Chapter 17 - Section 17.2 - Study Guide - Assess Your Learning Outcomes - Page 669: 6

The posterior pituitary gland releases hormones that are synthesized in the hypothalamus and then transported to the posterior pituitary for storage and subsequent release. Two important hormones released by the posterior pituitary are oxytocin and antidiuretic hormone (ADH), also known as vasopressin. Here are the details you asked for: 1. **Oxytocin:** - Abbreviation: OT - Target Organs/Effects: - **Uterus:** Oxytocin stimulates uterine contractions during labor, aiding in childbirth. It also promotes the movement of milk through the mammary ducts during breastfeeding. - **Mammary Glands:** Oxytocin triggers the ejection of milk from the mammary glands, facilitating breastfeeding. - Role of Neuroendocrine Reflexes: The release of oxytocin is regulated by neuroendocrine reflexes. During childbirth, the stretching of the cervix and uterus stimulates sensory neurons, which signal the hypothalamus to release oxytocin. Additionally, the suckling stimulus during breastfeeding stimulates nerve endings in the nipples, leading to the release of oxytocin, which facilitates milk ejection. This positive feedback loop enhances the effects of oxytocin. 2. **Antidiuretic Hormone (ADH) / Vasopressin:** - Abbreviation: ADH - Target Organs/Effects: - **Kidneys:** ADH acts on the kidneys to increase water reabsorption from the urine back into the bloodstream. This reduces urine volume and helps maintain water balance in the body. - **Blood Vessels:** In cases of high ADH levels, vasopressin causes vasoconstriction (narrowing of blood vessels), which can help increase blood pressure. - Role of Neuroendocrine Reflexes: The release of ADH is primarily regulated by osmoreceptors in the hypothalamus. When the blood's osmolarity (concentration of solutes) increases due to dehydration or other factors, osmoreceptors sense the change and trigger the release of ADH. This leads to increased water reabsorption in the kidneys, reducing blood osmolarity. ADH release is also influenced by factors such as blood volume and blood pressure. Neuroendocrine reflexes play a crucial role in regulating the release of these hormones from the posterior pituitary. These reflexes ensure that the body responds appropriately to physiological changes and maintains homeostasis. In both cases, sensory input triggers nerve impulses that travel to the hypothalamus, leading to the release of the corresponding hormone from the posterior pituitary gland.

The posterior pituitary gland releases hormones that are synthesized in the hypothalamus and then transported to the posterior pituitary for storage and subsequent release. Two important hormones released by the posterior pituitary are oxytocin and antidiuretic hormone (ADH), also known as vasopressin. Here are the details you asked for: 1. **Oxytocin:** - Abbreviation: OT - Target Organs/Effects: - **Uterus:** Oxytocin stimulates uterine contractions during labor, aiding in childbirth. It also promotes the movement of milk through the mammary ducts during breastfeeding. - **Mammary Glands:** Oxytocin triggers the ejection of milk from the mammary glands, facilitating breastfeeding. - Role of Neuroendocrine Reflexes: The release of oxytocin is regulated by neuroendocrine reflexes. During childbirth, the stretching of the cervix and uterus stimulates sensory neurons, which signal the hypothalamus to release oxytocin. Additionally, the suckling stimulus during breastfeeding stimulates nerve endings in the nipples, leading to the release of oxytocin, which facilitates milk ejection. This positive feedback loop enhances the effects of oxytocin. 2. **Antidiuretic Hormone (ADH) / Vasopressin:** - Abbreviation: ADH - Target Organs/Effects: - **Kidneys:** ADH acts on the kidneys to increase water reabsorption from the urine back into the bloodstream. This reduces urine volume and helps maintain water balance in the body. - **Blood Vessels:** In cases of high ADH levels, vasopressin causes vasoconstriction (narrowing of blood vessels), which can help increase blood pressure. - Role of Neuroendocrine Reflexes: The release of ADH is primarily regulated by osmoreceptors in the hypothalamus. When the blood's osmolarity (concentration of solutes) increases due to dehydration or other factors, osmoreceptors sense the change and trigger the release of ADH. This leads to increased water reabsorption in the kidneys, reducing blood osmolarity. ADH release is also influenced by factors such as blood volume and blood pressure. Neuroendocrine reflexes play a crucial role in regulating the release of these hormones from the posterior pituitary. These reflexes ensure that the body responds appropriately to physiological changes and maintains homeostasis. In both cases, sensory input triggers nerve impulses that travel to the hypothalamus, leading to the release of the corresponding hormone from the posterior pituitary gland.