Post on 14-Feb-2017
Comparative anatomy( Chordates)
Skeletal system
1-Human 2-Ruminant 3-Avian 4-Horse 5-Fish Dr.Omer
Comparative Anatomyinvolves comparing the body structures of
species is the study of differences and similarities
in the anatomy of different species . It is closely related to evolutionary biology
and phylogeny .
ConceptsPhylogeny: (inheritance) the history of
the evolution of a species or group, especially in reference to lines of descent and relationships among broad groups of organisms
Evolution: (modification and inheritance) evolution is the change in the characteristics of a species over several generations and relies on the process of natural selection
Convergence: found in distantly related groups; evolved independently.
Parallelism: found in closely related groups; evolved independently.
Comparative anatomy Includes:• Change, adaptation, and mutation of species
• The invasion of new territories
• Species compatibility with surroundings
How can comparative anatomy help us?
1-Understand our history 2- Show how organisms function 3-Consider plans for change 4-How they develop
5-Improve animal genetics6-Preserve endangered species
Why should we be aware of comparative anatomy?
Variations in care for animals
Differences in animal habits
Structural development
Homologous Structures
Analogous Structures
Homologous structures
Are structures that are similar in two organisms because they have a common ancestor Organs with similar structure but different functions are called Homologous structures
Bones in the forelimb of the human, whale, cat, bat, bird are used for vastly different movement, they all have remarkably similar structure and organization (bones, nerves, blood vessels)
This indicated common ancestry (DNA)
Homologous Structures (BONES in the FORELIMBS) Homologous Structures (BONES in the FORELIMBS)
Analogous structures
• Features of different species that are similar in function but are structurally different
• Do not have a common ancestry• Evolved due to a similar environmental challenge• Ex) Birds & insects have wings to fly although their
wing structure is different• Analogous structures are caused by convergent
evolution. In convergent evolution, two species evolve the same traits to adapt to an environment side by side, but they didn't come from the same ancestor
Analogous StructuresE.g. Bird wing and
insect wing
Embryology
• Humans have pouches in early development• In fish these pouches develop into gill slits• In humans they form the eustachian tube and auditory
canal.• Human embryo has a tail and body hair like embryos
of all other mammals but in the human embryo these features disappear before birth
Vertebrate Vertebrate embryos are embryos are structurally structurally similar in early similar in early embryonic embryonic stages.stages.
Directional Terms
Used to describe the positions of structures on the body relative to other structures or locations
DIRECTIONAL TERMSDIRECTIONAL TERMS Definition of terms:
Anterior (cranial) toward the headPosterior (caudal) toward the tailCranial head regionCaudal pertaining to the tail regionDorsal toward the back (top) of the
animalVentral toward the belly of the animalMedial toward the median lineDistal away from the center or originProximal toward the center or origin
Caudal Cranial
Dorsal
Ventral
REGIONAL NAMESThese names are given to specific regions of the body for reference.Examples: Cranial (skull), Thoracic (chest), Brachial (arm), Patellar (knee), Cephalic (head), Gluteal (buttock)
Body CavitiesVentral body cavity
Contains most of the soft organs; divided by thin diaphragm Thoracic cavity- heart, lung, esophagus, blood
vessels Abdominal cavity- digestive tract Pelvic cavity- urinary organs, reproductive organs
Dorsal body cavityContains the brain and spinal cord
Cranial cavity- brain Spinal cavity- spinal cord
Spinal Cavity
Dorsal Cavity
Ventral Cavity
Abdominal Cavity
Diaphragm
Thoracic Cavity
Cranial Cavity
Chordates All chordates have the following features at some
stage in their life (in the case of humans and many other vertebrates, these features may only be present in the embryo):
NotochordDorsal Hollow Nerve Cord Pharyngeal slits Post-anal tail
Characteristics of the ChordatesNotochord, dorsal hollow nerve cord, pharyngeal gill
slits, blocks of muscle, postanal tail
Pharyngeal SlitsPharyngeal slits are openings in the pharynx (the region just
posterior to the mouth) that extend to the outside environment
. In organisms that live in aquatic environments, pharyngeal slits allow for the exit of water that enters the mouth during feeding. Some invertebrate chordates use the pharyngeal slits to filter food out of the water that enters the mouth.
In vertebrate fishes, the pharyngeal slits develop into gill arches, the bony or cartilaginous gill supports.
In most terrestrial animals, including mammals and birds, pharyngeal slits are present only during embryonic development. In these animals, the pharyngeal slits develop into the jaw and inner ear bones.
Post-anal Tail
The post-anal tail is a posterior elongation of the body, extending beyond the anus.
The tail contains skeletal elements and muscles, which provide a source of locomotion in aquatic species.
In some terrestrial vertebrates, the tail also helps with balance, courting, and signaling when danger is near.
In humans and other apes, the post-anal tail is present during embryonic development, but is vestigial as an adult
Blocks of Muscle - Myotomes • Surrounding the notochord and nerve cord are blocks of muscle - myotomes
Higher Classification of ChordataPhylum Chordata
Subphylum Urochordata – tunicates, sea squirts
Subphylum Cephalachordata – lancelets
Subphlum Vertebrata- vertebrates
Vertebrate Higher ClassificationSuperclass Agnatha - without jawsClass Myxini – hagfishesClass Cephalaspidomorphi – lampreys
Superclass Gnathostomata – with jawsClass Chondrichthyes – sharks, rays,
chimaeras(Cartilaginous fishes)Class Actinopterygii – ray-finned fishesClass Sarcopterygii – lobe-fin fishesClass Amphibia – frogs, salamandersClass Reptilia – snakes, lizards, crocodilesClass Aves - birdsClass Mammalia - mammals
skeletal system The skeletal system consists of the bones and
joints along with the cartilage and ligaments that occur at the joints.
Bones: Hard Tissue, mostly calcium phosphate and calcium carbonate, provides support and makes Red Blood Cells
Ligaments: Strong, white bands of tissue that connect two bones together at a joint
skeletal systemCartilage: Hard tissue that prevents bones from
grinding against each other. Joints: Location of where two or more bones meet.Tendon: Connects muscle to bone.
Skeletal System - FunctionsProvides the frame and support for all the
other systems and organsAids in movementProvides protectionSite of mineral storageSite of blood cell formationMade up of bones,
cartilage, and connective tissue
Two types of skeleton
Exoskeleton (protective structure on the outside of the body)
Endoskeleton (protective structure on the inside of the body)
Endoskeleton
Exoskeleton
Types of Bone Long bones: longer than they are wide; shaft
& 2 ends (e.g.: bones of arms & legs,except wrist, ankle & patella)
Short bones: roughly cube-shaped (e.g.: ankle & wrist bones)
Sesamoid bones: short bones within tendons (e.g.: patella)
Flat bones: thin, flat & often curved (e.g.,: sternum, scapulae, ribs & most skullbones)
Irregular bones: odd shapes; don't fit into other classes (e.g.: hip bones & vertebrae)
Classification of Bones on the Basis of ShapeClassification of Bones on the Basis of Shape
Cartilage – Characteristics
Mostly water; no blood Mostly water; no blood vessels or nervesvessels or nerves
Tough, resilientTough, resilientNew cartilage forms from New cartilage forms from chondroblastschondroblasts
Heal poorlyHeal poorly
Types of Cartilage
Hyaline Cartilages: fine collagen fiber matrix- most abundant type- found in articular (movable joint) cartilages, costal cartilages (connect ribs to sternum), respiratory cartilages (in larynx & upper respiratory passageways) & nasal cartilages
Elastic Cartilages: similar to hyaline cartilage, more elastic fibers (very flexible) – found in external ear & epiglottis (larynx covering)
Fibrocartilage: rows of chondrocytes with thick collagen fibers; highly compressible with great tensile strength- found in menisci of knee, intervertebral discs & pubic symphysis
Types of Joint There are 4 types of joints :
HingeKnee
Ball and SocketHip
GlidingVertebrae
Fixed ( Cartliaginous)Skull
Hinge joint
Human Skeleton
206 Bones206 BonesAxial skeletonAxial skeleton: (80 : (80
bones) in skull, bones) in skull, vertebrae, ribs, vertebrae, ribs, sternum, hyoid bone sternum, hyoid bone
Appendicular Appendicular SkeletonSkeleton: (126 bones)- : (126 bones)- upper & lower upper & lower extremities plus two extremities plus two girdles girdles
Half of bones in hands Half of bones in hands & feet & feet
Skull
Sternum
Ribs
Vertebral column
Metatarsals
Metacarpals
Phalanges
ClavicleScapula
Humerus
RadiusPelvisUlnaCarpals
Femur
Patella
FibulaTibiaTarsals
Phalanges
The Skeletal System Section 36-1
Axial Skeleton
Appendicular Skeleton
Axial skeleton
Appendicular skeleton
7 Cervical Vertebras
13 Thoracic Vertebras
6 Lumbar Vertebras
5 Sacral Vertebars
18-20 Coccygial vertebras
Pneumatic bonesThe pneumatic bones are important to the
chicken for respiration.They are hollow bones connected to the chicken’s respiratory
system and are important for the chicken Examples of pneumatic bones:
skull, humerus, clavicle, keel(sternum)pelvic girdlelumbar and sacral vertebrae.
Medullary bonesThe medullary bones are an important source of
calcium for the laying hen.
Calcium is the primary component of egg shells and a hen Mobilizes 47% of her body calcium to make an egg
shell.
Examples:tibia, femur, pubic bones, ribs, ulna, toes, and scapula.
Fish skeletal system The function of the skeletal system is one of
support.Skeletal tissues:
Axial skeleton:
Head, trunk, and tail regions.Head: Trunk skeleton: modified portion of the
vertebral column.Tail skeleton: remainder of the vertebral
column
Fin :To allow the fish to stay upright, move, and maneuver in the water.
Rays : soft cartilage structure that supports the fins of the fish.Tail Fin : Helps to propel the fishDorsal and Anal Fins : balance and close quarters movements.Pectoral Fin : allows to fish to dive and also allows the fish to stay in one spot.Pelvic Fin : balances and positions .Lateral Line : helps the fish detect vibration, sensors, and helps the fish to find food and to navigate to avoid predators.
Cattle Sheep Horse Humans Poultry
Cervical 7 7 7 7 14
Thoracic 13 13-14 18 12
Lumbar 6 6-7 6 5
Sacral 5 4 5 (fused)
5 (fused)
Coccygeal 18-20 16-18 4 (fused)
6
Number of Vertebrae in Selected Animal Species
Bird
66