Nervous System & Endocrine System Lab Overview

Introduction

This study guide covers the essential anatomical structures and functions of the nervous and endocrine systems, as explored in lab activities using neuron models, brain models, torso models, and sheep brain dissections. Understanding these systems is crucial for integrating knowledge of how the body coordinates and regulates its activities.

Nervous System Anatomy

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.

Brainstem

The brainstem controls basic life functions such as breathing, heart rate, and sleep cycles.

• Midbrain: Involved in vision, hearing, motor control, sleep/wake, and temperature regulation.

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

• Medulla oblongata: Regulates vital functions like heart rate, blood pressure, and breathing.

Cerebellum

The cerebellum coordinates voluntary movements, balance, and posture.

• Gray matter: Contains neuron cell bodies; involved in processing information.

• Arbor vitae (white matter): Tree-like arrangement of white matter that transmits signals to and from the cerebellar cortex.

Diencephalon

The diencephalon is a region deep within the brain that includes several important structures.

• Thalamus: Relay station for sensory and motor signals to the cerebral cortex.

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

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

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

Cranial Nerves & Functions

Cranial nerves emerge directly from the brain and are responsible for sensory and motor functions of the head and neck.

• Olfactory bulbs: Receive axons from olfactory receptor cells; involved in the sense of smell.

• Cranial Nerve I (Olfactory nerve): Transmits sensory information for smell.

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

• Cranial Nerve II (Optic nerve): Responsible for vision.

Neuron Structure

Motor Neuron Model

Motor neurons transmit signals from the central nervous system to muscles, causing movement. Understanding their structure is key to grasping how nerve impulses travel.

• Cell body (soma): Contains the nucleus and organelles; integrates incoming signals.

• Nucleus: Contains genetic material and controls cell activities.

• Axon: Long, slender projection that conducts electrical impulses away from the cell body.

• Dendrites: Branch-like extensions that receive signals from other neurons.

• Schwann cell: Glial cell that forms the myelin sheath around axons in the peripheral nervous system.

• Myelin sheath: Insulating layer that increases the speed of nerve impulse transmission.

• Neurilemma: Outer membrane of Schwann cells; aids in regeneration of damaged nerve fibers.

• Node of Ranvier: Gaps in the myelin sheath where action potentials are regenerated, allowing rapid signal conduction.

Example: The motor neuron model demonstrates how signals travel from the dendrites, through the cell body and axon, jumping between nodes of Ranvier, to reach muscles.

Protection of the Central Nervous System

Protective Structures

The central nervous system (CNS) is protected by several layers and mechanisms to prevent injury and infection.

• Scalp and skin: First line of defense against physical injury.

• Vertebral column: Protects the spinal cord.

• Meninges: Three connective tissue membranes covering the brain and spinal cord:

  • Dura mater: Tough, double-layered outer covering attached to the skull.

  • Arachnoid mater: Middle layer with a web-like structure; contains cerebrospinal fluid (CSF) in the subarachnoid space.

  • Pia mater: Delicate inner layer that clings to the surface of the brain and spinal cord.

• Cerebrospinal fluid (CSF): Cushions the brain and spinal cord, provides nutrients, and removes waste.

• Blood-brain barrier: Selectively allows substances to pass from the blood into the CNS, protecting it from toxins and pathogens.

Endocrine System Anatomy & Function

Major Endocrine Glands and Hormones

The endocrine system consists of glands that secrete hormones to regulate body functions such as growth, metabolism, and stress response.

Integration of Nervous and Endocrine Systems

The nervous and endocrine systems work together to maintain homeostasis. The hypothalamus acts as a bridge, receiving neural signals and controlling the release of hormones from the pituitary gland.

• Example: In response to stress, the hypothalamus signals the pituitary to release ACTH, which stimulates the adrenal glands to produce cortisol.

Summary Table: Key Structures and Functions

Key Equations

• Nerve Impulse Conduction Speed:

• Hormone Regulation Example (Negative Feedback):

Additional info: Some details, such as the full list of cranial nerves and more in-depth hormone actions, have been inferred and expanded for academic completeness.