Unit 1 - Anatomy and physiology for health and exercise - Skeletal system Flashcards
What do bones consist of?
Bone consists of a mixture of water, protein and mineral salts, the latter of which constitutes roughly 50% of its structure.
What is bone strength the rsult of?
Bone strength is the result of a combination of the hardness of the minerals combined with the tensile properties of collagen.
What is collagen derived from?
Protein.
What happens to a bone if it had too little of collagen?
The bone would shatter like an eggshell.
What happens if the bone had too little of the mineral salts?
The bone will bend like a piece of rubber.
What is the process of bone formation called?
Ossification.
What does the hardening and growth process of bones involve?
Replacing a cartilage “framework” with mineral salts.
Why are bones of young children softer than those of adults?
Because they still contain significant proportions of cartilage.
When is the hardening process of bone complete?
It may not be complete until 30 years of age.
In early life, what does the ossification emphasize on?
The emphasis of ossification is very much on bone growth and bone hardening.
In adulthood, what does the ossification emphasize on?
The emphasis of ossification is more geared towards replacing and maintaining existing bone material.
What are the primary cells involved in bone growth?
Osteoblasts.
What is the function of osteoblast?
Its function is to replace worn out or damaged bone tissue.
Their activity is coordinated with what other cells?
Osteoclasts, which remove the old bony tissue.
Does the maintenance of a healthy skeletal system happen in every bone equally with osteoblast and osteoclast?
No, it can vary according to the region of bone concerned; then end of the femur, for example, can be completely remodelled every few months, which contrast with the bone shafts, which may never be fully remodelled.
What other factors will remodelling of bone tissue tend to follow?
The lines of stress placed upon the bone, such as exercise and habitual posture.
Give an example of bad remodelling of bone tissue.
Incorrect exercise technique coupled with generally poor alignment will lead to a remodelling process that may reinforce the predominating bad posture.
What is bone formation predominantly regulated by in the pre-puberty years?
Human growth hormone (HGH), produced by the pituitary gland (located in the brain).
What is bone formation regulated by at puberty?
Testosterone produced by the male testes and oestrogen produced by the female ovaries.
In what important functions is calcium involved in?
Apart from providing the skeletal system with rigidity, it is also involved in muscular contraction, the transmission of nervous impulses and regulating fluid balance.
Why do bones have calcium reservoirs?
The calcium reservoirs in bones can either take up or release calcium depending on the body’s needs.
What happens if calcium is scarce?
It will be withdrawn from the bones, which is why diets that are chronically low in calcium tend to increase the risk of osteoporosis.
How is osteoporosis, brittle bone disease, caused?
By an imbalance in the delicate balance of the bone remodelling, whereby osteoblast activity decreases causing a drop in bone growth. This leads to a gradual loss in bone density and ultimately gives rise to a skeletal system that is unable to withstand the forces placed upon it.
What may cause an imbalance in osteoblast and osteoclast activity?
there may be a number of causes of the condition; however one of the biggest is the drop in oestrogen levels associated with the menopause.
Why are women more prone to osteoporosis than men?
The drop in oestrogen levels associated with the menopause makes woman significantly more likely to develop the condition than men. In men, a proportion of circulating testosterone is converted into oestrogen and this is thought to provide men with significant protection against loss of bone mass.
What other risk is there to develop osteoporosis in females?
Low calorific intake and/or overtraining also increase the risk of osteoporosis in females by depleting body fat stores which are one of the primary sources of oestrogen. Poor quality diets which are lacking in or have an imbalance of minerals and vitamins also increase the risks by limiting the availability of calcium
List Osteoporosis risk factors.
→ female sex - due to a drop in oestrogen levels
→ calcium deficiency - through poor diet or poor absorption
→ lack of exercise
→ smoking - causes a drop in oestrogen levels
→ family history
→ certain drugs, such as alcohol which interrupt normal hormonal and calcium regulation
→ low body fat
→ overtraining
In what two forms does bone tissue come in?
Compact and cancellous.
Describe a compact bone.
→ It has a relatively high density of bone matter.
→ It forms the external surfaces of bones, predominates in the shafts of long bones and serves to resist compressive forces.
Describe a cancellous bone.
- It is relatively more porous than a compact bone and if viewed closely has a spongy appearance.
- It predominates in the interior of bones and especially at bone ends (ephiphyses).
What are the spaces within the cancellous bone good for?
They form a vital function by housing red marrow, which is responsible for red blood cell production.
Name the four shape categories of bones.
- Long bones
- Short bones
- Flat bones
- Irregular
- Sesamoid (“seed-like”)
Describe a long bone.
- They have a greater length than width and consist of a shaft with normally two extremities.
- They contain mostly cancellous bone in their ephiphysis and more compact bone in their diaphysis.
- They act principally as levers.
Give examples for long bones.
- Humerus
- Femur
- Fibula
- Tibia
- Ulna
- Radius
- Metacarpals
- Metatarsals
- Phalanges
Describe a short bone.
They have a cubed appearance and are predominantly cancellous bone with an outer shell of compact bone.
Give examples for short bones.
- Carpals (except for the pisiform - sesamoid)
* Tarsals (except for the calcaneus - irregular)
Describe a flat bone.
They are thin cancellous bones sandwiched between two compact layers affording protection or large areas for muscle attachment.
Give examples for flat bones.
Scapula, cranial bones, costals, sternum and ilum.
Describe an irregular bone.
It is from complex shapes and cannot be classified in the
Give examples for irregular bones.
Vertebrae.
Describe sesamoid bones.
They develop within particular tendons at a site of friction or tension. They serve to reduce wear and tear in the tendon and increase the leverage of muscle by moving the tendon away from the fulcrum.
Give examples for sesamoid bones.
Patella (kneecap) and pisiform (carpal bone).
What are the epiphysis?
The bone ends.
What are the epiphysis mainly comprised of?
Cancellous bone.
What is housed in the epiphysis?
It houses much of the red marrow involved in red blood cell production.
What is the diaphysis?
The shaft portion of a long bone.
What is the diaphysis mainly comprised of?
Compact bone, although the inside of the shaft is hollow.
What is the principal role of the diaphysis?
Support.
What are epiphyseal plates?
The end of a long bone that is originally separated from the main bone by a layer of cartilage but that later becomes united to the main bone through ossification.
What is the periosteum and what does it do?
The periosteum is a connective tissue that supports bone health and development. The thin tissue has two layers that function in different ways. The outer layer, known as the fibrous periosteum, allows for attachment of muscle tissue to the bone and provides pathways for blood and lymphatic tissues.
What is the medullary cavity?
The medullary cavity (medulla, innermost part) is the central cavity of bone shafts where red bone marrow and/or yellow bone marrow (adipose tissue) is stored; hence, the medullary cavity is also known as the marrow cavity.
What is the articular (hyaline) cartilage?
Articular cartilage is hyaline cartilage on the articular surfaces of bones, and lies inside the joint cavity of synovial joints, bathed in synovial fluid produced by the synovial membrane, which lines the walls of the cavity.
What is a joint?
It is defined as a meeting point of two or more bones.
In which three types are joints traditionally categorised in?
Fibrous, cartilaginous and synovial.
Describe fibrous (immovable) joints.
Fibrous joints are connected by dense connective tissue consisting mainly of collagen. These joints are also called fixed or immovable joints because they do not move. Fibrous joints have no joint cavity and are connected via fibrous connective tissue. The skull bones are connected by fibrous joints called sutures.
Describe cartilaginous (slightly movable) joints.
→ some limited potential for movement.
→ articulating bones are connected by fibrocartilage.
Examples: pubis symphysis and between the vertebral bodies.
→ provide moderate stability and some limited movement
Describe synovial (freely movable) joints.
→ allow the “large” movements we associate with exercise
→ come in a variety of different configurations for different types of movements
→ has no connective tissue joining the articulating surfaces
→ joint space
→ ends of the bones are covered with a form of cartilage (hyaline cartilage) - to reduce friction between the moving surfaces
By what are bony surfaces held together?
by a fibrous articular capsule (joint capsule)
→ flexible enough to allow plenty of movement
→ tough enough to support the joint where necessary
What happens when sections of the joint capsule thicken?
They form ligaments which provide additional support to the joint.
Where is the synovial membrane situated which secretes a lubricant called synovial fluid?
On the inner surface of the articular capsule.
Describe the consistency of synovial fluid.
→ consistency of uncooked egg white
→ more viscous (thick) when the joint is inactive
→ fluidity increases as activity increases
What does synovial fluid do?
→ serves to help lubricate the joint surfaces
→ provides nutrients to the articular cartilage, which has a poor blood supply.
Name the 6 categories of synovial joints.
- ball and socket
- hinge
- pivot
- gliding
- saddle
- ellipsoid
What is a ball and socket joint?
→ allows for movement in almost any direction.
→ hips and shoulders
Describe a hinge joint.
→ like the hinges of a door
→ relatively simple structure
→ primarily allows either flexion or extension movements
→ example: elbow joint
Describe a pivot joint.
→ allows rotation around an axis
→ example: 1. neck → the top 2 cervical vertebrae (the atlas and the axis) form a pivot joint allowing rotational movements of the head.
2. Forearm: the radius forms a pivot joint with the ulna, causing it to “radiate” around the ulna and allowing supination and pronation of the forearm.
Describe a gliding joint.
→ typically flat articulating surfaces
→ joint action is a relatively simple sliding movement
→ ligaments generally restrict movement to forwards, backward and side-to-side movements.
→ example: patella and femur (patellofemoral), between the carpals and tarsals and the acromion process and clavicle (acromioclavicular).
Describe a saddle joint.
→ resembles one upturned saddle resting on another
→ movements: back and forth + up and down
→ no rotation
→ example: articulation between the base of the metacarpal of the thumb and the trapezium (one of the carpals) - (carpometacarpal)
Describe an ellipsoid joint.
→ similar to ball and socket but the shape is more oval in nature and consequently, movements tend to be restricted to side-to-side and back and forth
→ example: wrist joint between the radius and the carpals (radiocarpal) and metacarpals and phalanges (metacarpophalangeal)
→ sometimes referred to as a condyloid joint
Give a general description of the vertebral column.
→ The vertebral column consists of a series of individual vertebrae that are arranged to form a strong and flexible rod, which provides the body with central support and facilitates movement.
→ Offers protection for the spinal cord
→ provides the means by which nerves are distributed throughout the body
Of how many individual vertebrae consists the vertebral column and how many are located in which section?
→ neck or cervical region = 7 → thoracic or chest section = 12 → lumbar = 5 → sacrum = 5 → coccyx = 4
What basic anatomical features do the vertebrae share?
→ Anterior: main vertebral body, which is a cylindrical bony disc.
→ the body provides the surface for the intervertebral discs to attach to and these form the main cartilaginous joints of the spine.
→ Posterior: series of bony projections which interlink with adjacent vertebra to form synovial facet joints.
→ A series of openings or foramen punctuate the vertebra, these allow nerves and blood vessels to pass through and out of the vertebral column.
What are the intervertebral discs, that are sandwiched between the bodies of neighbouring vertebrae, composed of?
→ fibrocartilage shell, that surrounds a softer gel
What is the primary function of intervertebral discs?
→ shock absorption, however, they are vulnerable to injury if the back is excessively loaded with poor alignment or if the back is held in a chronically poor posture
The adult human spine has three major curvatures (excluding the sacrococcygeal), these are:
→ a posterior cervical curvature - a posterior concavity of the cervical spine
→ an anterior thoracic curvature - a posterior convexity of the thoracic spine
→ a posterior lumbar curvature - a posterior concavity of the lumbar spine
Humans move or pick up objects via a basic system of levers. What is a lever?
A lever is a simple machine consisting of a rigid rod that moves or pivots around a fixed point (fulcrum).
What are the three basic forms of lever?
1st class levers, such as a seesaw. 2nd class levers, such as a wheelbarrow. 3rd class levers, the most common form of lever in the body.
What is a 1st class lever?
Like on a seesaw, the fulcrum is located between the effort and the load. By moving the fulcrum closer to, or further away from the load; speed, range of movement and force generated will vary.
Give examples for 1st class lever in the body.
Relatively scarce in the body:
→ triceps extending the forearm,
→ gastrocnemius and soleus plantarflexing the foot when it is off the ground.
What is a 2nd class lever?
Example, wheelbarrow. the fulcrum and the effort are at opposite ends with the load placed in between. This arrangement produces plenty of force.
What is a 3rd class lever?
Example, drawbridge. The fulcrum and the load are at opposite ends with the effort placed in between. Generally produces less force than the other forms of lever, but provides a much greater range of movement and speed.
Name the three basic planes that represent anatomical cross-sections.
→ frontal plane: a vertical plane that divides the body into anterior and posterior parts
→ sagittal plane: a vertical plane that divides the body into left and right parts
→ transverse plane: a horizontal cross-section through the body separating the upper body from the lower body
What is an axis of movement?
An axis is a line that passes through a plane, about which movement (rotation) occurs.
What is a medial-lateral axis?
It passes through the sagittal plane: rotation would occur in the sagittal plane.
What is an anterior-posterior axis?
It passes through the frontal plane: rotation would occur in the frontal plane.
What is a longitudinal axis?
It passes through the transverse plane: rotation would occur in the transverse plane.
