Anatomical Positions For humans: standing erect facing forward, with head level and eyes facing forward, feet flat on the floor and directed forward, and arms are at the sides of the body with palms turned forward.
Anatomical Position for Animals The animal should either be supine (laying on back facing upward) position with arms out be side
Planes of Reference Frontal plane: vertical plane that divides the body into an anterior/ventral or posterior/dorsal portions. Sagittal plane: vertical plane that divides the body or organ into right and left sides (midsagittal or median plane is down the middle of the body creating equal parts) Transverse plane: divides the body into superior (upper) or inferior (lower) portions.
Directional Terms Superior/Cranial: toward the upper part/head Inferior/Caudal: away from the head/lower part Anterior/ventral: nearer to or at front of body; stomach side Posterior/dorsal: nearer to or at the back of body; dorsal fin side Medial: nearer to midline Lateral: farther away from midline
Directional Terms Cont. Proximal: nearer to attachment of limb to trunk, nearer to origin Distal: farther away from attachment of limb to trunk, farther away from origin Superficial: toward or on surface of body Deep: away from surface of body
Try these… The heart is _______ to liver The stomach is ________ to lungs. The sternum (breastbone) is ______ to the spinal column. The esophagus is ________ to trachea (windpipe).
Try these… The stomach side of a dog is called ____. The ______ fin is located on the fish’s back. The ______ fin is also known as the tail fin. The head is ______ to the tail.
Symmetry Asymmetrical: irregularly shaped body, these animals are sessile Radial: divided along any plane, through central axis, into roughly equal halves, these animals are starfish or hydras Bilateral: can be divided down its length into similar right and left halves, these animals can use the anatomical terms such as posterior, ventral, etc.
Zygote Development Fertilization: sperm (male sex cell) and egg (female sex cell) meet Zygote is formed when these cells fertilize and repeatedly divide by mitosis Embryo: when cell division begins Blastula: fluid-filled cell Gastrulation: cell division continues until one side of the blastula moves inward
Embryo Development Ectoderm: outer surface of gastrula; develops into skin and nervous system Endoderm: inner surface of gastrula; develop into the lining of digestive syst. Mesoderm: “middle” between ectoderm and endoderm, eventually turn into muscles, circulatory, excretory, and some respiratroy systems
Development Cont. Protostome: opening of the gastrula develops into the mouth; examples: snails, earthworms, & insects Deuterostome: animal whose mouth developed NOT from the opening, but from cells elsewhere on gastrula, examples: sea stars, fish, toads, snakes, birds, & humans
Bilateral Symmetry & Body Plans Acoelomates: no body cavities; have 3 cell layers - ectoderm, endoderm, & mesoderm; Ex: flatworms Pseudocoelomates: space develops between ectoderm & endoderm, fluid-filled body cavity partly lined w/ mesoderm; one- way digestive tract; ex: roundworms Coelomate: body cavity fluid-filled space that is completely surrounded by mesoderm; organs & org. systems develop; Ex: earthworms
Animal Protection & Support Exoskeleton: hard covering on outside of body that provides framework for support –Prevent water loss –Protect soft body –Provide place for muscle attachment –Must molt & shed the old ones –Found in invertebrates (insects, crabs, etc)