Anatomy & Physiology: Nervous System, Endocrine System, and Special Senses Study Notes

Nervous System

Brain Structure and Function

The brain is a complex organ responsible for processing sensory information, coordinating movement, and regulating bodily functions. Key regions of the brain have specialized roles:

• Thalamus: Acts as the gateway to the brain, relaying sensory and motor signals to the cerebral cortex.

• Cerebellum: Ensures smooth, coordinated movement and balance.

• Cerebral Cortex: Site of conscious thought, perception, and voluntary action.

• Vomiting Center: Located in the brainstem, this center is absent from the blood-brain barrier and is responsible for initiating the vomiting reflex.

Example: Damage to the cerebellum can result in ataxia, a loss of coordination and balance.

Special Senses: The Eye

Eye Anatomy and Chambers

The eye is a sensory organ that detects light and enables vision. It contains several chambers and specialized structures:

• Optic Disk: The section in the back of the eye where the blind spot is located; it is the point where the optic nerve exits the retina.

• Anterior Chamber: The front section of the eye, filled with aqueous humor, a clear fluid that maintains intraocular pressure and nourishes the cornea and lens.

• Vitreous Humor: The gel-like substance filling the posterior chamber of the eye, helping to maintain its shape.

• Conjunctiva: The mucous membrane lining the eyelid and covering the sclera.

Example: Increased pressure in the anterior chamber due to excess aqueous humor can lead to glaucoma.

Endocrine System

Hormones and Glands

The endocrine system consists of glands that secrete hormones to regulate various bodily functions, including metabolism, growth, and blood chemistry.

• Thyroid Gland: Produces major metabolic hormones (e.g., thyroxine) that regulate metabolism.

• Parathyroid Gland: Regulates blood calcium levels by secreting parathyroid hormone (PTH).

• Pancreas: Produces hormones such as insulin and glucagon to regulate blood glucose levels.

• Pituitary Gland: Secretes growth hormone; hypo-secretion leads to pituitary dwarfism.

Endocrine Disorders

Disorders of the endocrine system result from hypo- or hyper-secretion of hormones:

• Graves Disease: An autoimmune disorder causing hyperthyroidism (excess thyroid hormone).

• Pituitary Dwarfism: Caused by hypo-secretion of growth hormone from the pituitary gland, resulting in stunted growth.

• Diabetes Mellitus: Caused by hypo-secretion of insulin from the pancreas, leading to high blood glucose levels.

Example: The parathyroid gland increases PTH secretion when blood calcium levels are low, stimulating bone resorption to restore calcium balance.

Operant Conditioning (Additional info)

Volatility in Operant Conditioning

In the context of operant conditioning, a stimulus must be volatile (able to evaporate and be detected by smell) to be effective in certain behavioral experiments.

• Volatile Substances: Easily vaporize and can be detected by olfactory receptors.

Example: Ammonia is a volatile substance often used in olfactory conditioning experiments.