Chapter 8 Human Physiology

Structural Organization of the Brain

Hindbrain

• Medulla Oblongata: Controls autonomic functions (e.g., blood pressure, heart rate, breathing).

• Cerebellum: Manages coordination and balance.

• Pons: Connects the cerebellum and spinal cord with higher brain centers.

Midbrain

• Function: Relays visual and auditory information. Contains the corpora quadrigemina.

  • Superior Colliculi: Involved in visual reactions.

  • Inferior Colliculi: Involved in auditory reactions.

Forebrain

• Thalamus: Processes and relays sensory information to higher brain areas.

• Hypothalamus: Regulates the endocrine system through the pituitary gland.

Cerebrum

• Function: Coordinates higher functions such as:

  • Language processing

  • Decision making

  • Conscious thought

  • Movement initiation

Lobes of the Cerebrum

1. Frontal Lobe: Responsible for motor control, intellectual functions, speech production (Broca’s area), and personality.

2. Parietal Lobe: Processes sensory information and language interpretation.

3. Temporal Lobe: Interprets auditory sensations and stores auditory/visual memories.

4. Occipital Lobe: Integrates visual information and supports conscious perception of vision.

5. Insula: Involved in memory, pain sensations, and visceral integration.

Speech Centers

• Wernicke's Area: Processes language comprehension. Receives input from auditory/visual areas.

• Broca’s Area: Produces speech; communicates with motor cortex for articulation.

Speech Aphasias

• Broca’s Aphasia: Affects speech production; individuals have difficulty speaking but understand language.

• Wernicke’s Aphasia: Impairs language comprehension; speech may be fluent but lacks meaning.

Limbic System

• Function: Governs emotions and behavior patterns. Key in experiencing emotions like fear, anger, and love. Works with the thalamus and hypothalamus for emotional regulation.

Imaging Techniques

• CT Scan: Uses X-ray beams to create brain images.

• PET Scan: Utilizes radioactive glucose to identify brain activity.

• MRI: Employs magnetic fields to produce high-resolution images without radiation.

• fMRI: Measures brain activity and blood flow during tasks.

Hypothalamus & Pituitary Gland

• Role: Regulates body temperature, hunger, thirst, and hormonal secretions through connections with the pituitary gland.

Reticular Formation & System

• Function: Modulates wakefulness and sleep. Activates selectively to sensory input.

Spinal Cord Tracts

• Ascending Tracts: Relay sensory information from body to brain.

• Descending Tracts: Transmit motor commands from brain to body. Most sensory information crosses over between the hemispheres.

Summary

The brain's structural organization is critical for various functions - from basic life support in the hindbrain to complex cognitive processes in the cerebrum, complemented by emotional regulation through the limbic system.