Hormones and the Endocrine System Chapter 45
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Transcript of Hormones and the Endocrine System Chapter 45
Animal hormones are chemical signals that are secreted into the circulatory system and communicate regulatory messages within the body
Hormones reach all parts of the body, but only target cells have receptors for that hormone
OVERVIEW: THE BODY’S LONG-DISTANCE REGULATORS
The endocrine system secretes hormones that coordinate slower but longer-acting responses including reproduction, development, energy metabolism, growth, and behavior
The nervous system conveys high-speed electrical signals along specialized cells called neurons; these signals regulate other cells
COORDINATION BETWEEN ENDOCRINE AND NERVOUS SYSTEMS
Essential knowledge 3.D.2: Cells communicate with each other through direct contact with other cells or from a distance via chemical signaling.Essential knowledge 3.D.2: Cells communicate with each other through direct contact with other cells or from a distance via chemical signaling.
Intercellular CommunicationThe ways that signals are transmitted between animal cells are classified by two criteria
The type of secreting cell The route taken by the signal in reaching its
target
CONCEPT 45.1: HORMONES AND OTHER SIGNALING MOLECULES BIND TO TARGET RECEPTORS,
TRIGGERING SPECIFIC RESPONSE PATHWAYS
Endocrine cells that release specific signaling molecules, which can travel long distances through the blood to reach all parts of the body.
Maintains homeostasis, mediates responses to stimuli, regulates growth and development
ENDOCRINE SIGNALING
Essential knowledge 3.D.2: Cells communicate with each other through direct contact with other cells or from a distance via chemical signaling. c. Signals released by one cell type can travel long distances to target cells of another cell type.Essential knowledge 3.D.2: Cells communicate with each other through direct contact with other cells or from a distance via chemical signaling. c. Signals released by one cell type can travel long distances to target cells of another cell type.
Paracrine signaling—target cells lie near the secreting cells
Autocrine signaling—target cell is also the secreting cell
Both use local regulators that travel short distances, reaching target cells by diffusion
Both play roles in regulating blood pressure, nervous system function, and reproduction
PARACRINE AND AUTOCRINE SIGNALING
Essential knowledge 3.D.2: Cells communicate with each other through direct contact with other cells or from a distance via chemical signaling. b. Cells communicate over short distances by using local regulators that target cells in the vicinity of the emitting cell.
Essential knowledge 3.D.2: Cells communicate with each other through direct contact with other cells or from a distance via chemical signaling. b. Cells communicate over short distances by using local regulators that target cells in the vicinity of the emitting cell.
Synaptic signaling--neurons form specialized junctions with target cells, called synapsesAt synapses, neurons secrete molecules called neurotransmitters that diffuse short distances and bind to receptors on target cells
SYNAPTIC AND NEUROENDOCRINE SIGNALING
Essential knowledge 3.D.2: Cells communicate with each other through direct contact with other cells or from a distance via chemical signaling. b. Cells communicate over short distances by using local regulators that target cells in the vicinity of the emitting cell.
Essential knowledge 3.D.2: Cells communicate with each other through direct contact with other cells or from a distance via chemical signaling. b. Cells communicate over short distances by using local regulators that target cells in the vicinity of the emitting cell.
Neuroendocrine signaling--specialized neurosecretory cells secrete molecules (neurohormones) that travel to target cells via the bloodstream (e.g. vasopressin—essential to kidney function and water balance)
SYNAPTIC AND NEUROENDOCRINE SIGNALING
Essential knowledge 3.D.2: Cells communicate with each other through direct contact with other cells or from a distance via chemical signaling. c. Signals released by one cell type can travel long distances to target cells of another cell type.Essential knowledge 3.D.2: Cells communicate with each other through direct contact with other cells or from a distance via chemical signaling. c. Signals released by one cell type can travel long distances to target cells of another cell type.
Members of the same animal species sometimes communicate with pheromones, chemicals that are released into the environment
Pheromones serve many functions, including marking trails leading to food, defining territories, warning of predators, and attracting potential mates
SIGNALING BY PHEROMONES
Essential knowledge 3.E.1: Individuals can act on information and communicate it to others. a. Organisms exchange information with each other in response to internal changes and external cues, which can change behavior. LO 3.42 The student is able to describe how organisms exchange information in response to internal changes or environmental cues.
Essential knowledge 3.E.1: Individuals can act on information and communicate it to others. a. Organisms exchange information with each other in response to internal changes and external cues, which can change behavior. LO 3.42 The student is able to describe how organisms exchange information in response to internal changes or environmental cues.
Endocrine glands – endocrine cells grouped together in ductless organs Secrete hormones
directly into surrounding fluid
Exocrine glands – have ducts and secrete substances onto body surfaces or into cavities
ENDOCRINE TISSUES AND ORGANS
The same hormone may have different effects on target cells that have
Different receptors for the hormone
Different signal transduction pathways
MULTIPLE EFFECTS OF HORMONES
Negative feedback inhibits a response by reducing the initial stimulus, thus preventing excessive pathway activity
FEEDBACK REGULATION
Essential knowledge 2.C.1: Organisms use feedback mechanisms to maintain their internal environments and respond to external environmental changes. a. Negative feedback mechanisms maintain dynamic homeostasis for a particular condition (variable) by regulating physiological processes, returning the changing condition back to its target set point.
Essential knowledge 2.C.1: Organisms use feedback mechanisms to maintain their internal environments and respond to external environmental changes. a. Negative feedback mechanisms maintain dynamic homeostasis for a particular condition (variable) by regulating physiological processes, returning the changing condition back to its target set point.
Positive feedback reinforces a stimulus to produce an even greater response
FEEDBACK REGULATION
Essential knowledge 2.C.1: Organisms use feedback mechanisms to maintain their internal environments and respond to external environmental changes. b. Positive feedback mechanisms amplify responses and processes in biological organisms. The variable initiating the response is moved farther away from the initial set-point. Amplification occurs when the stimulus is further activated which, in turn, initiates an additional response that produces system change.
Essential knowledge 2.C.1: Organisms use feedback mechanisms to maintain their internal environments and respond to external environmental changes. b. Positive feedback mechanisms amplify responses and processes in biological organisms. The variable initiating the response is moved farther away from the initial set-point. Amplification occurs when the stimulus is further activated which, in turn, initiates an additional response that produces system change.
Insulin produced by alpha cells of pancreatic islets Reduces blood glucose levels by Promoting the cellular
uptake of glucose Slowing glycogen
breakdown in the liver Promoting fat storage,
not breakdown
INSULIN AND GLUCAGON: CONTROL OF BLOOD GLUCOSE
Essential knowledge 3.D.2: Cells communicate with each other through direct contact with other cells or from a distance via chemical signaling. c. Signals released by one cell type can travel long distances to target cells of another cell type.Essential knowledge 3.D.2: Cells communicate with each other through direct contact with other cells or from a distance via chemical signaling. c. Signals released by one cell type can travel long distances to target cells of another cell type.
Glucagon produced by beta cells of pancreatic islets increases blood glucose levels by Stimulating conversion
of glycogen to glucose in the liver
Stimulating breakdown of fat and protein into glucose
INSULIN AND GLUCAGON: CONTROL OF BLOOD GLUCOSE
Essential knowledge 3.D.2: Cells communicate with each other through direct contact with other cells or from a distance via chemical signaling. c. Signals released by one cell type can travel long distances to target cells of another cell type.Essential knowledge 3.D.2: Cells communicate with each other through direct contact with other cells or from a distance via chemical signaling. c. Signals released by one cell type can travel long distances to target cells of another cell type.
Caused by a deficiency of insulin or a decreased response to insulin in target tissues
It is marked by elevated blood glucose levels Type 1 diabetes mellitus (insulin-
dependent) is an autoimmune disorder in which the immune system destroys pancreatic beta cells
Type 2 diabetes mellitus (non-insulin-dependent) involves insulin deficiency or reduced response of target cells due to change in insulin receptors
DIABETES MELLITUS
Essential knowledge 2.C.1: Organisms use feedback mechanisms to maintain their internal environments and respond to external environmental changes. c. Alteration in the mechanisms of feedback often results in deleterious consequences.
Essential knowledge 2.C.1: Organisms use feedback mechanisms to maintain their internal environments and respond to external environmental changes. c. Alteration in the mechanisms of feedback often results in deleterious consequences.
Endocrine pathways are subject to regulation by the nervous system, including the brain
CONCEPT 45.3: THE HYPOTHALAMUS AND PITUITARY ARE CENTRAL TO ENDOCRINE
REGULATION
The hypothalamus receives information from the nervous system and initiates responses through the endocrine system
Attached to the hypothalamus is the pituitary gland Posterior pituitary - stores
and secretes hormones that are made in the hypothalamus
Anterior pituitary - makes and releases hormones under regulation of the hypothalamus
COORDINATION OF ENDOCRINE AND NERVOUS SYSTEMS IN VERTEBRATES
The two hormones released from the posterior pituitary act directly on nonendocrine tissues
POSTERIOR PITUITARY HORMONES
• Oxytocin regulates milk secretion by the mammary glands
• Antidiuretic hormone (ADH) regulates water uptake by the kidneysEssential knowledge 3.D.2: Cells communicate with each other through direct contact with other cells or from a distance via
chemical signaling. c. Signals released by one cell type can travel long distances to target cells of another cell type.Essential knowledge 3.D.2: Cells communicate with each other through direct contact with other cells or from a distance via chemical signaling. c. Signals released by one cell type can travel long distances to target cells of another cell type.
Eating a bag of salty pretzels decreases blood osmolarity
This triggers the release of ADH by posterior pituitary
ADH makes kidneys retain more water and excrete more concentrated urine
Blood osmolarity increases, osmoreceptors in hypothalamus reduce ADH production
What do you think happens if you drink a large volume of water?
ANTIDIURETIC HORMONE (ADH)
Essential knowledge 2.C.1: Organisms use feedback mechanisms to maintain their internal environments and respond to external environmental changes. a. Negative feedback mechanisms maintain dynamic homeostasis for a particular condition (variable) by regulating physiological processes, returning the changing condition back to its target set point.
Essential knowledge 2.C.1: Organisms use feedback mechanisms to maintain their internal environments and respond to external environmental changes. a. Negative feedback mechanisms maintain dynamic homeostasis for a particular condition (variable) by regulating physiological processes, returning the changing condition back to its target set point.
Ch. 44
Hormone production here is controlled by releasing and inhibiting hormones from the hypothalamus
For example, prolactin-releasing hormone from the hypothalamus stimulates the anterior pituitary to secrete prolactin (PRL), which has a role in milk production
ANTERIOR PITUITARY HORMONES
Essential knowledge 3.D.2: Cells communicate with each other through direct contact with other cells or from a distance via chemical signaling. c. Signals released by one cell type can travel long distances to target cells of another cell type.Essential knowledge 3.D.2: Cells communicate with each other through direct contact with other cells or from a distance via chemical signaling. c. Signals released by one cell type can travel long distances to target cells of another cell type.
The release of thyroid hormone results from a hormone cascade pathway involving the hypothalamus, anterior pituitary, and thyroid gland
Hormone cascade pathways typically involve negative feedback
THYROID REGULATION: A HORMONE CASCADE PATHWAY
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Essential knowledge 2.C.1: Organisms use feedback mechanisms to maintain their internal environments and respond to external environmental changes. a. Negative feedback mechanisms…Essential knowledge 3.D.2: Cells communicate with each other through direct contact with other cells or from a distance via chemical signaling. c. Signals released by one cell type can travel long distances to target cells of another cell type.
Essential knowledge 2.C.1: Organisms use feedback mechanisms to maintain their internal environments and respond to external environmental changes. a. Negative feedback mechanisms…Essential knowledge 3.D.2: Cells communicate with each other through direct contact with other cells or from a distance via chemical signaling. c. Signals released by one cell type can travel long distances to target cells of another cell type.
Hypothyroidism, too little thyroid function, can produce symptoms such as
Weight gain, lethargy, cold intolerance Hyperthyroidism, excessive production of
thyroid hormone, can lead to High temperature, sweating, weight loss,
irritability, and high blood pressure Graves disease, a form of hyperthyroidism
caused by autoimmunity, is typified by protruding eyes
DISORDERS OF THYROID FUNCTION AND REGULATION
Essential knowledge 2.C.1: Organisms use feedback mechanisms to maintain their internal environments and respond to external environmental changes. c. Alteration in the mechanisms of feedback often results in deleterious consequences.
Essential knowledge 2.C.1: Organisms use feedback mechanisms to maintain their internal environments and respond to external environmental changes. c. Alteration in the mechanisms of feedback often results in deleterious consequences.
Thyroid hormone refers to a pair of hormones
Triiodothyronin (T3), with three iodine atoms
Thyroxine (T4), with four iodine atoms
Insufficient dietary iodine causes pituitary to secrete TSH
TSH levels lead to an enlarged thyroid gland, called a goiter
MALNUTRITION CAN ALTER THYROID FUNCTION
Essential knowledge 2.C.1: Organisms use feedback mechanisms to maintain their internal environments and respond to external environmental changes. c. Alteration in the mechanisms of feedback often results in deleterious consequences.
Essential knowledge 2.C.1: Organisms use feedback mechanisms to maintain their internal environments and respond to external environmental changes. c. Alteration in the mechanisms of feedback often results in deleterious consequences.
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Endocrine signaling regulates homeostasis, development, and behavior
CONCEPT 45.4: ENDOCRINE GLANDS RESPOND TO DIVERSE STIMULI IN REGULATING HOMEOSTASIS,
DEVELOPMENT, AND BEHAVIOR
Two antagonistic hormones regulate the homeostasis of calcium (Ca2+) in the blood of mammals
PARATHYROID HORMONE AND VITAMIN D: CONTROL OF BLOOD CALCIUM
• Parathyroid hormone (PTH) is released by the parathyroid glands
• Calcitonin is released by the thyroid gland
Essential knowledge 3.D.2: Cells communicate with each other through direct contact with other cells or from a distance via chemical signaling. c. Signals released by one cell type can travel long distances to target cells of another cell type.
Essential knowledge 3.D.2: Cells communicate with each other through direct contact with other cells or from a distance via chemical signaling. c. Signals released by one cell type can travel long distances to target cells of another cell type.
PTH releases Ca2+ from bone and stimulates reabsorption of Ca2+ in the kidneys
It also has an indirect effect, stimulating the kidneys to activate vitamin D, which promotes intestinal uptake of Ca2+ from food
Calcitonin decreases the level of blood Ca2+
It stimulates Ca2+ deposition in bones and secretion by kidneys
PTH INCREASES THE LEVEL OF BLOOD Ca2+
Essential knowledge 2.C.1: Organisms use feedback mechanisms to maintain their internal environments and respond to external environmental changes. Essential knowledge 2.C.1: Organisms use feedback mechanisms to maintain their internal environments and respond to external environmental changes.
The adrenal glands are adjacent to the kidneys
Each adrenal gland actually consists of two glands: the adrenal medulla (inner portion) and adrenal cortex (outer portion)
ADRENAL HORMONES: RESPONSE TO STRESS
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The adrenal medulla secretes epinephrine (adrenaline) and norepinephrine (noradrenaline)
They are secreted in response to stress-activated impulses from the nervous system
They mediate various fight-or-flight responses
HORMONES FROM THE ADRENAL MEDULLA
Epinephrine and norepinephrine Trigger the release of
glucose and fatty acids into the blood
Increase oxygen delivery to body cells
Direct blood toward heart, brain, and skeletal muscles and away from skin, digestive system, and kidneys
The release of epinephrine and norepinephrine occurs in response to involuntary nerve signals
SHORT TERM STRESS
Essential knowledge 3.E.1: Individuals can act on information and communicate it to others. a. Organisms exchange information with each other in response to internal changes and external cues, which can change behavior.
Essential knowledge 3.E.1: Individuals can act on information and communicate it to others. a. Organisms exchange information with each other in response to internal changes and external cues, which can change behavior.
The adrenal cortex releases a family of steroids called corticosteroids in response to stress
These hormones are triggered by a hormone cascade pathway via the hypothalamus and anterior pituitary (ACTH)
Humans produce two types of corticosteroids: glucocorticoids and mineralocorticoids
HORMONES FROM THE ADRENAL CORTEX
Glucocorticoids, such as cortisol, influence glucose metabolism and the immune system
Mineralocorticoids, such as aldosterone, affect salt and water balance
The adrenal cortex also produces small amounts of steroid hormones that function as sex hormones
Essential knowledge 3.D.2: Cells communicate with each other through direct contact with other cells or from a distance via chemical signaling. c. Signals released by one cell type can travel long distances to target cells of another cell type.Essential knowledge 3.D.2: Cells communicate with each other through direct contact with other cells or from a distance via chemical signaling. c. Signals released by one cell type can travel long distances to target cells of another cell type.
The gonads, testes and ovaries, produce most of the sex hormones: androgens, estrogens, and progestins
All three sex hormones are found in both genders, but in significantly different proportions
Synthesis of the sex hormones is controlled by FSH and LH from the anterior pituitary
GONADAL SEX HORMONES
The testes primarily synthesize androgens, mainly testosterone, which stimulate development and maintenance of the male reproductive system (sperm production)
Testosterone causes an increase in muscle and bone mass and is often taken as a supplement to cause muscle growth, which carries health risks
TESTOSTERONE
Essential knowledge 3.D.2: Cells communicate with each other through direct contact with other cells or from a distance via chemical signaling. c. Signals released by one cell type can travel long distances to target cells of another cell type.Essential knowledge 3.D.2: Cells communicate with each other through direct contact with other cells or from a distance via chemical signaling. c. Signals released by one cell type can travel long distances to target cells of another cell type.
Estrogens, most importantly estradiol, are responsible for maintenance of the female reproductive system and the development of female secondary sex characteristics
In mammals, progestins, which include progesterone, are primarily involved in preparing and maintaining the uterus
ESTROGENS AND PROGESTINS
Essential knowledge 3.D.2: Cells communicate with each other through direct contact with other cells or from a distance via chemical signaling. c. Signals released by one cell type can travel long distances to target cells of another cell type.Essential knowledge 3.D.2: Cells communicate with each other through direct contact with other cells or from a distance via chemical signaling. c. Signals released by one cell type can travel long distances to target cells of another cell type.