Skeleton – Joints

Skeleton – Joints

I really should have enjoyed Joints way more that what I did as a headache felt like I was being repeatedly stabbed… and I have noticed these notes are probably the least detailed I have done so far. But the essentials are there. Enjoy J

 

Joints hold bones in place but allow movement, it is the surface between two bones.

Kinesiology : The Study of Motion

Arthrology: The Study of Joints

 

Joints are classified regarding whether or not they have the synovial joint cavity and the type of connective tissue.

Function:

v  No movement =synathrosis

v  Limited movement = amphiarthrosis

v  Free movement = diarthrosis
Structure:

v  Fibrous Joint – synovial cavity absent

  • Bones held by fiberous connective tissue, (think the gap between the tibia and fibula, that is filled with connective tissue)
  • Amphiathrosis

v  Cartilaginous – synovial cavity absent

  • Are divided into Synchondroses which are Synathrosis, and Symphyes which is Ampiarthrosis

v  Synovial – synovial cavity present

  • Sits between the two bones
  • Diarthrosis
  • Cartilage = absorbs shock, allows the bones not to wear away
  • Cartilage not covered by the synvial joint

 

 

 

Synovial Joints:

v  Planar Joint:

  • Side to side and back to forth movement
  • Bone surface is flat or slight curve
  • Ligaments prevent the rotation

v  Hinge Joint

  • Convex bone surface fits into concave bone surface
  • Flexion, extension and hyperextention
  • Knee, elbow

v  Pivot Joint

  • Circular like a disk
  • Rotation on a longitudinal axis
  •  (turning head side to side – no)

v  Condyloid/ Ellipsoidal Joint

  • Oval shaped projection fits into oval shaped depression.
  • Abduct – away from body, adduct – towards body.  up flex and down extend
  • (wrist)

v  Saddle Joint

  • One bone fits as a person would in a saddle, the saddle being another bone
  • Allows thumb across palm, repositioning is when thumb returns

v  Ball and Socket Joint:

  • Ball fits into cup depression
  •  flexion and extension (forward and back), Adduction and Abduction (side towards and side away)
  • Rotation
  • Hip and shoulder joint

 

Sprain Vs Strain

v  A Sprain is a twist of the joint that tears the ligament, can damage nearby blood vessels, muscles or tendons.

v  Swelling, haemorrhage of blood vessels

v  A Strain is less serious, either over stretched or not fully torn muscle

 

Bursae and Tendon Sheaths:

v  Bursae are fluid filled scals that reduce friction

v  Tendon Sheaths are essentially a tube version of Bursae that wrap around tendons and joins muscle to the bone.

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Leaving On a Jet Plane and Books?

After my final exam today (anatomy and physiology) I am leaving Australia for a month. 

First stop China.

I have my hiking pack ready and it is full of …. I don’t even know, I plan to walk the Camino de Santiago  in Spain. So I have two sets of clothes and other bits and pieces.

So I get to go by public transport to my University with my pack, then catch peak hour trains to go to my aunts place while I wait for my flight.

I must admit I am thrilled, but this morning, hell the whole week instead of studying I have been booking accommodation, packing and repacking. The adrenalin rush I don’t think will kick in until I am on the plane…. I get air-sick, I found that out on my second long-haul flight over to the United Kingdom. AWESOME, I admit I do feel bad for the people who have to sit next to me on the flights.

And for anyone who did read the book = Pride and Prejudice and Zombies… I dont know what to say, I found it harder to read, I dont know why. It was written really well… I just couldnt get into it. at chapter 6 I hit a dead point where I felt like my brain was going to mush, dont get me wrong, I loved the original. But somehow adding zombies into the mix killed me(not literally), I felt so brain dead after reading the book that I ended up watching gypsy sisters (the most tacky and trashy tv show) for several hours.

Skeleton and the Names – Axial and Appendicular

Skeleton and all the names

Axial Skeleton:

Is made up of 80 bones and lies along the longitudinal axis of the body. It includes the:

v  Skull – cranial (cranium) (8 bones and 14 bones of the face)

  • Forms a cranial cavity and smaller cavities = nasal and eye
  • Some contain a mucus membrane lined cavity (paranasal sinuses)
    • Cavity that connect to the nasal cavity, lines by mucous membranes and serve to lighten the skull as well as something to do with speech (resonating chambers).
    • The frontal, sphenoid, maxilla and ethmoid  (all cranial bones) are containing the sinuses.
    • Sinusitis is the inflammation of the membrane due to an allergy
    • Sutures: are immovable joints that are between skull bones. They hold the skull bones together. They include: Coronal (front), sagital (top), lambodial (back of skull), squamous sutures and others.
    • Cranial Bones:
      • Frontal = above the bridge of the nose, across the eye socket half way and up to the crown of the head (only one of these)
      • Occipital = the bottom of the skull (follow the bones up your neck until you get under your skull, I would describe it as being there, it is single)
      • Parietal = between the frontal and the occipital (there is a right and left) sides and roof of the cranial cavity
      • Temporal = (has a right and left) sides of the head.

¨      Has many parts : temporal squama, zygomatic process. ect

  • Sphenoid = think of where your sinuses are, behind the eye socket and nose.
  • Ethmoid = is behind the nose, still covered  by frontal.

 

  • The cranial bones protects and is home to the brain and the ear bones, the outer surface provides muscle attachments for jaw, neck and facial muscles. The inner surface attachments stabilize the brain, blood vessels and nerves.

 

  • Fontanels are the top of the skull, it is what allows baby’s to be birthed, it is connective tissue membrane filled space between the cranial bones of a infant, they allow the skull to modify its size as it passes through the birth canal.  It also permits rapid growth. Eventually it will close up and ossify, although this is not always the case. During WW2, men in Australia whose scull hadn’t closed at the top were not allowed to fight even if they were healthy, willing and able. The fontanels that are the main ones are the anterior, posterior, anterolaterals and porterolaterals.

 

  • Facial bones:
    • Nasal (2 bones)
    • Mandible – Only the ear and the lower jaw (mandible) are movable
    • Maxillae (2 bones) – upper jaw
    • Zygomatic (2 bones)
    • Lacrimal (2 bones)
    • Palatine (2 bones)
    • Vomer
    • Inferiour nasal conchae (2 Bones)

 

  • Facial Bones protect the sense organs and soft tissue (taste, smell and sight). Which in turn support the entrance for the digestive and respiratory system.
  • Facial bones provide the framework of the face as well as provide support and house the blood vessels and nerves.

 

v  Hyiod (that is the loose bone in the throat)

  • It is that u shaped bone that just kind of floats around (it doesn’t exactly float though!) it is held in place by muscles and ligaments from the skull.
  • It is under your jaw and above the larynx.

v  Vertebrae – 26 bones

  • The vertebral column (along with the sternum and ribs) makes up the trunk of the skeleton.
  • The bones are arranged in 5 segments:
    • Cervical (looking at the back of the body, it would be in the area of the neck)
    • Thoracic (looking at the shoulders, it is the area from the shoulders down midway of the back. Thorax refers to the entire chest, a bony cage consists of the sternum, costal cartilages, ribs and the bodies of the thoratic vertebrae, it protects the organs and provides support for shoulder and upper limbs)
    • Lumbar (Lower back region)
    • Sacral (fused part of the low lower back)
    • Cocygeal (coccyx – fused sitting bones – lowest of the lower back)
    • Intervertebreal Disks: they absorb the weight shock,
    • All four curves of the spine are developed by 10 years old. The primary curves are formed in the womb, the secondary curves are formed when the baby first lifts it’s head and the lumbar forms during the sitting up and walking stage.
    • A herniated disk is a slipped sidk, the nerve becomes tra[[ed and eventually you will lose it.

v  Ribs –  24 bones

  • 1-7 are true ribs, attached with own cartilage towards the sternum, the other 8-12 are false and don’t attach directly. (11-12 are floating – don’t attach to anything)
  • 12 ribs are the structural support to the sides of the thoratic cavity.

v  Sternum 1 bone

  • Located in the anterior midline of the thoratic wall

v  Ear Ossicles (3 ear bones each ear (6 all up))

 

Appendicular Skeleton:

The remaining 126 bones, it is involved in the upper and lower extremities and the pelvic (hip) and  pectoral (shoulder) girdles that link the upper and lower extremities.

v  Pectoral (shoulder) girdle consists of:

  • Scapula and clavicle, the clavicle is attached to the sternum and the scapula, the scapula is held in place by muscle only under ribs.

v  Humerus (long bone of upper arm)

v  Ulna and Radius, (ulna on the medial side of the forarm and radius on the lateral side of the forarm) –thumbs pointing away. (ulna runs to little finger (each finger has 3 bones and thumb has 2) and the radium runs to thumb)

v  Carpals, Metacaples and Phalanges (wrist, palm and finger bones in laymans terms):

  • 8 carple bones are bound together by ligaments to make the wrist (proximal row –lateral to medial : Scaphoid, Lunate, Triqentrum, Pisiform (she looks too pretty))(distal row – lateral to medial : Traperzium, Trapezoid, Capitate, Hamate (try to catch her))
  • 5 metacarples in the palm of the hand
  • 14 phalanges, three in each finger, and two in each thumb, one is called : phalanx.

v  Pelvic Girdle:

  • Pelvic girdle is made up of two hipbones coming together at pubic, the hip bones (ilium, pubis and ischium) fuse after the baby is born.
  • Sacrum, coccyx and 2 hipbones make the pelvis. The pelvic brim separate false (houses the abdominal organs)and true pelvis.
  • The size of the pelvic rim determines gender:
    • Male: Larger, heavier, bigger surface area, large muscle attachment. Circle narrow, higher hips, the arch is small.
    • Female: wide and shallower, has larger inlet and outlet, more space in true pelvis and the pubic arch is >90degrees. Women have : lower hips (designed for childbearing) and a more round and wider.

v  Femur: largest and heaviest bone in the body, the neck of the bone is the most common fracture site.

v  Patella: kneecap. A sesamoid bone located anterior to the knee joint, it increases leverage and protect the knee joint

v  fibula = less dense, parallel/lateral to the tibia

v  tibia = really dense, (shin bone) medial weight bearing bone of leg

v  Tarsals, Metatarsals and Phalanges:

  • 7  tarsal bones make up the ankle (Talus = ankle, calcaneous =heel, Navicular = like a boat, Third Cuneiform = wedge shape –lateral ) (second cuneiform = wedge shaped – intermediate, first cuneiform – medial, cuboid = cube)
  • 5 metatarsal bones are in the foot
  • Phalanges in the toes are laid out like that in the fingers, 14 bones in each foot.

 

 

Types of Bones:

v  Long = compact (humorous)

v  Short =spongy except for the surface, which is a thin layer of compact bone (wrist and fingers, trapiziodal)

v  Flat =plates of compact enclosing the spongy, 2 layers. (Shoulder blade and sternum)

v  Irregular =variable (vertebra)

v  Sesamoid = development of tendons or ligaments (patella in knee)

v  Structural = in joint between the skull bones

 

SURFACE MARKINGS:

If you have ever watched a crime show where they identify a dead body that is only bone, or mostly bone, they are using the surface markers.

Look Out For:

v  Depressions and openings in joints or that allow the passage of soft tissue.

  • Fissures = narrow slit between the neighboring part of the bone
  • Foramen =an opening
  • Fossa = a shallow depression
  • Sulcus = a groove
  • Meatus = a canal (like inner ear)

v  Projections and outgrowth that are either attachment points for connective tissue/muscle or help form joints.

  • Condyle = large round bump that protrudes
  • Facet = smooth and flat articular
  • Head = round articular projection supported on the neck of a bone.
  • Crest = ridge or long projection
  • Epicondyle = projection above condyle
  • Line = long narrow ridge
  • Spinous Process = sharp and slender projection
  • Trochanter = very large projection
  • Tubercle = small and round projection
  • Tuberosity = large and round rough projection

Next Post on joints 🙂 hope you are excited!

Doctor Doctor Give Me Some News

I have just gotten back from an appointment with a doctor today regarding my mental health. Little did I know when I walked into the medical centre, I would have my consultation with a total super star.

In our talk there was no judgement, none not even a little. I felt so comfortable that I could say anything. and in a few sentences of me talking, he knew who I was to the ability he diagnosed the type of depression from the patterns. I felt like he was a psychic.

http://www.drnickkrasner.com/

I couldn’t believe I was talking to the man. Dr Krasner is one of my hero’s. Unlike people who’s hero’s or role models are footballers or supermodels, Mine are doctor and surgeon.  This is the first time one of the people I look up to are actually famous… well published. 

Here is the link to his book: 10 Simple Paths To Happiness . I still cant believe how lucky I was to talk to someone who actually understood, not just treated sick people before. At the time of course I had no idea who he was, and thinking about it, it doesn’t change anything. I knew he was a great doctor before I knew he wrote the book that put a definition to depression.

 

I know I am fan-girling, but that book, was/is the first step in the right direction. I dont think he really cares about being published that much, more about helping people from the heart.

Skeleton, Bones, Bone and more Bones

Alright, this is a little post about Bones, just a little info to make you day get more boring.  These are the first segment on the skeleton. I hope you enjoy it.

Anatomy and Physiology

Skeletal System: BONES

The bone is an organ, made up for lots of different tissues all working together:

  • Bone
  • Cartilage
  • Dense connective tissue
  • Epithelium
  • Blood forming tissue
  • Adipose tissue (yellow bone marrow) and
  • Nervous tissue (funny bone).

Bones are always changing through life, a bit like a bank account = the calcium deposits and releases.
The function of a bone:

  • Support the whole body together as the skeleton to which muscles are attached.
  • Protection.
  • Assistance with movement, muscles contract and bones are pulled.
  • Mineral homeostatis. The calcium imbalance is maintained by the bone, if body is lacking the bone will release calcium into the blood (bank account refernce)
  • Blood cell production and Triglyceride storage ( think : long bone).

 

A Long Bone is made up of:

  • Diaphysis (hollow in the middle) – grows in the shaft of the bone = a long cylinder- it maintains the proportion of the bone.
  • Medullary Cavity (bone is hollow, cavity is the medulla – lined with connective tissue)
  • Epiphysis ( grows over the proximal and distal of bone – the ends)
  • Metaphyses ( the neck of the bone where Diaphysis meets the epiphysis (including the epuphseal plate – determiins the length of the bone. The calcium turns to bone when growing has stopped and is then called the Epiphyseal lining))
  • Articular cartilage (white covering that protects the joint)
  • Endosteum (the connective tissue lining inside the hollow bone (the medulla cavity), is a single layer of bone forming cells as well as the connective tissue)
  • Periosteum (connective tissue that covers the whole bone except for the articulate cartilage that covers the joint. Has two layers, the outer fiber layer and the inner osteogenic layer. It allows growth in width but not length) is an attachment point for ligaments and tendons.

Types of cells in bones:

  • Osteogenic  cells (osteoprogenic cells – are undiffrenciated, the divide to replace themselves and become osteoblast, they are found in the periosteum and the endosteum)
  • Osteoblasts –immature cells they produce matrix and collagen (job to produce bone) they can not divide.
  • Osteocytes – mature cells, they don’t produce matrix or collagen. They just maintain bone.
  • Osteoclasts – are specialised cells from White Blood Cells (WBC eat bacteria) move along surface of bone and provide calcium from bone if it is required. (Eat bone via secreting enzymes which release the calcium)

Matrix of a bone:

  • Inorganic material – salt and mineral makes it hardy
  • Organic collagen fibers  make it felxibleso it doent stretch or tear
  • Bone is not solid, it has small spaces, in spongy bone, there are a lot and compact bone has little space.

Compact Bone:

  • Arranges in units called osteons (contain central blood vessles, lymphatic vessels, nerves, calcified matrix and osteocytes), they are aligned along the lines of stress.
  • Makes up the long shaft of long bones and the external layer covering all bones.
  • Helps resist stress caused by weight and movement.

Spongy Bone:

  • Also called Cancellous bone
  • Doesn’t have osteons, it instead has trabecules  (latticle network that forms along the lines of stress, where blood cells develop in the red bone marrow) surrounding the red marrow filled spaces.
  • Forms the structure of short, irregular and flat bones. As well as the epiphysis of long bones.
  • It protects the red bone marrow, it forms columns that form interlaced networks.

Bone Formation:

  • All embryonic connective tissue begins as mesenchymes (bone is formed from this tissue).
  • Bone formation is called ossification or osteogenisis (bone creation). The mesenchyme cells provide the template for ossification.
  • There are two types of Ossification:
    • Intramembranous Ossification: bones form from or within fiberous  connective tissue membranes : bone forms between two layers
    • Endochondral Ossification: in the formation of the bone from hyaline cartilage models (inside cartilage)

Most bones in the body (not the mandible or the skull though) are made via the endochondral bone formation: the process is:

v  Replacement of cartilage by bone. To make the cartilage model (a template): mesenchymal cells form a template of the bone,

v   the growth is due to the chondrocyte dividing and the matrix production, the cells in the middle  area of the bone then calcify (the cells in the middle of the bone burst which changes the pH and chondrocyde death occurs as does the calcification)

v  In the same area, osteoclasts and osteoblasts are brought : the osteoblasts deposit the bone matrix over the already calcifiedcartilage = spongy bone lattice (trabeculae), the osteoclasts on the other hand form the medullary cavity.

v  The blood vessels dissolve paths in the new matrix to form the cavity.

 

Growth in Length:

  • NOT GROWTH IN WIDTH
  • The growth plate (epiphyseal) is made up of :
    • Zone of resting cartilage – holds the growth plate to the bone
    • Zone of proliferated cartilage – rapid cell division
    • Zone of hypertrophic cartilage – cells enlarge but remain in column
    • Zone of calcified cartilage – cells are dead since the matrix calcified, the osteoclasts remove the matrix and osteoblasts and capillaries create bone over calcified cartilage.
    • The activity on the growth plate  is the only way Diaphysis can growth in length, when the growth has finished the plate closes and is replaced by bone = bone is done growing. It eventually will calcify.
    • The cartilage cells are produced by mitosis, they are then destroyed and replaced by bone = stop in growth. And the epiphyseal line is created
    • Between 18-22 growth stops as the epiphyseal plate closes

 

Growth In Thickness:

  • Only can grow wider due to appositional growth (adding layers of diameter to the bone)
  • STEPS:
    • Periosteal cells turn into osteoblasts and secrete collagen and other organic matter to create matrix.
    • Ridges fuse and the periosteum becomes the endosteum (EVENTUALLY)
    • New concentric llamellae are formed
    • Osteoblasts under periosteum form  new circumferential lamellae.

 

Bone Remodelling:

  • Old bone is constantly brokendown by osteoclasts  and new bone is formed by osteoblasts
  • Hormones and calcitriol control the bone remodelling and growth.
  • Osteoclasts form a tight seal on the cell and secrete enzymes bellow them = release of calcium into body and the osteoblasts then build new bone.

 

Repairing Bone

  • Fracture repair is repairing a break in the bone
  • It involves:
    • Bleeding, a clot must be formed (fracture hematoma) bleeding ceases
    • The fracture hematoma will be organised into granulation tissue (procallus, which will change into soft tissue) the clot will take around 6 hours to form, the bone cells will die and the inflammation brings in phagocytes to clean up the mess and new capillaries will grow in damaged area
    • Soft tissue(soft tissue is along the area of damage) will turn into spongy bone of hard callus (callus is protection until healed) which will join the two broken ends (takes around 3-4 months)
    • Then the callus will be turned back to original form
    • Bone is quicker to heal than cartilage
    • If bones are not aligned correctly they will need to be moved, by hand or by surgery (screws).
    • Any injury in the body where cells are damaged or die is cause for inflammation and the healing process will begin with phagocytes coming in to remove the debris. Inflammation is a good thing BUT it can get out of control.

 

 

 

Bone:

  • The bone is a huge supply of blood.
  • The more exercises you do  as a kid the better your bones will be as an adult. And the process of calcification only happens when collagen fibers are present.
  • Smoking stops growth.
  • The distal Femur is remodled completely every 4 months = due to impact and weight bearing.
  • Cardiac arrest if there is too much calcium in the body and Respiratory arrest will occur if too little. The parathyroid hormone is secreted if the level of calcium is low.
  • Loss of calcium in older people usually results in osteoporosis, bones also become fragile due to the decreased rate of protein synthesis.

 

Bone Disorders:

  • Rickets
    • Affects children
    • Calcium salts aren’t stored properly
    • Bones are soft (bow legs)
    • Bone deformities as a result
    • Osteomalacia
      • New adult bone doesn’t calcify
      • Hip fractures are common

Make sense? keep tuned for some more skeleton related anatomy and physiology notes by simply following my blog 🙂

Breakdown of the Day

Today something happened to me which hasn’t happened in a while. IRRATIONALITY!
the spontaneous tears.
After getting a call from a marketing company and having to explain to them why I can’t buy and sample their wines anymore I found myself in tears, hating everyone and anything.
To be honest I thought I was over the pity parties, but today on the phone was the realization that it doesn’t work like a magic wish.

Struggling to say no to alcohol is a very real problem for me. I have been sober for only three months in this stint, not the longest but defiantly it’s just as hard as every time before.

I found that having to speak to someone who’s job it is to sell alcohol, and figuratively put it down their throats over the phone, to be the most difficult of all.

I personally very much have the approach to dealing with my alcohol and mental health related problems to pretend it doesn’t exist… Well blogging is that little pity party. Sure I go to sessions, but the words don’t exactly escape my lips in leaps in bounds.

But the man I spoke to on the phone who was reading a specific selling speil didn’t seem to understand no was no. After trying to explain that I couldn’t drink alcohol for the third time because I couldn’t handle it, the man tried to be coy and said:

you don’t mean ‘can’t’ you mean won’t

I don’t know what it was but something in me wanted to explain for the fourth time. I could have hung up but I kept going. I was riled up for some reason as if I had to defend myself. I know it was so silly but I was so upset that I had to justify that i couldn’t buy his silly product just because he said he understood.
I don’t know if it bothers who is suffering from a disorder, mental or physical, and someone says they are too but doesn’t understand the limitations.

While in my hysterics I was trying to explain that I was an alcoholic, something I find difficult to admit to, the man chimed in that he was one also, yet continued to push the alcohol, saying that “since you are an alcoholic, you must love alcohol, so why don’t you get it?” What kind of person exactly does that?

I feel like I am having a tantrum over something so small (I actually know it is small) but I feel how I feel.

I haven’t burst into tears on the phone to a marketer for a long long long time…. And while it left me feeling empty and hateful inside I realized that that man was doing his job, while he did it in not an appropriate manner, I was the one who got upset because he wouldn’t drop it ( I realize now I could have simply hung up). But how many sales reps have someone crying on the phone in hysterics?

…. Actually don’t answer that, there are probably a number of them.

20130617-180244.jpg

I think deep down I knew it was irrational to get upset but on the plus side I must have really wanted to get it off my chest.

Introduction To Microbiology – Viruses

Microbiology – Viruses

Virus

  • Viruses basically invade cells, cause colds, influenza, HIV, small pox, MMR, warts, polio and many more.
  • Some viruses are asymptomatic= don’t show symptoms
  • Viruses have particular cells they can infect, lock and key
  • Host soecificity = lock and key
  • In Latin, virus means poison.
  • Existence proven by Ivanowski (Russian Scientist) 1892 – first started with plants
  • Virus are: self-reproducing particles that enter hosts and reproduce inside cells

 

Virology

Is a branch of Microbiology that looks at viruses.

Characteristics

  • Can only be seen by electronic microscope
  • Simplest form of life
  • Neither prokaryotes or eukaryotes
  • Smaller than bacteria
  • Can’t be cultures in labs
  • Huge diversity
  • They live inside cells – feeding, reproducing and growing = they need organisms to live = cant carry out metabolic reaction alone, viruses take over ribosomes
  • Potentially infectious = dependant on Host

Structure

  • Capside = protein layer that protects RNA or DNA, composed of protein unit called capsomeres.
  • Capsides have different shapes:
    • Polyhedral
    • Rod
    • Complex

Lacks ribosomes and other replication equipment. Our bodies can recognise the antigenic properties and build antibodies.

v  Some viruses have an additional protective layer , a lipid usually (envelope) – makes it weaker to environment change, naked viruses are more stranger to pH change

v  Viral enzymes are used to infect, they are targets for antiviral therapy

v  Outside the host cell, they are unable to carry out any metabolic reaction

Classification/ Terminology

Virion: mature virus; will have nucleic acid and capsid or nucleic acid, capsid and envelope: they are capable of transmission from one host to another

Virus: intracellular infectious particle consisting of nucleic acid and protein coat (capsid)

Viroids: Infectious agent, don’t have a capsid. Only have a closed circular RNA molecule

Prion: consists only of protein : not alive, lacks genetic material. BUT it can go to a host cell and infect it.

 

v  Shape is used for classification

v  Genetic Material found will depend on the nature and function of the virus

v  Division based on genetic material:

  • DNA
  • RNA
  • Single or Double strand

 

Types of Viral Infection:

v  Acute lytic:

  • Virus infects host cell > new viruses are created > host cell dies> virus spread to neighboring cells.
  • Identifiable symptoms and signs (You know they are sick)
  • Eg common cold, mumps, flu

v  Subclinical:

  • No recognisable symptoms or signs : swollen glandsand a sligh fever
  • Can harm a fetus if mum is incontact with it during pregnancy

v  Chronic:

  • Possible no symptoms
  • Virus lives in host at a low level carrier state
  • Unlikely to be cured
  • Infectious
  • Eh HIV and HepB

v  Latent:

  • Virus lies dormant- will reactivate later
  • Common in herpes virus
  • Initial symptoms >apparent recovery> virus will still be there
  • Eg. Chickenpox, Shingles, G – fever

Infection
Infection of host:

v  Inhaled droplets : rhinovirus, influenza

v  In food or water: HepA, Norovirus

v  Direct transfer: HIV, HepB

v  Vector: Yellow Fever, West Nile Virus

 

v  Viruses have a host specificity, restricted range of hosts. Thank Lock and Key Fit

Adsorption = Virus attaches to host receptor

Penetration = genetic material enters host cell

Uncoating = genetic material of virus hijacks the cell, taking cell away from it’s usual job

Synthesis and Assembly =  using host cell make new virus

Release = new virus released (lysis or budding), host cell is destroyed

Infection of nearby cells

 

Virus- Cancer:

v  As some viruses affect dna of host cell = it most usually helps cancer,

v  Cell replicates too much and gets cancerous (after the altercation of host dna, the host cell looses control over the replication)

  • HPV and STD = cause cervical cancer
  • HepB and C = are linked to liver cancer

Reproduction

Once a virus has hijacked a cell and used it’s ribosomes and cellular material to reproduce, host cell will produce many viruses and infect nearby cells. Certain proteins must fit to the receptors of a host cell surface in order to infect.

The replication process is depending on Single strand or double strand.
DNA: viral DNA wants to replicate so it goes into the host nucleus = replication and production of mRNA = sits on ribsosome and produce protein. Host cell left for dead after replication.
Single Strand RNA: viral DNA is synthesised from the ssRNA using a viral enzyme called: reverse transcriptase = the new DNA is transcribed into viral mRNA protein and new viral RNA.

Some viruses sit in chromosomes and pretend to be part of us = with us in our genes forever, 5% of our genes are virus.

The more the cell replicates, the higher chance of mutation= a new virus

Important Pathogens

Rhinovirus/ Adenovirus Common cold
Arbovirus / Herpes Virus Encephalitis
EBV G-Fever
HepA-E Hepatitis
HIV AIDS
Varicella zoster Chickenpox and Shingles
Rubella German Measles, can cause arthritis later on in life, is a major problem on fetus.
Papilloma Warts

Virus – Disease

Retrovirus (RNA virus) Promotes Tumour Growth
Filovirus Bleeding and coagulation and viral hemorrhagic fever
Paramyxovirus Measles and mumps
Arenavirus Lassa fever

Hep A:

  • Caused by a virus
  • Antibiotics wont work
  • Affects liver
  • Will be in feaces a lot (checkable – any unhygienic act can be transmitted – by poo)
  • Unsanitary conditions
  • Found in water and food
  • Can be immunised against

Prevention: vaccine, past exposure, good hygiene

Diagnosis

v  From symptoms

v  presence of other cases at the same time

v  blood test and cultures from blood samples, bodily fluid

v  PCR and ELISA = used to look at the Polmerase chain reaction = used to detect dna of other microbes.

v  Examination of blood or tissue under electronic microscope

Treatment

Little way to attack viruses unless they take their own enzymes “Reversetase” then we can attack.

v  Drugs (antiviral) – but can be very toxic to human cells

v  Viruses build up a resistant to antiviral drugs very easily.

  • Inferon Drugs=Protein (synthetic)  that slows the replication process
  • Immune Globulin = antibodies produced by others
  • Vaccines = help prevent infection

Host Defence Mechanism:

v  Phagocytosis

v  Antibodies