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HSC - Senior Science > Medical Technology - Bionics > Flashcards

Medical Technology - Bionics Flashcards

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0
Q

How do pins work to repair bone fractures?

A
  • pins are a versatile implant used to hold bone fragments where it is difficult to use a plate
  • Pins are used when it is difficult to obtain adequate stability of the bone fracture by any other means
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1
Q

How do screws work to assist repair of bone fractures?

A

Screws are some of the most widely used devices for repairing fractures. They are used to fix bone plates to bones.

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2
Q

How do bone plates assist repair of bone fractures?

A

Bone plates are designed to be very strong and absorb the large stress forces generated when the bone moves. Bone plates are fixed with the use of screws. They hold bone in place until the bone full repairs and re-binds together.

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3
Q

What is the role of artificial joints in the human body?

A 
Artificial joints are used in cases where joints have been largely destroyed by degenerative diseases such as Arthritis or damaged badly in an accident.
Artificial joints are commonly used in:
-Knee
-Hip
-Shoulder
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4
Q

What materials are used in artificial joints?

A

Most common materials are:

  • Stainless steel polyethylene
  • Cobalt-chromium alloy-polyethylene combinations

Others include:

  • Titanium
  • Ultra high molecular weight polyethylene (UHMWP) used to combat artificial knee joints sinking to the lower bone of the leg, causing crushing of the trabecular bone.
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5
Q

What is the role of a pacemaker?

A

Pacemakers are used to correct arrhythmias which is when the heart beats too fast, too slow or irregularly.

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6
Q

How does a pacemaker work?

A
  • Battery operation device designed to stimulate contraction of the heart at a certain rate
  • Connected to small electrode which is place near the wall of the heart, allowing small electrical charges to travel through a wire to the electrode stimulating the heart to contract
  • Can be internal (surgically implanted) and others external
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7
Q

What materials are pace makers commonly made out of?

A
  • Casing of pacemakers can be made of stainless steel or titanium
  • Electrodes are made from platinum or platinum iridium alloy
  • Silicon rubber, polypropylene or epoxy can be used to seal parts of the pacemaker
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8
Q

What is the role of artificial valves?

A

Artificial valves can be used to replace damaged valves in the body that are no longer functioning to keep the blood flowing in one direction ONLY.

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9
Q

What materials are used to construct artificial valves?

A
  • Fabric ring surrounding them which allows surgeon to sew the device into place during surgical implantations
  • Constructed from collagen-rich materials such as pericardial tissues which have been obtained from pigs or cows, and are treated (to denature any animal proteins) minimising risk of rejection by human body.

Other Materials include:

  • Colbat-chronium alloys
  • Low-temperature carbon and titanium alloy with pyrolytic discs or balls
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10
Q

What is a crown?

A

A crown is a tooth cap that is placed over an artificial or natural root system. They have traditionally been constructed from ceramic materials with have relatively low strength.

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11
Q

What are dentures?

A

Dentures (false teeth) are generally made of acrylics for ease of fabrication. Dentures present problems because they are not particularly stable, they do not always look natural and they allow the jawbone to absorb substances.

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12
Q

What is the role of artificial lenses?

A

Artificial lenses restore function in the eye where a cataract has caused the previous lens to go cloudy.

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13
Q

What materials are artificial lenses made out of?

A

Artificial lenses are commonly made from:

  • PMMA
  • Silicone rubber
  • Copolymer blends
  • Nylon
  • Dacron
  • Polypropylene
  • Small titanium/gold loop to hold lens in place
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14
Q

Outline the TWO different types of artificial lenses

A

Non-foldable: made from PMMA (a hard plastic material

Foldable: made of either silicone or acrylic

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15
Q

What is a cochlear implant? How does it work?

A

Cochlear implants are an artificial hearing device that can replace a damaged cochlear.
It is designed to stimulate nerves inside the inner ear, thus produce a hearing sensation. It works by converting sound into electrical impulses which can be used to stimulate auditory nerves, sending a signal to the brain, which creates a hearing sensation.

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16
Q

Brake down the functions of a cochlear implant

A

Cochlear implants generally consists of two components:

  1. Headset with a 11-channel stimulator in a titanium capsule, with platinum electrodes which are implanted inside the skull behind the ear close to the nerves
  2. A pocket speech processor which breaks down speech into its various components before transmitting it back to the stimulator
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17
Q

What is the role of prosthetic limbs?

A

These are artificial limbs that are used to replace entire limbs or part limbs on amputees. They are added to missing limbs or amputees and under extensive prosthetic rehabilitation by a prosthetist and inter-disciplinary teams of healthcare professionals such as physiotherapists.

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18
Q

What materials are used in prosthetic limbs?

A

Materials include:

  • Silicone matrix for liners
  • titanium, aluminium, stainless steel or carbon fibre composites
  • Modern prosthetic limbs often incorporate electronics and pneumatic mechanisms of considerable complexity
19
Q

Outline the role of the hearts pacemaker

A

The hearts pacemaker is found in the sinus node and controls the heartbeat. The node sends an electrical signal to the atria followed by an electrical signal to the ventricles.

20
Q

why are artificial pacemakers used instead of the hearts natural pacemaker?

A

Artificial pacemakers are used when the hearts pacemaker is not functioning effectively and the electrical signal from the sinus node is blocked from reaching the ventricles.

21
Q

How are pacemakers entered into the human body?

A

Pacemakers consist of 3 parts; a battery powered generator, circuits, and wires that connect to the heart. The generator is usually implanted just beneath the skin below the collarbone. The leads are threaded back into position through veins leading back to the heart.

22
Q

Explain the use of different materials in the pacemaker?

A
  • Stimulator is fully sealed in titanium casing due to titanium being NON-CORROSIVE and NON-REACTIVE in the human body
  • The electrode outlets are protected by a polypropylene cuff to prevent loss of electrical signal during transmission
  • Electrodes insulated with silicone or polyurethane rubber embedding cardiac wall ensuring that electrical signal is controlled and focused
  • Tip of electrode usually made of platinum-10% iridium alloy as it is mechanically strong and non-corrosive and non-reactive in the human body.
23
Q

What are the risks involved with faulty valves?

A

The heart must work harder which can cause a heart attack and/or death due to greater strain place on the heart.

24
Q

What are the symptoms of faulty valves?

A

Symptoms include shortness of breath during exercise, tiredness, a continual cough and occasional chest pain.

25
Q

What internal effects do faulty valves encompass?

A
  • Valves being inflamed may cause scar tissue to form a fuse parts of the valves together
  • If valve is damaged and cannot close completely, blood will be lost in back-flow and may not reach destination where it is needed
  • Damaged valve may obstruct blood flow through heart or vessels
  • The more damaged the valve is, the less efficient the heart is working creating strain on the heart
26
Q

Explain the role of the appendicular skeleton.

A

The appendicular skeleton is made up of the pelvic girdle, shoulders, arms and legs. The main function of the appendicular skeleton is to support the arms and legs.

27
Q

Outline the skeletal systems role in storing nutrients.

A

Apart from support and protection, the skeleton also serves to store mineral salts such as calcium and phosphorus. The skeleton also produces blood cells in the bone marrow.

28
Q

Explain the functions of the axial skeletal system.

A

The axial skeleton is made up of skull, backbone and the rib cage. It has two functions:

  1. To support the main body axis achieved by the spinal column
  2. To provide protection to vital organs
29
Q

Explain what is meant by synovial joint.

A

A synovial joint is a freely moving joint because there is a space between the bones forming the joint. A synovial membrane surrounds the joint, secreting synovial fluid into the space to provide lubrication and allow easy movement.

30
Q

Explain what is meant by a Ball-and-Socket Joint.

A

Ball and Socket joints occur where a rounded head ball fits into a cup-shaped socket on another bone. Examples include hip and shoulder joints.

31
Q

Explain what is meant by hinge joints.

A

Hinge joints occur where a bone with a concave shape meets a bone with a convex shape, permitting only back and forth movement such a bending and straightening. Examples include knee, knuckle and elbow.

32
Q

Explain what is meant by double-hinged joints.

A

Double-hinged joints are in place where two saddle-shaped surfaces join at right angles to eachother. The joint allows side-to-side and back-and-fourth. Examples include carpal and metacarpal bones of the thumb which allows the thumb to be placed across the palm of the hand. A double hinge joint is also known as a saddle joint.

33
Q

Describe what is meant by sliding joints?

A

Sliding joints occurs where two bones with flat surfaces slide on each other. Their movement is restricted by a number of ligaments. Sliding joints permit side-to-side and back-and-fourth movement. Examples include between thoracic vertebrate and ribs, and between the carpels and between the tarsals.

34
Q

Describe the role of cartilage.

A
  • Cartilage is a tough and fibrous substance that is between bone ends in some joints. The cartilage allows the bones to move freely over each other, reducing friction and protecting the bone ends.
  • Cartilage is thicker in the leg joints where the load is greater.
35
Q

Describe the role of synovial fluids.

A
  • Synovial fluid keeps the joints well oiled and acts like a cushion, keeping the bones apart.
  • It is secreted by the synovial membrane, the amount being dependent on the level of activity of the joint.
36
Q

Outline the role of silicone and its use in bionics.

A
  • It may be combined with silica (a filler) to improve its mechanical properties. This allows the silicone to be manufactured to the mechanical strength required for most applications.
  • It has high elongation properties before the addition of a filler i.e. it can be stretched if required.
  • The polymeric structure of silicone closely resembles the structure of natural polymer components, like collagen. This allows compatibility between living tissue and silicone.
  • It has a similar density to natural tissue
  • It has a high permeability to oxygen, which means minimal obstruction to the distribution of oxygen around the body.
37
Q

Why is UHMWPE a suitable alternative to cartilage surrounding a ball and socket joint.
Explain its:
1. Biocompatibility with surrounding tissue
2. Low friction
3. Durability

A

UHMWPE is biocompatible with surrounding tissue. It possesses a similar density to living tissue, and therefore tends not to cause problems in the body.

UHMWPE has a low friction coefficient and this, along with other exhibited characteristics, such as high hardness, high tensile strength, high elasticity, add to its suitability of it for use in joints as artificial cartilage.

UHMWPE is durable: it has no known effective solvent at mild temperatures. High temperatures and pressures must be used to manipulate the material and gain the desired product. UHMWPE also exhibits a very high creep resistance. Creep resistance is the tendency for polymers to deform when under constant stress.

38
Q

What characteristics of ‘superalloys’ and materials are essential for making a ball and stem components for large joints?

A
  • high strength
  • low weight
  • good compatibility with body tissue
  • inertness
39
Q

Explain how cement-free implants of artificial joints are undergone.

A

The artificial joint is designed to wrap around the remaining bone, once the diseased bone is removed. Cement-free implants possess a porous surface, which permits bone tissue to grow in and create an interface between bone and implant.
Cement-free implants are more vulnerable to loosening and take a longer time for the patient to fully recover.

40
Q

Explain how the cemented implant of artificial joints is undergone.

A

Once the diseased femoral head of the bone is cut off, the medullary canal is filled with a doughy bone cement, and the implant is inserted. Alignment of the implant with the other components of the joint is verified before the bone cement sets.

41
Q

outline the positives of cemented implants.

A
  • It allows the initial fixation of the implant to the bone.
  • It acts as a shock absorber for the joint, as it is a viscoelastic polymer.
  • It helps to spread the load more evenly over a large area and reduces the stress concentrated on the bone by the prosthesis.
42
Q

Identify the function of an artificial lung (iron lung).

A

The pressure inside the iron lung is varied, causing the thoracic cavity to move up and down and forcing breathing. In this way the artificial lung removes carbon dioxide from the lungs and replaces it with oxygen, identical to the functions of a natural lung.

43
Q

When would artificial lungs be used?

A

Artificial lungs may be used to treat patients with acute respiratory distress syndrome, pneumonia and chronic lung disease, as well as organ transplant patients and patients in intensive care.

44
Q

What is life support?

A

Life support is defined as any therapeutic technique or device used to maintain life function. The life support machines pictured by many are the ones used in intensive care, or in palliative care. These systems consist basically of a ventilator unit (assist breathing) and a heart rate monitor (to alert staff to any changes in heart beat).

45
Q

Describe pivot joints

A
  • Where a cylindrical bony point rotates within a ring of bone/ligament
  • Found in the neck

HSC - Senior Science (4 decks)

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