Biopsychology Quiz

The two main divisions of the nervous system are the central nervous system (CNS), which consists of the brain and spinal cord, and the peripheral nervous system (PNS), which connects the CNS to the rest of the body. The PNS is further divided into the somatic nervous system (which controls voluntary movements) and the autonomic nervous system (which controls involuntary bodily functions).

Neurotransmitters are chemicals that transmit signals across the synapse between neurons. When an electrical impulse reaches the end of a neuron (the axon terminal), neurotransmitters are released into the synapse, where they bind to receptor sites on the postsynaptic neuron, either exciting or inhibiting its activity. Excitatory neurotransmitters, such as glutamate, increase the likelihood of an action potential, while inhibitory neurotransmitters, like GABA, decrease the likelihood.

The endocrine system is responsible for regulating various bodily functions through the release of hormones. It consists of a network of glands that secrete hormones directly into the bloodstream. These hormones regulate processes such as metabolism, growth, mood, and reproductive functions. Key glands include the pituitary gland, thyroid gland, adrenal glands, and pancreas.

The fight or flight response is a physiological reaction to perceived danger, preparing the body to either confront or flee from a threat. Adrenaline, a hormone produced by the adrenal glands, plays a key role by increasing heart rate, dilating pupils, and redirecting blood flow to muscles. This prepares the body for immediate physical action. The response is part of the sympathetic nervous system, and it helps an individual cope with stress or danger.

Localisation of function refers to the idea that specific areas of the brain are responsible for specific functions or behaviours. For example, the motor cortex is responsible for voluntary movement, while the Broca’s area is associated with speech production. Different regions of the brain control sensory processes, motor activities, and cognitive functions.

Sensory Neurons: These neurons carry information from sensory receptors (e.g., in the skin, eyes, ears) to the central nervous system (CNS). They have long dendrites and short axons. Sensory neurons allow us to perceive stimuli like light, sound, or temperature.

Relay Neurons: These neurons are located within the CNS and connect sensory neurons to motor neurons. Relay neurons transmit information between the different regions of the brain and spinal cord, allowing for integration and processing of information.

Motor Neurons: These neurons carry signals from the CNS to muscles and glands to initiate movement or secretion. They have long axons and short dendrites. When a motor neuron is activated, it causes a muscle to contract or a gland to secrete.

Synaptic transmission begins when an action potential reaches the presynaptic terminal of the neuron. This causes the release of neurotransmitters from synaptic vesicles into the synaptic cleft. The neurotransmitters travel across the synapse and bind to receptor sites on the postsynaptic neuron.

Excitation: If the neurotransmitter is excitatory, like glutamate, it causes the postsynaptic neuron to become more likely to fire an action potential.

Inhibition: If the neurotransmitter is inhibitory, like GABA, it makes the postsynaptic neuron less likely to fire an action potential.
After binding to receptors, neurotransmitters are either reabsorbed into the presynaptic neuron (reuptake), broken down by enzymes, or diffused away.

The endocrine system regulates a wide range of bodily functions through the release of hormones from various glands. These hormones are carried through the bloodstream to target organs. Key components of the endocrine system include:

Pituitary Gland: Known as the "master gland," it controls other glands in the body, such as the thyroid and adrenal glands. It releases hormones like growth hormone (GH) and oxytocin.

Thyroid Gland: Releases thyroxine, which regulates metabolism, energy levels, and growth.

Adrenal Glands: These glands release adrenaline (to prepare the body for fight or flight) and cortisol (which helps manage stress).

Pancreas: Produces insulin to regulate blood sugar levels.

Gonads (Testes/Ovaries): Produce sex hormones like testosterone and estrogen, which are involved in reproductive functions and sexual characteristics.

The fight or flight response is a physiological reaction triggered by the sympathetic nervous system in response to a perceived threat or stressor.

Adrenaline is released by the adrenal medulla into the bloodstream, where it acts on various organs to prepare the body for rapid action.

• It increases heart rate and blood pressure to pump more oxygen to muscles.
• It dilates the pupils to improve vision.
• It causes the liver to release glucose for quick energy.
• Blood flow is redirected to the muscles and away from non-essential functions like digestion.
  This prepares the individual to either fight or flee from the threat.

Localisation of function refers to the idea that different areas of the brain are responsible for specific functions. Some key areas include:

• Motor Cortex: Located in the frontal lobe, it is responsible for voluntary movement. Different regions of the motor cortex control different parts of the body.
• Somatosensory Cortex: Located in the parietal lobe, it processes sensory information from the body, such as touch, pressure, and temperature.
• Visual Cortex: Located in the occipital lobe, it processes visual information received from the eyes.
• Auditory Cortex: Located in the temporal lobe, it processes auditory information from the ears.
• Language Centres: The Broca’s area (in the left frontal lobe) is responsible for speech production, while Wernicke’s area (in the left temporal lobe) is responsible for language comprehension. Damage to these areas can result in language impairments like aphasia.

Plasticity refers to the brain's ability to adapt and reorganise itself in response to experience or injury. In cases of brain trauma, such as stroke, plasticity allows undamaged areas of the brain to compensate for the lost function.

• Functional Recovery: After trauma, the brain can undergo functional recovery, where new neural connections are formed to restore lost functions. This can involve the recruitment of the opposite hemisphere or the activation of different brain regions to take over functions previously managed by damaged areas.
  Recovery is more likely in younger individuals, and therapies such as rehabilitation can support this process.

• fMRI (Functional Magnetic Resonance Imaging): This technique measures changes in blood flow to determine brain activity. It is non-invasive and provides high-resolution images of brain activity, making it useful for understanding the brain’s response to various stimuli. However, it has limited temporal resolution, making it less effective for studying fast neural processes.
• EEG (Electroencephalogram): EEG records electrical activity in the brain. It has excellent temporal resolution, allowing for real-time monitoring of brain activity, particularly useful for studying sleep, seizures, and brainwave patterns. However, it lacks spatial resolution and cannot pinpoint specific brain regions involved.
• ERPs (Event-Related Potentials): These are derived from EEG data and measure brain responses to specific stimuli. They are used to study cognitive processes such as attention and memory. ERPs have excellent temporal resolution but, like EEGs, lack precise spatial resolution.
  Overall, these techniques provide valuable insights but have limitations in terms of spatial or temporal precision.

• Circadian Rhythms: These are biological processes that occur on a 24-hour cycle, such as the sleep/wake cycle, body temperature, and hormone release. These rhythms are regulated by endogenous pacemakers, like the suprachiasmatic nucleus (SCN) in the hypothalamus, and influenced by exogenous zeitgebers like light.
• Infradian Rhythms: These rhythms last longer than 24 hours, such as the menstrual cycle, which lasts approximately 28 days.
• Ultradian Rhythms: These rhythms occur more frequently than once in 24 hours, such as the stages of sleep, which cycle multiple times throughout the night.

• Endogenous Pacemakers: These are internal biological processes, such as the SCN in the hypothalamus, which regulate the sleep/wake cycle. The SCN synchronises the circadian rhythm with external cues like light.
• Exogenous Zeitgebers: These are external environmental cues, such as light and social activities, that help to synchronise the internal biological clock with the outside world. Light is the primary zeitgeber influencing the sleep/wake cycle by affecting the production of melatonin in the pineal gland.

Endogenous pacemakers are crucial for maintaining the internal timing of biological rhythms. For example, the SCN controls the circadian rhythm, and research in animals (e.g., the removal of the SCN causes disruptions to the sleep/wake cycle). However, exogenous zeitgebers, especially light, are essential for synchronising the internal clock with the external environment. Studies on shift workers and jet lag demonstrate that disruption of light exposure can lead to misalignment of the circadian rhythm, causing sleep disturbances. While endogenous pacemakers are important, the interaction with exogenous zeitgebers is necessary for maintaining a regular sleep/wake cycle.