The Human Skeleton Flashcards
What is the function of the human skeleton ?
Support
Protection
Locomotion
Mineral reserve
Haemotopoiesis
How does the skeleton allow us to move ? (Involved in locomotion)
Muscles attach to bones using joints
When muscles contract - facilitate movement
Muscles use skeleton as an anchoring point
How does the skeleton act as a mineral reserve
90% of the body’s calcium stored as salts within the bones
Phosphates are also stored - within bones
What happens when calcium levels in the bone drop
calcium can be released from the skeleton and can when levels are high bones can absorb calcium
How are the bones important for blood cell production
Haematopoietic cells eg red blood cells and leukocytes and platelets -> are all produced in bone marrow
Explain bone marrow in children
All of the skeleton contains bone marrow - lots of blood cell production
Red one marrow
Explain bone marrow in adults
bone marrow is replaced and the red bone marrow is replaced with elbow bone marrow which has a higher adipose or fatty tissue content
Where is red bone marrow present in adults
skull, proximal femur and veritable column
What is this ?
Functional unit of bone called an osteon
Explain the composition of an osteon ?
Made from layers of bone and is almost like layers of tree trunk
Contains circular layers that contain important components
The bone is made up of what two components ?
Organic components
Inorganic components
What is the split between organic and inorganic
Organic - 30%
Inorganic - 70%
What is the organic comment of town made up of
Type 1 collagen
What is the inorganic component of bone made up of
Calcium and phosphate salts
What does collagen provide
Collagen give tensile strength and allows little bit of bending to occur
What is the role of inorganic component of bone
Hard mineral component
Makes bones sturdy and give them compressive strength
What is compressive strength
Weight of body passing through bones and squishing it down
Bones are able to withstand because they are hardy + strong
How is collagen organised
Fibres that run in opposite directions to each other
How does the organisation of collage aid in function
Allows bone to withstand force from different directions
What is within each osteon
Blood vessels providing nutrients as well as nerve cells
Why is bone classed as dynamic ?
Angle to respond to changes in the environment
How are bones remodelling ?
New bone being laid down and old bone is taken away
Which cells take part in bone remodelling ?
Osteoblasts and osteoclasts
What do osteoblasts do ?
Lay down new bone
What do osteoclasts do ?
Break down old bone
What is the main function of remodelling ?
Healing
What is the fibula ?
Bone in the lower limb in the leg
Take out collagen of bone what would happen ?
Only left with hard mineral component - make bones really brittle and it would break
Take out inorganic mineral component of bone, what would be left ?
Bone would become very flexible
What is rickets
Not enough mineral content in the bone
Bone becomes flexible and bendy (overly)
What causes rickets
Vitamin d deficiency
Explain how vitamin d deficiency causes rickets
Vitamin d is converted into calcitriol - this is needed to absorb calcium from the gut and form hard mineral content of bones
What does rickets look like in children
Bones become soft
As weight passes through bones - bone bends
What is osteogenesis imprefecta
Congenital
Genetic disorder which affects collagen production
Eg mutation in gene - not as much collagen produced
What is the effect of osteogenesis imperfects
Bones become brittle and fracture easily
Directly related to composition of the bone
What is the diaphysis of the bone
Long tube like
Shaft of the bone
How many epiphyses are there
2 - one at the bottom and one at the top
What is the epiphysis
Articular surfaces for joints
Mostly spongy bone but compact on the surface
What are two surfaces of the bone
Compact bone
Cancellous bone
What does cartilage provide
Nice smooth surface
What is spongy bone made up of
Interconnecting struts - tend to set in the direction of force
What happens to the struts in cancellous (spongy bone) when there’s a force passing through the bone ?
The struts can be remodelled to help direct the force or weight through t he bones
What can be found in the middle of diaphysis
An empty space
What is the empty space in the diaphysis
Medullary cavity
What is found in the medullary cavity and its function
Bone marrow which is involved in blood cell production
Where is bone marrow found
Medullary cavity and struts of bone in spongy layer
What can you see within epiphysis ?
Epiphyseal line
What is the ephiphyseal line
Also known as growth plate
This is where our growth occurs in development
Separates diaphysis (shaft of bone) from epiphysis
When growth is complete what happens to the growth plate
It turns into bone and therefore creates a line
-> growth plate has ossified creating epiphyseal line
What is the periosteum ?
Covers outer surface of bone
Site of attachment for muscle tendons
What is the endosteum ?
Lines internal surfaces of cavities within bones
Label this picture of a bone
Briefly describe bones in thee skull
Flat bones
Slightly different as they don’t have medullary cavity
Label this
Compact bone
Label this
Cancellous bone (diploe)
What is diploe ?
With bone marrow
What can bone cells not do ?
Cannot divide
How does bone grow
By being continuously laid down on top of surface of previous bone
What is required for bone growth
A growth plate which is made up of cartilage
What is the two ways cartilage can grow
Oppositional growth
Interstitial growth
What is appositional growth
new surface layers of matrix are added to the pre-existing matrix by new chondroblasts from the perichondrium.
Unlike other connective tissue what is cartilage ?
avascular (like epithelia). Cartilage is nourished by long range diffusion from nearby capillaries in the perichondrium
What is interstitial growth of cartilae
chondrocytes grow and divide and lay down more matrix inside the existing cartilage. This mainly happens during childhood and adolescence.
What is the surface of most cartilage covered by ?
covered by a layer of dense irregular connective tissue called the perichondrium (peri = around).
What is Intramembranous Ossification
compact and spongy bone develops directly from sheets of mesenchymal (undifferentiated) connective tissue.
In endrochondral ossification how does the bone develop ?
bone develops by replacing hyaline cartilage.
What is the role of cartilage in ossification ?
cartilage serves as a template to be completely replaced by new bone.
Which bones form via endrochondral ossification
Bones at the base of the skull and long bones form via endochondral ossification.
Explain endrochondral ossification
The bone is formed onto a temporary cartilage model.
The cartilage model grows then chondrocytes mature (zone of maturation) and growing cartilage model starts to calcify.
As this happens, the chondrocytes far from blood vessels, and are less able to gain nutrients etc, -> chondrocytes start to die
fragmented calcified matrix left behind acts as structural framework for bony material.
Osteoprogenitor cells and blood vessels from periosteum -> proliferate and differentiate into osteoblasts, which start to lay down bone matrix (osteogenic zone)
What happens after all cartilage replaced
Diaphysis and epiphysis are replaced
How can you classify bones ?
Based on shape
What does the shape of the bones tell you
Function of the bone
Describe long bones
Longer than they are wide
Long diaphysis : shaft
What are examples of long bones
Bones of the limb
Femur humerus tibia
Function of long bones
Tend to be involved in movement and in particular muscle attachment
Describe short bones
Similar to long bones
Width and length are similar
Tend to be cubed in shape
What are examples of short bones
Bones of the wrist and ankle - wrist or tarsal bones in the ankle
Describe flat bones
Thin and flat and usually curved
Describe the function of flat bones
Protective in function
Hat are examples of flat bones
Skull sternum scapula and ribs
What are irregular bones
Don’t fir in other categories
Shape is irregular
What are examples of irregular bones
Vertebrae, sternum, scapula and ribs
What are sesamoid bones
Small round bones embedded in tendons of muscles
Look like sesame seeds
What is the function of sesamoid bones
Protect tendons and increase movement
What are examples of sesamoid bones
Patella
A tendon with a sesamoid bone can lead to what
Increases range of movement at that part
How many bones in the human skeleton ?
206
How many bones in new borns
270
In a child what two things of bones are separated
Diaphysis and epiphysis
Why do newborns have more bones than adults
Bones are still growing so parts are separated and will fuse later on
With increasing age why can the number of bones decrease
Bones can fuse together with age too
Eg first rib to sternum
What are bones connected by
Joints
What are the 3 types of joints
Fibrous
Cartilaginous
Synovial
What are the 3 regions of the Skelton
Axial
Appendicular -> upper limb and lower limb
What forms part of the axial skeleton
What forms part the upper limb
Pectoral girdle
Bones of the arms and hands
What forms part of the lower limb
Pelvic girdle
Bones of the legs/feet
What is the appendicular skeleton formed by ?
Appendages
What is part of the Skelton that attaches the limb to the rest of the body
Appendicular Skelton
What is the most complex part of the Skelton
The skull
What is the function of the skull
Houses brain and special sense organs
Has a protective function
What is the facial skeleton called
The viscerocranium
How many bones are in the viscerocranium
14 bones
What is the rest of the surrounding Brain excluding facial Skelton called
Neurocranium
How many bones are in the neurocranium
8 bones
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