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41 Cards in this Set
- Front
- Back
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endocrine system
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chemical signaling by hormones is the function of this basic system of communication and regulation throughout the body. The hormones this system secretes regulates reproduction development, energy metabolism, growth, and behavior
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Paracrine Signaling
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The signaling cell releases local regulators that are intended for target cells that lie near the signaling/secreting cell.
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Autocrine Signaling
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The target cell (recipient of local regulators) is the secreting cell itself.
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local regulators
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Many types of cells produce and secrete these molecules that act over short distances and reach their target cells solely by diffusion.
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neuroendocrine signaling
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specialized neurons called neurosecretory cells secrete molecules that diffuse from nerve cell endings into the blood stream.
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neurohormones
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Specialized neurons secrete molecules into the blood stream during neuroendocrine signaling. What are these molecules called? An example is vasopressin (anti-diuretic essential to kidney function and water balance)
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exocrine glands
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Have ducts that carry secreted substances onto body surfaces or in body cavities. Includes the salivary glands
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steroid hormones
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hormones that are lipids that consist of four fused rings and are derived from cholesterol. Are fat soluble so they can diffuse through the cell membrane. They diffuse across the membrane of endocrine cells (secretion). Outside the cell, they bind to transport proteins that keep them soluble in an aqueous environment. the receptors for lipid soluble hormones are typically found in the cytoplasm or nucleus and are are called cytosolic receptors. Together the hormone receptor complex enter the nucleus and triggers changes in gene transcription one of the determining factors of gene expression.
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amines
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hormones that are synthesized from a single amino acid. Are water soluble so they must bind to cell surface receptors to trigger a signal transduction and ultimately a cell response. sectreted by exocytosis and travel freely throughout the blood stream
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polypeptide hormones
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hormones made up of polypeptide chains (insulin) Are water soluble so they must bind to cell surface receptors to trigger a signal transduction and ultimately a cell response. sectreted by exocytosis and travel freely throughout the blood stream
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epinephrine
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secreted by the adrenal glands in stressful situations, it binds to G coupled protein receptors on liver cell plasma membranes (the target cells). The binding of this hormone to the G Coupled protein receptor triggers a cascade of events involving the synthesis of cAMP (the second messenger). The activation of protein Kinase A by cAMP leads to the activation of an enzyme required for glycogen break down and inactivation of enzyme necessary for glycogen synthesis. This hormone s also known as adrenalin
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growth factors
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Present in both paracrine and autocrine signaling, they are polypeptide local regulators that stimulate cell proliferation and differentiation. Many types of cells grow, divide, and develop normally only when these local regulators are present in their extracellular environment. (another polypeptide local regulator are cytokines in the immune system)
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Nitric Oxide (NO)
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functions in the body as both a neurotransmitter and a local regulator. When the level of oxygen in the blood falls, endothelial cells in blood vessel walls synthesize and secrete this hormone. It activate an enzyme that relaxes smooth muscle cells, resulting in vasodilation improving blood flow to tissues. paracrine signaling of this local regulator causes erections
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Oxytocin
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Suckling by an infant stimulates sensory neurons in the nipples, generating signals in the nervous system that reach the hypothalamus. Nerve impulses from the hypothalamus then trigger the release of this neurohormone from the posterior pituitary gland. In response to this neurohormone circulating the blood, the mammary glands secrete milk. It also uses positive feedback mechanisms to induce contraction of target cells in the uterine muscles. This drives the birth process to completion. It also has an influence on behaviors like maternal care, pair bonding, and sexual activity
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insulin
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It's antagonistic hormone is glucagon and helps regulate the blood glucose concentration of the blood to remain around 70-110 mg/100mL. When blood glucose rises above this normal range, this hormone is secreted by the pancreas and triggers the uptake of glucose into body cells which decreases the blood glucose concentration
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glucagon
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When blood glucose levels drop below the normal range, the release of this hormone promotes the release of glucose into the blood from energy stores like liver (glycogen) which ultimately increases blood glucose levels.
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hypothalamus
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Plays a central role in integrating the endocrine and nervous systems. One of several endocrine glands located in the brain, it receives information from nerves throughout the body and initiates endocrine signaling appropriate to environmental conditions. Sends signals to the pituitary gland. (The posterior pituitary gland is just an extension of this gland). Endocrine signals generated here regulate hormone secretion of the anterior pituitary gland
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Posterior Pituitary gland
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It is an extension of the hypothalamus and secretes anti-diuretic hormone (ADH) and oxytocin
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Anterior Pituitary Gland
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An endocrine gland that synthesizes and secretes hormones in response to signals from the hypothalamus. Many of these hormones act as tropic hormones, meaning that they regulate the function of other endocrine cells or glands. The release of each hormone found here is regulated by a hypothalamic releasing/inhibiting hormone
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tropic hormones
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hormones that regulate the function of other endocrine cells or glands. Includes Follicle stimulating hormone, luteinizing hormone, and adrenocorticotropic hormone (ACTH)
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anti-diuretic hormone (ADH or vasopressin)
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Secreted by the posterior pituitary gland and is one of several hormones that regulates kidney function. It increases water retention in the kidneys, thus decreasing urine volume. The net result is to help maintain blood osmolarity within the normal range. It also plays an important role in social behavior
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portal vessels
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The hypothalamic releasing and inhibiting hormones are secreted near capillaries at the base of the hypothalamus. The capillaries drain into short blood vessels that subdivide into capillary beds in the anterior pituitary glands. What are these short blood vessels called?
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Thyroid Gland
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Secretes triiodothyronine and thyroxine (which stimulate and maintain metabolic processes) and calcitonin (which lowers blood calcium levels). It is an organ consisting of two lobes on the ventral surface of the trachea. It is stimulates by a hormone cascade pathway that looks like...
Thyrotropin-releasing hormone (TRH:Hypothalamus)→TSH/thyrotropin (anterior pituitary gland)→stimulation of this organ |
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Parathyroid gland
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releases PTH (which raises blood calcium levels: antagonistic of calcitonin)
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Pancreas
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Secrete insulin out of its Beta cells and glucagon out of it alpha cells
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Adrenal glands
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Secretes epinephrine and norepinephrine (which raise blood glucose levels, increase metabolic activities, and constrict certain blood vessels) when stimulated by the nervous system. It secrete glucocorticoids and mineralocorticoids.
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Pineal Gland
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A small mass of tissue near the center of the mammalian brain that secretes melatonin which is involved in circadian rhythm.
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Insulin-like growth factors
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when the liver is stimulated by GH, it produces this hormone which directly stimulate bone and cartilage growth.
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parathyroid
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A set of four small structures embedded in the posterior surface of the thyroid and plays a major role in blood Ca²⁺ regulation
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Parathyroid hormone (PTH)
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When blood Ca²⁺ fall below the normal range (10mg/100mL) this hormone is released to raise the level of Ca²⁺. It stimulates bones to decompose their mineral matrix and release Ca²⁺, it directly tells the kidneys to reabsorb Ca²⁺ through the renal tubules. It also promotes the conversion of vitamin D to an active hormone that directly acts on the intestines to stimulate the uptake os more Ca²⁺ from food.
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calcitonin
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If blood Ca²⁺ rises above the set point, the thyroid releases this hormone to maintain homeostatic balance. It inhibits bone absorption and enhances Ca²⁺release from the kidneys.
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norepinephrine and epinephrine
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secreted by the adrenal glands in times of high stress or extreme pleasure, a major activity of these hormones is to increase the amount of chemical energy available for immediate use (increase the rate of glycogen breakdown, stimulates the release of fatty acids from fat cells, increase heart rate and stroke volume, and dilate the bronchioles of the lungs). They also function as neurotransmitters however in the adrenal medulla, they function as neurohormones.
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Aldosterone
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a mineralocorticoid that maintains water and salt balance in the blood. It is stimulates by angiotension II and it itself stimulates cells in the kidneys to reabsorb sodium ions and water from filtrate, raising blood pressure and volume. It also functions in the body's response to severe stress.
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androgens
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The sex hormone that is primarily synthesized by the testes and are responsible for the male embryonic development and development of male secondary sex characteristics later in life.
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testosterone
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The main androgen secreted by males
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estrogens
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are responsible for the maintenance of the female reproductive system and for the development of female secondary sex characteristics
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estradiol
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The most important estrogen in females
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progestins
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Primarily involved in preparing and maintaining tissues of the uterus required to support the growth and development of an embryo
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progesterone
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a hormone classified as progestin
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melatonin
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A modified amino acid hormone involved in circadian rhythms and other biological rhythm such as reproduction. also affects skin pigmentation. It is the sleepy hormone and its released is stimulated by darkness.
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juvenile hormone (JH) |
secreted by a pair ofendocrine glands behind the brain. JH modulates the activityof ecdysteroid. As long as the level of JH is high, ecdysteroidstimulates molting (and thus maintains the “juvenile” larvalstate). When the JH level drops, ecdysteroid induces formationof a pupa, within which metamorphosis occurs. |
