1: Special Sensory: Olfaction and Gustation

Introduction to AHE II

• Changes include a liaison, open optional labs, and an identification manual.
• The course content is divided into blocks:
  • Block 1: Heart and Respiratory System
  • Block 2: Blood Vessels and Endocrine System
  • Block 3: Lymphatic and Digestive Systems
  • Block 4: Reproductive and Urinary Systems

Required Collaborative Activities and Optional Labs

• Required dates for collaborative activities are 1/21, 2/18, 3/20, and 4/15.
• Open lab opportunities are available from 10:30 AM to 12:30 PM.
  • 1/23: Heart and Respiratory System
  • 2/11: Head, Neck, and Upper Limb Vessels
  • 2/18: Thorax, Abdomen, Pelvis, and Lower Limb Vessels
  • 3/18: Digestive Tract
  • 3/25: Digestive Vessels and Accessory Organs
  • 4/15: Reproductive System
  • 4/22: Urinary System
• A pig heart dissection is an optional activity on 1/21 at 12:00 PM in Lecture Hall 2.

Formation of the Body Cavities and the Diaphragm

• A video describes the formation of body cavities and the diaphragm.

Sensory Overview, Gustation, Olfaction

• The nervous system's communication is described anatomically to aid in medical diagnoses.
• Special sense structures involved in processes of the larger nervous system are identified using virtual microscopy and 3D images.

Lecture Learning Objectives

• Review somatic and visceral sensory innervation.
• Define receptor types and transduction methods.
• Link gustatory structures (papillae and taste buds) to gustatory pathways.
• Chart gustatory pathways.
• Identify structures on special sense histology slides.
• Describe olfaction, the role of olfactory epithelium, associated structures, and its pathway.

Somatic Sensation

• Somatic sensation travels from the body through peripheral nerves, to dorsal roots and dorsal root ganglia (like the trigeminal nerve) then the spinal cord.
• Different body regions have different nerve pathways:
  • Face: Cranial nerve V
  • Neck and posterior head: Cervical plexus
  • Upper limbs: Brachial plexus
  • Thorax and abdomen: Spinal nerves
  • Lower limbs: Lumbar and sacral plexuses

Afferent Spinal Cord Pathways

• Dorsal column: Fine touch, vibration (some proprioception)
• Spinothalamic: Crude touch, temperature, and pain
• Spinocerebellar: Proprioception
• Somatic sensation is processed in the thalamus and projected to the postcentral gyrus of the parietal lobe.

Clinical Application: Phantom Pain

• Phantom pain is often associated with amputated body parts, persisting due to the sensory pathways from the removed limb still being active.
• The brain interprets signals from these pathways as if they were coming from the missing limb.

Visceral Sensation

• Most visceral sensations travel with parasympathetic fibers.
• Some visceral sensations travel via sympathetic fibers.
• Sensory innervation via cranial nerves plays a role in some instances.
• Parts of the body, like the heart, lungs, and abdominal/pelvic viscera, are innervated by specific sympathetic pathways.

Sensory Receptors

• Mechanoreceptors respond to touch, pressure, vibration, and stretch.
• Thermoreceptors respond to temperature changes.
• Nociceptors respond to pain stimuli (somatic or visceral). Different types of damage trigger different types of response.
• Photoreceptors are found only in the eye, detecting changes in light intensity, color, and movement.

Sensory Receptor

• Different receptors detect different stimuli, like chemicals, pressure or light changes
• Chemoreceptors detect chemicals in internal/external environments, such as tastes, oxygen/carbon dioxide levels in blood/interstitial fluids).
• Baroreceptors respond to changes in pressure within body structures, like blood pressure, and can be found in the stomach.

Receptors

• Transducers transform energy from one system to another (e.g., heat to nerve impulse).
• Tonic receptors respond to stimuli continuously.
• Phasic receptors detect changes in stimuli and their sensitivity decreases over time (can lead to adaptation).

Special Senses

• Special sensory information (vision, hearing, equilibrium, gustation, olfaction) relates to cranial nerves and associated cerebral lobes.

Gustation (Taste)

• Taste buds are chemoreceptors located on papillae (e.g., filiform, fungiform, vallate) of the tongue's surface.
• Structures like papillae, taste receptor cells, and taste pores are key components of the gustatory system.

Olfaction (Smell)

• Olfactory epithelium is located in the nasal cavity and contains olfactory receptor cells, supporting cells, and basal cells.
• Olfactory glands in the epithelium produce fluid flow for odour molecules to dissolve

Olfactory Pathway

• Olfactory receptor cells are modified bipolar neurons (primary neurons).
• Olfactory hairs detect airborne molecules.
• Afferent information travels through the olfactory tract to the primary olfactory cortex in the temporal lobe.
• The pathway can also connect to other areas of the brain like the thalamus, frontal lobe, hypothalamus, and limbic system

Olfactory Histology

• Olfactory and respiratory epithelium are layers of cells in the nasal concha.

Explore the key components of the AHE II course, including an overview of topics covered in each block from the heart and respiratory system to the reproductive and urinary systems. Learn about collaborative activities and optional labs that will strengthen your understanding of human anatomy. This introduction will prepare you for an engaging and informative experience in the field of health education.