipose, and reticular

dense connective tissue

high density fibers, primary collagen, supports, protects, and hold bones, muscles, and other tissues and organs in place

• includes regular, irregular, and elastic

cartilage

strong flexible connective tissue that protects joints and bones

• includes hyaline, fibrocartilage and elastic cartilage

bone

hard, mineralized tissue that provides structural support, protection, and a framework for movement

• includes spongey and compact bone

blood tissue

transports oxygen, nutrients, and waste products throughout the body

• includes living cells in a liquid matrix called plasma

• erythrocytes (red blood cells) lack nuclei

• some white blood cells have polymorphic (multi-lobed) nuclei

hyaline cartilage

found between long bones, ex. knee joint

fibrocartilage

found between vertebrae

elastic cartilage

found in the outer ear

endocrine glands

secrets hormones directly into the bloodstream, not into the ducts

exocrine ducts

secretes substances into ducts

holocrine ducts

entire cells are shed and secreted into a duct

apocrine glands

part of each cell is shed and secreted into a duct

merocrine glands

secrete substances into ducts without cell damage

skeletal muscle tissue

muscles attached to bones that facilitate voluntary movement and maintain posture

cardiac muscle tissue (myocardium)

found exclusively in the heart, responsible for the heart’s rhythmic contractions

smooth muscle tissue

lines the walls of many internal organs and blood vessels and is responsible for involuntary movements like digestion and blood pressure regulation

dendrites

branches of a neuron’s plasma membrane

synovial membranes

inner and outer layer with synovial fluid between

• ex. knee joint capsule

digestive mucous membranes

aids in digestion

• ex. esophagus, stomach, and intestines

respiratory mucous membranes

protects the respiratory tract

• ex. trachea, bronchial tubes

serous membranes

inner (visceral) and outer (parietal) layers with serous fluid between

• ex. peritoneal serous membrane and pleural serous membrane

skin

largest organ in the body

integumentary system functions

temperature regulation, protection, and sensation

layers of the integumentary system

epidermis (outer) and dermis (inner)

epidermis

composed of stratified squamous epithelial tissue

• avascular (contains no blood vessels

• contains specialized cell types like keratinocytes, langerhans cells, melanocytes, and merkel cells

merkel cells

function in tactile sensation

langerhans cells

immune cells of the integumentary system

melanocytes

produce melanin pigment to protect against UV damage

keratinocytes

produce keratin protein to protect against dehydration and damage

stratum corneum

outermost layer composed of keratinized dead cells

stratum lucidum

only found in thick skin (skin of palms and soles

stratum granulosum

contains keratohyalin granules

stratum spinosum

contains abundant desmosomes and langerhans cells

stratum basale

hemidesmosomes connect epidermis to basement membrane

dermis

vascular (contains blood vessels)

papillary layer

the most superficial layer of the dermis

reticular layer

the deeper layer of the dermis

pacinian corpuscle

functions as a sensor for changes in pressure

sebaceous gland

secretes oils

arrector pilli muscles

attach to hair follicles and cause hair to stand up (goosebumps)

• composed of smooth muscle

factors in skin color

carotene, erythrocytes (blood flow), and melanocytes (melanin)

sudoriferous glands

include eccrine and apocrine sweat glands

sebaceous glands

produce oils (sebum)

ceruminous glands

produce ear wax (cerumin)

mammary glands

produce milk

hypodermis (subcutaneous tissue)

about half of total body fat is stored here

• primarily composed of adipose tissue and some areolar connective tissue

hair

layers of a strand from outside to inside include cuticle, medulla, and cortex

functions of the skeletal system

stores calcium, fat and hematopoietic stem cells

adipose tissue

a specialized connective tissue primarily composed of adipocytes (fat cells) and other non adipocyte cells

dense connective tissue

supports, protects, and holds bones, muscles, and other tissues and organs in place

red bone marrow

contains hematopoietic stem cells (develops into blood cells)

spongey bone tissue

contains red bone marrow

• ex. occipital bone, pelvic bone, parietal bones, and sternum

yellow bone marrow

contains adipocytes (fat cells)

long bone anatomy

• there are two epiphyses in one long bone (one on each end)

• there is one diaphysis in one long bone (the shaft)

endosteum

the inner surface of the medullary cavity of a long bone

periosteum

the outer surface of a long bone

fontanelles

soft spots in a newborn’s skull where ossification is incomplete

anterior fontanelle

not fully ossified at birth

ossification

the hardening of tissue due to the deposition of mineral salts

endochondral bone formation

happens during embryonic development, where mesenchymal cells differentiate into chondrocytes

• leads to the development of long bones

intramembranous bone formation

produces flat bones like those of the skull

interstitial growth

describes elongation of a long bone at an epiphyseal plate until the epiphyseal plate ossifies

appositional growth

describes an increase in the diameter of a long bone

primary ossification center

located in the diaphysis of a long bone

secondary ossification center

appears in the epiphyses of a long bone

osteoclasts

remove calcium phosphate to form the medullary cavity of a long bone

• remove calcium phosphate from bone and deposits it into blood plasma

osteoblasts

deposits calcium phosphate to form bone matrix

osteogenic cells

stem cells that differentiate into osteoblasts

osteocytes

mature bone cells that regulate bone remodeling through osteoblast vs. osteoclast activities

spongey bone

organized in structures called trabeculae

compact bone

dense, hard outer layer of bone tissue, providing strength and support

osteons

a central (haversian) canal with blood vessels and nerves, surrounded by concentric rings called lamellae

lamellae

contains spaces called lacunae in which osteocytes are found

volkmans’s (perforating) canals

permit fluid to move between two osteons

canaliculi

small channels connecting lacunae within an osteon

thyroid gland

secretes calcitonin in response to hypercalcemia (high blood calcium)

parafollicular cells

found in the thyroid gland and produce calcitonin

calcitonin

suppresses osteoclast activity to decrease blood calcium levels

• ex. a patient with damage to thyroid parafollicular cells reducing calcitonin production is at risk of becoming Hypercalcemic (due to less suppression of osteoclasts)

parathyroid gland

secretes PTH (parathyroid hormone) in response to hypocalcemia

• PTH activates osteoclasts to increase blood calcium levels. 

• example: A patient with a glandular tumor overproducing PTH is at risk of becoming Hypercalcemic (due to excessive osteoclast activation)

hypocalcemia

low blood calcium

hypercalcemia

high blood calcium

adipose tissue

arrector pilli