Support Systems and Locomotion -...
Transcript of Support Systems and Locomotion -...
Chapter 39
SUPPORT SYSTEMS AND
LOCOMOTION
•Animals that lack a hard skeleton may have a
hydrostatic skeleton
•Hydrostatic skeletons act like a garden hose,
stiffening when hydrated and relaxing when
dehydrated
•Hydras, cnidarians and planarians use their
gastrointestinal cavity as a hydrostatic skeleton
HYDROSTATIC SKELETON
•Exo and endoskeletons are made of calcium carbonate
in mollusks and chitin in insects
•Calcium carbonate skeletons grow with the organism
and are largely protective.
•Chitin is jointed and movable, good for movement on
land.
•Vertebrate skeletons are composed of bone tissue and
are highly durable while occupying small amounts of
space
EXO AND ENDOSKELETON
•Humans have close to 350 bones at birth and 206 bones at an adult
•The cartilage built in the mammalian fetus eventually develops into bone.
•The conversion is due to the deposit of calcium salts into the cartilage by osteoblasts.
•Old bone tissue constantly replaces new bone tissue, particularly thanks to large inputs of calcium by the organism
• This is why children require large amounts of milk, but tend to develop lactose intolerance as they grow older
• The bones are done growing; milk is no longer as necessary
HUMAN SKELETAL SYSTEM
•The skull is built to support the brain.
•The major bones of the skull are the cranium,
the nasal bones, maxilla and mandible
•The mandible is the only freely moveable
portion of the skull, allowing for chewing,
formation of air and sound waves, and holds the
teeth
•Cartilage connects the bones in the skull, and
forms the entirety of the outer ear and the
majority of the inner ear.
THE SKULL
•The vertebral column supports the head and trunk and surrounds and protects the spinal cord.
•Vertebrae are separated into three sections making up a single column
• Cervical vertebrate in the neck (7)
• Thoracic vertebrae in the thorax (12)
• Lumbar vertebrae in the small of the back (5)
• 9 vertebrae fuse during development into the sacrum and coccyx, which support the body while sitting.
•Although connected through fibrocartilage, the vertebral discs support the body while allowing for movement and resistance .
VERTEBRAL COLUMN AND RIB
CAGE
•The rib cage emerges from the thoracic
vertebrae and contains the ribs, cartilage and
sternum (breastbone)
•There are twelve pairs of ribs• Seven *true* ribs that attach to the sternum
• Three false ribs attached by cartilage
• Two false *floating* ribs
•The rib cage’s amazing design strongly protects
the heart and lungs while allowing for expansion
of the stomach and lungs
VERTEBRAL COLUMN AND RIB
CAGE
•The pectoral girdle is made up of the clavicle and
scapula
•The scapula is freely moveable, held in place only by
muscles—high range of motion; low stability
•The free range affects the movability of the humerus
bone.
•The humerus is jointly attached to the radius and ulna,
two thin bones that allow the arm to twist.
•The hand contains 27 bones, providing for a huge
variety of motion.
PECTORAL GIRDLE AND ARM
•The pelvic girdle begins with the coxal bones
(hipbones).
•Anchored in the sacrum is the femur bone.
•The femur bone provides strength for the leg.
•It attaches to the tibia and fibula bones at the
patella (kneecap)
•The tibia and fibula attach to the foot bones.
•The foot contains 26 bones, also allowing for the
high range of motion.
PELVIC GIRDLE AND LEG
•Depending on the definition of a muscle there are 650-850
muscles in the human body.
•Bones are only capable of movement because muscles direct
them.
•Muscles follow the rule of antagonistic pairs (or opposite
pairs•Muscles only pull; they cannot push
•Therefore, for every muscle constriction there must be a muscle
relaxation.
•Muscles respond to an impulse from nerves, which trigger the
reaction of sarcomeres.
•Sarcomeres are sections of cells called myosin and actin,
which are responsible for muscle contraction
HUMAN MUSCULAR SYSTEM
•The sarcomere contains a sandwich of proteins that
make up muscle cells (the bread of the sandwich).
•In between the proteins are layers of actin and myosin
filaments.• The myosin are fixed in position within the muscle. They don’t
move
• The two separate sections of actin are moveable.
•During contraction, the muscle “pulls” when actins
reach toward each other, walking along the myosin.
•They are only able to maintain their contraction
momentarily, until the action potential ends, causing
relaxation
HUMAN MUSCULAR SYSTEM
This question is worth an extra 5% on your essay exam
You may check your answers with me ahead of time for a yes or no response as many times as you like.
•When babies are first born, a mother produces “colostrum,” instead of traditional milk. It is also typical in the first week of birth for babies to lose weight. Explain why.
EXTRA CREDIT