Human Physiology: Special Senses

Study Notes

Receptors for Special Senses

Mechanical Receptors: Located within the cochlea, responsible for hearing.
Chemoreceptors: Respond to chemical stimuli; involved in taste and smell.
Proprioceptors: Detect body position and movement; found in muscles and joints.
Free Nerve Endings: Respond to pain, temperature, and some tactile stimuli.

Eye Features on Fundoscopy

Optic Disc: Area where the optic nerve exits the eye; no photoreceptors, creating a blind spot.
Receptors in Human Eyes:
- Cones: Responsible for color vision and detail in bright light.
- Rods: Responsible for vision in low light conditions.

Tongue Features

Papillae Types: Filiform, fungiform, circumvallate, and foliate; each has specific roles in taste sensation.

Primary Cortices of Special Senses

Cortex Location: Primary visual cortex, auditory cortex, gustatory cortex, and olfactory cortex each located in relevant brain regions.

Eye Light Focusing Mechanism

Lens: Changes shape for accommodation, allowing for focus on near and distant objects.
Components: Cornea, lens, and retina work together to refract light onto the retina.

Body Response to Stimuli

Adaptation: The decreased sensitivity to continuous stimuli over time.

Taste and Gustatory Receptors

Types of Taste: Sweet, sour, salty, bitter, and umami; each has corresponding gustatory receptors.

Secretion Mechanisms

Autocrine: Cells respond to substances they secrete themselves.
Paracrine: Cells respond to substances secreted by nearby cells.

Endocrine Organs

Hypothalamus and Pituitary Connection: The hypothalamus regulates the pituitary gland, controlling many bodily functions.
Endocrine Glands: Secrete hormones such as thyroid-stimulating hormone (TSH) from the thyroid.

Hormones by Endocrine Glands

Thyroid Gland: Secretes hormones like thyroxine (T4) and calcitonin.
Adrenal Glands: Secrete cortisol, adrenaline, and sex hormones.

Hormones and Solubility

Hydrophilic Hormones: Water-soluble, cannot cross the cell membrane easily.
Hydrophobic Hormones: Lipid-soluble, can pass through cell membranes.

Hormone Targets and Functions

Parathyroid Hormone: Regulates blood calcium levels.
Calcitonin: Lowers blood calcium levels.
Insulin and Glucagon: Regulate blood sugar levels.
Growth Hormone: Stimulates growth and cell reproduction.
Luteinizing Hormone: Regulates ovulation and testosterone production.

Non-Endocrine Functions of Hypothalamus

Regulates basic drives: Hunger, thirst, body temperature, and circadian rhythms.

Common Endocrine Pathologies

Graves' Disease: An autoimmune condition leading to hyperthyroidism.

Blood Sugar and Calcium Regulation

Hormones involved: Insulin lowers blood sugar, while glucagon raises it. Parathyroid hormone increases blood calcium, and calcitonin decreases it.

Eye Structures

Refractive Structures: Lens focuses light, cornea provides initial refraction, and retina captures visual information.

Ear Structure Identification

External Ear: Auricle and ear canal.
Middle Ear: Ossicles (malleus, incus, stapes); amplifies sound.
Internal Ear: Cochlea and vestibular system; involved in hearing and balance.

Special Sense Receptors

Gustatory Cells: Involved in taste sensation.
Olfactory Bulb and Nerve: Essential for the sense of smell.

Endocrine vs Exocrine Systems

Endocrine Glands: Secrete hormones into the bloodstream for systemic effects.
Exocrine Glands: Secrete substances through ducts to the outside of the body or onto epithelial surfaces.

Example of an Endocrine Gland

Parathyroid Gland: Secretes parathyroid hormone, regulates calcium levels in the blood.

Description

This quiz covers the locations and functions of various sensory receptors involved in special senses such as hearing and vision. It encompasses details on mechanical receptors, chemoreceptors, proprioceptors, and features of the eye and tongue. Dive into the anatomical aspects and understand the key receptor types and their responses.