Unravelling the Wonders of the Nervous System: A Journey Through Neurons, Synapses, and Beyond

Biopsychology

The study of our brain and our nervous system and how it influences mental processes and behaviour.

 

Nervous system

A specialised network of cells in our human body called our nervous system, is a primary internal communication system. 

It's made up of 2 main functions:

   a) In our environment, it collects, processes and responds to information

   b) Co-ordinates working of different organs and cells in the body

Our nervous system is made up of 2 sub-systems:

•  Central nervous system
• Brain
• Centre of conscious awareness (if we had this, it would slow the reflex process down)
• The outer layer, the cerebral cortex, distinguishes our higher mental functions from animals as it is highly developed in humans
• Divided into 2 hemispheres
• Spinal cord
• extension of the brain 
• responsible for reflex actions like pulling a hand away from a hot plate

• Peripheral nervous system

        Transmits messages via nerve cells (neurons) to and from the central nervous system

• Autonomic nervous system
• Governs vital functions in the body like breathing, heart rate and digestion, sexual arousal and stress responses
• Autonomic is unconscious and involuntary. Auto- autopilot - controls vital functions without needing you. 
• Somatic nervous system
• Controls muscle movements and receives information from sensory receptors
• Somatic means "relates to the body", so you could think of it as relating to the senses?

As well as having the nervous system, we also have the endocrine system. The endocrine system has endocrine glands which release hormones into the bloodstream. You maybe wondering, like I once did about why we have two systems (the endocrine and nervous systems). The endocrine system releases hormones whereas the nervous system releases neurotransmitters.  Despite hormones being slower, it has long-lasting effects, in contrast neurotransmitters have rapid and short-lived effects. 

Another way that they are different, is that hormones are produced in endocrine glands and are secreted into the bloodstream. Neurotransmitters on the other hand are released by the presynaptic nerve terminal into the synapse. 

Endocrine system

Working alongside our nervous system is the endocrine system. Controlling vital functions in the body, it maybe slower but has widespread and powerful effects. 

Keywords:

Glands = organ in our body that synthesises substances such as hormones. 

Hormones= chemical substance that circulates in the bloodstream, affecting only target organs. Produced in large quantities and are very powerful, they disappear quickly.

Glands release hormones into the bloodstream. For example, the thyroid gland releases the hormone thyroxine into the bloodstream. 

        The effects are:

• Increases heart rate
• affects cells in the heart
• Metabolic rate
• chemical processes taking place in the cells

Affecting growth rate

In our body, we have *drumroll please* the MAJOR ENDOCRINE GLAND. The pituitary gland, aka the master gland. You maybe wondering why I was so dramatic. Well, located in the brain, it controls the release of hormones from all other endocrine glands in the body. 

Working hand-in-hand

During a stressful event, the endocrine gland and the autonomic nervous system work parallel with each other

Let's talk about the process this happens in FLIGHT OR FIGHT

1. Stressor is perceived
2. The hypothalamus triggers activity in the sympathetic branch of the autonomic nervous system
3. Causing our autonomic nervous system to change from the parasympathetic state (normal resting state) to the sympathetic state (physiologically aroused)
4. From the adrenal medulla (part of the adrenal gland), the stress hormone adrenaline is released into the bloodstream
5. Adrenaline triggers physiological changes in the body (like increased heart rate, breathing rate, dilated pupils, inhibited saliva production and digestion and contracts rectum), creating physiological arousal necessary for the flight or fight response. 
6. An acute response is the automatic reaction in the body which happens in an instant, as soon as the threat is detected. 
7. The parasympathetic nervous system returns the body to its resting state once the threat has passed. 
8. The actions are antagonistic to the sympathetic system and reduces the activities of the body that were increased by the actions of the sympathetic branch. AKA rest and digest response

Antagonistic = a substance which interferes with or inhibits the physiological action of another.