Anatomy & Physiology - Nervous System

What are 5 main hormones related to the Limbic system?

Cortisol: The primary stress hormone

Serotonin: Crucial for mood regulation, learning, and memory.

Dopamine: Central to the brain's reward system, motivation, and pleasure.

Norepinephrine (Noradrenaline): Involved in 'fight or flight' response.

Oxytocin: Often called the 'love hormone,' it plays a vital role in social bonding, trust, and empathy.

Where is limbic system located?

Inner part of the cerebrum & near brainstem

What is the function of the reticular activating system (RAS)?

Maintains wakefulness and sensory alertness.

Explain how the limbic system affects stress and endocrine responses.

Limbic system activates hypothalamic–pituitary stress responses via the HPA axis.

Explain how the vestibular system contributes to balance and spatial orientation.

vestibular system detects head motion via 3 semicircular canals, and 2 otolith organs (Utricle & Saccule) to maintain balance.

Define proprioception and identify where its receptors are mainly located.

proprioception : body position sense. (Conceiving where my nose is with eyes closed)

Receptors mainly in muscles, tendons, joints.

Which structure contains the primary motor cortex?

Frontal lobe

how does the limbic system interact with the hypothalamus to influence behaviour?

Limbic-hypothalamic link : Limbic emotions drive hormonal / autonomic responses via hypothalamus.

What is the cochlea (ear) is responsible for?

Processing sound waves (mechanical sound vibration → neural signals)

describe the pathway of pain from peripheral receptors (nociceptor) to the cerebral cortex. 

Pain pathway : Nociceptors → dorsal horn → Spinothalamic tract → Thalamus → cerebral cortex. 

what is the function of the dorsal-column medial lemniscus pathway?

Ascending sensory pathway. From spinal cord → Cerebral cortex.

*Touch, pressure, proprioception.

Which neurotransmitter is heavily involved in pain inhibition in spinal cord?

Serotonin.

Descending serotonergic fibres inhibit pain

Explain how the semicircular canals detect rotational acceleration?

The hair cells of 3 semicircular canals tilts → detects the fluid movement during head rotation. 

What does spinothalamic tract carry?

Pain and Temperature.

What is the main function of the hypothalamus in relation to the limbic system?

Hypothalamus integrates emotions with autonomic responses via limbic system

Which pathway carries Voluntary motor commands from the cortex to the spinal cord?

Corticospinal tract is the major descending voluntary motor pathway.

What is the difference between fast pain fibre and slow pain fibre?

Fast : A-Delta fibre.

-Myelinated

-Sharp pain

-For Mechanical & Thermal pain

Slow : C fibre 

-unmyelinated, slower conduction

-Dull pain, Throbbing pain

-Chemical, inflammatory pain. 

화상 can be in both fibres 

• you touch sth hot and instantly pull the hand away → A-delta fibre.

• Your skin keep stinging,  burning long after pulling the hand away → C fibre.

Which cranial nerve is responsible for Taste in the anterior 2/3 of the tongue?

Facial nerve.

The precentral gyrus is associated with ?

motor output

what happens if the right optic tract is damaged?

Lost of left vision field (partial) for both eyes.

= Left homonymous hemianopia

•  Left visual field : Right retinal of both eyes

• Right visual field : left retina of both eyes.

What does the stretch reflex helps to maintain?

Stretch reflex : knee-jerk reflex. 

It helps to maintain muscle tone. 

Knee-jerk reflex occurs when a muscle is suddenly stretched, → activating muscle spindles causing the same muscle to contract reflexively. → Helps maintain posture, Balance, Muscle length. 

What is the process of sound transduction in the inner ear?

AAT OOCV MMT

Sound wave → auricle → auditory canal → tympanic membrane → ossicles (MIS) → oval window → cochlear (organ of corti) → Vestibulocochlear → medulla → midbrain → thalamus → auditory cortex (temporal)

What is the main neurotransmitter involved in limbic system emotional response?

Dopamine (Reward & Pleasure & Motivation)

1. Rewarding event

2. VTA neurons (Ventral Tegmental Area) release dopamin → nucleus accumbens & Prefrontal cortex. → Amygdala & Hippocampus store this emotional memory → later, even anticipation of reward can trigger dopamin (this drives motivation)

Where does dorsal column medial lemniscus pathway terminate in?

Thalamus.
Decussation ≠ Termination.

Decussation = same neuron crosses to the opposite site (just change of direction).

2nd order neuron starts in Medulla, crosses over, ends in Thalamus.

How does the spinal cord facilitate reflex actions without brain involvement?

Withdrawal Reflex arcs 회피반사 : Sensory neuron → Entre via Dorsal Root → Intergration centre → Motor neuron exit via Ventral root.

*Ipsilateral, no decussiation! Fast response!

Integration centre : chooses which muscles to activate/inhibit, connects both sides of the body in reflexes when needed (contralateral - You step on a nail with your right foot, one leg withdraws, the other supports for balance)

Connect sensory → Neuron

*But Knee jerk reflex does NOT go through interneuron! (Direct synapse sensory → motor)

Which cranial nerve is tested the gag reflex?

Glossopharyngeal nerve

Afferent (Sensory - feels it) : Glossopharyngeal

Efferent (Motor - contracts pharyngeal muscle) : Vagus

Describe the mechanism of Phototransduction (light energy → electrical signals in the photoceptor cells) in rods

Light → Opsin activation → Hyperpolarisation → Bipolar cell → Ganglia cell → Optic nerve → Brain