LS Challice Regulation

Overview of Human Body Systems

Nervous System

• Definition: The human body uses a communication network involving the nervous system and the endocrine system to regulate bodily functions and maintain homeostasis as environmental changes occur.

• Components:

  • Central Nervous System (CNS): Comprises the brain and spinal cord.

  • Peripheral Nervous System (PNS): Consists of all nerves branching from the spinal cord to the rest of the body.

Major Divisions of the Nervous System

• CNS:

  • Function: Responds to changes in the environment (FAST responses).

  • Example Structures: Brain, spinal cord.

• PNS:

  • Function: Carries signals between the CNS and the rest of the body.

  • Somatic Nervous System: Controls voluntary actions.

  • Autonomic Nervous System: Controls involuntary actions (includes:

    • Sympathetic Nervous System: Prepares the body for fight or flight (increases heart rate, etc.).

    • Parasympathetic Nervous System: Restores the body to a state of rest (decreases heart rate, etc.).

Neurons

• Definition: Basic functional unit of the nervous system, consisting of:

  • Dendrites: Receive impulses.

  • Cell Body (Soma): Contains the nucleus.

  • Axon: Transmits impulses away from the cell body; protected by myelin sheath.

  • Terminal Buttons: Release neurotransmitters to communicate with other neurons.

• Types of Neurons:

  • Sensory Neurons: Carry impulses from receptors to the CNS.

  • Interneurons: Connect sensory and motor neurons; located in the CNS.

  • Motor Neurons: Carry signals from the CNS to effectors (muscles or glands).

Reflexes

• Definition: Automatic responses to stimuli beneficial for survival.

• Components of Reflex Arc:

  • Stimulus: Change in the environment (e.g., touching a hot surface).

  • Receptors: Sense organs (e.g., skin) detect stimuli.

  • Sensory Neuron: Carries messages to the CNS.

  • Interneuron: Integrates messages and connects sensory input to motor output.

  • Motor Neuron: Sends response message to effectors.

  • Effector: Muscle or gland that performs the response (e.g., withdrawing hand).

Neurotransmitters

• Function: Chemicals in the nervous system that transmit messages across synapses from one neuron to another.

• Synapse: The gap between two neurons where information is transferred through neurotransmitters.

• Impact of Substances: Toxins, drugs, and alcohol can disrupt neurotransmitter function, preventing message transmission.

Endocrine System

• Definition: Comprised of glands that release hormones, regulating various body functions and maintaining homeostasis.

• Key Components:

  • Pituitary Gland: Often termed the “master gland”; controls other endocrine glands and releases several hormones.

  • Thyroid Gland: Located in the neck; regulates metabolism and releases hormones.

  • Adrenal Glands: Located atop kidneys; responsible for adrenaline and stress response.

  • Pancreas: Regulates blood sugar levels through hormone release (insulin and glucagon).

  • Gonads: Ovaries (female) and testes (male); regulate reproductive functions.

Hormones

• Function: Serve as chemical messengers that target specific cells within the body to elicit responses based on the body's changing conditions.

• Mechanism: Hormones bind to receptor molecules on target cells to initiate their effects.

Feedback Mechanisms

• Purpose: Maintain homeostasis by regulating various body functions.

• Types:

  • Negative Feedback: Reverses effect of a change (e.g., body temperature regulation).

  • Positive Feedback: Enhances the effect of a change (less common, e.g., childbirth).

• Examples:

  • Sweating: Lowers body temperature in response to heat.

  • Blood Sugar Regulation: Insulin and glucagon ensure stable blood glucose levels.

Diseases Related to Endocrine System

• Goiter: Thyroid disease due to iodine deficiency affecting thyroxin production.

• Diabetes: Dysregulation of insulin production from the pancreas leads to abnormal blood sugar levels.