Chp 5-6 & 21 Study Guide PDF

Ch 5-6 + 21 Study Guide 1. Study the Chemical Classification of Messengers (pg. 128-129, Tables 5.1-5.2) Functional Classification of Chemical Messengers: CLASS Paracrine SECRETORY CELL TYPE DISTANCE TO TARGET CELL (Several) Short Neurotransmitter Neuron Short Hormone Long Endocrine MODE...

Ch 5-6 + 21 Study Guide 1. Study the Chemical Classification of Messengers (pg. 128-129, Tables 5.1-5.2) Functional Classification of Chemical Messengers: CLASS Paracrine SECRETORY CELL TYPE DISTANCE TO TARGET CELL (Several) Short Neurotransmitter Neuron Short Hormone Long Endocrine MODE OF CHEMICAL TRANSPORT CLASSIFICATION TO TARGET OF MESSENGER CELL Diffusion Amines, peptides/proteins, eicosanoids Diffusion Amino acids, amines, peptides/proteins Blood Amines, Steroids, Peptides/Proteins - Paracrine chemical messenger: o It’s a chemical that signals a nearby cell. - Autocrine chemical messenger: o It’s a subclass of paracrine, and this chemical signals the same cell that secreted it. - Neurotransmitter: o It’s a chemical messenger that is produced by neurons and it gets released into the ECF of the synaptic cleft. - Hormone: o This type of chemical messenger is produced by endocrine cells which is secreted into the blood via the interstitial fluid. - Neurohormone: o It is a special class of hormones and a messenger that is produced by neurons and gets secreted into the blood. Chemical Classification of Messengers: CLASS CHEMICAL LOCATION OF PROPERTY RECEPTORS ON TARGET CELL Amino acids Lipophobic Plasma membrane Amines Lipophobic Plasma membrane Peptides/Proteins Lipophobic Plasma membrane Steroids Eicosanoids Cytosol Cytosol Lipophilic Lipophilic FUNCTIONAL CLASSIFICATION Neurotransmitters Paracrines, neurotransmitters, hormones Paracrines, neurotransmitters, hormones Hormones Paracrines - Lipophobic: o It is water soluble but not lipid soluble and it does not cross the cell membrane. o Its target response is via enzyme activation and membrane permeability changes. - Lipophilic: o It is lipid soluble but not water soluble, it can easily cross the cell membrane. o Its target response is via gene activation. - Amino Acid Messengers: o It is lipophobic. o The only 4 amino acids that functions as neurotransmitters (chemical messengers) in the brain are: ▪ Glutamate ▪ Aspartate ▪ Glycine ▪ Gamma-Aminobutyric acid (GABA) - Amine Messengers: o These chemical messengers are mostly lipophobic except for thyroid hormones. o These chemical messengers are derived from amino acids that contains an amine group (-NH₂). o Examples include: ▪ Catecholamines: Made from tyrosine. ▪ Dopamine, norepinephrine, epinephrine ▪ Thyroid hormones: Made from two tyrosine amino acids. ▪ Histamine: Made from histidine ▪ Serotonin: Made from tryptophan - Peptide/Protein Messengers: o These chemical messengers are lipophobic and made of chains of amino acids which are: o Peptide ligand (<50 amino acids) o Protein ligand (>amino acids) - Steroid Messengers: o These chemical messengers are lipophilic and all of them are derived from cholesterol as it also functions as hormones. - Eicosanoid Messengers: o These chemical messengers are lipophilic and most of them are derived from arachidonic acid which is a cell membrane phospholipid. o Examples include: ▪ Prostaglandins & Leukotrienes. 2. Study the Transport of Messengers (pg. 132-133, Figure 5.7) - Diffusion through interstitial fluid: o The source and target are close. o The chemical messenger gets quickly degraded in the interstitial fluid and becomes inactive which minimizes the spread of their signaling. o Examples include: ▪ Paracrines, autocrines, neurotransmitters, and most cytokines. - Bloodborne transport: o The source and target are located at a distance. o The lipophobic messengers dissolves in plasma. o The lipophilic messengers binds to a carrier protein. o Examples include: ▪ Hormones, neurohormones, and some cytokines. - Messenger half-life: o This is the amount of time it takes for the hormone in the blood to decrease its concentration by half. o The concentration of the messenger could be in the blood or interstitial fluid. o The messengers that are dissolved in plasma have a relative short half-life. ▪ For example, the half-life of insulin is less than 10 mins. o The messengers that bounds to plasma protein have a relative long half-life. ▪ For example, the half-life of cortisol is 90 mins. 3. Study the factors affecting magnitude of target cell response to a chemical messenger (pg. 134-135) - Strength of response depends on three factors: o The concentration of the messenger (ligand) ▪ The concentration of the chemical messenger is like the number of snacks available. If there's a high concentration of the messenger around a target cell, it's more likely to bind to the cell and trigger a response. o The number of receptors per target cell that are present. ▪ The more receptors a target cell has, the more opportunities there are for the messenger to bind to the cell and initiate a response. It's like having more locks available to open with the same key. o The affinity of the receptor for the messenger: ▪ Affinity refers to how strongly the receptor and messenger are attracted to each other. It's like how strongly a magnet attracts metal. ▪ If the receptor has high affinity for the messenger, even a small amount of messenger can trigger a response because they bind tightly together. ▪ If the affinity is low, it might take a higher concentration of messenger to produce the same response because they don't bind as effectively. 4. Study Agonist and Antagonist (pg. 135) - - - Agonist: o It’s a chemical that binds to a receptor. o Its action mimics the normal response. Antagonist: o It’s a chemical that binds to a receptor, however the binding does not result in a response. o It competes with the normal ligand (messenger). o The response is the opposite of that to an agonist. Examples of Receptor Agonists and Antagonists: o β-endorphin: Endogenous opiate: ▪ β-endorphin binds to µ opiate receptors, producing analgesia. o Morphine: µ receptor Agonist: ▪ Administration of morphine produces analgesia. o Naloxone: µ receptor Antagonist ▪ Administration of naloxone blocks morphine- or β-endorphin– produced analgesia and ▪ It is 10x greater affinity for the µ receptor than morphine. 5. Study Mechanisms of Signal Transduction - Intracellular mediated responses: o Cell response is via gene activation. o This refers to the process where signals are transmitted from the cell membrane (where receptors are located) to the interior of the cell. - Channel-linked mediated responses: o In this mechanism, the receptor acts as a channel that opens when it detects a specific signal molecule (ligand). o The action is direct. o The change in transport of ions through the channel causes the target response. - Enzyme-linked mediated responses: o In this mechanism, the receptor itself has enzymatic activity, meaning it can catalyze chemical reactions inside the cell when activated by a signal molecule. ▪ It's like having a key that not only unlocks a door but also starts a machine when inserted into a slot – the ligand activates the receptor, which then triggers a series of chemical reactions inside the cell to produce a response. o Action is direct. - G protein-coupled mediated responses: o This is one of the most common mechanisms in signal transduction. It involves a receptor that interacts with a special protein called a G protein when activated by a ligand. ▪ Think of the receptor as a switch and the G protein as a messenger. When the ligand activates the receptor, it triggers the G protein to relay the signal to other molecules inside the cell, initiating a response. o G proteins link ECF messenger to: ▪ Ion channels ▪ Amplifier enzymes o Slow Ligand-Gated Channels: ▪ Action is indirect. ▪ These are channels in the cell membrane that open in response to a specific chemical messenger (ligand), but their opening process is relatively slow compared to other types of channels. o The five secondary messengers: ▪ Cyclic AMP (cAMP) ▪ Cyclic GMP (cGMP) ▪ Inositol triphosphate (IP3) ▪ Diacylglycerol (DAG) ▪ Calcium ions o Pathway of cAMP: ▪ (1) The first messenger binds to the receptor, activating a Gs protein. (Some messengers inhibit the cAMP second messenger system by activating a Gi protein. ▪ (2) The G protein releases the alpha subunit, which binds to and activates the enzyme adenylate cyclase. ▪ (3) Adenylate cyclase catalyzes the conversion of ATP to cAMP. ▪ (4) cAMP activates protein kinase A, also called cAMP-dependent protein kinase. ▪ (5) The protein kinase catalyzes the transfer of a phosphate group from ATP to a protein, thereby altering the protein’s activity through covalent regulation. ▪ (6) Altered protein activity causes a response in the cell. o Pathway of IP3/DAG: ▪ (1) The messenger binds to its receptor, activating a G protein. ▪ (2) The G protein releases the alpha subunit, which binds to and activates the enzyme phospholipase C. ▪ (3) Phospholipase C catalyzes the conversion of PIP2 to DAG and IP3, each of which functions as a second messenger. ▪ (4a) DAG remains in the membrane and activates the enzyme protein kinase C. • (4b) IP3 moves into the cytosol. ▪ (5a) Protein kinase C catalyzes the phosphorylation of a protein. • (5b) IP3 triggers the release of calcium from the endoplasmic reticulum. ▪ (6a) The phosphorylated protein brings about a response in the cell. • Depending on the cell, calcium then does one of 2 things: o (6b) It acts on proteins to stimulate contraction or secretion. o (6c) It acts as a second messenger by binding to calmodulin, thereby activating a protein kinase that phosphorylates a protein that produces a response in the cell. 6. Study Primary and Secondary Endocrine Organs (pg. 149-158, Table 6.1) - Primary Endocrine Organs: o Hypothalamus and pituitary gland ▪ Hormones of Posterior Pituitary: • Antidiuretic hormone (ADH/Vasopressin) o Paraventricular nucleus o Water balance and osmolarity • Oxytocin o Supraoptic nucleus o Milk ejection o Pineal gland ▪ Secretes melatonin. o Thyroid gland and parathyroid glands: ▪ Thyroid gland hormones: • Tetraiodothyronine (thyroxine) (T4) • Triiodothyronine • Thyroid Hormone: o Regulates metabolism. • Calcitonin o Regulates/lowers calcium levels in the blood. ▪ Parathyroid Hormone: • It raises calcium levels in the blood. o Thymus ▪ It secretes thymosin. • Which regulates the T-cell function. o Adrenal glands ▪ Mineralocorticoids (aldosterone) • Secreted from zona glomerulosa. • Regulates sodium and potassium levels to help regulate the blood pressure and electrolyte balance of our body. ▪ Glucocorticoids (cortisol) • Secreted from zona fasciculata and zona reticularis. • Regulates the body's response to stress. • Regulates metabolism. ▪ Sex hormones (androgens) • Secreted from zona fasciculata and zona reticularis. • Regulate reproductive function. ▪ Adrenal Medulla • Secretory cells = chromaffin cells o 80% epinephrine o 20% norepinephrine o <1% dopamine • Under neural control o Pancreas ▪ Exocrine Pancreas: • Acinar and duct cells. o Secrete fluid and enzymes. o Secretions enter the digestive tract via the pancreatic duct. ▪ Endocrine Pancreas: • Islets of Langerhans o Alpha cells: glucagon o Beta cells: Insulin o Delta cells: Somatostatin o F cells: Pancreatic polypeptide o Gonads ▪ Testes • Androgens (testosterone, androstenedione) ▪ Ovaries • Estrogens (estradiol) - Secondary Endocrine Organs: o Heart ▪ Atrial natriuretic peptide o Kidneys ▪ Erythropoietin o GI tract ▪ Several hormones are released: • Cholecystokinin • Secretin • Gastrin o Liver ▪ Insulin-like growth factors (IGFs) o Skin and kidneys ▪ 1,25-Dihydroxy vitamin D3 o Fat ▪ Leptin 7. Study Tropic Hormones of the Hypothalamus and Anterior Pituitary (pg. 152-153) - Tropic Hormones o These are hormones released by one gland that stimulate another gland to produce and release its own hormones. - Hypothalamic Tropic Hormones: o The hypothalamus produces and releases several tropic hormones that control the secretion of hormones from the anterior pituitary gland. o These hypothalamic tropic hormones are often referred to as releasing hormones because they stimulate the anterior pituitary to release specific hormones. o Examples include: ▪ Growth Hormone-Releasing Hormone (GHRH): • It stimulates the release of growth hormone (GH) from the anterior pituitary. ▪ Thyrotropin-Releasing Hormone (TRH): • It stimulates the release of thyroid-stimulating hormone (TSH) from the anterior pituitary. ▪ Corticotropin-Releasing Hormone (CRH): • It stimulates the release of adrenocorticotropic hormone (ACTH) from the anterior pituitary. ▪ Gonadotropin-Releasing Hormone (GnRH) • It stimulates the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from the anterior pituitary. - Anterior Pituitary Hormones: o In response to the hypothalamic tropic hormones, the anterior pituitary gland secretes its own hormones, which then regulate various physiological processes throughout the body. o Examples include: ▪ Growth Hormone (GH): • It regulates growth, metabolism, and body composition. ▪ Thyroid-Stimulating Hormone (TSH): • It stimulates the thyroid gland to produce and release thyroid hormones, which regulate metabolism. ▪ Adrenocorticotropic Hormone (ACTH): • It stimulates the adrenal glands to produce and release cortisol, which is involved in the body's response to stress. ▪ Follicle-Stimulating Hormone (FSH) & Luteinizing Hormone (LH): • It regulates the reproductive functions such as menstrual cycle and fertility in both males and females. 8. Study the Thyroid and Parathyroid Glands (pg. 154) - - Thyroid Gland: o It appears as a butterfly-shaped structure located on the ventral surface of the trachea. Thyroid gland hormones: o Tetraiodothyronine (thyroxine) (T4) o Triiodothyronine o Thyroid Hormone: ▪ Regulates metabolism. o Calcitonin ▪ Regulates/lowers calcium levels in the blood. - - Parathyroid Glands: o It contains 4 glands which are smaller structures located on the posterior surface of the thyroid gland. Parathyroid Hormone: o It raises calcium levels in the blood. o Parathyroid hormones act on the bones, kidneys, and intestines to increase blood calcium levels. 9. Study the Adrenal Glands, hormones, catecholamines (pg. 154-155, Figure 6.9) - Adrenal Glands: o These glands are a pair of small glands that are located on top of each kidney, and they are also known as the suprarenal glands. o They are divided into two main parts: the outer adrenal cortex and the inner adrenal medulla. Each part secretes different hormones that play important roles in regulating various physiological processes in the body. o Adrenal Cortex: ▪ Mineralocorticoids (aldosterone) • Secreted from zona glomerulosa. • Regulates sodium and potassium levels to help regulate the blood pressure and electrolyte balance of our body. ▪ Glucocorticoids (cortisol) • Secreted from zona fasciculata and zona reticularis. • Regulates the body's response to stress. • Regulates metabolism. ▪ Sex hormones (androgens) • Secreted from zona fasciculata and zona reticularis. • Regulate reproductive function. o Adrenal Medulla: ▪ Epinephrine (Adrenaline): • This hormone is released in response to stress and prepares the body for the "fight or flight" response. It increases heart rate, blood pressure, and blood flow to muscles, while also dilating airways to improve oxygen intake. ▪ Norepinephrine (Noradrenaline): • Like epinephrine, norepinephrine is released in response to stress and helps prepare the body for action. It increases heart rate and blood pressure, constricts blood vessels, and enhances alertness and arousal. 10. ** Review hormones, organ that secretes, target cells, and functions from anatomy a. Table 6.1 in physiology book 11. Study the Uptake, Utilization, and Storage of Energy in Carbohydrates (pg. 604, Figure 21.1, Table 21.1-21.2) - The steps of the Uptake, Utilization, and Storage of Energy in Carbohydrates: o (1) Molecules of glucose are transported into cells throughout the body by glucose transporters. o (2) Inside cells, glucose can be oxidized for energy. o (3) Which generates carbon dioxide as a waste product; can provide substrates for other metabolic reactions. o (4) Excess energy can be converted to glycogen for storage o (5) If glucose levels in the cell decrease, glycogen can be broken down to glucose by glycogenolysis 12. Study the Uptake, Utilization, and Storage of Energy in Proteins (pg. 604, Figure 21.1, Table 21.1-21.2) o (1) Amino acids rather than whole proteins are transported in the bloodstream. Following uptake into cells. o (2) Amino acids are used for the synthesis of proteins. o (3) Or catabolized for energy by proteolysis. ▪ Proteolysis: • It is the breakdown of proteins into smaller polypeptides or amino acids through the hydrolysis of peptide bonds by a protease. o (4) Because proteins consist of amino acids, protein catabolism produces amino acids. o (5) Which can then be catabolized for energy or released into the bloodstream for use by other cells - Cells utilize protein catabolism for energy less so than carbohydrates and lipids, but when proteins are used, ammonia (NH3) and carbon dioxide are produced. The highly toxic ammonia is converted by the liver to urea, which is eventually eliminated in the urine. 13. Study the Uptake, Utilization, and Storage of Energy in Fats (pg. 604-605, Figure 21.1, Table 21.1-21.2) o (1) To facilitate entry into cells, triglycerides at the outer surface of lipoproteins are broken down by the enzyme lipoprotein lipase. ▪ Which is located on the inside surface of capillaries throughout the body and is particularly dense in capillaries running through adipose tissue (body fat). o (2) This enzyme breaks down triglycerides into fatty acids and monoglycerides; the fatty acids are then taken up by nearby cells. ▪ while the monoglycerides remain in the bloodstream and are eventually metabolized in the liver. o (3) After entering cells, fatty acids may be oxidized for energy. o (4) Or combined with glycerol to form new triglycerides. ▪ which are stored in fat droplets in the cytosol. This storage occurs mainly in adipocytes, adipose tissue cells that are specialized for fat storage. (The glycerol used in triglyceride synthesis is not derived from absorbed triglycerides, but instead is synthesized within adipocytes.) o (5) Stored triglycerides can subsequently be broken down into glycerol and fatty acids. o (6) Which can be catabolized for energy or released into the bloodstream for use by other cells. ▪ The catabolism of glycerol and fatty acids produces carbon dioxide as a waste product. The breakdown of triglycerides to fatty acids and glycerol, such as occurs in step 1 or step 5, is called lipolysis. 14. Study Metabolism During the Absorptive State, storage of glucose, fats, amino acids (pg. 607-609, Figure 21.1, Table 21.1-21.2) - During the absorptive state: o Nutrients from the diet, including glucose, fats, and amino acids, are absorbed into the bloodstream, and utilized for energy production, tissue repair, and storage. o Glucose is stored as glycogen in the liver and muscles, fats are stored as triglycerides in adipose tissue, and amino acids can be used for protein synthesis, energy production, or converted into fatty acids for storage. o These stored nutrients provide a reserve of energy and building blocks for cellular processes during periods of fasting or between meals. 15. Study the Factors Affecting Insulin Secretion (pg. 611-612, Figure 21.5) - During the absorptive period: o increased plasma glucose levels stimulate insulin secretion from pancreatic beta cells through a series of steps involving glucose entry into beta cells, ATP generation, potassium channel closure, beta cell depolarization, and subsequent insulin release. o This process helps the body prepare for the absorption of nutrients and transition to the absorptive state. o Insulin secretion is regulated by inhibitory signals from the sympathetic nervous system and circulating epinephrine to maintain glucose balance. 16. Study Negative Feedback Control of Blood Glucose by Insulin and Glucagon (Figure 21.8) - - - - Increased blood amino acids from high-protein, low-carbohydrate meals stimulate both insulin and glucagon release. o Insulin promotes amino acid and glucose uptake into cells, potentially causing hypoglycemia if carbohydrate intake is low. On the other hand, glucagon counteracts the effects of insulin by promoting the release of glucose from storage forms, helping to maintain proper blood glucose levels. These hormonal responses help ensure adequate energy availability despite variations in nutrient intake. Negative feedback control: o The negative feedback control of blood glucose by insulin and glucagon involves the coordinated actions of these hormones to regulate glucose homeostasis in response to changes in blood glucose levels. o This feedback loop helps maintain blood glucose levels within a narrow range to support the energy needs of the body's cells. 17. Study the Factors Affecting Cortisol Secretion (Figure 21.19) - - - - - Cortisol o It is the primary glucocorticoid released from the adrenal cortex. Stress: o Cortisol is often called the "stress hormone" because its secretion increases in response to stress. When our body perceives stress, it triggers the release of cortisol to help us cope with the stressor. Circadian Rhythm: o Cortisol levels naturally fluctuate throughout the day in a pattern known as the circadian rhythm. o Cortisol levels are typically highest in the morning to help wake up the body and provide energy for the day, and they gradually decrease throughout the day and night. Sleep: o Disrupted or inadequate sleep can affect cortisol secretion. o Poor sleep patterns or insufficient sleep duration may disrupt the normal circadian rhythm of cortisol secretion, leading to alterations in cortisol levels. Nutrition and Diet: o Nutritional factors, such as fasting or low-calorie diets, can influence cortisol secretion. o Prolonged fasting or severe calorie restriction may increase cortisol levels as the body responds to perceived energy deprivation. Emotional States: o Emotional states, such as anxiety, depression, or excitement, can impact cortisol secretion. o Emotional stressors can trigger the release of cortisol as part of the body's response to perceived threats or challenges.