A P Unit 1 1 How do hypothalamic hormones travel to the adenohypophysis Adenohypophysis anterior three quarters of pituitary with large anterior lobe Releasing hormones from the hypothalamus travel in the blood stream to the adenohypophysis where they stimulate it to release hormones No nervous connection linked to it by a complex of blood vessels called the hypophyseal portal system which consists of a network of primary capillaries in the hypothalamus portal venules and secondary capillaries in the anterior pituitary Hypothalamus controls the anterior pituitary by secreting hormones that enter the primary capillaries travel down the portal venules and diffuse out of the secondary capillaries into the pituitary tissue 2 Why must endocrine glands be highly vascularized Need own blood supply to deliver hormones to each of the major organs in the body Release secretions into the bloodstream Have intracellular effects alter cell metabolism Unusually high density of blood capillaries that pick up and carry away hormones Vessels are highly permeable with patches of large pores to allow for easy uptake of matter from gland tissue 3 What is a tropic hormone Hormones that have other endocrine glands as their target Most produced and secreted by the anterior pituitary Hypothalamus secretes tropic hormones that target the anterior pituitary Example Thyroid gland secretes thyroxine which targets the hypothalamus 4 What do tropic hormones regulate The release of other hormones 5 How does the thyroid gland differ from other glands Only gland that is able to store its secretions outside its principle cells Store the hormones it produces Largest 6 What do T3 T4 norepinephrine and epinephrine have in common All derived from the AA Tyrosine 7 Compare calcitonin and parathyroid hormone on their actions on bone the gut and the kidney Calcitonin stimulates osteoblast activity promotes calcium deposition and bone formation Parathyroid hormone raises blood calcium levels 8 What hormones are produced by the adrenal medulla and the adrenal cortex Adrenal medulla mixture of catecholamines previously referred to as neurotransmitters epinephrine 75 norepinephrine 25 and dopamine which increase alertness and prepare body for physical activity Adrenal cortex produces 25 steroid hormones collectively known as corticosteroids or corticoids 3 categories Mineralocorticoids Aldosterone Glucocorticoids Cortisol Sex steroids Androgens 9 What are the endocrine functions of the pancreas Regulate glycemia blood glucose concentration Alpha cells secrete glucagon between means when blood glucose falls below 100 mg dL Beta cells secrete insulin during and immediately following a meal when levels are rising Delta cells secrete somatostatin concurrently with release of insulin by beta cells PP F cells secrete pancreatic polypeptide inhibits gallbladder and intestinal contractions and section of stomach acid and pancreatic digestive enzymes G cells secrete gastrin stimulates stomach s acid secretion motility and emptying 10 What are the endocrine functions of the gonads Ovaries secrete estradiol progesterone inhibin and estrogen Testies secrete testosterone inhibin and weak amounts of estrogens and androgens 11 What are the water soluble and lipid soluble biogenic amines Modifications of AA Tyrosine Thyroid hormones T3 and T4 Catecholamines epinephrine norepinephrine 12 What is the precursor for lipid based hormones Derived from cholesterol gonadal and adrenocortical hormones 13 What hormone is responsible for regulating sodium What triggers its release Aldosterone Decrease in blood volume triggers release 14 What hormone is released during long term stress Acute stress Long term cortisol from glucocorticoids released 35 40 minutes after stress Short term epinephrine 15 What is the mode of action of lipid based hormones Pass through the cell membrane Bind to hydrophilic protein Once at target cell bound hormones are released right into the cell through capillary walls Activity takes place at level of nucleus rather than at cell membrane 16 Why are the walls of the atria and the right and the left ventricle different in thickness Atria walls are thin and flaccid only pump into ventricles directly below Wall of left ventricle is two to four times thicker than the right because it pumps blood through the entire body right ventricle only pumps to the lungs 17 How does blood flow from the atria to the ventricles Through AV valves tricuspid right and bicuspid mitral left Cordae tendinae connected to papillary muscles on floor of ventricles prevent AV valves from flipping inside out bulging into atria when ventricles contract Semilunar valves regulate flow from ventricles to great arteries Pulmonary valve controls opening from right ventricle into pulmonary trunk Aortic valve controls opening from left ventricle to aorta Each has 3 cusps shaped like shirt pockets and no tendinous cords 18 What is the advantage and disadvantage of electrical junctions Allow for extremely fast reflex Simple Allow for synchronized action Transmits signals in both directions bidirectional Signal gets weaker as it travels to other synapses 19 How does the all or none law apply to the heart The bidirectional signals allow the heart to function as a single unit Whole organ contracts as one or not at all 20 What structure are the chordae tendinae attached and what is the purpose of its attachments Connect AV valves to papillary muscles Prevent eversion prolapse by tensing up and pulling flaps to hold closed 21 What is a functional syncytium Term used to describe how the heart functions as a single unit 22 What is most responsible for the plateau phase of the cardiac action potential Ca2 entering through slow Ca2 channels prolongs depolarization of membrane creating the plateau Plateau falls slightly because of some K leakage but most K channels remain closed until the end of the plateau 23 Where does the intrinsic rhythm of the heart begin Sinoatrial SA node 24 What are the differences in autorhythmic cells that allow them to spontaneously depolarize Spontaneously depolarize due to a slow continuous influx of sodium through the sodium channels 25 What happens during the quiescent period Relaxation period diastole Rapid ventricular filling AV valves OPEN Filling slows and valves begin to close Pressure into and out of heart is greater than atrium ventricles 26 What is the term of the volume in the heart after filling End diastolic volume EDV 27 What is