Control and Coordination-Notes

Main Functions

• Sensation: Receives signals from the environment.
• Integration: Processes and interprets sensory inputs.
• Response: Commands effectors (muscles/glands) to produce reactions.

Types of Nervous System

• Central Nervous System (CNS): Processes & integrates information
  
  
  • Brain: Control center: thinking, memory, emotions, coordination
  • Spinal Cord: Pathway for messages to/from brain, reflex actions



• Peripheral Nervous System (PNS): Connects CNS to body parts
  
  
  • Cranial Nerves:

    - Nerves that emerge directly from the brain (mainly the brainstem), not the spinal cord.
    - 12 pairs (each with left and right).
    - Connect the brain to different parts of the head, neck, and internal organs; involved in sensory (vision, smell, hearing, taste), motor (movement of eyes, face, tongue), and mixed (both) functions.

  • Spinal Nerves:
    - Nerves that arise from the spinal cord.
    - 31 pairs (each with left and right).
    - Connect the spinal cord to the rest of the body (skin, muscles in arms, legs, trunk—sensory and motor functions).



• Endocrine System (Associated with Harmones): The endocrine system is a network of glands in the body that produce hormones
  
  
  • Pituitary: Master gland: regulates other glands, growth, puberty
  • Thyroid: Controls metabolism, growth and development
  • Parathyroid: Regulates calcium balance in blood
  • Adrenal: Stress response, blood pressure, energy
  • Pancreas: Controls blood glucose level
  • Testes: Develops male sex organs, secondary sexual characteristics
  • >Ovaries: Develops female sex organs, menstrual cycle
  • Hypothalamus: Links nervous & endocrine system, regulates pituitary

• Receptor: all cells/muscles that receives stimulus



• Effector: are tissues/muscles/ glands which act in response to stimulus received
• Response: is the reaction towards the stimulus by the organism

Neurons

Neurons, also known as nerve cells, are the basic units of the nervous system. They are responsible for receiving sensory information and sending motor commands to muscles.

Structure

• Neurons have three parts: a cell body, an axon, and dendrites.
• The cell body contains the nucleus, Golgi apparatus, endoplasmic reticulum, and mitochondria.
• The axon is a tube-like structure that carries electrical impulses from the cell body.
• The dendrites are branch-like structures that receive messages from other neurons.

Types of Neurons

• There are three main types of neurons: sensory neurons, motor neurons, and interneurons.
• Sensory neurons carry information from the body to the brain.
• Motor neurons carry information from the brain to the muscles.
• Interneurons carry information between different neurons in the body.

Function:

• Neurons receive and transmit signals to different parts of the body.
• They allow us to move our muscles, feel the external world, think, and form memories.
• A group of neurons forms a nerve.
• Nerve signals travel rapidly along the axons of myelinated nerves.

Neurogenesis

The creation of new neurons in the brain is called neurogenesis, and this can happen even in adults.

SENSORY NEURONS

Sensory neurons are nerve cells that carry information from the body's sensory organs to the brain and spinal cord. They are part of the peripheral nervous system, which is located outside the brain and spinal cord.

INTERNEURONS

Interneurons are neurons that connect sensory and motor neurons in the brain and spinal cord. They are also known as association neurons.

MOTOR NEURONS

Motor neurons are nerve cells that control muscle movements. They are part of the central nervous system (CNS) and are found in the brain and spinal cord.

Structure:

• Motor neurons are multipolar, meaning they have one axon and multiple dendrites.
• The cell body of a motor neuron is called the soma.
• The axon is a long extension that transmits information from the soma to the dendrites.
• The dendrites are branch-like structures that receive and send information from other neurons.

Types of motor neurons:

• Upper motor neurons: Travel between the brain and spinal cord.
• Lower motor neurons: Travel from the spinal cord to the muscles.

The path followed by a Nerve Impulse during reflex action is an unconscious response to a sudden stimulus.

• Fore Brain
  • Cerebrum: Responsible for Voluntary Actions, Mental abilities, Control thinking, memory, reasoning, perceptions, emotions, speech
  • Thalamus: It relays sensory information to cerebrum
  • Hypothalamus: It controls sleep, hunger, thirst etc. It forms a link between the nervous System and the endocrine System
• Mid Brain
  • The midbrain is involved in motor control, particularly eye movements.
  • It processes visual and auditory signals.
• Hind Brain
  • Cerebellum: Balancing activities e.g. walking on a straight line, cycle riding controlled by cerebellum
  • Pons: Regulate breathing cycle and sleep cycle
  • Medulla: B.P., Salivation, vomiting is controlled by Medulla

Coordination in plants refers to the way plants control and integrate different physiological processes in response to internal and external stimuli. Unlike animals, plants do not have a nervous system or specialised organs for coordination. Instead, plants coordinate their activities using chemical signals known as plant hormones or phytohormones.

Plant Movements:

• Tropic Movements:
  • Growth Dependent Movement
  • Directitional Movement with respect to stimulus
  • More or less permanent or irreversible
  • Found in all plants
  • Slow Action
• Nastic Movements:
  • Growth independent Movement
  • Non Directional
  • Temporary and reversible
  • Found only in speicialised plants
  • Immediatre action

Animal hormones are chemical messengers, produced by endocrine glands, that regulate bodily functions and maintain homeostasis by travelling through the bloodstream to target organs

Types of Animal Hormones:

• Steroid Hormones:
  Derived from cholesterol and include hormones like testosterone, estrogen, and progesterone.
• Peptide Hormones:
  Made up of chains of amino acids, examples include insulin, growth hormone, and thyroid-stimulating hormone.
• Other Important Hormones:
  • Insulin: Regulates blood sugar levels.
  • Adrenaline (Epinephrine): Prepares the body for "fight or flight" situations.
  • Growth Hormone: Promotes growth and development.
  • Thyroid Hormone: Regulates metabolism
  • Antidiuretic Hormone (ADH): Regulates water balance
  • Oxytocin: Involved in childbirth and milk production
  • Cortisol: A stress hormone