Control and coordination

• Endocrine glands secrete hormones such as pituitary gland, thyroid gland, adrenal gland, pancreas
• Major endocrine glands in humans include:

  • Pituitary
  • Hypothalamus
  • Pineal
  • Thyroid
  • Parathyroid
  • Thymus
  • Pancreas
  • Adrenal
  • Testis in men / ovary in women
• Feedback mechanism (positive and negative) regulates the action of hormones
• Characteristics of hormones:

  • Act as chemical messengers
  • Secreted by living cells/tissues or organs called glands
  • Secreted in very small quantities
  • Act upon specific cells, tissues, or organs called target sites
  • Generally slow in action, but have long-lasting effects
  • Either accelerate or inhibit a reaction
• Various Glands:

  • Pituitary gland:
  • Located at the base of the brain
  • Secretes growth hormone (GH)
  • Required for proper body growth
  • Hyposecretion causes dwarfism
  • Hypersecretion causes gigantism in children and acromegaly in adults
  • Thyroid gland:
  • Located close to trachea in the neck
  • Produces thyroxine
  • Required for regulating metabolism
  • Hyposecretion causes hypothyroidism
  • Excess secretion causes hyperthyroidism
  • Parathyroid Gland:
  • Four glands present on the back side of thyroid glands
  • Secrete parathyroid hormone (PTH)
  • Regulates calcium ions in the bloodstream
• • Excess PTH removes calcium from bones
  • Pancreas:
  • Produces insulin and glucagon
  • Maintains blood sugar level
  • Deficiency of insulin results in diabetes
  • Adrenal Gland:
  • Located on the upper part of each kidney
  • Cortex secretes hormones like cortisol
  • Medulla secretes adrenaline
  • Gonads:
  • Testes in males and ovaries in females
  • Male sex hormone is testosterone
  • Female sex hormones are estrogen and progesterone
  • Deficiency of estrogen causes infertility
• Control and coordination:

  • Working together of various integrated body systems in response to changes in the surrounding for the maintenance of bodily functions
  • Nervous system and endocrine system provide control and coordination in animals
• Nervous system:

  • Neurons are functional units of the nervous system
  • Types of neurons: sensory, motor, relaying or intermediate
  • Nerve is a collection of nerve fibers enclosed in a tubular medullary sheath
  • Synapse is a small gap between neurons
  • Human nervous system divided into central nervous system (CNS) and peripheral nervous system (PNS)
  • CNS consists of the brain and spinal cord
  • PNS consists of nerves connecting CNS to different body parts
• • Brain is enclosed in the cranium and spinal cord is protected by vertebral column
  • Brain classified into forebrain, midbrain, and hindbrain
  • Forebrain consists of cerebrum.
  • Midbrain consists of hypothalamus and pituitary gland.
  • Hindbrain consists of pons, medulla, and cerebellum
  • Spinal cord runs through the vertebral column
  • Three types of responses: reflex action, voluntary action, involuntary action
• • Abscisic acid promotes seed dormancy
  • Ethylene regulates fruit ripening
• Plants respond to stimuli by showing movement

  • Examples of movements in plants:
  • Sensitive plant folds its leaves when touched
  • Seed germination involves root growth down and stem growth up
  • Movement in plants can be growth-independent or growth-dependent
  • Tropic movement: towards or away from stimulus
  • Nastic movements occur in response to environmental stimulus
  • Tropic movements include phototropism, geotropism, thigmotropism, hydrotropism
  • Hormones in plants:
  • Auxin promotes stem growth
  • Gibberellin promotes stem elongation
  • Cytokinin promotes cell division