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MCAT Bio. Ch. 5
| Question | Answer |
|---|---|
| Endocrine Signaling Involves The Secretion Of Hormones Directly: | Into the bloodstream. |
| Peptide Hormones Are Composed Of: | Amino acids and are derived from larger precursors that are cleaved during posttranslational modification |
| Peptide Hormones Are Polar And Cannot Pass Through: | The plasma membrane |
| Hormones Bind To Extracellular Receptors Where: | They trigger the transmission of a second messenger |
| Each Step Of The Signaling Cascade For Peptide Hormones Can Demonstrate: | Amplification of the signal |
| Peptide Hormones Usually Have Rapid Onset But: | Are short-lived |
| Peptide Hormones Travel Freely in The Bloodstream And: | Do not require a special carrier |
| Steroid Hormones Are Derived From: | Cholesterol |
| Steroid Hormones Are Minimally Polar And Can Pass Through: | The plasma membrane |
| Steroid Hormones Bind To Intracellular Or Intranuclear Receptors Where: | The promote conformational change and bind to DNA which affects the transcription of a particular gene |
| Steroid Hormones Usually Have Slow Onset But: | Are long-lived |
| Steroid Hormones Cannot Dissolve In The Bloodstream And Must Be Carried By: | Specific proteins |
| Amino Acid-Derivative Hormones Are: | Modified amino acids. Their chemistry shares some features with peptide hormones and some features with steroid hormones. Different amino acid-derivative hormones share different features with other hormone classes. |
| Common Examples Of Amino Acid-Derivative Hormones Include: | Epinephrine, norepinephrine, triiodothyronine, and thyroxine |
| Direct Hormones Have Major Effects In: | Non-endocrine tissues |
| Tropic Hormones Have Major Effects In: | Other endocrine tissues |
| Hypothalamus | Bridge between the nervous and endocrine systems |
| Release Of Hormones From The Hypothalamus Is Mediated By A Number Of Factors Including: | Projections from other parts of the brain, chemo- and baroreceptors in the blood vessels and negative feedback from other hormones. |
| Negative Feedback | Final hormone or product of a pathway inhibits hormones or enzymes earlier in the pathway to maintain homeostasis |
| Hypothalamus Stimulates The Anterior Pituitary Gland Through: | Paracrine release of hormones into the hypophyseal portal system which directly connects the two organs |
| Gonadotropin-releasing Hormone (GnRH): | Promotes the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) |
| Growth Hormone-releasing Hormone (GHRH): | Promotes the release of growth hormone |
| Thyroid-releasing Hormone (TRH): | Promotes the release of thyroid stimulating hormone (TSH) |
| Corticotropin-releasing Factor (CRF): | Promotes the release of adrenocorticotropic hormone (ACTH) |
| Prolactin-inhibiting Factor (PIF or dopamine): | Inhibits the release of prolactin |
| Anterior Pituitary Releases Hormones In Response To Stimulation From: | Hypothalamus |
| Follicle-stimulating Hormone (FSH): | Promotes the development of ovarian follicles in females and spermatogenesis in males |
| Luteinizing Hormone (LH): | Promotes ovulation in females and testosterone production in males |
| Adrenocorticotropic Hormone (ACTH): | Promotes synthesis and release of glucocorticoids from the adrenal cortex |
| Thyroid-Stimulating Hormone (TSH): | Promotes synthesis and release of triiodothyronine and thyroxine from the thyroid |
| Prolactin: | Promotes milk production |
| Endorphins: | Decrease perception of pain and can cause euphoria |
| Growth Hormone (GH): | Promotes growth of bone and muscle and shunts glucose to these tissues. It raises blood glucose concentrations. |
| Posterior Pituitary: | Releases two hormones produced in the hypothalamus |
| Antidiuretic Hormone (ADH or Vasopressin) Is Secreted In Response To: | Low blood volume or increased blood osmolarity and increases reabsorption of water in the collecting duct of the nephron, which increases blood volume and decreasing blood osmolarity |
| Oxytocin: | Is secreted during childbirth and promotes uterine contractions. This also promotes milk ejection and may be involved in bonding behavior. It also has a positive feedback loop. |
| Thyroid Is Located: | At the base of the neck in front of the trachae, and produces three key hormones |
| Triiodothyronine (T3) and Thyroxine (T4) Are Produced By: | Follicular cells and contain iodine. They increase basal metabolic rate and alter the utilization of glucose and fatty acids. They are required for proper neurological and physical development in children. |
| Calcitonin Is Produced By: | Parafollicular (C) cells. It decreases plasma calcium concentration by promoting calcium excretion in the kidneys, decreasing calcium absorption in the gut and promotes calcium storage in bone. |
| Parathyroid Glands Release: | Parathyroid hormone (PTH) which increases blood calcium concentration |
| PTH Decreases Excretion Of: | Calcium by the kidneys and increases bone resorption directly to increase blood calcium concentration. |
| PTH Activates: | Vitamin D which is necessary for calcium and phosphate absorption from the gut |
| PTH Promotes Resorption Of: | Phosphate from bone and reduces reabsorption of phosphate in the kidney but Vitamin D promotes absorption of phosphate from the gut. These two effects cancel each other out. |
| Adrenal Cortex Produces Three Classes Of Steroid Hormones: | Glucocorticoids, mineralocorticoids, and cortical sex hormones |
| Glucocorticoids Such As Cortisol And Cortisone: | Increase blood glucose concentration, reduce protein synthesis, inhibit the immune system, and participate in the stress response |
| Glucocorticoid Release Is Stimulated by: | ACTH |
| Mineralocorticoids Such As Aldosterone Promote: | Sodium reabsorption in the distal convoluted tubule and collecting duct thus increasing water reabsorption. Aldosterone also increases potassium and hydrogen ion excretion. |
| Mineralocorticoids Are Regulated By: | The renin-angiotensin-aldosterone system not ACTH |
| Cortical Sex Hormone Include | Androgens (testosterone) and estrogen in both males and females |
| Adrenal Medulla Is Derived From: | The nervous system and secretes catecholamines into the bloodstream |
| Catecholamines Include: | Epinephrine and norepinephrine which are involved in the fight-or-flight (sympathetic) response |
| Catecholamines Promote: | Glycogenolysis, increase the basal metabolic rate, increase heart rate, dilate the bronchi, and alter blood flow |
| Endocrine Pancreas Produces Hormones That Regulate: | Glucose homeostasis |
| Glucagon Is Produced By: | α-cells and raises blood glucose levels by stimulating protein and fat degradation, glycogenolysis, and gluconeogenesis |
| Insulin Is Produced By: | β-cells and lowers blood glucose levels by stimulating uptake by cells and anabolic processes like glycogen, fat, and protein synthesis |
| Somatostatin Is Produced By: | δ-cells and inhibits insulin and glucagon secretion |
| The Testes Secrete: | Testosterone |
| The Ovaries Secrete: | Estrogen and progesterone |
| The Pineal Gland Releases: | Melatonin which helps to regulate circadian rhythms |
| The Pineal Gland Releases: | Melatonin which helps to regulate circadian rhythms |
| Cells In The Stomach And Intestine Produce Hormones Like: | Secretin, gastrin, and cholecystokinin |
| The Kidneys Secrete: | Erythropoietin which stimulates bone marrow to produce erythrocytes (red blood cells) in response to low oxygen levels in blood. |
| The Atria Of The Heart Secrete: | Atrial natriuretic peptide (ANP) which promotes excretion of salt and water in the kidneys in response to stretching of the atria (high blood volume) |
| The Thymus Secretes: | Thymosin which is important for proper T-cell development and differentiation |