KIN 292 1st Edition Lecture 4 These are the notes from Professor Starnes lecture of Clinical Human Physiology These come from the slideshows provided by the professor and include extra notes and explanations Highlighted or bolded information are things that I believe to be information that is important to look over multiple times The notes in red are my personal additions and quotes of Professor Starnes from the class lecture Outline of Last Lecture I 5 3 Signaling Transduction Mechanisms Outline of Current Lecture I Introduction Long distance communication by nervous and endocrine II systems III 6 1 Primary Endocrine Organs IV 6 2 Secondary Endocrine Organs V 6 3 Hormone Actions at the Target Cell VI 6 4 Abnormal Secretion of Hormones VII 6 5 Hormone Interactions Current Lecture The Nervous and Endocrine Systems provide communication throughout the body They communicate using different types of secretory cells messengers and receptors however there is some overlap The systems work in a coordinated and integrated manner to attempt to maintain homeostasis throughout the body Chap 5 4 Long Distance Communication for brief intro Sometimes called the Neuroendocrine system because they work so closely together Figure 5 20 Signal transmission in neurons vs endocrine glands Nerve cells can transmit signals long distances then secrete messengershort distance across synapse to target cell Receptors are generally ion channels which communicate very fast andfor a short duration Endocrine glands secrete messenger long distances via the blood These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute Generally communicate with receptors that alter protein synthesis or activate G proteins which are relatively slow but longer lasting processes We ll start with endocrine system All endocrine glands derived from epithelial tissue Hypothalamus and Pituitary Gland Hypothalamus Located in the brain Pituitary gland Anterior lobe Posterior lobe Infundibulum Hypothalamus and pituitary gland regulate almost every body system through the secretion of many different hormones Connected by infundibulum Pineal gland Secretes melatonin May be involved in circadian rhythms daily day night cycles Neural input from hypothalamus inhibits melatonin release in daylight hours Melatonin release at night may help with sleeping and is usedtherapeutically for sleep disorders Figure 6 3 Connection between the hypothalamus and the posterior pituitary gland Oxytocin ADH are called neurohormones because they are secretedinto blood by neurons not endocrine glands Hormones of Posterior Pituitary Antidiuretic hormone also called ADH or vasopressin Target tissue kidney Water balance and osmolarity Oxytocin Target tissues uterus in pregnancy breasts postbirth Uterine contractions Milk ejection Figure 6 4 The hypothalamic pituitary portal system Anterior pituitary hormones Portal system o Links two capillary beds Hypothalamic tropic hormones are delivered o fairly precisely and in high concentration to their target cells in the ant pit o tropic hormones Those that regulate secretion of other hormones Hypothalamic Pituitary Portal System Summary The hypothalamus secretes releasing or inhibiting hormone into theprimary capillary bed Blood with tropic hormones enters the portal vein Hypothalamic tropic hormones access the anterior pituitary secretory cells through the secondary capillary bed Anterior pituitary tropic hormones enter the bloodstream in the same secondary capillary bed They travel to the distant endocrine gland to trigger release of the hormone Hypothalamic and anterior pituitary tropic hormones hormones that regulate secretion of other hormones Axis The relationship among a hypothalamic tropic hormone its anteriorpituitary tropic hormone and the target endocrine gland Note not alltargets are endocrine glands ex Breasts Thyroid and parathyroid glands Thyroid hormones T4 Tetraiodothyronine thyroxin and T3 Triiodothyronine Regulate metabolism Calcitonin Regulates calcium levels in the blood Parathyroid hormone Regulates calcium levels in the blood Thymus Thymus big role in immune system T cells used in immune system mature here Secretes thymosin o Regulates T cell function Figure 6 9a Anatomy of the adrenal gland Medulla secretes catecholamines Stimulates Flight or fight Secretory cells known as chromaffin cells 80 epinephrine 20 norepinephrine 1 dopamine Under neural control Hormones of the Adrenal Cortex secretes Adrenocorticoids Mineralocorticoids aldosterone Regulates sodium and potassium levels Glucocorticoids cortisol Regulates the body s response to stress Regulates metabolism Sex hormones androgens Regulate reproductive function Figure 6 10 Anatomy of the pancreas Controls of Hormone Release Neural input starts in the brain Hormonal Negative feedback Figure 6 6 Negative feedback loops affecting hypothalamic and anterior pituitary tropic hormones Prevents buildup of excess tropic hormone May also loop to hormone 2 secretion as shown in next slide Figure 6 7 Regulation of cortisol release Many hormones are not under control of the brain Examples of humoral control of hormone release Hormone secretion is typically in response to either neural signals orhumoral bloodborne signals Hormone Concentration in Blood has a very big impact on the magnitude of the response by its target cell See ch 5 for relationship of M and receptor binding Hormone level controlled by Rate of hormone secretion Half life in plasma Hydrophobic hormones bound to plasma proteins have longer half lifethan hydrophilic Rate of hormone metabolism Primarily by target cell and liver 6 4 Abnormal Regulation of Hormone Secretion or Tissue Response can Cause Disease Hormone levels must be kept in balance Pathologies Hyposecretion Too little o Diabetes mellitus type 1 Hypersecretion Too much o Acromegaly Abnormal tissue responsiveness Normal hormone levels Tissue responds inappropriately Primary Versus Secondary Secretion Disorders Primary Secondary Abnormality in the endocrine organ secreting the hormone Abnormality in tropic hormone o Hypothalamic tropic hormone o Anterior pituitary tropic hormone Figure 6 13aAbnormal secretion of cortisol o Abnormality in the endocrine organExcess cortisol in blood decreases CRH and ACTH by negative feedback but adrenal gland keeps pumping out cortisol Cancer is a possible cause o Cushing s disease see Clinical Connections