Biology 1106 Test 2

• Paracrine regulations: Molecules that are released and act within an organ on nearby cells, allowing cells of an organ to regulate one another.
• Hormones: Regulatory chemicals that are secreted into the extracellular fluid, carried by blood, and act at a distance from its source.
• Autocrine Regulations: a cell releases and binds to a receptor on the same cell so that it regulates itself. Common in the immune system
• Pheromones: Chemicals that are released into the environment for communication between individuals of a single species.
• Neurohormones: Molecules that are released into the blood stream by neurons.
• Exocrine glands: secretes chemicals into a duct that empties to the outside of the body. Exit. Duct, non-hormone secretion
• Gland A (Exocrine) & Gland B (Endocrine)

  
• Endocrine gland: secrete hormones into the blood, which carries the hormones to the target cells. Ductless
• Two types of communication in the body: Nervous system and Endocrine system
• Nervous system: rapid communications & electrochemical signals (action potentials)
• Endocrine system: slower communication & hormones
• The nervous system and endocrine system work together to maintain homeostasis, regulate physiology and development.
• Chemical Messengers

  
• Lipophilic hormones: steroid hormones and thyroid hormones. They are fat-soluble, with a transport protein, intracellular receptor, and it takes hours to days
• Hydrophilic Hormones: protein, peptide and most amino acid derivatives, water soluble, membrane receptor and it takes minutes to hours
• Hydrophilic hormones are "water-loving" so they are soluble in water. These hormones are soluble in blood because it is a water-based solution. Hydrophilic hormones cannot readily diffuse through the interior of the phospholipid bilayer of the target cell; the interior is hydrophobic. As such, hydrophilic hormones bind to receptors on the exterior of the target cell to initiate a response.
• Lipophilic hormones are "fat-loving" so they are soluble in fats. These hormones are not soluble in blood since they are not water-soluble. Lipophilic hormones can diffuse through the interior of the phospholipid bilayer of the target cell. As such, lipophilic hormones bind to receptors that are on the interior of the target cell.
• Chemical properties of Hormones

  
• In order for an organ to be classified as part of the endocrine system, it has to secrete hormones into the bloodstream.
• The thyroid gland is responsible for regulating basal metabolism and development.
• Thyroxine is the hormone that is secreted by the thyroid gland, and this hormone regulates metabolism.
• Hypothalamus: 1. controls anterior pituitary by secreting, releasing and inhibiting hormones. 2. Produces oxytocin and ADH which are stored and released by the posterior pituitary
• What is the hypophyseal portal vein? system of veins that links the hypothalamus and anterior pituitary gland through a system of veins that start and end in capillaries to quickly transport and exchange hormones
• Anterior pituitary: produces 7 hormones whose release is controlled by the hypothalamus. TSH, ACTH, GH
• Adrenocorticotropic hormone (ACTH): Peptide, tropic hormone; stimulates adrenal glands
• Thyroid-stimulating hormone (TSH): glycoprotein, tropic hormone; stimulates thyroid gland
• Growth hormone (GH): Protein, stimulates tissue growth and regulates metabolism
• parathyroid gland: are small glands attached to the thyroid gland
• Parathyroid hormone helps regulate blood calcium levels by causing bones to release calcium
• Adrenal gland: located above each kidney and has an inner layer (adrenal medulla) and outer layer (adrenal cortex)
• pancreas: produces insulin and glucagon, regulates blood glucose. has both endocrine and exocrine functions
• insulin: a hormone that is produced by the pancreas and regulates blood glucose levels
• After a meal, the concentration of glucose in the blood rises. This results in an increased production of insulin. insulin by the β cells of the islets of Langerhans in the pancreas. The response is the movement of glucose from blood into cells, which returns the blood glucose to a normal level.
• During a fasting state in between meals, the concentration of glucose in the blood decreases. This results in an increased production of glucagon.
•  glucagon by the 𝛼 cells of the islets of Langerhans in the pancreas. The response is the hydrolysis of glycogen to glucose, which returns the blood glucose to a normal level.
• insulin is a hydrophilic hormone
• insulin and glucagon work antagonistically with each other, which is important for maintaining homeostasis of the body.
• hydrostatic skeletons: Consists of a fluid-filled cavity surrounded by muscles; some examples of organisms with this type are soft-bodied terrestrial invertebrates and soft-bodied aquatic invertebrates.
• endoskeletons: Consists of rigid internal elements that offer sites for muscle attachment; some examples of organisms with this type are echinoderms and vertebrates.
• exoskeletons: Consists of a rigid outer covering that protects internal organs; some examples of organisms with this type are arthropods and fungi.