The Brain + Imaging Techniques
- Receptor cells gather information about changes in your internal and external environment, which your brain processes.
- Your brain produces a coordinated response using all this information (if necessary).
Functions:
- Hypothalamus: Regulates temperature and water balance. The hypothalamus generates crucial hormones that connect the nervous and endocrine systems, regulating the body's internal conditions.
- Pituitary gland: Stores and releases hormones that regulate many body functions.
- Medulla: Controls automatic actions, e.g., heart and breathing rates.
- Cerebrum: A highly folded outer layer that controls complex behaviours like learning, memory, personality, and conscious thought.
- Skull: Bones to protect the brain (cranium).
- Vertebra: Protects spinal cord.
- Spinal cord: Carrying info from brain to rest of the body.
- We can investigate brain function by examining stroke victims and individuals with brain damage, using modern techniques such as imaging.
Imaging
CT/CAT (Computerised Axial Tomography):
- CT scans use X-rays and a computer to create detailed images of the body.
- It aids in the diagnosis of tissue damage, strokes, and cancer, as well as the imaging of complex fractures around joints.
- Inject a dye into the body to improve image quality.
- The investigation solely focuses on a specific part of the body, not the entire body.
- Different tissues absorb X-rays to varying degrees.
- Trained radiographers can interpret these X-rays to generate an image, particularly those suitable for computer-based photo production.
- Health risks for unborn babies: Lack of exposure can lead to cancer.
- Pregnant women should avoid X-rays because they emit ionising radiation and are susceptible to its harmful effects.
MRI (Magnetic Resonance Imaging):
- Uses strong magnetic fields and radio waves to produce detailed images. Consists of a large tube with powerful magnets.
- It observes how the hydrogen nuclei in H₂O molecules react to variations in magnetic fields and radio waves.
- It can differentiate between various tissue types, including cancerous cells.
- It offers the highest level of resolution for images, including all common techniques.
- The procedure is painless and safe, requiring no ionising radiation, but it is very expensive and requires highly trained staff.
EEG (electroencephalography):
- All over the scalp, small sensors detect electrical signals when the brain's cells exchange messages. Highly trained specialists can read these changes to detect unusual activity.
- Used to detect epilepsy and other memory problems.
- There's no image.
PET (Positron Emission Tomography):
- Provides images of blood flow/biochemical functions.
- The patient receives an injection of a short-lived radioactive isotope, which emits a gamma ray as it decays.
- To detect gamma rays, a doughnut-shaped structure containing gamma-ray detectors places the patient on a flat table.
- The detectors send signals to a computer that produces images in the form of a slice through the patient's body.
Nervous System Damage
- Any PNS or CNS damage is nervous system damage. This can occur from:
→ Injury (e.g., falling off a ladder).
→ Disease (e.g., some forms of cancer or diabetes (thin retinal).
→ Genetic conditions, e.g., Huntington's disease.
→ Ingesting a toxic substance (e.g., lead).
- Damage to PNS can affect sensory and motor neurones. It can result in:
→ Inability to detect pain
→ Numbness
→ Loss of coordination/movement
- The PNS has a limited ability to regenerate. Minor nerve damage often self-heals, and symptoms gradually decrease. Surgery treats more severe damage.
- However, the risks associated with surgery can result in damage to nearby parts of the brain.
- The CNS cannot regenerate. If surgery cannot repair the damage, it remains permanent.
- Damage to CNS (more severe) can lead to:
→ Loss of control over body systems
→ Partial/complete paralysis
→ Memory loss/processing difficulties
- Disease or damage to the spinal cord or brain is often impossible to repair, especially if the damage is in a location that is difficult to access. Brain damage is difficult to diagnose even with advanced imaging techniques.
- Treatments are available for some conditions and include:
→ Radiotherapy and chemotherapy (e.g., brain tumour).
→ Surgery, such as the removal of diseased or damaged brain tissue, or deep brain stimulation/implants, such as the insertion of electrodes or an implant to treat conditions like Parkinson's disease, are among the options available.