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human biology 3ab > Chapter 13 - The Skeleton > Flashcards

Chapter 13 - The Skeleton Flashcards

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1
Q

List the functions of the skeleton.

A
  • Articulation
  • Protection if vital organs.
  • Act as storage organs for mineral salts and fat.
  • Blood cell production in red marrow.
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2
Q

What mineral salts and fat are stored in the bones of the skeleton?

A
  • Calcium, phosphorus, sodium and potassium are the main minerals store within bone.
  • These can be distributed to other regions of the body by the circulation system when required.

Eg. Prego woman’s diet does not contain enough calcium, it can be removed from her skeleton and used for the growth of bones in the developing foetus.

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3
Q

What does a Long Bone consist of?

A
  • A shaft, Diaphysis - making up the main portion of the bone
  • The ends, Epiphyses - enlarged ends of the bone; a thin layer of cartilage, the articular cartilage, covers each epiphysis.
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4
Q

Explain the structure of the Diaphysis.

A
  • Hollow cylinder of compact bone surrounding a cavity.

* This cavity is used as a fat storage site and is often cells the Yellow Bone Marrow cavity.

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5
Q

Explain the structure of the Epiphyses.

A

They have a compact bone on the outside but their central regions contain spongy or cancellous bone.

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6
Q

What is a Cancellous bone?

A

It is more porous than a compact bone, and contains many large spaces filled with marrow. In certain bones this may be red bone marrow, where blood cell production takes place.

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7
Q

What is located on the outer surface if the bone?

A

There is a dense, white, fibrous covering, the periosteum.

There is no periosteum at the joints where the bone is covered with an articular cartilage.

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8
Q

What are bones classified as?

A

Connective tissues.

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9
Q

What do Connective Tissues consist of ?

A

Cells separated from each other by large amounts of non-cellular material called matrix.

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10
Q

Why are inorganic salts deposited in the matrix?

A

These increase it’s rigidity and strength and make it the hardest of the connective tissues.

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11
Q

What does a compact bone consist of?

A

Many similar units called Osteons or Haversian systems.

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12
Q

Explain the structure of the Oesteons or Harversian systems.

A

At the centre of each Oesteon is a central canal (Haversian canal), around which are concentric layers of bony matrix called lamellae.

  • Between the lamellae are small spaces in the matrix, the lacunae.
  • A bone cell, or osteocyte, occupies each lacuna. Tiny canals, known as canaliculi, run between the lacunae.
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13
Q

How are material passed from cell to cell?

A

Projections from the bone cells enter the canaliculi and make contact with adjacent bone cells. In this way materials can be passed from cell to cell.

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14
Q

What does the central canal (located in the middles of each Osteon) contain?

A

At least one blood capillary. It may also contain nerves and lymph capillaries.

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15
Q

What gives the osteons maximum strength?

A

The fact that they run parallel to the long axis of the bone.

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16
Q

What are Spongy bone?

A

AKA Cancellous Bone

  • Not organized into Osteons.
  • It consists of an irregular arrangement of thin, bony plates called Trabeculae.
  • The bone cells occupy spaces in the Trabeculae, but the lamellae are not arranged in concentric layers, and nerves and blood vessels pass through irregular spaces in the matrix.
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17
Q

When does bone grow?

A

Bone grows as an individual passes through infancy and adolescence to adulthood.

In an adult, the bones of the skeletal system are capable of repair and continue their functions if blood cell formation and storage.

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18
Q

What is a Cartilage?

A

Like bone, it is a connective tissue.

It contains numerous fibres made of a protein called collagen.

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19
Q

What is a Chondrin?

A

It is where the Collagen/ protein fibres are embedded in; It is a firm matrix of protein-carbohydrate complex.

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20
Q

Explain the structure of the Chondrin.

A

This form matrix enables cartilage to function as a structural support, while the preserve of fibres gives cartilage a certain amount of flexibility.

Because of these properties it is found on the surface if the bones at the joints and in the trachea and bronchi, and forms the nose, larynx and outer ear.

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21
Q

What are Chondroblasts?

A
  • They are cartilage cells which are contained within spaces in the matrix.
  • They produce matrix and gradually become surrounded by it until they are trapped in small spaces called lacunae.

->Once this has occurred, the cells are considered to be mature and are referred to as chondrocytes.

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22
Q

Why do Collagen fibres have to be classified?

A

Because the collagen fibres in the matrix range in thickness from extremely fine, so that they can just be seen with a microscope, to quite coarse.

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23
Q

The variation in the fibrous structure of the cartilage is used to classify it into 3 types:

A
  1. Hyaline cartilage
  2. Elastic cartilage
  3. Fibrocartilage
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24
Q

Explain the structure of the Hyaline Cartilage.

A
  • Contains many closely packed collagenous fibres throughout the matrix.
  • These fibres are so fine that they are not distinguishable under a light microscope.
  • They give the cartilage strength along with flexibility.
  • Hyaline cartilage makes up the rings of the trachea and bronchi, and is also found at the ends of bones where two bones meet to form a movable joint.
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25
Q

Explain the structure of the Elastic Cartilage.

A
  • Has conspicuous elastic fibres.
  • It also contains collagenous fibres similar to those in hyaline cartilage, but they are not closely packed.

• Elastic cartilage provides edible elastic support in places such as the external ear.
-> Folding your ear down and letting it go shows how springy this cartilage is.,

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26
Q

Explain the structure of the Fibrocartilage.

A
  • Has a coarse appearance from the parallel bundles of thick collagenous fibres that make up this tissue.
  • The fibres are not compacted as much as in hyaline cartilage and therefore it is able to be compressed slightly.
  • This is ideal for regions where the weight of the body is being supported or where there is a need to withstand heavy pressure.
  • Fibrocartilage is found in the intervertebral discs of the spinal column, whee it provides a cushion between the vertebrae; in the articular cartilage of the knee joint; and the tissue joining the two sides of the pelvis.
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27
Q

Cartilage does not contain any blood vessels; list all the functions that will be affected.

A
  • All nutrition and waste removal for the cells depends on diffusion through the matrix.
  • This is a slow process and results in the chondrocytes having a slow rate of metabolism and cell division.
  • Injured cartilage therefore takes quite some time to heal.
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28
Q

Where does the blood supply for they cartilage come from?

A

Blood vessels located in the inter layer of the Perichondrium. This is a fibrous membrane of connective tissue that covers the external surface of cartilage, except where the cartilage forms the articular surface of a joint.

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29
Q

What two sections are the bones of the skeleton divided into?

A
  1. Axial Skeleton

2. Appendicular Skeleton

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30
Q

Explain the structure of the Axial Skeleton.

A
  • It consists of the bones that lie around the central axis of the body.
  • It provides the main support for erect posture, and protects the central nervous system and the organs contained within the thorax.
  • The bones that form the skull, vertebral column, ribs and sternum (breastbone) make up the axial skeleton.
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31
Q

Explain the structure of the Appendicular Skeleton.

A
  • It consists of the bones of the upper and lower limbs and the bones of the pectoral (shoulder) and pelvic (hip) girdles.
  • These two girdles allow for the articulation of the limbs with the axial skeleton.
32
Q

What is a Joint?

A

It is the site at which two or more bones come together.

33
Q

Explain the structure of the joints.

A
  • Some joints are rather rigid and permit little or no movement.
  • Most, however, allow the bones to move in relation to each other.
34
Q

Compare tightly fitted joints and loosely fitted joints.

A
  • If the bones fit together tightly, the joint is strong and there is generally very little movement.
  • Loosely fitted joints, on the other hand, allow a great range of movement but are weaker and prone to dislocation.
35
Q

What is Functional and Structural classifications.

A
  • Functional - classified according to range of movement.

* Structural - according to the type of connective tissue that binds the bones together.

36
Q

When is a joint described as fibrous (or fixed/immovable) ?

A

When no movement occurs between the bones concerned.

  • The bones are held in place by fibrous connective tissue, as is the case with the structures of the skull.
  • It is very difficult to damage this type if joint, as it is so strong that the bone is usually broken, resulting in a fractured skull, before the joint gives way.
  • This joint also occurs between the teeth and the jaw.
37
Q

What are cartilaginous joints?

A

They are held in place by cartilage, which allows slight movement to occur.

• The junction of the two pelvic bones (the symphysis pubis), joints between adjacent vertebrae, and the joints between he ribs and the sternum are examples of slightly movable or cartilaginous joints.

38
Q

What limits the movement of some joints ?

A

Most joints of the body are freely movable; the amount of movement possible is limited by ligaments, muscles, tendons and adjoining bones.

  • These joints are also known as synovial joints and they occur at the shoulder, elbow, wrist, fingers, hip, knee, ankle and toes.
  • It is these joints that are most commonly injured in sporting and other accidents.
39
Q

How are Synovial joints categorized?

A

By the type of movement that occurs between the articulating surfaces of the bones.

40
Q

List the 6 types of synovial joints that occur in the arm.

A
  1. Ball-and-socket joints
  2. Hinge Joints
  3. Pivot Joints
  4. Gliding Joints
  5. Saddle Joints
  6. Condyloid (ellipsoid) Joints
41
Q

Explain the structure of the Ball-and-socket joints.

A
  • It is form when the spherical head of one bone fits into a cup-like cavity of another.
  • There are two such joints in the human body -
  1. The head of the humerus (upper arm bone) fits into a depression in the scapula (shoulder blade)
  2. while The head of the femur (thigh bone) articulates with the pelvis.
42
Q

Explain the structure of the Hinge joints .

A
  • It allows the movement in one place only, much like that of a hinged door.
  • They form when the convex surface of one bone fits into the concave surface of another.
  • The best examples of this type of joint are the elbow and the knee, but it also occurs at the ankle and between the bones of the fingers and toes.
43
Q

Explain the functions of the Pivot Joint.

A
  • They are formed when the rounded, pointed or conical end of one bone articulates with a ring, formed partly by bone and partly by a ligament.
  • The best example is the joint between the first vertebra, on which the head is balanced (the atlas), and the second vertebra (the axis). This allows the head to rotate. Another pivot joint is between the radius and ulna of the forearm; here the joint allows rotation of the hand.
44
Q

Explain the functions of the Gliding Joint.

A
  • Allow movement in any direction in a side-to-side or back-and-forth motion, restricted only by the ligaments or bony processes surrounding the joint.
  • Gliding joints are found between carpal bones, tarsal bones, the sternum and clavicle, and the scapula and clavicle.
45
Q

Explain the functions of the Saddle Joint.

A

The only true saddle joint in the body is where the thumb joins the palm of the hand.

The two bones forming the joint are both saddle-shaped - that is, concave in one direction and convex in the other.

They fit together in such a way that they allow both side-to-side and back-and-forth movements.

46
Q

Explain the functions of the Condyloid (ellipsoid) Joint.

A
  • Condyloid joints have on surface or bone slightly convex which fits into a slightly concave depression in another bone.
  • Such joints occur between the radius and the carpal bones, the metacarpal bones and the phalanges of the fingers, and between the metatarsal bones and the phalanges of the toes.
  • They allow movement in two directions such as up and down and side to side.
  • For example, hold your index finger erect. You can move it up and down as if beckoning someone, but you can also move it from side to side.
47
Q

Why are freely movable joints called synovial joints?

A

Because there is a space, or a synovial cavity, between the articulating surfaces of the bones.

48
Q

What is a synovial membrane?

A

It surrounds the synovial cavity, and there is articular cartilage on the bone surfaces.

49
Q

Define Articulation.

A

Articulation allow varying degrees I movement depending in the bones involved, so the skeleton determines the extent of movement of body parts.

50
Q

Explain the structure of the Anticular Capsule.

A

It surrounds and encloses the joint.

The capsule comprises 2 layers:

  1. The Outer layer
  2. The Inner Layer
51
Q

Explain the structure of the Outer Layer of the Anticular Capsule.

A
  • The fibrous capsule, consists of dense, fibrous connective tissue attached to the periosteum of the articulating bones.
  • Its flexibility permits movement at the joint, whereas its strength resists dislocation.
  • The fibrous capsule is one of the principal structures that hold the bones together.
52
Q

Explain the structure of the Inner Layer of the Anticular Capsule.

A
  • The synovial membrane makes up the inner layer of the capsule.
  • It consists of loose connective tissue, the inner surface of which is well supplied with blood capillaries.
  • The synovial membrane lines the entire joint cavity, except the articular cartilages and a structure called the articular disc (if present).
53
Q

What is a typical synovial joint?

A

The knee joint, where the femur meets the tibia, is a typical synovial joint. The patella, or kneecap, is also part of the structure of this joint.

54
Q

What is the Synovial Fluid?

A

-It is secreted by the synovial membrane. it fills the synovial cavity.

55
Q

What is the role of the Synovial Fluid?

A
  • It lubricates the joint and provides nourishment for the cells of the articular cartilage.
  • It also contains phagocytic cells that remove micro-organisms and any debris resulting from wear and tear at the joint.
56
Q

Describe the physical characteristics of the Synovial Fluid.

A

This fluid is similar in appearance and consistency to egg white, and helps to keep the articulating surfaces from making contact with one another.

It forms a thin film over surfaces within the capsule. Only a small amount of fluid is normally present (about 0.5ml in the case of a knee joint.) However this amount may increase, especially in a joint that is injured or becomes inflamed. In such cases, enough fluid may be produced to cause swelling and discomfort.

57
Q

Explain the structure of the Anticular Capsule.

A

It surrounds and encloses the joint.

The capsule comprises 2 layers:

  1. The Outer layer
  2. The Inner Layer
58
Q

Explain the structure of the Outer Layer of the Anticular Capsule.

A
  • The fibrous capsule, consists of dense, fibrous connective tissue attached to the periosteum of the articulating bones.
  • Its flexibility permits movement at the joint, whereas its strength resists dislocation.
  • The fibrous capsule is one of the principal structures that hold the bones together.
59
Q

Explain the structure of the Inner Layer of the Anticular Capsule.

A
  • The synovial membrane makes up the inner layer of the capsule.
  • It consists of loose connective tissue, the inner surface of which is well supplied with blood capillaries.
  • The synovial membrane lines the entire joint cavity, except the articular cartilages and a structure called the articular disc (if present).
60
Q

What is an Articular Cartilage?

A

It covers the articulating surfaces of the bones forming the joint.

-This tissue provides a smooth surface for movement.

61
Q

What is an Articular discs.

A
  • They occur in some synovial joints. In the knee, there are menisci (singular, meniscus) consisting of fibrocartilage extending inward from the articular capsule.
  • They divide the synovial cavity into two.
  • Flow of synovial fluid can then be directed to areas of greatest friction.
  • A tearing of the meniscus, commonly referred to as torn cartilage, often occurs in athletes.
62
Q

What is a Bursae?

A
  • Little sacs of synovial fluid, are another feature of some joints.
  • These are positioned in such a way as to prevent friction between a bone and a ligament or tendon, or between a bone and the skin, in cases where a bone inside a joint capsule is near the body surface.
63
Q

What are Accessory Ligaments?

A

They hold the bones together in many joints.

64
Q

What are the factors that keep the articular surfaces of synovial joints in contact with each other.

A
  1. The fit of the articulating bones - for eg. The way the head of the humerus fits into the socket of the scapula to form the shoulder joint.
  2. There is the strength of the joint ligaments (the hip joint illustrates this well).
  3. The tension provided by the muscles around the joint: in the knee joint, the fibrous capsule is formed principally from tendons attached to the muscles acting on the joint.
65
Q

List the terms use to describe types of movements at a joint.

A
  • Flexion
  • Extension
  • Abduction
  • Adduction
  • Rotation
66
Q

Define Flexion.

A

Flexion or bending, which usually decreases the angle between the articulating bones.

Eg. Bending the knee or bending the elbow.

67
Q

Define Extension.

A

Extension or straightening, which usually increases the angle between the articulating bones.

Eg. Straightening of the arm or leg after flexion.

68
Q

Define Abduction.

A

Which is a movement away from the midline of the body.

Eg. Lifting the Arms upwards and away from the body.

69
Q

Define Adduction.

A

Which is a movement towards the midline of the body.

Eg. Returning the arms to the sides after abduction.

70
Q

Define Rotation.

A

Which is the movement of a bone around its long axis.

Eg. Rotation of the humerus occurs when the palm is turned upwards by twisting the forearm from the shoulder.

71
Q

Explain the Effects of Ageing on the Skeletal System.

A

Bone is a living tissue and a person’s bone mass continues to grow until about the age of 30 years.

After this the bones gradually begin to deteriorate.

There is a gradual decrease in bone density as the bones lose calcium and other minerals. (This is particular pronounced in women after menopause.)

72
Q

Define Osteoporosis.

A

It is when the loss of bone mass that occurs with ageing becomes sufficient to impair normal functioning.

-As bone density decreases, the risk of fractures increases so that even minor bumps or falls can result in serious fractures.

73
Q

Which bones are most likely to be affected by osteoporosis.

A

The vertebrae, ribs, pelvis, wrist and upper arm, although any bone can be affected.

74
Q

What is usually the first signs of Osteoporosis?

A

A fracture.

75
Q

What are ways to prevent Osteoporosis?

A
  • People need adequate calcium intake in the diet.
  • An adequate amount of vitamin D (sunlight/dietary intake).
  • Plenty of exercise.
76
Q

What is Osteoarthritis?

A

It is a gradual change in the joints that occurs over time and is frequently associated with ageing.

In this disease the joint cartilage deteriorates so that the bone surfaces are no longer protected. The exposed bone begins to wear away and bony spurs or growths may develop from the exposed ends of the bone forming the joint. These growths and spurs decrease the space within the joint cavity, restricting movement of the joint.

77
Q

What are other factors that causes Osteoarthritis?

A
  • Irritation of joints

- Wear and Abrasion

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