Medicine - Fast Facts

 Elderly Brains

With age, the brain shrinks, particularly in the regions of the hypothalamus and the frontal lobe. The frontal lobe controls important cognitive skills in humans, such as emotional expression, problem solving and memory. This explains the loss in memory and other body functions seen in the elderly.  The hypothalamus is important for homeostasis (maintaining a constant internal environment). This includes regulation of body temperature, blood glucose, hunger, thirst and circadian rhythms. 

When elderly people suffer a knock to the head, the reduced size of the brain causes it to rattle inside the skull. This is what makes an elderly person falling so dangerous and explains why it is something that is highly regulated in elderly care. Geriatric doctors often look at patients’ feet in order to see what measures can be taken to prevent a fall. 

MRI and CT scans 

Magnetic resonance imaging is a medical application of NMR (Nuclear Magnetic Resonance), which uses strong magnetic fields and radio waves to generate an image. Atoms absorb energy and emit a radio frequency. This creates contrast between different tissues and enables detection of a stroke, tumour, injury, local infection or blood clot.

Image A is an MRI of a healthy brain, compared to B, of a patient with cerebral atrophy. Cerebral atrophy is the loss of neurones and their connections in brain tissue, a  common feature of many diseases that affect the brain, such as cerebral palsy and Alzheimer’s disease.  MRI image C shows part of the brain lit up, indicating the presence of a brain tumour.  MRIs can also be used to detect spinal injuries, such as a lumbar disc hernias, as illustrated here. Disc hernias can result in nerve roots becoming trapped, often causing pain all the way down a leg, and restricting movement. 

A CT (computerised tomography) scan combines a series of X-ray radiographs taken from different angles to generate a better image. Like MRI, this technique can generate high resolution images. However, X-rays are ionising radiation and can be harmful, in particular to unborn children. Thus, pregnant women are strongly advised against them and usually elect MRI or ultrasound scans, instead. 

Before a CT scan, a contrast medium may be injected into a patient’s vein or swallowed as a pill to provide better detail on the image.

This image depicts an ischemic stroke, which occurs when parts of the brain are not receiving sufficient Oxygen, due to blockage of arteries. Bone fractions are also usually analysed by CT scans. 

Melanoma

A melanoma is a type of cancer that develops from melanocytes, typically found in the skin. About 25% of melanomas develop from moles. Changes in a mole's appearance that indicate melanoma include expansion of the mole, irregular edges, change in colour, itchiness, or skin breakdown. Melanomas are primarily caused by excess exposure to UV light. Metastasis of early melanomas is uncommon. When they do spread, melanomas an affect the liver, bones and lymph notes. 

Pulse

Our pulse can be measured on our arteries. Arteries carry oxygenated blood from the heart to other tissues (apart from the coronary artery, which brings oxygenated blood from the lungs to the heart). Veins transport deoxygenated blood from tissues back to the heart. Arteries have a smaller lumen and thicker walls than veins, and therefore can carry blood under higher pressure than veins.  A tachycardia (heart beat over 100 bpm) may indicate hypertension. Arrhythmia is a condition that causes a non-constant heart rate, which is often unproblematic. 

Blood pressure 

Blood pressure measurements yield two numbers; e.g. 110/70mmH (normal blood pressure). 

The top number is the systolic blood pressure: the highest blood pressure when your heart beats and pushes blood around your body. The bottom number is the diastolic blood pressure: the lowest pressure when your heart relaxes between beats. 

• You have hypertension (high blood pressure) when the top number > 140 or the bottom number > 90, regardless of the other number; 
• You have hypotension (low blood pressure) when the top number < 90 or the bottom number < 60, regardless of the other number.