Nervous System & Endocrine System Lab

Introduction

This study guide covers the essential structures and functions of the nervous and endocrine systems, as explored in lab models and sheep brain dissection. It emphasizes the identification of anatomical features, their functional relationships, and the integration of brain structures with endocrine glands and hormones.

Nervous System

Cerebral Cortex

The cerebral cortex is the outer layer of the cerebrum, responsible for higher brain functions such as thought, memory, and voluntary movement.

• Frontal lobe: Involved in reasoning, planning, movement, and problem-solving.

• Parietal lobe: Processes sensory information such as touch, temperature, and pain.

• Temporal lobe: Responsible for auditory processing and memory.

• Occipital lobe: Main center for visual processing.

Corpus Callosum: A thick band of nerve fibers connecting the two cerebral hemispheres, allowing communication between them.

Diencephalon

The diencephalon is located deep within the brain and includes key structures for sensory and endocrine integration.

• Thalamus: Relays sensory and motor signals to the cerebral cortex.

• Hypothalamus: Regulates homeostasis, controls the pituitary gland, and links the nervous and endocrine systems.

• Pineal body (gland): Secretes melatonin, regulating sleep-wake cycles.

• Pituitary gland: Known as the "master gland," it controls other endocrine glands and is connected to the hypothalamus by a stalk.

Brainstem

The brainstem controls basic life functions and connects the brain to the spinal cord.

• Midbrain: Involved in vision, hearing, and motor control.

• Pons: Relays signals between the cerebrum and cerebellum; involved in sleep and respiration.

• Medulla oblongata: Regulates vital functions such as heart rate and breathing.

Cerebellum

The cerebellum coordinates voluntary movements and maintains balance and posture.

• Gray matter: Contains neuron cell bodies.

• Arbor vitae: The tree-like arrangement of white matter within the cerebellum.

Cranial Nerves & Functions

Cranial nerves emerge directly from the brain and control sensory and motor functions of the head and neck.

• Olfactory bulbs: Receive action potentials from olfactory receptors (smell).

• Optic nerves and optic chiasm: Transmit visual information from the eyes to the brain (vision).

Neuron Structure

Motor Neuron Model

Neurons are specialized cells for transmitting electrical signals throughout the nervous system.

• Cell body (soma): Contains the nucleus and organelles.

• Dendrites: Receive signals from other neurons.

• Axon: Conducts impulses away from the cell body.

• Schwann cell: Produces the myelin sheath in the peripheral nervous system.

• Myelin sheath: Insulates the axon, speeding up signal transmission.

• Neurilemma: Outer layer of Schwann cell, important for nerve regeneration.

• Node of Ranvier: Gaps in the myelin sheath where action potentials are regenerated.

Action Potential Equation:

Additional info: The equation above is a simplified representation; actual action potential generation involves complex ionic movements.

Endocrine System

Major Glands and Hormones

The endocrine system consists of glands that secrete hormones to regulate body functions.

• Adrenal gland: Releases cortisol (increases glucose during stress) and epinephrine/norepinephrine ("fight or flight" response).

• Pineal gland: Secretes melatonin (regulates sleep).

• Pancreas: Produces insulin (lowers blood glucose).

• Thyroid gland: Releases thyroxine (increases metabolism).

• Testis: Produces testosterone (male sex hormone).

• Ovary: Produces estrogen (female sex hormone).

Pituitary Gland & Hormones

The pituitary gland controls other endocrine glands through hormone secretion.

• Growth hormone (GH): Stimulates growth and cell reproduction.

• Prolactin: Stimulates milk production.

• Thyroid-stimulating hormone (TSH): Signals the thyroid gland to release thyroxine.

• Adrenocorticotropic hormone (ACTH): Stimulates the adrenal gland to release cortisol.

• Antidiuretic hormone (ADH): Promotes water reabsorption by the kidneys.

• Oxytocin: Stimulates milk let-down and uterine contractions.

Gland-Hormone-Action Relationships

Each endocrine gland produces specific hormones that have targeted actions in the body.

Integration of Nervous and Endocrine Systems

Functional Relationships

The nervous and endocrine systems work together to maintain homeostasis and coordinate body functions.

• The hypothalamus links the nervous system to the endocrine system via the pituitary gland.

• Neural signals can trigger hormone release, and hormones can affect neural activity.

Example: Stress activates the hypothalamus, which signals the pituitary to release ACTH, stimulating the adrenal glands to produce cortisol.

Summary Table: Brain Structures and Functions

Additional info: These tables and explanations provide a comprehensive overview for lab identification and understanding of structure-function relationships in the nervous and endocrine systems.