Human Anatomy and Physiology Notes Week 2
Human Anatomy and Physiology Notes Week 2 Bio 204-001
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This 5 page Class Notes was uploaded by Michael Fucci on Friday January 29, 2016. The Class Notes belongs to Bio 204-001 at Adelphi University taught by Dr. Schweyer in Spring 2016. Since its upload, it has received 29 views. For similar materials see Human Anatomy and Physiology II in Biology at Adelphi University.
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Date Created: 01/29/16
Classification of Hormones +Hormones are classified either by chemical means or transport+ Classification by Transport Freely Circulating Hormones (i.e. Amino) o These are relatively small o They are removed from transport medium to the cell rather quickly Hormones that are bound to transport proteins (i.e. some types of catecholamine) o These are bigger and bulkier o Harder to remove from transport medium to get into the cell o Therefore, it takes several hours to remove them What is the goal of the hormone after being produced? Answer: to cause a change in the metabolic activity of a cell o Goals include: mitosis & meiosis, transcription, translation, and protein synthesis o Hormones mediate all of these events Note: some hormones cannot directly affect cells so they must use a secondary messenger system (such as the peptide and amino hormones). **In order for a hormone to affect a cell, they must get into the cell** Mechanisms of Hormone Action The mechanism begins with the target cell The hormone is first released, and fits into the selective receptor site (Note: this stage is considered the first messenger) o If it is a Lipid, it will pass through the layer o If it is a amino/ peptide/ catecholamine, it will required a secondary messenger Secondary messengers include: o cAMP o cGTP The secondary messenger system helps bring the hormone into the cell, but cannot do it alone: o The Gprotein comes in and connects/ bridges the secondary messenger and hormone o The information travels to the secondary messenger and it will now affect the cell. Receptor sites for catecholamine, peptide hormones, and eicosanoids are in the cell membrane of the target cells and then the secondary messenger system will be employed. The Thyroid and Steroid hormones directly cross the membrane and bind to receptors in the cytoplasm or nucleus. Brief Step by Step for Secondary Messenger Hormones bind to receptor site (first messenger) Secondary messenger connects to hormone via Gprotein The secondary messenger is altered and may act as an enzyme inhibitor or promote enzyme activity; therefore, altering metabolic activity Example of a First Messenger System: The Thyroid Hormone Directly attaches to the nucleus and mitochondria after passing through plasma membrane Nucleus binding leads to gene activation, transcription, and translation (formation of proteins) Binding to the mitochondria will cause an increase in ATP production Hyperthyroidism (overactive thyroid) – overproduction of hormone, over production of ATP, too much energy, hyperactive Hypothyroidism (underactive thyroid) – underproduction of hormone, will result in sluggishness, under production of ATP, no energy Control of Hormone Secretions The hypothalamus regulates the activity of the nervous and endocrine systems o Directly controls pituitary glands by secreting a regulatory hormone o Many endocrine structures are directly controlled too How does it regulate these systems? o Secretes a regulatory hormone (can either inhibit or increase production of hormones) This controls the anterior pituitary o Releases hormones at the posterior pituitary (this is how the hypothalamus releases its own hormones) o Has a direct neural control of the medulla of adrenal glands The infundibulum connects the hypothalamus to the pituitary gland The Pituitary “Master” Gland (AKA Hypophysis) Releases nine important peptide hormones o Seven are located in the Anterior; 2 in the posterior o All bind to membrane receptors and therefore needs cyclic GTP Anterior Pituitary (Adenohypophysis) hormones o TSH – Thyroid stimulating hormone Causes the thyroid to secrete o ACTH – Adrenocorticotropic Hormone Causes adrenals to secrete o FSH – follicle stimulating hormone Secretes estrogen o LH – luteinizing hormone Causes ovulation o PRL – prolactin Causes mammary glands to produce milk o GH/STH –growth hormone (somatotropin) Causes growth o MSH – melanocyte stimulating hormone Causes melanocytes to secrete melanin (which causes pigmentation) Nonfunctioning in adulthood Remember the hypothalamus controls: o The WHAT and WHEN of the anterior pituitary by releasing regulatory hormones o It releases its own hormones (ADH/OXT) via the posterior pituitary o It has direct neural sympathetic control to the adrenal glands. Posterior Pituitary (neurohypophysis) hormones o ADH – antidiuretic hormone Causes reabsorption of water from the kidneys Prevents you from peeing a lot o OXT oxytocin Causes labor contractions o These hormones are produced in the hypothalamus, but are released in the posterior pituitary Hypophyseal Portal System o A portal system is a system of blood vessels o Why is the pituitary gland so vascular? The goal is to transport the hormone as quickly as possible Notes to keep in mind Adeno means gland Tropin means it will affect another endocrine gland Cortisol is the key stress hormone Gonadotropin glands are FSH and LH GH is nontropic Mammary gland is exocrine not endocrine Pitocin is the synthetic form of oxytocin Acromegaly This is a tumor of the pituitary Causes over secretion of GH Affects cartilage Note: the patient was still normal height o The onset of this is during middle age, so the epiphyseal plate is sealed o Therefore, the cartilage grew while the bones couldn’t – results in big ears, big nose, and large mandible Pituitary Gigantism Tumor in pituitary; causes over secretion of GH The question becomes time of the tumor o The onset of this tumor is early in the patients lifespan o The epiphyseal growth plate is not sealed and causes pure gigantism Pituitary Dwarfism Caused by a different type of pituitary tumor; results in the under secretion of GH The Thyroid Gland Hormones: o T3: Triiodothyronine o T4: Thyroxine o Calcitonin These types of hormones diffuse into the cell straight through the membrane, like steroids They are involved with energy (production of ATP) The loves of the thyroid gland are connected by the isthmus It is located right below the Adams apple The CCell is scattered throughout the thyroid o The CCell produces calcitonin, which lowers the calcium levels in the blood o CCells are also known as parathilicular cells The thyroid hormone is calorigenic (deals with calories and energy). The lack of iodine results in a lack of thyroid production and loss of energy Thyroid Disorders Hyperthyroidism in babies can lead to newborns being born retarded Hypothyroidism as well as a lack of iodine can result in goiters The Parathyroid Gland Produces parathyroid hormone (PTH), which increases blood calcium level and is associated with osteoclastic activity The parathyroid chief cell is the actual endocrine cell Calcitonin, on the other hand, activates osteoblastic activity Note that the blood calcium level range should be: 8.5 mg/deciliter – 11 mg/decileter The results of low levels of calcium include o Kidney failure o Similar to the effects of chemotherapy o This is known as hypocalcemia Hypercalcemia (high levels of calcium) o Overactive parathyroid o Ulcers may form (too much Vitamin D) o May result in cancers (may produce a protein that increases calcium secretion into the blood) Adrenal Gland The connection between the brain and adrenal medulla is sympathetic Adrenal Medulla o Epinephrine aka adrenaline makes up 80% of hormone production o Norepinephrine aka noradrenaline makes up 20% o Epinephrine and norepinephrine cause heart and blood pressure increase, increase in glucose metabolism, breathing rate increases Adrenal Cortex o Made up of epithelial cells and secretes steroid hormones, which are based upon cholesterol. They enter cell via diffusion. o Mineralcorticoids will affect sodium and potassium ions. Causes kidneys to retain salt and water and excrete potassium into urine. o Glucocorticoids affects glucose metabolism by raising blood sugar levels. Disorders include Addison’s disease (where the Adrenal glands do not secrete enough steroids) and Cushing’s disease (where a pituitary tumor causes over secretion of the Adrenal glands