Human Bio Exam 2 Skeletal, Muscular, and Cardiovascular

Define ossification

Bone formation

Define intramembranous ossification

Bone develops from fibrous membranes (flat bones of skull, clavicles)

Define endochondral ossification

Bone replaces hyaline cartilage (most bones form this way)

Define axial skeleton

Bones along the midline: skull, vertebral column, rib cage

Define appendicular skeleton

Bones of limbs and girdles (shoulder and pelvic)

Structures of the skeletal system

Bones, cartilage, ligaments, joints

Functions of the skeletal system

Support, protection, movement, storage of minerals/fat, blood cell formation

Compact bone

Dense, strong bone forming outer layer

Spongy bone

Porous bone with trabeculae, found in epiphyses

Long bones

Longer than wide (femur, humerus)

Short bones

Cube‑shaped (carpals, tarsals)

Flat bones

Thin, flat, often curved (skull, ribs, sternum)

Irregular bones

Complex shapes (vertebrae, hip bones)

Sesamoid bones

Bones embedded in tendons (patella)

Diaphysis

Shaft of a long bone

Epiphysis

Ends of a long bone

Articular cartilage

Hyaline cartilage covering epiphyses for smooth movement

Periosteum

Outer fibrous covering of bone

Endosteum

Inner lining of bone cavities

Medullary cavity

Central cavity containing marrow

Sharpey’s fibers

Perforating fibers anchoring periosteum to bone

Red bone marrow

Site of blood cell formation

Yellow bone marrow

Fat storage

Epiphyseal plate

Growth plate made of cartilage

Epiphyseal line

Remnant of growth plate after growth stops

Spongy bone (microscopic)

Trabeculae with open spaces

Compact bone (microscopic)

Osteons tightly packed

Volkmann’s canal

Canals running perpendicular to Haversian canals

Central (Haversian) canal

Canal containing blood vessels and nerves

Canaliculus

Tiny channels connecting osteocytes

Lacuna

Small cavity housing an osteocyte

Osteocyte

Mature bone cell

Lamella

Rings of bone matrix in an osteon

Chemical composition of bone

Minerals (calcium salts) + collagen fibers

Five bone cell types

Osteoblasts, osteoclasts, osteocytes, osteogenic cells, bone‑lining cells

Long bone formation

Begins as cartilage, replaced by bone (endochondral)

Long bone growth

Occurs at epiphyseal plate

Long bone remodeling

Osteoblasts build bone; osteoclasts break bone down

Long bone repair

Hematoma → fibrocartilage callus → bony callus → remodeling

Major axial bones

Skull, vertebrae, ribs, sternum

Major appendicular bones

Limbs, scapula, clavicle, pelvis

Function of joints

Allow movement and hold bones together

Three types of joints

Fibrous (skull sutures), cartilaginous (pubic symphysis), synovial (knee, shoulder)

Motor unit

One motor neuron and all muscle fibers it controls

Axon

Long nerve fiber carrying impulses

Neuromuscular junction

Where a motor neuron meets a muscle fiber

Neurotransmitters

Chemical messengers (ACh in muscles)

Action potentials

Electrical signals along a neuron or muscle fiber

Synaptic cleft

Gap between neuron and muscle fiber

Origin

Muscle attachment to immovable bone

Insertion

Muscle attachment to movable bone

Prime mover

Main muscle causing movement

Antagonist

Muscle that opposes prime mover

Synergist

Muscle that assists prime mover

Sarcolemma

Muscle cell membrane

Sarcoplasm

Muscle cell cytoplasm

Sarcoplasmic reticulum

Stores calcium for contraction

Structures of muscular system

Muscles, tendons, fascia

Functions of muscular system

Movement, posture, heat production, stabilization

Skeletal muscle

Striated, voluntary

Cardiac muscle

Striated, involuntary, heart only

Smooth muscle

Non‑striated, involuntary, hollow organs

Tendon

Connects muscle to bone

Fascicle

Bundle of muscle fibers

Perimysium

Connective tissue around fascicle

Endomysium

Connective tissue around each muscle fiber

Epimysium

Connective tissue around whole muscle

A band

Dark band (thick + thin filaments)

I band

Light band (thin filaments only)

H zone

Center of A band with thick filaments only

M line

Middle of sarcomere

Z disc

Boundary of sarcomere

Thick filament

Myosin

Thin filament

Actin

Sarcomere

Functional unit of muscle contraction

Neuromuscular junction process

Neuron releases ACh → muscle fiber depolarizes

Sliding filament theory

Myosin pulls actin → sarcomere shortens

ATP pathways

Creatine phosphate, anaerobic glycolysis, aerobic respiration

Muscle fatigue factors

Lactic acid buildup, low ATP, ionic imbalances

Oxygen debt repayment

Heavy breathing restores oxygen and ATP levels

Effects of exercise

Increased strength, endurance, capillaries, mitochondria

Flexion

Decreases angle of joint

Extension

Increases angle of joint

Rotation

Bone moves around its axis

Abduction

Movement away from midline

Adduction

Movement toward midline

Circumduction

Circular movement

Dorsiflexion

Foot upward

Plantar flexion

Foot downward

Inversion

Sole inward

Eversion

Sole outward

Supination

Palm up

Pronation

Palm down

Muscle naming criteria

Location, size, shape, direction, number of origins, action

Composition of whole blood

Plasma + formed elements

Plasma composition

Water, proteins, nutrients, hormones, wastes

Importance of plasma

Transports substances and maintains blood volume

Formed elements

RBCs, WBCs, platelets

RBC function

Carry oxygen

WBC function

Fight infection