Archive for the ‘Higher National Diploma’ Category

The idea of competitive and non-competitive antagonism can be a tricky one to understand.

An antagonist could be a medicine which binds to a receptor on a cell and blocks access to that receptor. This will prevent an agonist (i.e. one of the body’s own chemicals such as a hormone) from binding to that receptor, blocking its effect.

The antagonist can bind in two different ways, competitively or non-competitively:

a) Competitive Antagonism
The antagonist binds to the same receptor that the agonist wishes to use, effectively preventing the agonist from doing so.
It is competitive because both the agonist and the antagonist are competing for the same receptor.
The awesome artwork of Animal Care student, Sarah Mills, illustrates this point beautifully:

The young lady represents the hormone which has a desire to sit in the chair (bind to the receptor). The unco-operative green chap represents an antagonist who will not allow the hormone to access the receptor.

Our heroine in pink represents the agonist which has a desire to sit in the chair (bind to the receptor). The unco-operative green chap represents an antagonist who will not allow the agonist to access the receptor. Image: © Sarah Mills 2015

b) Non-Competitive Antagonism
In non-competitive antagonism, the antagonist and the agonist are not trying to bind to the same receptor. The antagonist will bind to a different part of the cell but, due to the antagonist’s shape, access to the receptor is still blocked. It is ‘non-competitive’ because the agonist and the antagonist are not competing for the same receptor.

Here, the green antagonist is not using the same receptor that our young agonist desires, yet he still blocks access to the agonist's desired receptor.

Here, the green antagonist is not using the same receptor that our young agonist desires, yet he still blocks access to the agonist’s desired receptor. Image: © Sarah Mills 2015


Chemotaxis for Phagocyte!


When the body is invaded by infectious organisms such as bacteria, viruses or parasites, it is vital that the body’s immune cells get to the sourse of infection as quickly as possible.

Infectious organisms (known as ‘pathogens‘) as well as damaged cells all release chemicals into the tissues around the infection or area of cell damage.  The immune system recognises the presence of these chemicals and sends its immune cells in the direction of the chemicals in order to fight the pathogens or remove the damaged cells.  This process is known as ‘Chemotaxis‘ and the first immune cells to arrive at the problem are the ‘Phagocytes‘.

Neutrophil engulfing anthrax bacteria, taken w...

Neutrophil (a type of phagocyte) engulfing anthrax bacteria. (Photo credit: Wikipedia)

A common quandry in parasitology is identification of different types of parasites.
When it comes to the subject of lice, there are some happy coincidences which make life easier.

For Sucking Lice, simply remember the initial letter ‘S:

They Suck
They have Small heads
They move Slowly
They have Sideways or forward pointing antennae
They are around 5mm in size
(ok, stretching it but the number ‘5’ looks a wee bit like an ‘S’)

For Biting Lice, the letter ‘B‘ is all important:

A Biting Louse
They Bite
They have Big heads
They Move Bloomin’ quick (ahem!)
They have Backward pointing antennae
They are around 3mm in size
(if you draw a vertical line through the start of the number ‘3’, it becomes a ‘B’)

The linings of the body cavities are named.
  • Lining the cranial cavity and spinal cavity are the protective membranes known as the meninges.
    Inflammation of the meninges is known as meningitis.
  • Lining the abdomen (belly) is a membrane known as the peritoneum.
    Inflammation of the peritoneum is known as peritonitis.
  • Lining the thorax (chest) is a membrane known as the pleura.
    This does not follow the usual naming conventions as inflammation of the pleura is known as pleurisy (although pleuritis is sometime heard).
Compassion in World Farming's founder Peter Roberts

Compassion in World Farming's founder Peter Roberts

The ‘Five Freedoms’ of Animal Welfare are a set of ideal standards for Animal Welfare rather than a piece of law.

They were originally developed as part of a UK government report into farm animal welfare in the early 1960s.  They have since been adopted for all aspects of animal welfare by many governments and organisations around the world.

As well as looking at the titles of the ‘freedoms’, it is important to understand their meaning:

  • Freedom from Hunger and Thirst
    This freedom relates to provision of fresh water as well as a diet to maintain full health and vigour.
    If you provide an animal with food but it is not the correct food to provide for the animal’s needs you are failing to meet this freedom.
    You may also be failing to meet this freedom if you provide food which makes an animal obese as you are failing to provide a diet which maintains full health and vigour.
  • Freedom from Discomfort
    This freedom is concerned with providing an appropriate environment, shelter and resting area.
    It is more concerned with provision of appropriate accommodation than with discomfort caused by disease or injury (which is covered by a different freedom).  If an animal does not have secure shelter from rain, wind or bad weather or has no bedding (or the wrong kind of bedding or substrate), the person responsible for this animal is failing to comply with this freedom
  • Freedom from Pain, Injury and Disease
    Complying with this freedom ensures that pain, disease or injury are prevented or that if they are not preventable, that any pain, disease or injury is quickly diagnosed and treated.
    It is important to realise that is not against welfare standards for a person to be responsible for an animal which is in pain or ill. If you are responsible for an animal, however, and it is in pain (or injured or suffering from a disease) and you choose to ignore it and fail to seek treatment then you are neglecting the welfare of this animal (and therefore breaking the law).
  • Freedom to Express Normal Behaviour
    This freedom points to the provision of sufficient space, proper facilities and, where appropriate, company of the animal’s own kind.
    These areas are concerned with allowing an animal to exhibit behaviours which are as close as possible to those it would exhibit in the wild.
  • Freedom from Fear and Distress
    This freedom concerns itself with removing circumstances which would bring about mental suffering.
    It could cover, for example, issues such as keeping prey animals in full view of predator species, subjecting an animal to an unreasonable workload or treating an animal cruelly that it became fearful.

Although, in itself, not a piece of law, the following extract from the Animal Health and Welfare (Scotland) Act, 2006 shows how strongly Scottish welfare legislation draws on these standards:

Section 24 – Ensuring welfare of animals

1) A person commits an offence if the person does not take such steps as are reasonable in the circumstances to ensure that the needs of an animal for which the person is responsible are met to the extent required by good practice.

3) For the purposes of subsection (1), an animal’s needs include—

(a) its need for a suitable environment,
(b) its need for a suitable diet,
(c) its need to be able to exhibit normal behaviour patterns,
(d) any need it has to be housed with, or apart from, other animals,
(e) its need to be protected from suffering, injury and disease. 

The Canine HeartRemembering the names of the valves of the heart can be difficult – especially trying to remember which valve goes on which side.
You may have heard names like Tricuspid Valve and Bicuspid Valve or even Mitral Valve.

There’s an easier way of naming the valves, however, where the names actually tell you about their position:
Between each Atrium and Ventricle is a valve, which is there to stop blood flowing in the wrong direction.  If you use the name Atrio-Ventricular Valve or A-V Valve, the name tells you that the valve is between the Atrium and Ventricle.  To make sure everyone knows which side you’re talking about, you should use the names Left Atrio-Ventricular Valve or Right Atrio-Ventricular Valve.

One of the main problems with diarrhoea is that it’s so bloomin’ difficult to spell.
If you have trouble remembering how to spell ‘Diarrhoea’, remember this handy phrase:

Dashing – In – ARush? – Really – Hurry – Or – Else – Accident.

Kidney & Adrenal GlandCortex and Medulla are words which pop up all over the subject of anatomy.  The cortex is always the bit around the outside of a structure and the medulla is always the bit in the middle.

Examples include:

The Renal Cortex – the bit around the outside of the kidney
The Adrenal Cortex – the bit around the outside of the adrenal gland
The Cortex of bones (also known as Cortical Bone) – the thick dense bone tissue around the outside of bones
The Cerebral Cortex – the bit around the outside of the brain

Long Bone SectionThe Renal Medulla – the bit on the inside of the kidneys
The Adrenal Medulla – the bit on the inside of the adrenal gland
The Medulla of bones (also known as the medullary cavity) – the space in the middle of a long bone where the bone marrow is found

Use the similar sounds of the words MEDULLA and MIDDLE to help you remember!