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notochord, dorsal tubular nerve cord, pharyngeal gill slits/ pouches, endostyle/thyroid gland, postanal tail

5 chordate characteristics

neural spines

a dorsal projection of a vertebra that functions as a muscle attachment site

tripartite brain

forebrain, midbrain, hindbrain

anatomy

branch of science concerned with the bodily structure of animals and living organisms

morphology

study of form and function as an integrated design

morphogenesis

movements and reorganizations of the cells as part of the tissue layers during embryonic development

zygote

youngest state of the embryo

vegetal pole

portion of the egg where most yolk is concentrated (bottom)

animal pole

portion of egg where there is less yolk and the haploid nucleus resides

microlecithal

small amount of yolk

mesolecithal

moderate amount of yolk

macrolecithal

large amount of yolk

cleavage

repeated mitotic cell division of the zygote

blastomeres

cells produced from the early cleavage divisions of the ovum

blastula

hollow ball of cells around an internal cavity called the blastocoel

holoblastic cleavage

occurs in vertebrates where the yolk is sparse; mitotic furrows pass through the entire zygote from animal to vegetal pole

unequal holoblastic

moderate amount of yolk; blastomeres of the animal pole divide more than the vegetal pole

blastoderm

embryonic disk that gives rise to the endoderm, mesoderm, ectoderm

meroblastic

in zygotes where yolk is plentiful; yolk slows the mitotic furrowing and only a portion of the cytoplasm is cleaved

discoidal

an extreme case of meroblastic cleavage where extensive yolk occurs in the egg, so cleavage is restricted to a small animal pole

gastrulation

embryo forms a distinct endodermal tube that constitutes the early gut

ectoderm

germ layer that forms the skin and the nervous system

mesoderm

germ layer that forms skeleton, muscle, and circulatory system

endoderm

germ layer that forms the digestive tract and visceral derivatives

mesochyme

embryonic connective tissue; loosely connected mesodermal cells

epimere (paraxial)

region of mesoderm located dorsally; epimere becomes organized into loosely whorled mesenchymal cells and develops into somites

somitomeres

organized whorls of mesenchymal cells

mesomere

between epimere and hypomere; later gives rise to parts of the kidney

hypomere (lateral plate)

occurs ventrally; develops heart, blood vessels, and mesenteries

neurulation

process of forming the ectodermal tube (neural tube); begins with a dorsal thickening of the ectoderm into a neural plate

neural crest cells

cells unique to vertebrates that differentiate into a great variety of structures such as: peripheral nervous system, schwann cells, hormone producing cells, heart tissue, etc.

histogenesis

tissue formation; cells produced during the cleavage are placed into one of the cellular germ tissues

organogenesis

differentiation of organs from tissue; two germ layers combine to form a single organ (ex. integument)

epithelial

sheet of cells that covers external and internal surfaces; forms physical and chemical barriers and glands; contains basement membrane

basement membrane

condensed region of connective tissue matrix secreted by both epithelial and connective tissue

microvilli

projections of cells that increase surface area

cilia

hair like projections used to move particles

connective tissue

composed of relatively few cells and a matrix of extracellular fibers (collagen) suspended in a ground substance

loose connective tissue

anchors blood vessels, nerves, and body organs

dense connective tissue

forms tendons, ligaments, and fasciae

fasciae

sheets or bands of tissue surrounding skeletal muscles

blood and lymph

specialized connective tissue

adipose

specialized connective tissue that stores fat

cartilage

specialized connective tissue that makes up joints; matrix consists of chondroitin sulfate and protein fibers

bone

specialized connective tissue that supplies structural support and muscle attachment

muscular tissue

tissues that produce movement

muscle fiber

structural unit of muscular tissue

striated muscle

appear transversely striped with alternating dark and light bands

skeletal muscle (voluntary)

striated muscle that is extremely long and cylindrical and has multinucleated

cardiac muscle (involuntary)

striated muscle that is shorter and has one nucleus per cell; found in vertebrate heart; individual cells are interconnected by junctional complexes called intercalated disks

smooth (visceral) muscle

involuntary; lack striated bands; long and tapering with a single nucleus

neurons

receive stimuli and conduct impulses; functional unit of the nervous system

cell body (soma)

contains the cell's nucleus and organelles

dendrites

projections from the cell body that receive electrical impulses from receptors or other nerve cells and transfer them to cell body

axon

carries signal away from cell body to other nerve cells or to an effector organ

effector organ

organ affected by a nerve

neuroglia

non-neuron cells that insulate neuron membranes, provide nutrients, other functions

myelin sheath

insulating sheath that increases the speed at which electrical signals are transmitted along an axon

oligodendrocytes

form the myelin sheath in the CNS

schwann cells

form myelin sheath in the PNS

synapsis

a region where communication occurs between two neurons or between a neuron and an effector cell such as a muscle or glandular cell

presynaptic neuron

nerve cell that carries a nerve impulse toward a synapse

postsynaptic neuron

nerve cell that carries a nerve impulse away from a synapse

general connective tissue

fibrous connective tissue; forms tendons, ligaments, and the dermis; composed of fibroblast cells which secrete the extracellular matrix

extracellular matrix

network of protein (collagen) fibers in a ground substance of polysaccharide gel

special connective tissue

bone, cartilage, blood

mineralization

general process wherein various inorganic ions (Fe, Mg, Ca) are deposited into the organic matrix of tissues to harden them

calcification

specialized mineralization where in vertebrates, calcium phosphate is deposited in the organic matrix

ossification

specialized type of calcification unique to vertebrates, involving the deposition of calcium phosphate on the collagenous matrix, leading to bone formation

hydroxyapatite

calcium phosphate

lacunae

spaces within the matrix of a cartilage/bone cell and contain chondrocytes/osteocytes

perichondrium

fibrous connective tissue that surrounds the cartilage (not vascular)

hyaline cartilage

most widespread cartilage; makes up the model of bones in embryos before ossification

fibrocartilage

solid ground substance reinforced with many collagen fibers; occurs in invertebral discs, the pubic symphysis, and knee cartilage

elastic cartilage

flexible and springy due to elastic fibers in the matrix

osteoblast

produce new bone (osteogenesis)

osteocyte

maintain fully formed bone

osteoclast

remove existing bone

canaculi

tiny canals that connect lacunae and provide nutrients to bone tissue

spongy (cancellous) bone

porous bone

compact bone

dense bone

cortical bone

outer layer of bone

medullary bone

Lines the core of the bone

cellular bone

contains bone cells

acellular bone

no bone cells

vascular bone

many blood channels

avascular

few or no blood channels

nonlamellar bone

immature woven bone; characterized by disorderly, irregular arrangement of collagen within the matrix; contains more osteocytes per unit of volume; typical of fast growing bone

lamellar bone

characterized by orderly, regular arrangement of collagenous fibers within the matrix; stronger and less flexible

lamella

layer of bone matrix with its closely packed collagen fibers assigned in parallels

haversian bone

special lamellar bone; organic salts are arranged in a regular and highly ordered unit called an osteon

osteon

series of concentric rings made up of bone cells and layers of bone matrix

central canal (haversian canal)

canal that houses blood vessels located at the center of the osteon

volkmann's canal

runs horizontally through bone, contains blood vessels and nerves between osteons

lines of arrested growth

lines are produced when growth ceases, may be slight erosion or absorption of previously deposited bone

zonal bones

bones with LAGs

periosteum

fibrous connective tissue that surrounds bone; divided into an outer "fibrous layer" (fibroblasts) and inner "cambium layer" (osteoblasts)

diaphysis

middle shaft of bone

epiphysis

end of bone

metaphysis (epiphyseal plate)

region between diaphysis and epiphysis