Skeletal, Muscular, and Integumentary System
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SKELETAL, MUSCULAR, AND INTEGUMENTARY SYSTEM Chapter 45
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Chapter 45. Skeletal, Muscular, and Integumentary System. Intercellular Junctions . A tight junction completely encircles an epithelial cell near its apex (top) and joins it tightly to the neighboring cells. Like a six pack, each cell have complementary groves and ridges to make it zipper like. - PowerPoint PPT Presentation
Transcript of Skeletal, Muscular, and Integumentary System
SKELETAL, MUSCULAR, AND INTEGUMENTARY SYSTEM
Chapter 45
INTERCELLULAR JUNCTIONS
A tight junction completely encircles an epithelial cell near its apex (top) and joins it tightly to the neighboring cells. Like a six pack, each cell have complementary groves and ridges to make it zipper like.
For nurtrient regulation it can be “unzipped” in like the small intestine
A desmosomes is like a snap on a pair of jeans. It is a patch that holds cells together and enables a tissue to resist mechanical stress, but does not totally encircle a cell. Common in the epidermis, cardiac and cervix of the uterus
Gap (communicating) junctions A gap junction is formed by a ring-like
connexon, which consists of six transmembrane proteins surrounding a water-filled pore.
Gap junction are found in the intercalated discs of cardiac muscle and between the cells of most smooth muscle.
Section 1
THE HUMAN BODY PLAN
BODY TISSUES Tissue: collection of cells that are
similar in structure and that work together to perform a particular function
Four main types of tissues: Muscle Nervous Epithelial Connective
MUSCLE TISSUE Composed of cells that can contract Three types of muscle tissue:
Skeletal Smooth Cardiac
SKELETAL TISSUE
Moves the bones in your trunk, limbs, and face
SMOOTH TISSUE
Handles body functions you can’t control
CARDIAC TISSUE
Heart muscle; pumps blood through body
NERVOUS TISSUE Contains cells that receive and transmit
messages in the form of electrical impulses Neurons: specialized cells that send and
receive messages throughout the body Make up your brain, spinal cord, and
nerves Sense changes in the internal and
external environment Cause the body to move in response
EPITHELIAL TISSUE Consists of layers of cells that line or
cover all internal and external body surfaces Formed from cells that are tightly bound
Found in various thicknesses and arrangements Ex: line blood vessels, outer skin
CONNECTIVE TISSUE Binds, supports, and protects structures
in the body Most abundant and diverse
Include bone, cartilage, tendons, fat, and blood
Characterized by cells embedded in fluid called matrix Matrix an be solid, semisolid, or liquid
ORGANS AND ORGAN SYSTEMS Organ: consists of various tissues that
work together to carry out a specific function
Organ system: groups of organs that interact
BODY CAVITIES Body cavities: compartments where
organs and organ systems are housed Protect internal organs from injuries and
permit organs to move while being supported
BODY CAVITIES Five main body cavities:
Cranial brain
Spinal spinal cord
Thoracic cavity heart, esophagus, respiratory system organs
Abdominal cavity Digestive system organs
Pelvic cavity Reproductive and excretory system organs
Section 2
SKELETAL SYSTEM
THE SKELETON Human skeleton is composed to two
parts: Axial skeleton
Skull, ribs, spine, sternum Appendicular skeleton
Arms, legs, scapula, clavicle, pelvis
BONE FUNCTION AND STRUCTURE Bones provide a rigid framework
against which muscles can pull, give shape and structure to the body, and support and protect internal organs Bones store minerals Internal portion of many bones produce red
blood cells, platelets, and some white blood cells
BONE FUNCTION AND STRUCTURE Bones make up less than 20% of the
body’s mass They are moist, living tissues
LONG BONE STRUCTURE
Consists of a porous central cavity surrounded by a ring of dense material
Periosteum: tough membrane that covers bone Contains a
network of blood vessels
BONE DEVELOPMENT Most bones develop from cartilage
Ossification: the process by which cartilage is slowly replaced by bone as a result of the deposition of minerals
Some bones develop directly into hard bone without forming cartilage first
BONE ELONGATION Bones continue to develop after birth
Bone cells gradually replace the cartilage in long bones of limbs (arms and legs)
Bone elongation takes place near the end of long bones at the epiphyseal plate Composed of cartilage cells Growth continues until bone has replaced
all of the cartilage in the epiphyseal plate
BONE ELONGATION
Epiphyseal plate• Region
where cartilage cells divide, enlarge, and push older cells to the middle of the bone
JOINTS Joint: the place where two bones meet Three major types of joints:
Fixed Semimovable Movable
FIXED JOINT Fixed joints prevent movement Found in the skull where they permit no
movement of those bones Small amount of connective tissue in a
fixed joint also helps absorb impact to prevent the bones from breaking
SEMIMOVABLE JOINTS Semimovable joints permit limited
movement Found in the vertebral column; allow the
body to bend and twist Also found in the rib cage; connect the
upper ten pairs of ribs to the sternum
MOVABLE JOINTS Movable joints enable the body to
perform a wide range of movements and activities Include:
Hinge Ball-and-socket Pivot Saddle Gliding
MOVABLE JOINTS Hinge joint: found in the elbow Ball-and-socket: shoulder joint Pivot joint: formed between the top two
vertebrae in the neck Saddle: found at the base of each
thumb Gliding: fount between the small bones
of your foot
JOINT STRUCTURE Joints are subjected to a great deal of
pressure and stress, but their structure is well suited to meet these demands Bones that come into contact are covered
with cartilage Protects against friction
JOINT STRUCTURE Ligaments: tough bands of connective
tissue Hold the bones of the joint in place
Synovial fluid: lubricating substance that helps protect the ends of bones from damage by friction
JOINT STRUCTURE Knee joint is the most susceptible
because it carries the body’s weight
JOINT STRUCTURE Arthritis: used to describe disorders
that cause painful, swollen joints Two forms of arthritis:
Rheumatoid arthritis: develops when the immune system begins to attack body tissues
Osteoarthritis: degenerative joint disease in which cartilage becomes thinner and rougher, so bones rub against each other
Section 3
MUSCULAR SYSTEM
MUSCLE TYPES Muscle: an organ that can contract in a
coordinated fashion Includes:
Muscle tissue Blood vessels Nerves Connective tissue
MUSCLE TYPES Skeletal muscle is responsible for
moving parts of the body Made of muscle fibers (elongated cells)
Each muscle fiber contains many nuclei and is crossed by light and dark stripes (called striations)
Skeletal muscle fibers are grouped into fascicles (dense bundles)
A group of fascicles are bound together to form a muscle
MUSCLE TYPES Voluntary muscles: muscles you can control Involuntary muscles: muscles you can’t
control Smooth muscle
Makes up the walls of the stomach, intestines, blood vessels, and other internal organs
Cells are spindle-shaped, have a single nucleus, and form sheets
Lacks striations Fibers surrounded by connective tissue
MUSCLE TYPES Cardiac muscle
Make up the walls of the heart Muscle is striated Involuntary muscle Each cell has one nucleus
MUSCLE STRUCTURE A skeletal muscle fiber is a single,
multinucleated muscle cell Made up of hundreds or thousands of
muscle fibers Cells are soft and easy to injure Covered by connective tissue
MUSCLE STRUCTURE Health of a muscle depends on nerve
and blood supply Each muscle fiber has a nerve that controls
it Require lots of oxygen and nutrients Make lots of waste that are removed
through the veins
MUSCLE STRUCTURE Myofibrils: bundles of threadlike
structures Made of two protein filaments: thick and
thin Thick filaments made of myosin Thin filaments made of actin
Anchored at their endpoints to the Z line Region from one Z line to the next is a sarcomere
MUSCULAR CONTRACTION The sarcomere is the functional unit of
muscle contraction When a muscle contracts, myosin and
actin filaments interact to shorten the sarcomere
MUSCULAR CONTRACTION When a nerve impulse stimulates a muscle
to contract, the myosin filament heads attach to points between the actin filament The myosin heads bend inward, pulling the
actin with them The myosin heads then let go and bend
back into their original position and attach to a new point Shortens the sarcomere
MUSCULAR CONTRACTION Requires energy to contract muscles
Provided by ATP (must have a continuous supply)
Muscle contraction is an all or nothing response Either the muscles contract or they don’t
Section 4
INTEGUMENTARY SYSTEM
SKIN One of the body’s largest organs Contains sensory receptors that
monitor the external environment and rids the body of wastes
Composed of two layers: Epidermis Dermis
SKIN Epidermis
Outer layer of skin Composed of many sheets of flattened
epithelial cells Top layers made mostly of dead skin
Scraped and rubbed away on a daily basis Cells filled with keratin
Gives skin leathery texture and waterproof quality
SKIN Epidermis
Melanin: brown pigment that determines skin color
Produced in lower cells of epidermis Absorbs UV rays Amount produced depends on:
Heredity Length of time that skin is exposed to UV rays
SKIN Dermis
Inner layer of skin Composed of living cells, sensory neurons,
blood vessels, muscle fibers, hair follicles, and glands
Goose bumps produced by muscle fibers contracting and pulling hair upwards
Layer of fat below the dermis Provide energy; insulate against heat loss
GLANDS Exocrine glands: release secretions
through ducts Sweat glands: release excess water, salts,
and urea Helps regulate body temp
Oil glands: secrete sebum Sebum coats surface of skin preventing water
loss and soften hair and skin
NAILS Nails form from nail roots under skin
folds As new cells form, nail grows longer Comprised mostly of keratin Grow about 1 mm per week Nails lie on blood vessels, which give them
their pink color Changes can indicate disease somewhere
else in the body
HAIR Protects and insulate the body Produced at the base of hair follicles Hair shaft composed of dead, keratin-
filled cells that overlap Hair color results because of melanin in
the hair shaft Influenced by hereditary factors
