Musculoskeletal system Flashcards
What are the general functions of the musculoskeletal system?
Support, protect, allow movement
Where are mechanical forces generated by muscle contraction typically transmitted?
To skeletal structures of chitin or bone to produce motion.
What type of skeletons do invertebrates have?
Hydrostatic skeletons or exoskeletons
What type of skeletons do vertebrates have?
Endoskeletons
What are hydrostatic skeletons?
The fluid-filled body compartments of many soft-bodied invertebrates
What are examples of animals with hydrostatic skeletons?
Cnidarians, flatworms, annelids, and roundworms, sea anemones, earthworms, and other invertebrates
How do hydrostatic skeletons work?
Fluid is held under pressure in the body; when muscles in the compartment wall contract, they push against the tube of fluid. The force is transmitted through the fluid, changing the shape and movement of the body
What is the fluid-filled compartment present in animals with hydrostatic skeletons called?
Coelom
Why are hydrostatic skeletons called hydrostatic?
The compartment is under hydrostatic pressure because of the fluid, and supports the other organs of the organism.
How do hydrostatic skeletons work in cnidarians?
Two body layers work in antagonistic fashion—contraction of the epidermal layer causes shortening; contraction of the inner layer causes lengthening
What kind of skeleton do sea stars and sea urchins have?
They have an endoskeleton, but they move their tube feet using a type of hydrostatic skeleton.
How do hydrostatic skeletons work in earthworms?
In annelid worms (earthworm), septa isolate portions of the body cavity, allowing the hydrostatic skeletons of each segment to be largely independent of one another.
What do most animals do in regard to their skeletons?
Most animals deposit a nonliving, protective exoskeleton over their outer epithelium.
Why do animals with exoskeletons have to shed?
Because exoskeletons are acellular and don’t grow
What type of skeleton do sharks and rays have?
Cartilage endoskeletons
Echinoderms and chordates have internal skeletons consisting of what?
Plates or shafts of living tissue (such as cartilage or bone).
The echinoderm endoskeleton consists of what?
Spines and plates of calcium salts embedded in the body wall, beneath the epidermis like an internal shell.
What are the two sections of the vertebrate endoskeleton?
Axial and appendicular
Describe the axial skeleton
Located along the central axis of the body; consists of the skull, vertebral column, ribs, and sternum (breastbone)
Describe the appendicular skeleton
Bones of the limbs (arms and legs), and bones of the pectoral (shoulder) girdle and pelvic (hip) girdle, which connect the limbs to the axial skeleton
What does the axial skeleton consist of?
The skull, ossicles of the middle ear, the hyoid bone, the vertebral column, and the thoracic (rib) cage
Describe the vertebral column (How many vertebrae of each type?)
24 vertebrae: 7 cervical, 12 thoracic, 5 lumbar; and 2 bones composed of fused vertebrae, the sacrum and coccyx.
The rib cage consists of what?
The sternum, thoracic vertebrae, and (in mammals) 12 pairs of ribs.
What does the skull consist of? What does it do?
The cranial and facial bones which protect the brain and form the face.
What do spinal curves do?
Increase the strength and flexibility of the spine.
What does the thoracic (rib) cage do?
Protects the lungs and heart
Each human limb consists of what?
30 bones and terminates in 5 digits (fingers/toes)
What does the pectoral girdle consist of?
2 collar-bones (clavicles) and 2 shoulder blades (scapulas)
What do the upper limbs consist of?
Humerus of the upper arm, radius and ulna of the forearm, eight bones of the carpus, five bones of the metacarpus, and 14 bones of the phalanges
What are the scapulas (shoulder blades) attached to and how?
Loosely attached to the vertebral column by muscles
What does the pelvic girdle consist of?
A pair of large bones fused to the vertebral column
What does each large bone of the pelvic girdle consist of?
Each large bone is 3 fused hipbones: illium, ischium, pelvic bone
What do the lower limbs consist of?
The femur of the thigh, Patella (kneecap), Tibia & Fibula of the leg, 7 tarsal bones of the ankle, 5 metatarsals, 14 phalanges
How is the female pelvis different because of reproduction?
The female pelvis is lighter, wider, shallower, and has a broader angle between the pubic bones than the male pelvis.
Describe long bone
Long, found in limbs, mostly compact bone
Describe short bone
Cube-like, mostly spongy, and sesamoid
Describe flat bone
Spongy bone embedded within parallel layers of thin compact bone
Describe irregular bone
Vertebrae and hip bones, complicated shapes, and mostly spongy with a thin covering of compact bone
What are the four shapes of bone?
Long, short, flat, and irregular
What is long bone covered in and why?
Long bone is covered by periosteum allowing attachment of muscle tendons and ligaments. It also has a thin dense & hard outer shell of compact bone
What does spongy bone do in long bones?
Beneath the compact bone is a network of spongy bone filled with bone marrow that provides mechanical strength
Describe the growth center in children
The cartilage growth center (metaphysis) lies between the wide ends (epiphyses) and main shaft (diaphysis)
What does the growth center become at maturity?
Epiphyseal lines
Describe yellow and red bone marrow
Yellow marrow consists mainly of fatty connective tissue, red marrow produces blood cells.
What does compact bone consist of?
Interlocking osteons containing osteocytes within lacunae, arranged in concentric circles around Haversian canals
Describe the organization of spongy bone
Noosteon, organization is based on lines of stress; Trabeculae in spongy bone are arranged such that one side of the bone bears tension and the other withstands compression, and lamella andosteocytesare irregularly organized;
How do long bones form in fetal development?
Long bones develop from cartilage templates (endochondral bone development) .
Where do bones ossify in fetal development?
Bones ossify in diaphysis and epiphyses.
How do bones that aren’t long bones form in fetal development?
They develop from a noncartilage, connective tissue scaffold (intramembranous bone development).
Define endochondral ossification
The process of bone development from hyaline cartilage
What is the periosteum?
It’s the connective tissue on the outside of bone that acts as the interface between bone, blood vessels, tendons, and ligaments.
What are osteoblasts?
Bone-building cells that secrete collagen
What are osteocytes?
Mature bone cells isolated within lacunae in the matrix
What are osteoclasts?
Large, multinucleated cells that break down bone
What are joints and what are they also called?
Also called articulations, they’re are junctions between two or more bones that allow flexibility and movement.
What are bone surfaces in contact with joints covered in?
Articular cartilage
What are the three types of joints?
Fibrous, cartilaginous, and synovial
How are fibrous joints held together?
By fibrous connective tissue
How are cartilaginous joints held together?
The bones are connected by cartilage
What are examples of types of synovial joints?
Planar, hinge, pivot, condyloid, saddle, and ball-and-socket
What are synchondrosis? Where are they found?
A type of cartilaginous joint, the bones are joined by hyaline cartilage. They’re found in the epiphyseal plates of growing bones in children.
What are synovial joints and their synovial fluid typically reinforced by?
Ligaments
What type of muscle allows for locomotion and manipulation?
Skeletal muscle
Where is smooth muscle typically found?
In tubular organs
Describe smooth muscle and its contraction
Not under voluntary control; typically contract in response to simple stretching. Their contraction tends to be slow, sustained, and strong
Describe cardiac muscle
Contracts and relaxes in alternating rhythm, propelling blood
What controls cardiac muscle?
Not under voluntary control; contraction initiated by pacemaker cells
What powers cardiac muscle?
Fibers are electrically coupled by gap junctions (heart beats independent of nervous
What is the source of movement in cardiac muscle fibers?
The contractile proteins actin and myosin are the source of motion in muscle fibers
Describe skeletal muscle contraction
Skeletal muscles pull on tendons, which pull on bones on each side of a joint—muscle contraction pulls one bone toward or away from the bone with which it articulates.
Skeletal muscles act ____ to one another
Antagonistically
What is the muscle that produces a particular action called?
The agonist
What is the muscle that produces the opposite motion of the agonist called?
The antagonist
What does skeletal muscle consist of?
Long, striated cells with many nuclei organized in bundles wrapped by connective tissue (muscle fibers).
What are the two types of myofilaments?
Thick myosin filaments and thin actin filaments
What makes up myofibrils?
Two types of myofilaments
What makes up a skeletal muscle fiber?
Myofibrils
What surrounds a skeletal muscle fiber?
A plasma membrane called the sarcolemma with a cytoplasm called the sarcoplasm
Describe the sarcolemma
Fine transparent tubular sheath which envelops the fibers of skeletal muscles that has multiple inward extensions that form transverse tubules.
What are the sarcoplasm and endoplasmic reticulum called together?
The sarcoplasmic reticulum.
What do the thin actin filaments consist of, besides actin? What do they do?
They also contain the proteins tropomyosin and troponin, which regulate interaction with myosin filaments.
What are sarcomeres?
Myosin and actin filaments are organized into repeating units
How are sarcomeres joined?
At their ends by the Z-line
