Control and Coordination

2 Control and Coordination

2.1 Overview

• Multicellular organisms consist of various body systems that work in concert.

• Communication occurs through electrical impulses and chemical signals.

• Coordination of communication is key for maintaining a stable internal environment.

2.2 Coordination and Control

• Multicellular Organism: Organisms composed of many cells that must communicate and share resources.

• Homeostasis: The body's ability to maintain a stable internal environment, including blood glucose, pH, and body temperature.

• Stimulus-Response Model: Describes how a change (stimulus) detected by receptors leads to an appropriate response.

  • Negative Feedback: Response counteracts stimulus to return to normal range.

2.2.1 Working Together

• Body systems must work together to supply nutrients, remove waste, and keep cells functioning.

• Examples of system interactions:

  • Digestive system breaks down food into nutrients for cells.

  • Circulatory system transports nutrients throughout the body.

  • Respiratory system manages oxygen supply and carbon dioxide removal.

2.2.2 Stimulus-Response Model

• Effectors: Organs that respond to stimuli (e.g., muscles and glands).

• Receptors detect internal/external stimuli and relay information to the central nervous system.

• The control center processes this information to generate a response.

2.2.3 Feedback Mechanisms

• Negative Feedback: Restores normal conditions (e.g., insulin regulates blood glucose).

• Positive Feedback: Enhances or amplifies changes (e.g., childbirth contractions mediated by oxytocin).

2.3 The Nervous System — Fast Control

• Components of the Nervous System:

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

  • Peripheral Nervous System (PNS): Nerves that connect CNS to the body.

• Neurons: Specialized cells transmitting nerve impulses; consist of dendrites, cell body, and axon.

  • Sensory neurons carry impulses to the CNS, motor neurons carry impulses away.

2.4 Getting the Message

• Sense organs detect environmental stimuli through receptors.

• Types of receptors include:

  • Photoreceptors: Detect light.

  • Mechanoreceptors: Detect pressure and sound.

  • Chemoreceptors: Detect chemical stimuli (taste/smell).

2.5 The Brain

• The brain is the body’s control center for functions, emotions, and memories.

• Hindbrain, Midbrain, Forebrain: Each part serves distinct roles in processing sensory information and regulating bodily functions.

2.6 The Endocrine System — Slow Control

• The endocrine system uses hormones for long-term regulation.

• Hormones are released from glands into the bloodstream and affect target cells.

• Major Glands:

  • Pituitary Gland: Master gland controlling other endocrine glands.

  • Thyroid Gland: Regulates metabolism.

  • Adrenal Glands: Produce hormones for stress responses.

2.7 Plant Hormones

• Plants use hormones (auxins, cytokinins, gibberellins, abscisic acid, ethylene) for growth and responses to stimuli.

• Some hormones coordinate reactions such as flowering and fruit ripening.

2.8 Emotions and the Limbic System

• The limbic system is crucial for emotion processing and memory formation.

• Key components:

  • Amygdala: Processes emotional responses (fear/anger).

  • Hippocampus: Forms and stores memories.

2.9 Memory

• Memory Formation Stages:

  • Sensory Register: Briefly holds sensory information.

  • Working Memory: Active processing where information can be manipulated.

  • Long-Term Memory: Information stored for extended periods, often requiring rehearsal and encoding.

2.10 Sleep

• Sleep is regulated by the brain's reticular formation and circadian rhythms.

• Melatonin, produced by the pineal gland, promotes sleepiness.

• Sleep cycles include REM and non-REM stages, with varying functions.

2.11 The Teen Brain

• Neural pathways continue to develop throughout adolescence, including synaptic pruning and myelination.

• The prefrontal cortex, responsible for decision-making and impulse control, develops last.

2.12 Damage to the Nervous System

• Paralysis: Loss of movement resulting from spinal cord damage.

• Motor Neuron Disease: Gradual paralysis without affecting sensory function.

2.13 Studying the Brain

• Technologies such as fMRI, PET scans, and EEGs provide insights into brain structure and function.

• Neuroplasticity shows that neuronal pathways can change with stimuli and learning.

2.14 Review

• Multicellular organisms rely on internal systems for coordination and control, enabling responses to environmental changes and maintaining homeostasis.

• The nervous and endocrine systems work together, utilizing feedback mechanisms for regulation.

• Hormones and neurotransmitters play critical roles in emotional and physiological responses, influencing behavior and learning.

• Multicellular Organisms: Composed of many cells that need to communicate and share resources.

• Homeostasis: The ability to maintain a stable internal environment (e.g., blood glucose, pH, body temperature).

• Stimulus-Response Model: A process where changes (stimuli) detected by receptors lead to appropriate responses, with negative feedback mechanisms restoring normal conditions.

• Nervous System: Fast control system consisting of the Central Nervous System (CNS) and Peripheral Nervous System (PNS), facilitating quick communication through neurons.

• Endocrine System: Slow control using hormones released into the bloodstream for long-term regulation (e.g., metabolism, stress response).

• Feedback Mechanisms: Negative feedback restores normal conditions (e.g., insulin), while positive feedback amplifies changes (e.g., childbirth contractions).

• Limbic System: Important for emotion processing and memory formation, involving key components like the amygdala and hippocampus.

• Memory: Involves stages such as sensory register, working memory, and long-term memory.

• Sleep: Regulated by brain mechanisms and includes REM and non-REM stages.

• Teen Brain Development: Neural pathways develop throughout adolescence, impacting decision-making and impulse control.

• Nervous System Damage: Includes conditions like paralysis and motor neuron diseases, which affect movement and sensory functions.

Multicellular Organisms: Multicellular organisms are composed of numerous specialized cells that must communicate effectively to share resources and maintain their functions. This communication is essential for the survival of the organism as a whole.

Homeostasis: Homeostasis refers to the body’s ability to maintain a stable internal environment despite external changes. This includes regulation of critical factors such as blood glucose levels, pH balance, and body temperature, which are vital for normal physiological functions.

Stimulus-Response Model: The stimulus-response model describes the process in which changes, or stimuli, detected by receptors in the organism lead to appropriate responses. Negative feedback mechanisms play a crucial role in this model, restoring normal conditions to ensure consistent internal balance. For example, when blood glucose levels rise, insulin is released to lower them back to a normal range.

Nervous System: The nervous system is the body’s fast control system, which comprises the Central Nervous System (CNS)—including the brain and spinal cord—and the Peripheral Nervous System (PNS), which connects the CNS to the rest of the body. Neurons are the specialized cells responsible for transmitting nerve impulses, and they allow for quick communication throughout the organism.

Endocrine System: In contrast to the nervous system, the endocrine system provides slow control through hormones. Hormones are chemical messengers released into the bloodstream by glands, and they regulate long-term physiological processes, including metabolism, growth, and stress responses.

Feedback Mechanisms: Feedback mechanisms are essential for maintaining homeostasis. Negative feedback mechanisms restore normal conditions in the body (e.g., the release of insulin to decrease high blood sugar), whereas positive feedback mechanisms enhance or amplify changes (e.g., the release of oxytocin during childbirth to increase contraction strength).

Limbic System: The limbic system is a critical brain region involved in emotional processing and memory formation. Key components include the amygdala, which processes emotional responses such as fear and anger, and the hippocampus, which is responsible for forming and storing memories.

Memory: Memory formation occurs in stages, including sensory register (briefly holding sensory information), working memory (active manipulation of information), and long-term memory (storage of information for extended periods, often relying on rehearsal and encoding).

Sleep: Sleep is a vital process regulated by the brain's reticular formation and circadian rhythms. The production of melatonin by the pineal gland promotes sleepiness, and sleep cycles include both REM (rapid eye movement) and non-REM stages, serving different restorative functions.

Teen Brain Development: During adolescence, neural pathways continue to develop, characterized by processes like synaptic pruning and myelination. The prefrontal cortex, which governs decision-making and impulse control, is one of the last areas to mature.

Nervous System Damage: Damage to the nervous system can lead to severe conditions such as paralysis (loss of movement) resulting from spinal cord injury or motor neuron disease, which involves gradual paralysis of voluntary muscles without affecting sensory functions.