ADH also causes the blood vessels to constrict thereby elevating blood pressure

Adh also causes the blood vessels to constrict

This preview shows page 6 - 8 out of 14 pages.

ADH also causes the blood vessels to constrict, thereby elevating blood pressure. Because of this blood pressure–elevating effect, ADH is also called vasopressin Oxytocin The second posterior pituitary hormone is oxytocin. The target organs of oxytocin in the female are the uterus and the mammary glands (breasts). Oxytocin release occurs in response to neuroendocrine reflexes, that is, in response to signals from the nervous system. Oxytocin stimulates the muscles of the uterus to contract and plays a role in labor and the delivery of a baby. Oxytocin also plays a role in breast-feeding. When the baby suckles at the breast, oxytocin is released and stimulates contraction of the smooth muscles around the mammary ducts within the breasts, thereby releasing breast milk. The release of milk in response to suckling is called the milk let-down reflex Thyroid Gland The thyroid gland is located in the anterior neck; it is situated anterior to the trachea and is easily palpated.The thyroid gland is butterfly shaped and has two large lobes connected by a band of tissue called the isthmus. The thyroid gland contains two types of cells: the follicular cells, located within the thyroid follicle, and the parafollicular cells, located between the follicles. Thyroid Follicle The thyroid gland is composed of many secretory units called follicles. The cavity in each follicle is filled with a clear, viscous substance called colloid. Follicular cells secrete two thyroid hormones: triiodothyronine (T3 ) and tetraiodothyronine (T4 , or thyroxine). What Thyroid Hormones (T3 and T4 ) Do
Image of page 6

Subscribe to view the full document.

The thyroid hormones T3 and T4 have similar functions, although T3 is more potent. Thyroid hormones regulate all phases of metabolism; they increase the release of energy from carbohydrates and fatty acids, increase protein synthesis. The “keep it running” at rest is called the basal metabolic rate or BMR. Thyroid hormones: think metabolic rate! In addition, thyroid hormones are essential for the normal maturation of the nervous system and for normal growth and development; they also play a permissive role in that they are necessary for the proper functioning of all other hormones. Hypothyroidism in an adult results in a slowed-down metabolic state characterized by a slow heart rate, sluggish peristalsis resulting in constipation, a low body temperature, low energy, loss of hair, and weight gain. If an infant is born with no thyroid gland, a condition called cretinism develops. An infant with cretinism fails to develop both physically and mentally. An excess of thyroid hormones produces hyperthyroidism, a speeded- up metabolic state that is characterized by an increase in heart rate, an increase in peristalsis resulting in diarrhea, elevation in body temperature, hyperactivity, weight loss, and wide emotional swings.
Image of page 7
Image of page 8

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern

Ask Expert Tutors You can ask 0 bonus questions You can ask 0 questions (0 expire soon) You can ask 0 questions (will expire )
Answers in as fast as 15 minutes