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Veterinary A & P
Endocrine System - Test Yourself & Notable ?'s
Question | Answer |
---|---|
homeostasis | balance in the body/body systems |
neurotransmitters | chemical messengers of the nervous system |
hormones | chemical messengers of the endocrine system |
endocrine glands | basic units of the endocrine system. Located throughout the body and secrete tiny amounts of hormones directly into the bloodstream |
Endocrine System Characteristics: Function | Regulation of body functions to maintain homeostasis |
Endocrine System Characteristics: Reaction to stimuli | Slow |
Endocrine System Characteristics: Duration of effects | Long |
Endocrine System Characteristics: Target Tissues | Virtually all body cells and tissues |
Endocrine System Characteristics: Messenger Producing Cells | Endocrine gland cells or modified neurons |
Endocrine System Characteristics: Distance from Chemical Message | Long (via bloodstream) production to target |
System Characteristics: Function | Regulation of body functions to maintain homeostasis |
System Characteristics: Reaction to stimuli | Fast |
System Characteristics: Duration of effects | Short |
System Characteristics: Target Tissues | Muscle and glandular tissues |
System Characteristics: Messenger Producing Cells | Neurons |
Nervous System Characteristics: Distance from Chemical Message | Short (across synaptic space) |
Anterior Pituitary produces what hormones | Growth Hormone (GH), Luteinizing Hormone (LH), (Adrenocorticotropic Hormone (ACTH), Follicle Stimulating Hormone (FSH), Thyroid Stimulating Hormone (TSH), Melanocyte Stimulating Hormone (MSH), Prolactin (PRL) |
Posterior Pituitary stores/releases | Oxytocin (OXT), Antidiurectic Hormone (ADH) |
Growth Hormone Target/Action | All body cells/Growth, metabolic regulation |
Prolactin Target/Action | Female: mammary gland/Lactation Male: no known effect/None |
Thyroid Stimulating Hormone Target/Action | Thyroid Gland/Thyroid Hormone production (T3, T4, and Calcitonin) |
Adrenocorticotropic Hormone Target/Action | Adrenal Cortex/Adrenocortical hormone production |
Follicle Stimulating Hormone Target/Action | Female: ovary (follicles)/Oogenesis Male: testis (seminiferous tubules)/Spermatogenesis |
Luteinizing Hormone Target/Action | Female: ovary (follicles/corpus luteum)/Ovulation and corpus luteum production Male: testis (interstitial cells)/Testosterone Production |
Melanocyte Stimulating Hormone Target/Action | Unknown/Unknown |
Antidiuretic Hormone Target/Action | Kidney/Water Conservation |
Oxytocin Target/Action | Female: Uterus/Contraction at parturition |
Thyroid produces what hormone | T3, T4, and Calcitonin |
T3 & T4 Target/Action | All body cells/Growth, metabolic regulation T3 (less)-the active hormone. T4 (more)-considered a prohormone (steroid?). T3 and T4 are named for the number of iodine atoms each molecule of hormone contains. T4 can be converted to T3 in peripheral tissues. |
Calcitonin Target/Action | Bones/Prevents hypercalcemia |
Parathyroid produces what hormones | Parathyroid hormone |
Parathyroid hormone Target/Action | Kidneys (retain calcium), intestines (absorb more calcium from food), bones (calcium release)/Prevents hypocalcemia |
Adrenal Cortex produces what hormones | Glucocorticoid hormones, mineralocorticoid hormones, sex hormones |
Glucocorticoid Hormone Target/Action | Whole body/Increases blood glucose, blood pressure maintenance |
Mineralocorticoid Target/Action | Kidneys/Sodium and water retention, potassium elimination |
Adrenal Cortex Sex Hormones Target/Action | Whole body/Minimal effects |
Adrenal Medulla produces what hormones | Epinephrine and Norepinephrine |
Epinephrine and Norepinephrine Target/Action | Whole body/Part of Fight-or-Flight response |
Endocrine Pancreas (Islets) produces what hormones | Insulin and Glucagon |
Insulin Target/Action | All body cells/Movement of glucose into cells and its use for energy |
Glucagon Target/Action | Whole body/Increased blood glucose |
Testis produce what hormones | Androgens like testosterone |
Androgens Target/Action | Whole body/Anabolic effect, development of male secondary sex characteristics |
Ovaries produce what hormones | Estrogens and Progestins |
Estrogens Target/Action | Whole body/Preparation for breeding and pregnancy |
Progestins Target/Action | Uterus/Preparation for and maintenance of pregnancy |
How do endocrine glands differ from exocrine glands? | Endocrine glands (ductless glands) secrete small amounts of hormones directly into the bloodstream. Exocrine glands secrete their products onto epithelial surfaces through tiny tubes called ducts. |
In what ways are the functions and characteristics of the endocrine system similar to those of the nervous system? In what ways are they different? | Endocrine & Nervous system are both responsible for body wide homeostasis. The endocrine system is slow to act, but its effects are long lasting, its chemical messengers travel long distances to reach their targets, which effects virtually all body cells. |
In what ways are the functions and characteristics of the endocrine system similar to those of the nervous system? In what ways are they different? continued | Endocrine chemical messengers: Hormones. The nervous system is opposite in response time, duration of effect, and distance to travel to target (synaptic space). Its chemical messengers are neurotransmitters. |
What is a hormone? | chemical messenger produced by the endocrine system and released directly into the bloodstream |
What is a hormone target? | a cell that has receptors for a particular hormone |
What are the three main chemical groups of hormones? | hydrophilic Peptide Hormones (chains of few - 200+ amino acids arranged like pearls in a necklace), hydrophobic Steroid Hormones (bind to hydrophilic transport proteins to travel in plasma)(bound or free hormone), and Monoamine Hormones |
Which chemical hormone group(s) bind to receptors on the target cell membrane? In the cytoplasm or nucleus? | peptide hormones and epinephrine and norepinephrine bind to receptors on the target cell membrane. Thyroid and steroid hormones bind to receptors within the cytoplasm or nucleus. |
How does the negative feedback system control the secretion of many hormones? | adequate levels of hormone in the blood directly or indirectly "feeds back" to the gland that produced it and stops the activity of the gland. Most common. |
Superovulation? | FSH and similar drugs are used in preparation of embryo transfer. Transfer occurs after the eggs have been fertilized. |
Clinical Application: Growth Hormone (GH) | To treat dwarfism and alopecia |
Through what mechanism does the hypothalamus control the production or release of hormones from the pituitary gland? | Through release of chemicals through tiny blood vessels (portal system) at the anterior pituitary or adenohypophysis and nerve fibers in the stalk at the posterior pituitary or neurohypophysis. |
How do the hypothalamus' effects on the anterior and posterior portions of the pituitary differ? | Anterior-a portal system by releasing or inhibiting factors (hormones) controlling production and release of hormones within the adenohypophysis. Posterior-more direct through nerve fibers (axons) delivering hormones for storage and eventual release. |
Why is the pituitary gland referred to as the master endocrine gland? | Many of its hormones direct the activity of other endocrine glands around the body. |
Other than promoting growth in young animals, what are some other effects of GH? | Growth of bone and muscle. Regulated the metabolism of proteins (anabolism-synthesis of proteins) materials for growth, regeneration, and repair of tissues, carbohydrates, and lipids (release) catabolism (breakdown) for energy productions |
What stimulates the continued release of prolactin during lactation? | teat or nipple stimulation. Nursing or milking. |
Do FSH and LH play important roles in male animals? If so, what are they | Yes. Follicle stimulating hormone stimulates spermatogenesis. Luteinizing Hormone stimulates interstitial cells in the testes to develop and produce the male sexual hormone testosterone. |
Does ADH help promote or prevent the loss of large amounts of water in the urine? | It prevents it by telling the kidneys to reabsorb more water from urine they are producing back into the bloodstream |
What effects would the inhibition of ADH release have on the body? | It cause an increased thirst (polydipsia) and more water to be released by the kidneys into the urine (polydipsia). Diabetes Insipidus is cause by a deficiency of ADH. Symptoms: large amounts of dilute urine, large quantities of water consumption, |
When milking a cow by hand, why does it take a minute or two of teat stimulation before milk starts to flow freely? | (lag) That is how long it takes for the sensory stimulation to reach the brain and signal the hypothalamus to release oxytocin from the posterior pituitary and for the oxytocin to reach the mammary glands via the blood circulation. |
What hormone plays an important role in helping an animal maintain its body temperature under cold environmental conditions? How does it produce its effects? | Thyroid hormone through its calorigenic effect. The metabolic rate allows a body to generate heat and maintain a constant internal temperature regardless of environmental factors. |
How do clinical signs of hypothyroidism and hyperthyroidism relate to the normal function of thyroid hormone? | Hypothyroidism- thyroid hormone deficiency. Most common in dogs. Slowing of the metabolism: alopecia, dry skin, lethargy, reluctance to exercise, and weight gain without increase in appetite. Seek out heat. |
What two hormones play important roles in maintaining homeostasis of blood calcium levels in the body? Which one prevents hypercalcemia? Which prevents hypocalcemia? | Calcitonin & Parathyroid Hormone: Calcitonin restricts the release of calcium and potassium from bone thus preventing hypercalcemia. Hypocalcemia is prevented by the release of parathyroid hormone. |
What three groups of hormones are produced in the adrenal cortex? What are their effects? | Glucocorticoid: hyperglycemic result. Maintains blood pressure, and helps the body resist the effects of stress. Mineralocorticoid: regulate levels of important electrolytes (mineral salts) in the body. (Aldosterone)-sodium, potassium, and hydrogen ion. |
How are the hormones of the adrenal medulla involved in the fight-or-flight response? | non-feedback related control. Direct control of hormone secretion (epinephrine and norepinephrine) by the nervous system when an animal feels threatened. This prepares the animal for intense physical activity. |
Which four hormones have hyperglycemic effects in the body? What is the only hormone that acts to lower the blood glucose level? | Insulin acts to lower blood glucose levels. |
Which hormone are anabolic steroid drugs related to? | testosterone |
How do the basic actions and purposes of estrogens and progestins differ? | FSH stimulates estrogen production. Estrogen is responsible for the physical and behavioral changes that prepare a female for breeding and pregnancy. LH stimulates progestin production. Progesterone supports pregnancy. (steroid hormone) |
How does relaxin help prepare a pregnant animal for parturition? | It causes ligaments between bones surrounding the birth canal to soften and relax in preparation for parturition. May also play a role in mammary development. |
Why are patients with kidney failure often anemic? | Because the kidneys produce erythropoietin which stimulates red bone marrow to increase production of oxygen-carrying red blood cells. |
How do the actions of gastrin on the stomach differ from those of secretin and cholecystokinin? | gastrin is produced in the cell wall of the stomach. Secretion of gastrin is stimulated by the presence of food in the stomach. Gastrin stimulates stomach glands to produce hydrochloric acid and digestive enzymes. It also encourages muscular contractions. |
Why are prostaglandins referred to as tissue hormones? | Because they only travel a short distance from where they are produced (a variety of body tissues). |
Why do hormone-like drugs generally have a high potential for undesirable side effects? | They are similar to hormonal testosterone and can cause undesirable side effects in the reproductive system, behaviorally, and other body systems. Because the effects are so interrelated. |
Steroid Hormones are | lipids and are synthesized from cholesterol. (hydrophobic) so they pass easily through the cell membrane to reach their receptors |
Hypothalamus | Located in the ventral part of the brain behind the eye/dorsal to the pituitary gland. Appetite control, body temperature regulation, control of wake/sleep cycles. Connection between the brain and the endocrine system. Controls the pituitary (hypophysis) |
Monoamine Hormones | Thyroid (hydrophobic), and Catecholamine hormones -epinephrine & norepinephrine (hydrophilic) |
Pituitary gland placement | ventral to the hypothalamus in a small pocket in the sphenoid bone of the skull called the pituitary fossa. |
Gonadatropins | FSH & LH |
Hyperthyroidism continued | Opposite hypothyroidism. Most common in cats. Nervousness, excitability, weight loss, increased appetite, tachycardia, vomiting, diarrhea, polyuria, polydipsia. Usually treated by removing the thyroid gland or long term thyroid inhibiting drug admin. |
How do the actions of gastrin on the stomach differ from those of secretin and cholecystokinin? continued | Secretin stimulates the pancreas to secrete fluid rich in sodium bicarbonate into the duodenum to neutralize the acidic chyme from the stomach. Cholecystokinin stimulates the release of digestive enzymes from the pancreas into the duodenum. |
How do the actions of gastrin on the stomach differ from those of secretin and cholecystokinin? continued | Secretin and cholecystokinin inhibit gastric gland secretion and stomach motility and stimulate the gall bladder of the liver to contract sending bile into the small intestine to help in the digestion and absorption of fats and fat-soluble vitamins. |