Endocrine System 2

• The body responds to different stimuli and changes resulting from various activities
• The body sends appropriate signals to other organs through electrical and chemical signaling by the nervous and endocrine systems
• Internal communication is usually performed through electrical and chemical signaling by the nervous and endocrine systems
• The endocrine system synthesizes, stores, and releases hormones that serve as chemical signals for other body tissues to perform specific tasks
• A vast majority of body tissues are receptive to hormones
• The endocrine system is made up of multiple glands that release hormones directly into the bloodstream
• The hypothalamus is one of the major endocrine organs that maintain homeostasis in the human body
• The pituitary glands, known as the master gland, control many other endocrine glands' functions and activities
• The pineal gland produces the hormone melatonin, important for regulating sleep-wake patterns
• The thyroid gland produces hormones that help regulate the metabolic rate of the body
• The thyroid gland requires an adequate amount of iodine from the bloodstream to synthesize thyroid hormones
• The parathyroid glands control calcium and phosphorus levels by synthesizing and regulating the secretion of the parathyroid hormone
• The thymus plays a role in the maturation of T cells of the immune system and produces hormones required for normal bodily functions
• The adrenal glands synthesize hormones like adrenaline, cortisol, and aldosterone with various functions in the body
• The gonads, including the testes and ovaries, serve important endocrine functions by secreting hormones like estrogen, progesterone, and testosterone
• The pancreas plays a role in regulating blood sugar levels by producing insulin and glucagon
• Testosterone functions:

  • Regulates secondary sexual characteristics in males
  • Regulates bone mass, muscle mass, and sperm production
• Pancreas functions:

  • Exocrine function: secretes enzymes like trypsin, chymotrypsin, amylase, and lipases for food digestion
  • Endocrine function: produces insulin and glucagon to regulate blood sugar levels
• Feedback mechanisms:

  • Positive feedback: amplifies changes in the body, e.g., oxytocin release during childbirth
  • Negative feedback: reverses changes in the body, e.g., insulin and glucagon regulating blood sugar levels
• Nervous system divisions:

  • Central nervous system (CNS): includes the brain and spinal cord
  • Peripheral nervous system (PNS): includes nerves outside the CNS
  • Autonomic nervous system: regulates involuntary body functions like cardiovascular, respiratory, and digestive processes
• Autonomic nervous system divisions:

  • Sympathetic nervous system: regulates fight-or-flight responses
  • Parasympathetic nervous system: regulates rest-and-digest functions
• Hormones associated with the anterior and posterior pituitary glands:

  • Anterior lobe hormones: TSH, GH, ACTH, LH, FSH, Prolactin
  • Posterior lobe hormones: Vasopressin, Oxytocin
• Hypothalamus and pituitary gland:

  • Linked by the hypophyseal portal system to influence pituitary endocrine secretions
  • Hypothalamus receives signals from the body to regulate hormone release
• Key Points:

  • Endocrine system produces hormones for various functions
  • Positive feedback amplifies changes, negative feedback reverses changes
  • Nervous system has central, peripheral, autonomic, and somatic divisions