Support systems in animals - the human skeleton Flashcards
Which animals have hydrostatic skeletons
Snails (mollusca) and earthworms (anelida)
What is a hydrostatic skeleton
It is when animals have fluid filled bodies and that give them their structure and support. These organisms secrete watery fluid (coelomic fluid) that is trapped inside the body cavity (coelom)
Which animals have exoskeletons
Arthropoda (crabs, millipedes, insects)
What kind of skeletons can vertebraes have
They can have cartilaginous skeletons (sharks and rays) or bony skeletons (endoskeletons) because they are internal
What are the advantages of the human skeleton
- support
- protect
- point of attachment for muscles and movement
- allows growth
How many bones does the adult human skeleton have
206
What parts of the skeleton are the axial skeleton
vertebral column, rib cage, skull and sternum
What parts of the skeleton are the appendicular skeleton
shoulder girdle, pelvic girdle and lower and upper limbs
How does the skull start off
It starts off as 29 bones during embryonic development (excluding teeth) which later on are connected through fibrous cartilage. The lines that the joints form disappear at ages 30 to 40
How many bones does the cranium have
8
What does the cranium do
It protects the brain and sensory organs
How many facial bones are there
14
What are the names of the upper and lower jaw and how many bones do they each have
upper jaw: maxilla; 2 bones on each side
lower jaw: mandible; 1 bone on each side
What are the smallest bones in the body
The 6 auditory ossicles in the ear; hammer, stirrup and anvil at each side
What is the foramen magnum
a large opening at the base of the skull through which the spinal chord passes.
On either side of it is a projection which articulates with the first vertebra (atlas) to allow nodding movements
How many teeth does the adult human have
32
How many milk teeth do children have
20
What type of teeth do humans have, how many of them do they have and what do they do
incisors: 4,bite
canines: 2, tear and grip
premolars: 4
molars: 6, chew and grind
What are heterodont and homodont mammals and why
Heterodont: humans, they have different teeth which perform different functions
Homodont: dolphins, teeth have the same basic structure
What is the hardest substance in the body
tooth enamel
What are teeth embedded in
tooth sockets
What is another word for dental bone
dentine
What is the vertebral column
The vertical support of the body and the true axis that allows movements
What are the first two cervical vertebrae
atlas and axis
Describe the atlas
- Supports the skull and allows nodding movements
- Does not have a centrum or spinal processes
- Transverse processes are short and thick
- Transverse processes form articulation facets on which the condyles of the skull can rest
Describe the axis
- Centrum is shaped into an odontoid process that forms around the axis around which the atlas can rotate
- Odontoid process is kept in position by a strong ligament. The transverse processes are small to allow rotations of the head
- Axis allows rotation of skull
True or False
The thoracic vertebrae are the vertebrae with a structure closest to that of typical vertebrae
true
Why are the thoracic vertebrae slightly larger than the cervical vertebrae
to lend more support
Where are articulation facets found on thoracic vertebrae
at each side and against the transverse processes of the first 10 vertebrae articulating with the ribs, these joints move slightly when we breathe
Why are the lumbar vertebrae large and solid and prominent
to carry the weight of the body and anchor muscles used to bend and rotate the lower back. The cartilage discs in this area are under a lot of pressure
Which part of the vertebral column has no function in the human body
the coccyx
What do the vertebrae of the sacrum fuse to form
a strong triangular bone that articulates with the hip bones
How many pairs of ribs does the rib cage have
12
What is the front of the ribs attached to
sternum (breast bone)
What does the sternum do
serves as extra protection for the heart and lungs
What attaches the ribs and sternum
elastic cartilage
What are true ribs and how many are there
They are attached directly to the sternum and there are 7 pairs
What are false ribs
They are attached to the cartilage of the previous ribs with cartilage
What are the last two ribs called and why
They are floating ribs because they are not attached to anything
What are the two layers of muscle that cover the ribcage
external and internal intercostal muscles
What happens to the external and internal intercostal muscles when you inhale
They contract to lift the ribcage up and outwards. They also relax to let you exhale
Internal intercostal muscles contract to decrease the volume of the thorax and put more pressure on the lungs so air is forced out of the lungs
What is the scapula
a flat triangular bone with a prominent ridge on the back for the attachment of muscles, that moves over the ribs at the back and assists movement and is not attached to the axial skeleton
Explain what the shallow socket that the scapula has is
It is an articular facet known as the glenoid cavity into which the humerus fits to form a ball and socket joint
What is the clavicle
An s shaped bone that articulates with the scapula one one side and the sternum on the other side. It is most frequently broken because it takes the full impact of falls on outstreched arms
How many bones are there in the wrist joint
8 irregular carpal bones
How many metacarpal bones are in the palm of the hand
5
How many phalanges do humans have
14
What does the pelvic girdle consist of
2 hip bones that form a strong girdle with the sacrum
What are the 3 parts of the hip bones and why are these bones fused
ilium, ischium and the pubic bone/pubis; they are fused for strength
What are the pubic bones joined by
fibrous cartilage that allows small movement in women during birth, this joint is called the pubic symphysis
What is another word for tibia
shin bone
What is another word for fibula
calf bone
How many bones does the ankle have
7
How many metatarsal bones are there
5
What is a joint
A junction where two or more bones are joined by ligaments or cartilage
How can joints be classified
- immovable joints: eg. sutures between skull bones
- semi movable joints: usually connected by elastic cartilage eg. the ribs and breastbone
- movable joints: Also called synovial joints eg. shoulder or elbow where bones are connected by ligaments.
What characterises synovial joints
Bones are joined by ligaments
The whole joint is enclosed in a tough joint capsule
Friction during movement is decreased by synovial fluid
What makes the bodies of animals with hydrostatic skeletons firm
The pressure of the coelomic fluid against the muscles which can also contract to enable movement
What qualities does water have that makes it suitable to a skeleton
It cant be compressed and distributes changes in pressure evenly
What re the advantages of a hydrostatic skeleton
- Watery environment keeps surfaces moist and prevents desiccation
- Water supplies extra support
What are the disadvantages of a hydrostatic skeleton
- Inefficient movement
- Not protected against mechanical injuries
- Sensitive to temperature changes
What are the advantages of an exoskeleton
- Support
- Point of attachment for muscles
- Mobile seams enhance movement
- Fair resistance to temperature changes
- Protection against injury, toxins and desiccation
- Camouflage
What are the disadvantages of an exoskeleton
- Restricts growth and vulnerable during molting
2. Relatively mobile
What is an endoskeleton
An internal framework of bone and cartilage
What are the disadvantages of an endoskeleton
Bones may break or crack due to pressure exerted on them
True or False
The bones of the skeleton lower the resistance that the muscles collaborate against to produce movement.
False
The bones supply the resistance
What are the functions of the human skeleton
- Movement
- Protection
- Support
- Mineral storage (calcium and phosphates)
- Hearing (auditory ossicles)
- Blood cell formation (red bone marrow)
What two groups of bones does the skull consist of
the cranium and facial bones
What joins the bones in the cranium
immovable joints; sutures
What does the vertebral column consist of
24 articulating vertebrae and 9 fused vertebrae in sacrum and coccyx
What is fibrocartilage
discs found between the vertebrae to prevent friction and act as shock absorbers during movement
How do spinal nerves enter and leave the spinal cord
small gaps between adjacent vertebrae
What stabilises the vertebrae and helps to help control movement
Strong ligaments and muscles areound the spine
What is the basic structure of all vertebrae
- consists of a centrum, neural arch and processes for attachment of muscles/ligaments
- Between the neural arch and centrum a spinal canal (Foramen) is formed. It surrounds and protects the spinal cord (attached to foramen magnum)
What outgrowths are visible in the vertebrae
- neural spin
- two transverse processes
- articular surfaces (occur for articulation with the previous and successive vertebrae and articulation with the ribs and thoracic vertebrae
What are the functions of the vertebral column
- Supports the skull
- Surrounds and protects the spinal cord
- Separate vertebrae and s shaped curvature provide flexibility allowing humans to bend backwards, forwards and sideways
- Fibrocartilage discs between vertebrae act as shock absorbers
What does a typical ribcage consist of
12 pairs of ribs, sternum, costal cartilages and 12 thoracic vertebrae
What does the pectoral girdle consist of
two scapulae and two clavicles
How is the pectoral girdle connected and why
It is connected to the back of the thorax by muscles to enable it to have a supporting structure as well as giving the shoulders greater freedom of movement for greater arm mobility
What provides limit of movement in the pectoral girdle
the clavicle
What are the functions of the pectoral girdle
- Forms a strong support structure for the attachments of the arms
- Provides large area of bone for the attachment of muscles
- Forms ball and socket joints with the arms which allows the arms to move freely
What kind of joint do the bones of the forearm form in the elbow
a hinge joint
Describe the shape/position of the ulna
- largest bone of the forearm situated on the pinky finger
2. c shaped articular facet that articulates with the humerus to form the elbow joint
Describe the shape/position of the radius
- thinner bone of the forearm situated on the thumb side
2. Lower end is wider than upper end and articulates with carpals to form wrist joint
Why are carpal bones one of the most flexible bones in the body
They can slide over each other to allow high degree of movement
What does the pelvic girdle consist of
Two hip bones joined in the middle by a semi movable joint called the pubic symphysis
What is the deep socket that occurs where the 3 fused hip bones are found
acetabulum
What kind of joint does the head of the femur and the acetabulum form
a ball and socket joint
Name and describe the two types of bone
- Compact bone: hard, dense bone tissue
Forms the surface of bones and shafts of long bones
Provides strength and support - Spongy bone: softer, light bone tissue
Form head of long bones and contains red marrow
Exert resistance against forces that act on bones
Briefly describe what cartilage is
It is semi transparent, tough elastic connective tissue
Briefly describe what tendons are
inelastic, white fibrous connective tissue that attach muscle to bone
Describe what ligaments are
- Tough yellow elastic connective tissue that attach bone to bone
- Stretch only enough to control movement in a joint
- Hold bones in position (stabilise joints)
What covers the ends of two bones in a synovial joint
hyaline cartilage
Name and explain the types of synovial joints
- Ball and socket joint
One bone fits into the other; movement in any direction eg. Shoulder and hip joint - Hinge joint
Movement in one plane eg. elbow and knee joint - Pivot joint
One bone rotates around the other eg. atlas around the axis - Gliding joint
Flat articular surface of one bone slides over another eg. wrist bones/ ankle joint
Name and explain the types of bones in the skeleton
- Long bones
Consist of a shaft (diaphysis) and head (epiphysis) eg. humerus and femur - Short bones
Have a shaft but no head g. ribs and rapal bones - Flat bones
eg. scapula and hip bones - Irregular bones
no specific shape eg. vertebrae and auditory ossicles
What is the epiphysis
The head of each end of a long bone which consists largely of spongy bone and is covered with hyaline cartilage
What is spongy bone
Found in the epiphysis of long bones and contains red marrow
What is red bone marrow
Found in the spaces between trabeculae in spongy bone and the is the area where white and red blood cells are made
What are trabeculae
The struts in the network of irregular bony plates in the epiphysis of bones which transfer stresses from the epiphysis to the diaphysis which has a much thicker layer of compact bone and resists stress better
What is the diaphysis
Cylindrical shaft of a long bone composed of hard compact bone on the outside
What is the periosteum
Membrane of dense fibrous connective tissue which surrounds the outside surface of the shaft of a long bone
It has blood vessels to nourish bone and repair injuries
Provides surface of attachment for muscles through tendons/ligaments
Endosteum
The delicate connective tissue layer lining the inside surface of compact bone
Marrow cavity
This is filled with yellow marrow which consists largely of fat
What is a lever
a rigid rod that rotates around a specific point
What are the 3 main components of a lever
Fulcrum (turning point) F
Effort (where the force must be exerted) E
Load (where teh load has to be moved) L
Explain and give an example of what a class 1 lever is
LFE/EFL
The load at one end is balanced by the effort on the other side; the fulcrum is found between the two
When one pushes down on one side the other will lift vice versa
eg. nodding your head
Explain what a class 2 lever is
FLE/ELF
Has the load and the effort on the same side as the fulcrum and the fulcrum is always at one end of the lever; force must be exerted in the same direction as load must be moved
eg. ankle
Explain what a class 3 lever is
FEL/LEF
The effort and the load are on the same side on the fulcrum but the effort is exerted closer to the fulcrum than the load
eg. during a biceps curl
What are antagonistic muscles
Muscles that work opposite to one other (in pairs) when one contracts the other relaxes eg. biceps (flexor muscle) and triceps (extensor muscles)
Briefly describe the position of the biceps
On one end two tendons are attached to the pectoral girdle while the other end is attached to the radius
Describe the position of the triceps
One end is attached to the pectoral girdle with three tendons while the other is attached to the ulna
What muscles are involved during muscle contraction for movement
skeletal muscles (cross striated, voluntary muscles)
What causes striations in skeletal muscles
The arrangement of longitudinal, contractile myofibrils in the cylindrical muscles cells
What are the characteristics of skeletal muscles
- Attached to the skeleton by inelastic tendons
- Striations
- Voluntary
What is osteoarthristis
The most common form of arthritis, which is caused by an inflammation of the joints. It is usually accompanied with pain and swelling
What is osteochondritis
An inflammation of the cartilage and bone; it leads to defective growth and deformity
What is osteogenesis impefecta
A hereditary condition in which a baby is born with very fragile bones
What is osteomalacia
A softening of the bones, caused by a deficiency of vitamin D
What is osteomyelitis
A bacterial infection of the bone marrow
What is osteoporosis
A change in the mass or texture of bone, caused by a depletion in the level of calcium it contains; as a result the bones become weak
