Ch 40 Flashcards
What is the stratum corneum?
the uppermost layer of the epidermis, this is where keratinized, dead cells are
What is the stratum basale?
the lowest, “basement” layer of the epidermis, this is the source of new skin cells
What is the dermis composed of?
dense, fibrous connective tissue
What are the uses of the integumentary system?
physical protection, lubrication, insulation, protection against water loss, defense, sensory reception, and homeostasis
What is the job of skeletal systems?
to support and protect the body, to trasmit mechanical forces generated by contractions
What are the three types of skeletal systems?
hydrostatic, exoskeleton, endoskeleton
Describe the hydrostatic skeleton.
it is found in soft-bodied invertebrates such as cnidarians, flatworms, and annelids, it is basically fluid in a closed body compartment, it transmits forces generated by contractile cells or muscle, the circular contractile fibers are like a belt on the creature moving the fluid in the way they want their body to go
Describe exoskeletons.
found in mollusks and arthropods (example: cicadas), it is composed partly of chitin, it’s jointed for flexibility, since it is a non-living skeleton it does not grow, therefore these animals muse molt periodically, also these animals use chitin rather than keratin
Describe endoskeletons.
an endoskeleton is an internal skeleton that can grow, it consists of calcium-impregnated tissue such as cartilage and bone
What is the vertebrate axial skeleton? What is the vertebrate appendicular skeleton?
The vertebrate axial skeleton consists of the skull, vertebral column, ribs, and sternum, it is all of the bones on the body’s axis; the vertebrate appendicular skeleton consists of bones of the limbs, the pectoral girdle, and the pelvic girdle, it is all of the bones that “hang off of” the axial skeleton
What are the two types of bone?
intramembranous bone and endochondral bone
How is endochondral bone formed?
a bone begins to ossify (become bony) in its diaphysis, and secondary sites of bone production develop in the epiphyses, the part of the bone between the ossified regions can grow, eventually the ossified regions fuse
How is intramembranous bone formed?
develop from a noncartilage, connective tissue scaffold (this includes the flat outer bones of the skull)
What is the structure of long bone?
long bone consists of a thin outer shell of compact bone, an inner spongy bone, and a central cavity with bone marrow, the outside of the this bone is covered in periosteum which is a connective tissue membrane that muscle ligaments and tendons can connect to, the periosteum can produce new layers of bone, thus increasing the bone’s diameter, the main shaft of a long bone is the diaphysis, and each end is the epiphysis, in children, a disc of cartilage, the metaphysis, lies between the epiphyses and the diaphysis, metaphyses are growth centers that disappear at maturity, becoming vague epiphyseal lines, the central cavity of the bone that contains bone marrow has two types of bone marrow, yellow (fatty, connective tissue), and red (sometimes produces blood cells)
What is the difference between osteoblasts and osteoclasts?
osteoblasts produce bone (build), osteoclasts break down bone (crush)
What is osteoporosis?
it is a disease when there are too many holes in bones (porosis–pores/holes)
What cells shape and remodel bone?
osteoblasts and osteoclasts
What is a joint?
a joint is a junction of two or more bones
What are ligaments?
Ligaments are connective tissue, they are bands that connect bones, the limit movement at the joint and are a rubbery tissue
What are the three types of joints? What is an example of each type?
Immovable: joints in the skull, slightly moveable: vertebrae joints, and freely moveable: joints that are enclosed by a joint capsule lined with a membrane that secretes synovial fluid
What are the three types of freely moveable joints? Give an example of each.
ball and socket joint (shoulder), hinge joint (elbow), and pivot joint (wrist)
What is synovial fluid?
a fluid that is secreted by the membrane that lines freely moveable joints, it is a viscous fluid that reduces friction during movement and absorbs shock
What is the difference between flexion and extension?
flexion is moving forward, extension is moving backwards (in vertebrae)
What attaches muscles to bones?
tendons
What is peristalsis?
it is when muscles move in a wave-like motion, much like how earthworms move their bodies or how humans digestive systems move food
What is the hierarchy of skeletal muscle?
skeletal muscle is made up of long muscle fibers which have many nuclei, myofibrils, which are threadlike structures, run lengthwise through the muscle fiber, the myofibrils consist of even smaller structures, called myofilaments, or simply filaments, there are two types of myofilaments, actin and myosin, myosin filaments are thick and actin filaments are thin (muscles, fasicles, muscle fibers, myofibrils, myofilaments, actin/myosin)
What is a sarcomere?
a sarcomere is the basic unit of muscle contraction that is made up of myosin and actin filaments, sarcomeres are repeating, hundreds of sarcomeres connected end to end make up a myofibril
How is a muscle contracted? What are the steps?
1) A motor neuron releases acetylcholine, which binds with receptors on the muscle fiber, 2) the impulse spreads, stimulating a Ca2+ release from the sarcoplasmic reticulum, 3) Ca2+ binds to troponin (aka actin) causing change in shape. Troponin pushes tropomyosin away, exposing active sites on actin filaments, 4) ATP is split. the myosin head, now cocked, binds to the exposed active site, forming a cross bridge, 5) Pi is released, 6) the cross bridge flexes and the actin filament is pulled toward the center of the sarcomere. this movement is the power stroke. ADP is released, 7) the actin-myosin complex binds ATP and myosin detaches from actin
What provides the energy for muscle contractions?
ATP hydrolysis (provides the energy to cock the myosin), Creatine phosphate (is used for intermediate energy storage), glycogen (is the fuel stored in muscle fibers, is the hardest to break down)
What are the two types of muscle fibers?
the slow (red) fibers: rich in mitochondria and myoglobin, used for endurance activities AND fast (white) fibers: rapid response
