Endocrine and Metabolism - Tutorial 5
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State five ways that the endocrine system maintains homeostasis (affects body tissues)
• Altering metabolism • Regulating growth and development • Regulating reproduction • Regulate circadian rhythms • Regulate activity of smooth muscle, cardiac muscles and glands
Explain why water soluble hormones cannot be administered via the oral route
Water soluble hormones are destroyed by digestion so insulin cannot be taken orally but must be injected
Name the organ that has both endocrine & exocrine functions
Pancreas
Explain how hormones are inactivated and excreted from the body.
Most hormones are inactivated by the liver and excreted by the kidneys or in the faeces
Describe the three stimuli that trigger hormone secretion
Signals from the nervous system - Sympathetic nervous system sends impulses to stimulate the adrenal medulla to release adrenaline (epinephrine) The levels of a chemical in the blood - Some endocrine glands secrete their hormones in direct response to changing levels of critical ions and nutrients Another hormone -Many endocrine glands are themselves stimulated by hormones
Describe the structure and location of the pituitary gland
Small gland that lies in a hollow of the sphenoid bone
Name the two hormones released from the posterior pituitary and state where they are produced
Oxytocin and Antidiuretic hormone (ADH), is produced in the hypothalamus
Name the six hormones produced by the anterior pituitary
• Growth hormone, GH • Thyroid stimulating hormone, TSH • Adrenocorticotropic hormone, ACTH • Follicle stimulating hormone, FSH • Luteinizing hormone, LH • Prolactin
Describe three clinical situations that arise from alterations to secretion of Growth Hormone (GH)
Dwarfism - hyposecretion during growth years results in dwarfism Giantism - hypersecretion in childhood results in giantism Acromegaly - Hypersecretion in adulthood results in acromegaly
State the location of the adrenal glands
Located at the top of the kidneys
Name the two areas within each gland and what hormones are produced by each of these areas
• Adrenal cortex that secretes cortisol and aldosterone • Adrenal medulla that secretes adrenalin and noradrenaline
State a clinical situation where glucocorticoids (cortisol) might be prescribed
• Cortisol medications are often prescribed to suppress the inflammatory response in chronic conditions and are prescribed for organ transplant patients to avoid organ rejection
State six effects/actions of adrenaline
• Increases rate and force of heart contraction • Increases cardiac output • Increase blood pressure • Increase blood flow to the myocardium, liver, skeletal muscles
Name the two hormones that control blood calcium levels
• Parathyroid hormone (PTH) is the main hormone which increases blood calcium level • Calcitonin is the hormone which decreases blood calcium levels
State three uses for calcium in the body
• Transmission of nerve impulses • Muscle contraction • Blood clotting
Describe three actions of PTH
• Stimulates osteoclasts to resorb bone and raise blood calcium • Enhances reabsorption of calcium by the kidneys • Activates vitamin D to become calcitriol which is needed to absorb calcium from food
Name the hormone that is produced from the pineal gland
Melatonin
Describe the location of pineal gland
Is attached to the roof of the 3rd ventricle
Name the three stages of the stress response
• An initial fight or flight response • A slower resistance reaction • Exhaustion
Name two health implications of stress
Stressors - heat, cold, environmental poisons, bacterial toxins, heavy bleeding or a strong emotional reaction Homeostatic mechanisms - attempt to counteract stress it is controlled by the hypothalamus in three stages: 1. An initial fight or flight response 2. A slower resistance reaction 3.Exhaustion
Describe four age related changes to the endocrine system
• Growth hormone decreases allowing muscle atrophy • Thyroid gland decreases production of thyroid hormones - decrease in metabolic rate, increase in body fat • Pancreas releases insulin more slowly and cells are not as responsive to insulin (insulin resistance) • Ovaries become unresponsive to FSH and LH so decrease oestrogen production - osteoporosis, high blood cholesterol and atherosclerosis • Testosterone levels decline but effects aren’t apparent until old age
Define the terms anabolism & catabolism
• Anabolism: is the building of complex molecules from numerous simple one. • Catabolism: is the breakdown of complex molecules into numerous simple ones.
Name the two products resulting from lipolysis & what they are used for
• Glycerol and Fatty Acids • Glycerol - converted into pyruvate (pyruvic acid) and enters the kerbs cycle to produce ATP, can also be converted to glucose by gluconeogenesis Fatty acids - converted into acetyl coenzyme A (CoA) in the liver, then enters kerbs cycle to produce ATP, if CoA levels are to high for the Krebs cycle to process the liver will converts CoA to ketone bodies
Describe what causes an increase in ketones
• Severe starvation • Uncontrolled diabetes