Skeletal system Flashcards
What is a hydrostatic skeleton and example organisms
- fluid filled cavity surrounded by muscles
- e.g. jellyfish, earthworm, snail
(Image: https://www.slideshare.net/nirmalajosephine1/biology-form-5-chapter-2-locomotion-support-21-part-1)
How does a hydrostatic skeleton work?
- Fluid provides support against muscles that contract
- The pressure that the fluid exerts changes the animals shape according to which muscles are contracting
- This brings about movements
(image: http://faculty.fmcc.suny.edu/mcdarby/BIO170Book/12-AnimalStructure.html)
Advantages of a hydrostatic skeleton
- Anatomy simple, no extra support organs needed
- Body elastic and can change shape easily
- No need for a specialised support system, living in water, the water provides support
Disadvantages of hydrostatic skeleton
- Animals are slow in moving
- Require aquatic or moist environment
- Limited size of animal
- No protection from skeleton
What is an exoskeleton and examples of animals
- An external skeleton
- made of chitin on the outside of the animals body
- E.g. arthropods (insects)
- Some animals have it further hardened with calcium carbonate (e.g. crabs)
(Image: http://www.dierk-raabe.com/biological-natural-materials/)
Advantages of an exoskeleton
- Supports and protects underlying tissue and organs
- The inside is a place of attachment for muscles
- The skeleton has joints for flexibility
- Quick movement possible
- The skeleton prevents desiccation (drying out)
Disadvantages of an exoskeleton
- Limited size of the animal as it is heavy
- Larger, heavier animals have more limited movement
- Limits growth and the animal needs to moult
- Moulting leaves the animal vulnerable as a new skeleton forms
- Exoskeleton impermeable to gases so a specialized respiratory system needed.
What is an Endoskeleton and examples of animals
- An internal skeleton on the inside of the animals body
- made of bone and cartilage
- Found in vertebrates e.g. fish, frogs, reptiles and mammals
Advantages of an Endoskeleton
- skeletal tissues grow as the animal grows
- protects vital organs e.g. Brain
- provides good structure to give the body shape
- provides a place for muscles to attach for movement
- joints between bones make the body flexible
Disadvantages of Endoskeleton
- More vulnerable to desiccation (drying out)
- No outer protection
Vertebrate animals
- Animals with a vertebral column made of bone or cartilage
- Members of the phylum Chordata
- e.g. fish, frogs, reptiles, birds and mammals
(Image: http://byjus.com/biology/vertebrates/)
Invertebrate animals
- Animals without a vertebral column
- about 95% of animals are in this group
- e.g. jellyfish, flatworms, roundworms and arthropods
Different types of skeletons in animals
- Hydrostatic skeleton
- Exoskeleton
- Endoskeleton
Joints
The junction in the skeleton where two or more bones meet and are joined by ligaments or cartilage
immovable joints
- A joint not allowing any movement
- e.g. serrated joints between bones of the cranium
semi-movable joints
- Joints that allow a small amount of movement
- e.g. between vertebra
synovial joints
Joints allowing free movement
parts of a synovial joint
- Bones covered with hyaline cartilage
- A enclosing sac made of ligament called the joint capsule
- Capsule lined with a synovial membrane
- Capsule contains synovial fluid
- Ligaments attach the two bones of the joint
Types of synovial joint
- Ball and socket joints e.g. hip and shoulder
- Hinge joints e.g. elbow and knee
- Pivot joints e.g. atlas and axis
- Gliding joint e.g. wrist and ankle joints
x-Ray photo’s
- High energy x-rays penetrate soft tissue and less so bones
- making it possible to visualize the internal skeleton.
- Used by doctors to diagnose bone fractures and dislocation of joints
skeletal muscles
- Muscles attached to the skeleton
- to bring about movement of parts of the body.
- Attached by in elastic tendons
- They have light and dark bands (striated)
- They are voluntary muscles
Structure of skeletal muscles
- Made up of many muscle fibres (muscle cells)
- bound together by connective tissue into perimysium bundles
- Perimysium bundles are bound together to form the epimysium, the complete skeletal muscle
(Image: https://training.seer.cancer.gov/anatomy/muscular/structure.html)
Structure of a muscle fibre
- A single elongated cylindrical cell
- Consists of thousands of myofibrils
- Myofibrils contain myosin and actin protein filaments
- Myosin thicker and darker than actin giving the fibre a banded appearance
Sarcomere of a muscle fibre
- A functional unit of a muscle allowing it to contract.
- Region where actin and myosin filaments overlap.
How a muscle fibre contracts
- Nerve fibres transmit impulses to the sarcomere.
- Thin actin filaments slide past thicker myosin filaments to increase their overlap.
- The sarcomeres shorten
- This shortens the overall length of the muscle fibres and in tern the whole muscle.
Antagonistic muscles and an example in the arm
- Skeletal muscles arranged in pairs
- When one contracts, the other relaxes
- Allow coordinated movements
- e.g. The bicep and tricep muscles in the forearm
(Image: http://www.jeron.je/anglia/learn/sec/science/body/muscle.htm)
How the arm straightens
- Tricep contracts and bicep relaxes
- The elbow joint extends and the arm is straightened
How the arm lifts/bends
- The bicep contracts and the tricep relaxes
- The elbow joint bends and the forearm is lifted.
(Image: http://www.mychhs.colostate.edu/david.greene/Yamagata2007_distal_upper_extremity_lecture.htm)
What is rickets?
- A childhood deficiency disease affecting the skeleton
- bones become soft, bend and weaken
Symptoms of rickets
- Bones still growing are deformed e.g. bent/bow legs
- High incidence of bone fractures and weakness
- Delayed growth,
- Pain in the spine, pelvis and legs.
Causes of rickets
- Shortage of vitamin D
- Vitamin D is needed for absorption of calcium
- Calcium is needed for bone and teeth development
What is osteoporosis?
- A disease of the bones
- Characterized by a decrease in bone density
- Bones become porous and less dense
Causes of osteoporosis
- Shortage of calcium
- Greater bone absorption than bone building
- A lack of certain hormones, particularly estrogen in women
- Lack of exercise
Prevention of osteoporosis
- Peak bone density is reached at approximately 25 years of age,
- it is important to build strong bones by that age.
- Sufficient calcium and vitamin D intake to ensure sufficient bone building.
- Sufficient exercise while bones are growing
Symptoms of osteoporosis
- Usually bone density loss starts long before symptoms
- Weakened bones
- Increased risk of fracture of hips, spine and wrists
- Curved back and decreased height
What is arthritis
- A disease that causes severe pain in the joints
- Loss of movement in joints
- Inflammation of the joints
What causes inflammation?
- Inflammation causes swelling, pain and loss of movement of the affected area
- Usually caused by the bodies immune system reaction to injury or pathogens
What is osteoarthritis?
- Cartilage of a joint aging and disintegrating with time
- Bones grind against each other causing inflammation
- Common in hips, knees, feet, fingers and spine
Factors that might lead to osteoarthritis
- Being overweight.
- Getting older.
- Joint injury.
- Joints that are not properly formed.
- A genetic defect in joint cartilage.
- Stresses on the joints from certain jobs and playing sports.
What is rheumatoid arthritis?
- Synovial membranes in joints thicken
- Too much synovial fluid causes inflammation
- Causes deformation of joints
- Usually affects finger joints, wrists, knees and toes
Causes of rheumatoid arthritis
- An autoimmune disease
- Bodies immune system attacks its own tissues
- In this case the cartilage, ligaments, bones and tendons.
Ilium
Pubis
Ischium
Skull
Frontal bone
Mandible
Incisors
Canines
Molars
Premolars
Nasal Bones
Maxilla bones
Zygomatic bones
Temporal bone
Paretial bone
Occipital bone
Atlas
Axis
The hole where the spinal cord enters the skull
Foramen magnum
Cervical vertebra
Thoracic vertebra
Lumbar vertebra
Sacrum
Coccyx
Floating ribs
True ribs
Costal cartilage
Sternum
Clavicle
Scapula
Humerus
Ulna
Radius
Carpals
Metacarpals
Phalanges
Tarsals
Metatarsals
Phalanges (toes)
Femur
Patella
Tibia
Fibula
Type of skeleton
Exoskeleton
Type of skeleton
Endoskeleton
Type of skeleton
Endoskeleton
Type of skeleton
Hydrostatic skeleton
Type of skeleton
Hydrostatic skeleton
Type of disease
Rhumatoid arthritis
Type of disease
Osteoarthritis
Type of disease
Arthritis
Type of disease
Osteoporosis
Type of disease
Rickets
Epiphysis
Diaphysis
Type of bone in the epiphysis
Spongy bone
Outer membrane surrounding a bone
Periosteum
White substance covering the tops of each epiphysis on a long bone
Cartilage
Types of bones according to shape
- Long (e.g. femur)
- Flat (e.g. frontal)
- Irregular (e.g. vertebra)
- Short (e.g. carpal)
- Sesamoid (e.g. patella)
