Exam 1 Flashcards
Endocrine system, hormones, and blood
The endocrine system is composed of
The endocrine system is composed of endocrine glands
as well as specialized endocrine cells found throughout the body
Hormones
Chemical messengers secreted by endocrine glands
Hormones are transported…
Hormones are transported
in the blood to their target tissues, or effectors, where they stimulate a specific response
Communication systems: Nervous system
Nervous system transmits messages directly to its target cells through action potentials and the release of neurotransmitters at synapses
Communication systems: Endocrine system
Transmits messages to its target cells through secretion of hormones into the bloodstream
Hypothalamus: Nervous system
Hypothalamus regulates nervous system functions such as detecting changes in body temperature and serving as a regulator of autonomic function
Hypothalamus: Endocrine system
Hypothalamus regulates endocrine function at the level of the pituitary gland. The hypothalamus synthesizes and secretes several hormones that can either stimulate or inhibit the release of other hormones from the pituitary gland
Neuropeptides
Hormones secreted by neurons; aka neurohormones
Major endocrine glands and tissues and where theyre located
Hypothalamus: Brain
Pineal gland: Beneath corpus callosum
Pituitary gland: Below hypothalamus
Thyroid: Front of larynx and trachea
Parathyroids: Posterior part of thyroid
Thymus: Behind sternum and in front of heart
Adrenals: Top of kidneys
Islets of Langerhans: Pancreas
Ovaries/Testes
Similarities between endocrine system and nervous system
Hypothalamus: Regulates nervous system functions and regulates endocrine function; Synthesizes and secretes hormones
Shared chemical messengers: Certain molecules are used by both nervous and endocrine systems; Ex: Norepinephrine
Differences between endocrine system and nervous system
Mode of transport: Nervous system secretes neurotransmitters that are released directly into target cells; Endocrine system secretes hormones that are transported in bloodstream
Speed of response: Nervous system responds faster than endocrine system
Duration of response: Nervous system activates targets quickly and only for as long as action potentials are sent to target. Target cells response is terminated shortly after action potentials cease; Endocrine system has longer-lasting effects. Hormones remain in bloodstream for even weeks and activate their target issues as long as they are present in circulation
Modulation of signal intensity: Hormones secreted by most endocrine glands are amplitude-modulated signals (total amount of signal that is produced). This type of signal consists of fluctuations in the concentration of hormones in bloodstream; Action potentials carried along axons are frequency-modulated signals (how often a signal is sent in a certain period of time). Vary in the number of signals within that time period. Low frequency=weak stimulus
Endocrine-regulated Processes
1) Growth and development: Hormones stimulate bone cells to screte new matrix, neurons to form and strengthen synapses, enlargement of skeletal muscle fibers, etc
2) Metabolism: Hormones stimulate cells to take up or release glucose, produce enzymes essential for breakdown and absorption of food, as well as modifications in heart rate, blood pressure, and breathing rate to adapt to variations in metabolic demand
3) Blood composition: Many hormones regulate actions of the kidney to conserve or excrete ions and water, as well as regulating pH of the plasma, the number and types of blood cells, and the amount of certain proteins found in the plasma of blood
4) Reproduction: hormones are the key regulators of reproduction. They allow males and females to produce gametes and enable female body to nourish offspring
Classes of chemical messengers
1) Autocrine: Stimulates cell that originally secreted it. Stimulated by cells in a local area; Ex: Those secreted by white blood cells during an infection. Stimulates own replication so total number of white blood cells increase rapidly
2) Paracrine: Act locally on neighboring cells. Secreted by one cell type into extracellular fluid and affect surrounding cells; Ex: Histamine. Stimulates vasodilation in nearby blood vessels; Includes substances that play a role in modulating the sensation of pain, such as endorphins and prostaglandins
3) Neurotransmitters: Secreted by neurons that activate an adjacent cell. Secreted into synaptic cleft, rather into bloodstream. Travels short distances and influences postsynaptic cells; Ex: Acetylcholine and epinephrine
4) Endocrine: Secreted into bloodstream by certain glands and cells. Travel through general circulation to target cells. Results in hormones; Ex: Thyroid hormones, growth hormone, insulin, epinephrine, estrogen, testosterone, progesterone
Control of hormonal secretion
Three types of stimuli that regulate hormone release
1) Humoral stimuli: Metabolites and other molecules in the bloodstream can directly stimulate the release of some hormones. Cells that secrete these hormones have receptors for certain substances i the blood; Ex: glucose, Ca2+ and Na+ can stimulate hormone secretion. When blood level of particular substance changes, hormone is released in response to molecules concentration; Humoral = fluids of the body
2) Neural stimuli: Following an action potential, a neuron releases a neurotransmitter into a synapse with a hormone-producing cell. Neurotransmitter stimulates cells to secrete their hormone; Ex: Stimulating adrenal gland to secrete epinephrine and norepinephrine into blood during stress or exercise. When stimulus no longer present. then neural stimulation declines, and the secretion of those two hormones decrease; Some neurons secrete their chemical messengers directly into blood when stimulated making chemical messengers hormones (neuropeptides). Some neuropeptides stimulate hormone secretion from other endocrine cells are called releasing hormones. When a neuron releases a neurotransmitter at a synapse to stimulate a hormones secretion, it is neural stimulus
3) Hormonal stimulus: When hormones stimulate the secretion of other hormones; Ex: Tropic hormones: A releasing hormone from hypothalamus stimulates the release of a tropic hormone from pituitary gland which then travels to separate endocrine gland and stimulates the release of a hormone from target endocrine gland
Patterns of hormone secretion
1) Chronic: Results in relatively constant blood levels of hormone over long periods of time; Ex: Thyroid hormones circulate in blood within a small range of concentrations
2) Acute: Occurs when hormone’s concentration changes suddenly and irregularly, and its circulating levels differ with each stimulus; Ex: Epinephrine is released in large amounts in response to stress of physical exercise
3) Episodic: Occurs when hormones are secreted at fairly predictable intervals and concentrations; Ex: Reproductive hormones fluctuating a month in cyclic fashion
Classes of hormones
1) Lipid-soluble: Nonpolar and include steroid hormones (testosterone and aldosterone), thyroid hormones, and fatty acid derivative hormones, such as eicosanoids (or prostaglandins)
2) Water-soluble: Polar molecules that include most amino acid derivatives (epinephrine), peptides (insulin, thyrotropin-releasing hormone), or proteins (thyroid-stimulating hormone, growth hormone), including glycoproteins
Binding proteins
Many hormones are broken down after entering bloodstream. These hormones require binding proteins that protect hormone so that they arrive intact and functional at target. Once hormones attach to a binding protein, they are called bound hormones; For small hormones, the binding protein protects them from degradation by hydrolytic enzymes and from being filtered from the blood in the kidney; For lipid-soluble hormones that are insoluble in plasma, being bound to a binding protein causes them to become more water-soluble. Hormones bind to specific binding proteins. Hormones that attach to binding proteins tend to circulate longer than hormones that do not
Free hormones
The binding of hormones to binding proteins is reversible. Hormones dissociate (detach) from their binding proteins at their target tissues. Once the hormones detach, they are called free hormones. Some hormones always exist as free hormones because they do not have specific binding proteins to which they attach. Some hormones are “always free.” The binding proteins affinity for its hormone determines the concentration of free hormones. The reversible binding hormones to their binding proteins is important because only hormones are able to diffuse through capillary walls and bind to target tissues. Water-soluble hormones are often free hormones because they can dissolve directly into the plasma of the blood and are delivered to their target tissue without binding to a binding protein. They diffuse from blood into tissue spaces slowly
Regulation of hormone levels in blood
1) Negative feedback: Most hormones are regulated by a negative-feedback mechanism, whereby the hormones secretion is inhibited by the hormone itself. It is a self-limiting system; Ex: thyroid hormones inhibit secretion of their releasing hormone from hypothalamus and tropic hormone from anterior pituitary
2) Positive feedback: Hormones secretion is stimulated by the hormone itself. It is a self-perpetuating system
Half-life of hormones
Hormone concentrations are stable in bloodstream; however, some hormones are more stable than others. Life span of a given hormone varies with its chemical nature. Larger, more complex hormones are more stable. A hormones life span can be expressed as its half life, which is the amount of time it takes for 50% of the circulating hormone to be removed from circulation and excreted; Ex: Thyrotropin-releasing hormone has a short half life because of its simple composition, whereas cortisol is a steroid hormone with a longer half life of 90 minutes. Its lipid-soluble nature causes it to not easily degrade and it can continue to activate target cells for more than an hour
Elimination of hormones from bloodstream
All hormones are destroyed either in the circulation or by enzymes at their target cells. The destruction and elimination of hormones limit the length of time they are active, and body processes change quickly when hormones are secreted and remain functional for only short periods. Without binding proteins, lipid-soluble hormones would quickly diffuse out of capillaries and be degraded by enzymes of the liver and lungs or be filtered form the blood by the kidneys and would be unable to effectively regulate their targets
Conjugation: Used to terminate a lipid-soluble hormone response. Occurs when specific enzymes in the liver attach water-soluble hormones to the hormones. Once the lipid-soluble hormones are conjugated, they cannot reenter the blood where they could overstimulate their targets. Instead, kidneys and liver excrete them into urine and bile
Proteases: Hydrolytic enzymes within bloodstream that break down water-soluble hormones and lead to kidneys removing hormone breakdown products from blood
Hormones must be able to
Hormones must be able to interact with their target tissue in a specific manner to activate a coordinated set of events; Ex: formation of reproductive organs in fetus is activated by reproductive steroid hormones; Hormones must be able to regulate specific cellular pathways once they arrive at their targets and bind to target cell proteins called receptors; A hormone can stimulate only when the cells that have the receptor for that hormone. The specific portion of each receptor molecule where a hormone binds is called a binding site, and the shape and chemical characteristics of each receptor site only allow a specific type of hormone to bind to it. The tendency for each time of hormone to bind to one type of receptor and not to others is called specificity
Agonists and Antagonists
Drugs with structures similar to those of specific hormones will compete with those hormones for the same receptor. A drug that binds to a hormone receptor and activates it is an agonist; Ex: Some asthma inhalers use drugs that mimic epinephrine and can activate epinephrine receptors; A drug that binds to a hormone receptor and inhibits its action is an antagonist; Ex: Some anti-stroke medications are epinephrine antagonists that prevent epinephrine-stimulated platelet aggregation and thus prevent the blockage of blood vessels
Classes of receptors
1) Lipid-soluble hormones bind to nuclear receptors: Lipid-soluble hormones are small and nonpolar, so they can easily diffuse through plasma membrane and bind to nuclear receptors. Nuclear receptors are often found in nucleus or cytoplasm. Cytoplasm receptors move to nucleus when activated. When hormones bind to nuclear receptors, hormone-receptor complex interacts with DNA in nucleus or with cellular enzymes to regulate transcription of particular genes in target tissue; Ex: thyroid hormones and steroid hormones
2) Water-soluble hormones bind to membrane-bound receptors. Water-soluble hormones are large and cannot pass through plasma membrane, so they interact with membrane-bound proteins, which are proteins that extend across plasma membrane, with their hormone-binding site exposed on plasma membranes outer surface. When hormone binds to receptor on outside of plasma membrane, hormone-receptor complex initiates response inside cell; Ex: Proteins, peptides, and some amino acid derivatives, such as epinephrine and norepinephrine
Action of nuclear-receptors
1) After lipid-soluble hormones enter their target cell, they bind to their receptors
2) Lipid-soluble hormones either bind to cytoplasmic receptors and travel to nucleus or bind to nuclear receptors
3) Hormone-receptor complex binds to DNA to produce new proteins. The receptors that bind to DNA have fingerlike projections that recognize and bind to specific nucleotide sequences in the DNA called hormone-response elements. The combination of the hormone and its receptor forms a transcription factor
4) When the hormone-receptor complex binds to the hormone-response element, it regulate the transcription of specific messenger RNA 9mRNA) molecules
5) Newly formed mRNA molecules move to cytoplasm of cell and bind to ribosomes to be translated into specific proteins
6) New proteins produce cell’s response of the lipid-soluble hormone
Ex: Testosterone stimulates synthesis of proteins that are responsible for male secondary sex characteristics. Steroid hormone aldosterone affects its target cells in kidneys by stimulating the synthesis of proteins that increase the rate of Na+ and K+ transport
G protein-coupled receptors
Most common membrane-bound receptor pathway involves G proteins. G proteins allow for transduction of an extracellular signal, such as a water-soluble hormone, into an intracellular signal, which includes molecules called second messengers. This mechanism is usually employed by hormones that are unable to cross plasma membrane. A G protein-coupled receptor pathway is often referred as a second-messenger system. In an endocrine second-messenger system, the first messenger is the hormone, which binds to its receptor. The receptor is coupled to a 3-subunit G protein that produces a second messenger molecules when activated
G protein subunits
1) Alpha: Largest subunit. Classified into families according to alpha subunit. The type of alpha subunit that determines the specific cellular response. In the inactive state of G protein, a guanine diphosphate molecule is bound to the alpha subunit and the three subunits form a complex of G alpha beta gamma
2) Beta: Middle largest subunit
3) Gamma: Smallest subunit
Alpha subunits that increase intracellular levels of cAMP
When this family of G proteins with an alpha subunit is activated, it stimulates the enzyme adenylate cyclase. Adenylate cyclase converts ATP to the second messenger, cAMP. Cyclic AMP carries out cellular metabolic processes; Ex: cAMP binds to protein kinases and activates them;
Attachment of a phosphate to another molecule is called phosphorylation. Depending on enzyme, phosphorylation increases or decreases enzyme activity. The amount of time cAMP is present to produce a response in a cell is limited. An enzyme in the cytoplasm, called phosphodiesterase, breaks down cAMP to AMP. Once cAMP levels drop, the enzymes in the cell are no longer stimulated. Cyclic AMP can elicit many different responses in the body because each cell type posses a unique set of enzymes; Ex: Glucagon, epinephrine, antidiuretic hormone, luteinizing hormone, and follicle-stimulating hormone
Alpha subunits that increase intracellular levels of Ca2+
Third family of G proteins has alpha subunit that when activated stimulate activation of the enzyme phospholipase C. Active phospholipase C converts the molecule PIP2 to the second messengers called diacylglycerol and inositol triphosphate. DAG activates enzymes that synthesize prostaglandins, which increase smooth muscle contraction. IP3 releases Ca2+ from endoplasmic reticulum or opens Ca2+ channels in plasma membrane, allowing ions to enter the cytoplasm and increase contraction of smooth muscle cells; Ex: Oxytocin when stimulating contraction of smooth muscle in reproductive system
Guanylate cyclase receptors
Cyclic guanine monophosphate, a second messenger, is synthesized in response to a hormone binding to a membrane-bound receptor. The hormone binds to its receptor, activating an enzyme called guanylate cyclase embedded in plasma membrane. Guanylate cyclase converts guanine triphosphate to cGMP. Cyclic GMP then activates specific enzymes in target cell, and these enzymes produce the cells response to hormone
Receptor tyrosine kinases
The insulin receptor is a receptor tyrosine kinase that is composed of four subunits: two extracellular and two embedded in plasma membrane with enzymatic portion in cells cytoplasm. Binding of a hormone to the extracellular portion of receptor causes a conformational change that initiates interactions among the four subunits of the receptor. Ultimately, tyrosine amino acids within the receptor become phosphorylated, which activates receptor. Receptor then phosphorylates cytoplasmic proteins in target cell that elicit hormones effects; Ex: Insulin resistance is most likely caused when insulin receptor has reduced phosphorylation activity, resulting in fewer glucose transporters being inserted into plasma membrane of insulin target cells, leading to glucose not being taken up as readily and blood glucose levels increasing
Down-regulation of receptors
Desensitization occurs when number of receptors rapidly decreases after exposure to certain hormones, aka down-regulation. Because most receptor molecules are degraded over time, a decrease in their synthesis rate reduces the total number of receptor molecules in a cell. Often, the target cells internalize the receptors and destroy them
Hormone interactions
1) Permissive interactions: Some hormones assist other hormones. Without permissive effects of these types of hormones, the other hormone elicits a weaker response by the target tissue; Ex: Thyroid hormones promote synthesis of receptors for epinephrine in the heart
2) Synergistic interactions: When two or more synergistic hormones exert their effects on a target tissue, the overall response is even larger than with either hormone alone; Ex: In reproductive system, reproductive steroid hormones synergize with hypothalamic hormones to promote the synthesis of gonad regulating tropic hormones
3) Antagonistic interactions: Certain hormones work in opposition to each other to very tightly regulate a specific parameter; Ex: PTH and calcitonin with blood Ca2+ levels, and insulin and glucagon with blood glucose levels
Structure that integrate nervous system and endocrine system
Pituitary gland: Connected to base of brain, just inferior to hypothalamus. A stalk of tissue called infundibulum connects pituitary gland to hypothalamus. Pituitary gland rests in sella turcica of sphenoid bone and is 1cm in diameter and weigh 0.5-1.0g
Posterior pituitary: Neurohypophysis because continuous with hypothalamus in brain. Part of nervous system, so its hormones are called neuropeptides or neurohormones
Anterior pituitary: Adenohypophysis because derived from glandular epithelium. Includes thin band of tissue called pars intermedia at its border with posterior pituitary; Derived from epithelial tissue, not from neural tissue, so hormones secreted are traditional hormones
Relationship of pituitary gland and hypothalamus
Hypothalamus regulates anterior pituitary through specialized set of blood vessels, called a portal system. Portal system consists of two capillary networks directly connected by portal system vessels. Portal system that connects hypothalamus to anterior pituitary is called hypothalamohypophysial portal system. One of major portal systems in body; In contrast, hypothalamus regulates posterior pituitary through specialized neural pathway called hypothalamohypophysial tract
Hypothalamic control of anterior pituitary
1) Neurons of hypothalamus produce neuropeptides and secrete them into a capillary
bed in the hypothalamus. Stimuli within the nervous system regulate the secretion of
releasing hormones and inhibiting hormones from neurons of the hypothalamus
2) Releasing hormones and inhibiting hormones pass through the hypothalamohypophysial
portal system to the anterior pituitary
3) Once neuropeptides arrive at anterior pituitary gland, they leave the blood and bind to membrane-bound receptors involved with regulating anterior pituitary hormone secretion
4) In response to releasing hormones, anterior pituitary hormones travel in blood to target tissue, which in some cases, are other endocrine glands
Hormones of pituitary gland
1) Antidiuretic hormone (ADH): Smell peptide; Targets kidneys; Increases water reabsorption (less water is lost in the form of urine)
2) Oxytocin: Small peptide; Targets uterus and mammary glands; Increases uterine contractions during birth; increases milk expulsion from mammary glands; unclear function in males
Hormones of anterior pituitary
1) Growth hormone (GH): Protein; Targets most tissues; Increases growth in tissues; increases acid uptake and protein synthesis; increases breakdown of lipids and release of fatty acids from cells; increases glycogen synthesis and increases blood glucose levels; increases IGF production; Increases in stressed adults and decreases in stressed children
2) Thyroid-stimulating hormone (TSH): Glycoprotein; Targets the thyroid gland; increases thyroid hormone secretion
3) Adrenocorticotropic hormone (ACTH): Peptide; Targets adrenal cortex; increases glucocorticoid hormone secretion
4) Lipotropins: Peptide; Targets adipose tissues; increases lipid breakdown
5) Beta endorphins: Peptides; Targets brain, but not all target tissues are known; Analgesia in the brain; Inhibition of gonadotropin-releasing hormone secretion
6) Melanocyte-stimulating hormone (MSH): Peptide; Targets melanocytes in skin; increases melanin production in melanocytes to make skin darker in color; memory functions in CNS
7) Luteinizing hormone (LH): Glycoprotein; Targets ovaries in females and testes in males; ovulation and progesterone production in ovaries; testosterone synthesis and support for sperm cell production in testes
8) Follicle-stimulating hormone (FSH): Glycoprotein; Targets follicles in ovaries in females and seminiferous tubules in males; Follicle maturation and estrogen secretion in ovaries; Sperm cell production in testes
9) Prolactin: Protein; Targets ovaries and mammary glands in females; Milk production in lactating females; increases response of follicle to LH and FSH; unclear reproductive function in males
Antidiuretic hormone (ADH)
A water conservation hormone secreted by posterior pituitary. ADH prevents the output of large amounts of urine. Alternate name is vasopressin because it also constricts blood vessels and raises blood pressure when large amounts are released. ADH molecules are synthesized predominantly by neurosecretory neuron cell bodies in supraoptic nuclei of hypothalamus. ADH is then transported to posterior pituitary for storage
Oxytocin
Stimulates labor in pregnant animals. Stimulates smooth muscle contraction in uterus. Causes contraction of uterine smooth muscle in nonpregnant females, primarily during mensuration and sexual intercourse. Uterine contractions help rid uterus of its lining along with small amounts of blood during menstruation. Oxytocin also facilitates movement of sperm cells through uterus after sexual intercourse. Oxytocin is responsible for milk letdown in breastfeeding females. It promotes contraction of smooth muscle-like cells surrounding milk ducts in mammary glands. Oxytocin is associated with maternal nurturing and bonding. Oxytocin is transported to posterior pituitary for storage after being synthesized by hypothalamus
Growth hormone (GH)
Protein hormone that stimulates growth in most tissues and plays an important role in determining how tall a person becomes. It regulates metabolism. GH plays role in regulating blood nutrient levels after eating. GH increases movement of amino acids into cells, favors their incorporation into proteins, and slows protein breakdown. GH increases lipolysis and release of fatty acids from adipocytes into blood. Fatty acids then can be used as energy sources to drive chemical reactions by other cells. GH increases glucose synthesis by the liver, which releases glucose into blood. Increased use of lipids as an energy source accompanies a decrease in glucose usage. GH activates the use of lipids to promote growth and protein synthesis
GH binds directly to membrane-bound receptors on target cells to produce responses. These response are called the direct effects of GH and include the increased breakdown of lipids and the decreased use of glucose as an energy source
GH also has indirect effects on some tissues. It increases the production of a number of polypeptides, primarily by the liver but also the muscle and other tissues. These polypeptides are called insulin-like growth factors (IGFs). Named because of their structural resemblance to insulin and because receptor molecules function through a mechanism similar to that of insulin resceptors
Growth hormone and growth disorders
Two possible disruptions in GH secretion:
1) Hyposecretion of GH leading to reduced growth; Chronic hyposecretion of GH in infants and children leads to pituitary dwarfism. Insufficient amounts of GH delay bone growth, resulting in short stature. Bones usually have normal shape and people exhibit normal intelligence, in contrast to those who have reduced growth caused by hyposecretion of thyroid hormones; Other symptoms from lack of GH include mild obesity and delayed development of adult reproductive functions
2) Hypersecretion of GH leading to excessive growth
Prolactin
A protein hormone that plays an important role in milk production by mammary glands of lactating females. Binds to membrane-bound receptor, which is linked to a kinase that phosphorylates intracellular proteins. Phosphorylated proteins produce the response in the cell. PRL can also enhance progesterone secretion by ovaries after ovulation
Thyroid-stimulating hormone (TSH)
AKA thyrotropin. A glycoprotein hormone that stimulates the synthesis and secretion of thyroid hormones from thyroid gland. TSH is glycoprotein dimer consisting of two subunits, alpha and beta, that bind to membrane-bound receptors of thyroid gland. Alpha subunit is common among glycoprotein hormones, but the beta subunit is what dictates the specificity of each of the glycoprotein hormones. TSH receptors respond through a G protein mechanism that increases intracellular cAMP levels. cAMP then initiates a series of actions in the target tissue
Adrenocorticotropic hormone (ACTH) and related substances
A peptide hormone from anterior pituitary that stimulates secretion of cortisol from adrenal cortex. ACTH is one of four smaller molecules derived from a large precursor protein called proopiomelanocortin. POMC is synthesized in the anterior pituitary and is broken down into multiple, smaller peptides. Many of these peptides are also hormones, like ACTH.
Environmental stress is a key stimulus for ACTH secretion. Once ACTH arrives at its target tissues, it activates a G protein-mediated cAMP mechanism. Primary action of ACTH is release of the principal hormone that regulates chronic stress. This hormone is cortisol from the adrenal cortex. In pathological conditions such as Addison disease, the adrenal cortex degenerates, usually due to an autoimmune condition. Blood levels of ACTH and related hormones are chronically elevated, and the skin becomes markedly darker. This is because ACTH and melanocyte-stimulating hormone bind to melanocytes in skin and increase skin pigmentation
Melanocyte-stimulating hormone (MSH)
Binds to membrane-bound receptor on skin melanocytes and stimulates increased melanin deposition in skin. Regulation of MSH secretion and its function in humans is not well understood, but studies show its important in regulating appetite and sexual behavior
Luteinizing hormone (LH) and follicle-stimulating hormone (FSH)
Gonadotropins are glycoprotein hormones capable of promoting the growth and function of gonads, the ovaries and testes. Two major gonadotropins secreted by anterior pituitary are LH and FSH. Both play important role in regulating reproduction
Thyroid gland
Synthesizes and secretes three hormones
1) Triiodothyronine
2) Tetraiodothyronine
3) Calcitonin
Composed of two lobes connected by narrow band of thyroid tissue called isthmus. Lobes are lateral to upper portion of trachea just inferior to larynx, and the isthmus extends across anterior aspect of trachea. Thyroid gland is one of largest endocrine glands and it is highly vascular, so its a darker red than surrounding tissues
Thyroid gland contains numerous follicles, which are small spheres whose walls are composed of a single layer of cuboidal epithelial cells. center of each thyroid follicle is filled with a gelatinous material called colloid. Colloid is composed of a high concentration of a protein called thyroglobulin
Thyroid hormones
1) Triiodothyronine: T3; Secreted from thyroid follicles
2) Tetraiodothyronine: Thyroxine or T4; Secreted from thyroid follicles; Precursor for T3 and accounts for 80% of secretions from thyroid gland
2.5) Both: Amino acid derivative; Targets most cells of the body; Increases metabolic rate; increases protein synthesis; essential for normal growth and maturation
3) Calcitonin: constitutes about 10% of secretions from thyroid gland; Peptide; Targets bone; Decreased rate of breakdown of bone by osteoclasts; prevention of a large increase in blood Ca2+ levels (lowers calcium levels)
Parathyroid gland hormones
Parathyroid hormone (PTH): Peptide; Targets bone, kidneys, small intestine; Increased rate of breakdown of bone by osteoclasts; increased reabsorption of Ca2+ in kidneys; Increased reabsorption of Ca2+ from small intestine; increased vitamin D3 synthesis; Increases blood Ca2+ levels
T3 and T4 synthesis
Iodide ions are taken up by thyroid follicle cells via secondary active transport by a sodium iodide symporter (NIS). The active transport of the I- is against the concentration gradient of approximately 30-fold in healthy individuals
Effects of T3 and T4
Affect nearly every tissue in the body. Two broad classes of thyroid hormone function:
1) Increases in the basal metabolic rate: Normal rate of metabolism for an individual depends on an adequate supply of thyroid hormone, which increases the rate at which glucose, lipids, and proteins are metabolized. Metabolic rate can increase 60-100% when blood T3 and T4 are elevated, whereas low levels of T3 and T4 have opposite effect. Normal body temperature is partly due to adequate thyroid hormones. Thyroid hormones increase activity of Na+-K+ pumps. Also alters number and activity of mitochondria leading to greater ATP synthesis
Regulation of thyroid hormone secretion
Thyrotropin-releasing hormone (TRH) from hypothalamus and TSH from anterior pituitary function together to increase T3 and T4 secretion from thyroid gland. Stress and exposure to cold cause increased TRH secretion, and prolonged fasting decreases TRH secretion
Calcitonin
Parafollicular cells, or C cells, secrete the hormone calcitonin in response to increased calcium levels in the blood. These cells are dispersed between thyroid follicles throughout thyroid gland. Primary target is bone. calcitonin binds to membrane-bound receptors, decreases osteoclast activity, and lengthens life span of osteoblasts. resulting bond deposition leads to decreases in blood calcium and phosphate levels.
3 important functions:
1) Protection of young children and infants against hypercalcemia after a meal
2) Stimulation of Ca2+ and PO4- secretion in the kidney (removes from body)
3) Inhibition of actions of PTH that dissolve bone to release Ca2+ and PO4-
Blood levels of calcitonin decrease with age to a greater extent in females than in males leading to osteoporosis
Parathyroid glands
Usually embedded in posterior part of each lobe of thyroid gland and are made of two cell types: chief cells and oxyphils
Adrenal glands
Also known as suprarenal glands. Near superior poles of kidneys. Lie below peritoneum and are surrounded by abundant adipose tissue. Enclosed by connective tissue capsule and have a well-developed blood supply
Hormones of adrenal medulla
Modified sympathetic nervous system ganglion. Secretes two major hormones: Epinephrine (adrenaline), which accounts for 80% of adrenal medulla hormones, and norepinephrine. Norepinephrine is a precursor to formation of epinephrine; Amino acid derivatives; Targets heart, blood vessels, liver, adipose cells; Increased cardiac output; increased blood flow to skeletal muscles and to heart; vasoconstriction of blood vessels; increased release of glucose and fatty acids into blood; preparation for physical activity
Adrenal cortex
All adrenal cortex hormones have a similar structure because they’re steroids. Lipid-soluble, so they are not stored in adrenal gland cells but diffuse from cells as they are synthesized. Adrenal cortical hormones are transported in blood bound to specific plasma proteins; they are metabolized in liver and excreted in bile and urine. Hormones of adrenal cortex bind to nuclear receptor and stimulate synthesis of specific proteins responsible for producing target cells responses. Adrenal cortex is organized into three distinct layers, each of which produces a different type of steroid hormone
Hormones of adrenal cortex
Adrenal cortex is organized into three distinct layers, each of which produces a different type of steroid hormone:
1) Mineralocorticoids (aldosterone): Steroid: Targets kidney: Increased Na+ reabsorption and K+ and H+ excretion; enhanced water reabsorption; Regulates ion balance in blood. Major secretory products of zona glomerulosa of adrenal cortex. Aldosterone is produced in greatest amounts. Aldosterone is secreted under low blood pressure conditions. It returns blood pressure to normal range through modulation of kidney function. Reabsorption of water increases blood volume, which increases blood pressure
2) Glucocorticoids (cortisol): Steroids; Targets most tissues; Increased protein and lipid breakdown; increased glucose production; inhibition of immune response and decreased inflammation; Help provide energy for cells by stimulating increased use of lipids and proteins. Zona fasciculata of adrenal cortex that secretes glucocorticoid hormones
3) Androgens: Steroids; Targets most tissues; Of minor importance in males; in females, development of some secondary sex characteristics, such as axillary and pubic hair
Pancreas
Both endocrine and exocrine gland. Exocrine portion consists of acini, which produce pancreatic juice, and a duct system, which carries the pancreatic juice to the small intestine. Endocrine part, consisting of pancreatic islets of Langerhans, secretes hormones that enter plasma of blood. Pancreas lies behind the peritoneum between the greater curvature of the stomach and the duodenum
Satiety center
Collection of neurons in hypothalamus that controls appetite
Insulin
Primary function is to lower blood glucose levels by stimulating glucose transport into body cells. Insulin is secreted when blood glucose is elevated, such as after a meal. Insulin binds to membrane-bound receptors on target cells. Once insulin binds to its receptor, the receptor causes specific proteins in the membrane to become phosphorylated. Part of the cells’ response to insulinis to increase the number of transport proteins in the plasma membrane for glucose and amino acids. Finally, insulin and its receptor enter the cell by endocytosis. The insulin is released from the insulin receptor and broken down within the cell, and the insulin receptor returns to the plasma membrane
In general, the target tissue responds to insulin by increasing its ability to take up and use glucose and amino acids, Glucose molecules that are not needed immediately as an energy source to maintain cell metabolism are stored as glycogen in skeletal muscle, the liver, and other tissues and are converted to lipids in adipose tissue. Amino acids can be broke down and used as an energy source, or they can be converted to protein. Without insulin, the ability of these tissues to take up and use glucose and amino acids is minimal
Factors that increase insulins secretion
1) Hyperglycemia, or elevated blood levels of glucose, directly stimulates insulin secretion from pancreatic beta cells
2) Certain amino acids also stimulate insulin secretion by acting directly on pancreatic beta cells
3) Parasympathetic stimulation associated with food intake acts with elevated blood glucose levels to increase insulin secretion
4) Gastrointestinal hormones involved with regulating digestion, such as gastrin, secretin, and cholecystokinin, increase insulin secretion
Hormones that regulate blood nutrient levels
After a meal and under resting conditions, secretion of glucagon, cortisol, GH, and epinephrine is reduced. Both increasing blood glucose levels and parasympathetic stimulation elevate insulin secretion to increase the uptake of glucose, amino acids, and lipids by target tissues. Substances not immediately used for cell metabolism are stored. Glucose is converted to glycogen in skeletal muscle and the liver, and it is used for lipid synthesis in adipose tissue and the liver. The rapid uptake and storage of glucose prevent too large an increase in blood glucose levels. Amino acids are incorporated into proteins, and lipids that were ingested as part of the meal are stored in adipose tissue and the liver. If the meal is high in protein, a small amount of glucagon is secreted, thereby increasing the rate at which the liver uses amino acids to form glucose
Hormones of reproductive system
Reproductive hormones are secreted primarily from the ovaries, testes, placenta, and pituitary gland. The main endocrine glands of the male reproductive system are the testes. The functions of of the tests depend on the secretion of FSH and LH from the anterior pituitary gland. The main hormone secreted by the testes is testosterone, an androgen. Testosterone regulates the production of sperm cells by the testes and the development and maintenance of male reproductive organs and secondary sex characteristics. The testes secrete another hormone, called inhibin, which inhibits the secretion of FSH from the anterior pituitary gland
Testes hormones
1) Testosterone: Steroid; Targets most cells; Aids in spermatogenesis, development of genitalia, maintenance of functional reproductive organs, secondary sex characteristics, and sexual behavior
2) Inhibin: Polypeptide; Targets anterior pituitary gland; Inhibits FSH secretion
Ovaries hormones
1) Estrogen: Steroid; Targets most cells; Aids in uterine and mammary gland development and function, maturation of genitalia, secondary sex characteristics, sexual behavior, and menstrual cycle
2) Progesterone: Steroid; Targets most cells; Aids in uterine an mammary gland development and function, maturation of genitalia, secondary sex characteristics, and menstrual cycle
3) Inhibin: Polypeptide; Targets anterior pituitary gland; Inhibits FSH secretion
4) Relaxin: Polypeptide; Targets connective tissue cells; Increases the flexibility of connective tissue in the pelvic area, especially the symphysis pubis
Pineal gland
Located in epithalamus of the brain and secretes hormones that act on the hypothalamus and the gonads to inhibit reproductive functions, such as inhibiting the secretion of certain reproductive hormones; Sleep-wake cycles
Pineal gland hormones
1) Melatonin: Amino acid derivative; Targets at least the hypothalamus; Inhibition of gonadotropin-releasing hormone secretion, thereby inhibiting reproduction; May help regulate sleep-wake cycles
2) Arginine vasotocin: Peptide; Targets possible the hypothalamus; Possible inhibition of gonadotropin-releasing hormone secretion
Thymus
Important for immune system. Located in the neck and is superior to the heart in the thorax. Secretes thymosin
Graves disease
Caused by altered regulation of hormone secretion. Specifically, the elevated secretion of thyroid hormones from the thyroid gland. Size of thyroid gland expands, called a goiter. Connective tissue components are deposited behind the eyes, causing them to bulge. Treatment is radioactive iodine atoms that destroyed a substantial portion of thyroid gland
Addison disease
Low levels of aldosterone and cortisol from adrenal cortex; low blood Na+ levels, low blood pressure, and excessive urination
Gestational diabetes
Develops in pregnant females due to actions of placental hormone, human placental lactogen (HPL); in some females, HPL overly desensitizes the female’s insulin receptors; causes elevated blood glucose levels in the mother and, if left untreated, excessive fetal growth
Diabetes insipidus
Due to lack of ADH from posterior pituitary; results in excessive urination
Hashimoto thyroiditis
Autoimmune disease in which thyroid hormone can be decreased; metabolic rate is decreased, weight gain is possible, and activity levels are depressed
Functions of blood
1) Transport of gases, nutrients, and waste products: O2 enters blood in lungs and carried to cells. CO2 produced by cells and is carried in blood to lungs where its exhaled. Blood transports ingested nutrients, ions, and water from the digestive tract to the cells, and the blood transports the cells’ waste products to the kidneys for elimination
2) Transport of processed molecules: Many substances are produced in one part of body and transported in blood to another part, where they are modified; Ex: Precursor to vitamin D is produced in skin and transported by blood to liver and then to kidneys and turn into active vitamin D3. Active D3 transported to small intestine, where it promotes uptake of calcium
3) Transport of regulatory molecules: Includes chemical messengers, such as hormones, that regulate activities of many physiological processes. Includes enzymes that are important to normal metabolism
4) Regulation of pH and osmosis: Buffers, which keep blood pH within normal 7.35-7.45, are in blood. Osmotic composition maintains normal fluid and ion balance throughout body
5) Maintenance of body temperature: Movement of warm blood from interior of body to surface releases heat
6) Protection against foreign substances: Cells and chemicals in blood make up part of immune system
7) Clot formation: Blood clotting prevents excessive blood loss when blood vessels are damaged
Composition of blood
Blood is a type of connective tissue consisting of liquid matrix containing cells and cell fragments. Plasma is liquid matrix, and formed elements are cells and cell fragments. Plasma makes up 55% total blood volume. Total blood volume in average adult female is 4-5L, whereas in a male its 5-6L. Blood makes up 8% of total weight of body
Plasma
Liquid matrix of blood. A pale yellow fluid that consists of about 91% water and 9% other substances, such as proteins, ions, nutrients, gases, waste products, and regulatory substances. Plasma is a colloid, which is a liquid containing suspended substances that do not settle out of solution. Plasma proteins can be classified into three groups: albumins, globulins, and fibrinogen
Formed elements
Consists of cells and cell fragments. Cells include red blood cells and white blood cells. Cell fragments are called platelets
Hematopoiesis
Process of blood cell production. In embryo and fetus, hematopoiesis occurs in many different tissues such as the yolk sac of the embryo, liver, thymus, spleen, lymph nodes, and red bone arrow. After birth, hematopoiesis is confined primarily to red bone marrow
Red blood cells
Most abundant; Lack nuclei; 700 times more numerous than white blood cells and 17 times more numerous than platelets in the blood. Males have 4.7-6.1 million red blood cells per microliter, whereas females have about 4.2-5.4 million per microliter
Structure of red blood cells
Discs about 7.5um in diameter, and they are biconcave, meaning their edges are thicker than their center. Red blood cell structure enhances its function. Biconcave shape increases cell’s surface area, thereby allowing gases to move into and out of red blood cell more rapidly. A red blood cells move through capillaries, they change shape. Because of biconcave shape, red blood cell can fold or bend around its thin center, thereby decreasing its size and enabling it to pass more easily through smaller blood vessels. Red blood cells cannot move on their own; they are passively moved by forced that cause blood to circulate
Red blood cells are derived from specialized cells that lose their nuclei and nearly all their cellular organelles during maturation
Components of red blood cells
Main component of red blood cell is pigmented protein hemoglobin. Hemoglobin occupies about 1/3 of total volume of a red blood cell and accounts for its red color. Other blood cell contents include lipids, adenosine triphosphate (ATP), and the enzyme carbonic anhydrase; Lacks nuclei
Function of red blood cells
Primary function is to transport O2 from lungs to various body tissues and to transport CO2 from tissues to lungs. Approximately 98.5% of O2 in blood is transported in combination with hemoglobin in red blood cells. Remaining 1.5% is dissolved in plasma
Hemoglobin
Complex protein consisting of four subunits. Each subunit is composed of one polypeptide chain called globin that is bound to one heme group. Each heme is a red-pigment molecule containing one iron atom. There are three forms of hemoglobin:
1) Embryonic: First type of hemoglobin to be produced during development. Replaced with fetal by third month of development
2) Fetal: At 2 to 4 years of age, fetal hemoglobin makes up less than 2% of hemoglobin, and in adulthood only traces of fetal hemoglobin can be found; Two alpha globins (one of each type) and two gamma globins (one of each type)
3) Adult: At birth 60-90% of hemoglobin is adult hemoglobin; Two alpha globins (one of each type) and two beta globins (one of each type)
Hemoglobin affinities
Different forms of hemoglobin have different affinities of, or abilities to bind to, O2. Embryonic and fetal hemoglobin have a higher affinity for O2 than adult hemoglobin does. In embryo and fetus, hemoglobin picks up O2 from the mothers blood at the placenta. Even though placental blood contains less O2 than does air in mothers lungs, adequate amounts of O2 are picked up because of the higher affinity of embryonic and fetal hemoglobin for O2. After birth, hemoglobin picks up O2 from the air in the baby’s lungs
O2 and hemoglobin
Oxygen bind to heme group. Each oxygen molecule that is transported by the hemoglobin is associated with iron center of heme group; therefore, iron is necessary for normal hemoglobin function. 2/3 of iron found in body is associated with hemoglobin. When hemoglobin exposed to O2, one oxygen molecule can become associated with each heme group. One hemoglobin molecule can carry up to four O2 molecules. Oxygenated form of hemoglobin is called oxyhemoglobin. A single red blood cell contains about 280 million hemoglobin molecules, each of which carries up to four O2 molecules. Hemoglobin not bound to O2 is called deoxyhemoglobin. Oxyhemoglobin is brighter red than deoxyhemoglobin.
CO2 and hemoglobin
Hemoglobin also transports CO2, however, CO2 doesn’t combine with iron atoms as O2 does. Instead, CO2 attaches to globin molecule. This hemoglobin form is called carbaminohemoglobin
NO and hemoglobin
Hemoglobin transports nitric oxide. As hemoglobin picks up O2 in lungs, cysteine in each beta-globin binds with NO molecule to form SNO When O2 is released in tissues, so is NO, where it functions as chemical messenger that induces relaxation of smooth muscle of blood vessels
CO and hemoglobin
Carbon monoxide binds strongly to iron of hemoglobin to form the relatively stable compound carboxyhemoglobin. As a result of the stable binding of CO, hemoglobin cannot transport O2
Life history of red blood cells
Process by which new red blood cells are produced is called erythropoiesis. Time required to produce a single red blood cell is about 4 days.
Hemocytoblast -> myeloid stem cells -> proerythroblast -> early erythroblast (basophilic erythroblasts) -> intermediate erythroblasts (polychromatic erythroblasts) produce hemoglobin and most of their ribosomes and organelles degenerate -> late erythroblasts lose nuclei to become immature red blood cells -> reticulocytes ribosomes degenerate -> mature red blood cells
Hemolysis
Occurs when red blood cells rupture and hemoglobin is released into plasma. Hemoglobin is released into plasma will denature as molecules change shape in a new environment
Types of white blood cells
1) Granulocytes: White blood cells with large cytoplasmic granules and lobed nuclei. Granules stain with dyes that main cells more visible when seen through a light microscope. There are three types:
a) Neutrophils: Stain with acidic and basic dyes
b) Eosinophils: Stain red with acidic dyes
c) Basophils: Stain dark purple with basic dyes
2) Agranulocytes are white blood cells that seem to have no granules when viewed with a light microscope. They have granules, but they’re too small to be seen. Both have nuclei that are not lobed. There are two types:
a) Lymphocytes
b) Monocytes
Pus
Accumulation of dead white blood cells and bacteria, along with fluid and cell debris
Neutrophils
Compose 55-70% of white blood cells. Have small cytoplasmic granules that stain with both acidic and basic dyes. Nuclei is lobed, with number varying from two to five. Often called polymorphonuclear neutrophils or PMNs to indicate their nuclei can occur in more than one form. The first of white blood cells to respond to infection. Normally remain in blood for about 10-12 hours and then move into other tissues. Once leave blood, they seek out and phagocytize bacteria, antigen-antibody complexes, and other foreign matter. They secrete a class of enzymes called lysozymes, which are capable of destroying certain bacteria. usually survive 1-2 days after leaving blood
Eosinophils
Compose of 1-4% of white blood cells. Contain cytoplasmic granules that stain bright red with eosin, an acidic stain. Often have two-lobed nucleus. Important in defense against certain worm parasites. Although not able to phagocytize large parasites, they attach to the worms and release substances that kill parasites. Increase in number in tissues experiencing inflammation. Modulate inflammatory response by producing enzymes that destroy inflammatory chemicals, such as histamine
Lymphocytes
Compose 20-40% of white blood cells. Play important roles in immunity; Ex: B cells divide and form cells that produce antibodies, aka immunoglobulins. T cells protect against viruses and other intracellular microorganisms by attacking and destroying cells they’re found in
Monocytes
Compose 2-8% of white blood cells. Largest of white blood cells. Remain in blood for 3 days. Leave blood and transformed into macrophages. Macrophages migrate through tissues and phagocytize bacteria, dead cells, cell fragments, and other degree. Stimulate responses from other cells in 2 ways:
1) By releasing chemical messengers
2) By phagocytizing and processing foreign substances, which are then presented to lymphocytes
Platelets
Minute fragments of cells. Consist of small amount of cytoplasm surrounded by plasma membrane. Glycoproteins and proteins on surface allow platelets to attach to other molecules. Some surface molecules help control blood loss. Platelet cytoplasm contains actin and myosin. Life expectancy is 5-9 days. Derived from megakaryocytes, which are extremely large blood cells found in bone marrow. Small fragments of these cells break off and entre blood as platelets.
Prevent blood loss by forming platelet plugs that seal holes in small vessels and promote formation and contraction of clots that seal off larger wounds in vessels
Hemostasis
Cessation of bleeding. If not stopped, excessive bleeding from a cut or torn blood vessel can result in positive-feedback cycle, consisting of ever-decreasing blood volume and blood pressure that disrupts homeostasis and results in death
Vascular spasm
Immediate but temporary constriction of blood vessel. Occurs when smooth muscle within wall of vessel contracts. This closes small vessels completely and stops blood flow through them. Damage to blood vessels can activate nervous system reflexes to cause this. Chemicals released by cells of damaged vessel as well as platelets can also stimulate vascular spasm
Platelet plug formation
Accumulation of platelets that can seal breaks in blood vessels. Not same as blood clot, but its important in maintaining integrity of circulatory system. Small tears occur in smaller vessels and capillaries many times a day, and platelet plug formation closes them. During formation of platelet plug, platelets release thromboxanes, which lead to constriction of blood vessels
Clotting factors
Blood clot formation depends on clotting factors, or coagulation factors, which are proteins found within plasma. Normally, clotting factors are in an inactive state and do not cause clotting. After injury, clotting factors are activated. Activation is a complex process that involves many chemical reations
Control of clot formation
To prevent unwanted clotting, blood contains several anticoagulants to prevent clotting factors from initiating clot formation under normal concentrations in blood. At site of injury, so many clotting factors are activated that anticoagulants are unable to prevent clog formation. Away from injury site, activated clotting factors are diluted in blood, anticoagulants neutralize them, and clotting is prevented
Clot retraction and dissolution
Blood clot dissolved within few days after clot formation. Process that dissolves blood clot is called fibrinolysis. During this process, an enzyme called plasmin hydrolyzes, or breaks, fibrin, thereby dissolving clot
Transfusion vs infusion
Used if large quantities of blood are lost, due to the patient’s likelihood of going into shock and dying unless red blood cells are replaced to restore blood’s oxygen-carrying capacity
Transfusion: Transfer of blood or blood components from one individual to another
Infusion: Introduction of a fluid other than blood, such as a saline or glucose solution, into the blood
ABO blood group
ABO blood group system is used to categorize human blood based on presence or absence of A and B antigens on surface of red blood cell.
Type A: Has type A antigens
Type B: Has type B antigens
Type AB: Has both A and B antigens
Type O has neither A or B antigens on surface of red blood cells
Rh blood group
Antigen involved is D antigen. Rh-positive if have D antigen on surface of red blood cells, and Rh-negative if not. About 85% of white people and 88% of black people are Rh-positive. Usually expressed together with ABO blood type as the positive or negative after the blood type
Blood typing
Used to prevent transfusion reactions. Determines the ABO and Rh blood groups of blood sample. Usually, cells are separated from serum and tested with known antibodies to determine type of antigen on cell surface; Ex: Patients blood cells agglutinate when mixed with anti-A antibodies but don’t with anti-B antibodies, the cells have type A antigen
Complete blood count (CBC)
Analysis of blood. Consists of a red blood count, hemoglobin and hematocrit measurements, a white blood count, and a differential white blood count
Red blood count
Number (expressed in millions) of red blood cells per microliter of blood. Erythrocytosis is an overabundance of red blood cells
Hematocrit measurement
Percentage of total blood volume that is composed of red blood cells. Determined by placing blood in tube and spinning it in centrifuge. Formed elements are forced to one end of tube
White blood count
Measures total number of white blood cells in blood. Leukopenia is lower than normal WBC resulting from depression or destruction of red marrow. Viral infections, radiation, drugs, tumors, and vitamin deficiencies can cause this. Leukocytosis is abnormally high WBC. Leukemia, a cancer of red marrow, often results in leukocytosis, but white blood cells have abnormal structure and function
Platelet count
Normal is 150000-400000 platelets per microliter of blood. Thrombocytopenia, platelet count is reduced, resulting in chronic bleeding through small vessels and capillaries. Caused by decreased platelet production as result of hereditary disorders, lack of vitamin B12, drug therapy, or radiation therapy
Blood chemistry
Composition of materials dissolved or suspended in plasma can be used to assess functioning of body systems; Ex: High blood glucose levels can indicate pancreas isn’t producing enough insulin; high blood urea nitrogen (BUN) can be a sign of reduced kidney function; increased bilirubin can indicate liver dysfunction or hemolysis; and high cholesterol levels can signify an increased risk for cardiovascular disease
Rheumatoid arthritis
Chronic autoimmune disease that primarily affects joints, causing pain, swelling, stiffness, and decreased function
Congenial adrenal hyperplasia
Missing 1 or more enzymes needed for cortisol synthesis. Cannot complete cortisol synthesis process; too many precursors. Adrenal cortex gets larger; Hyperplasia. Decreased cortisol leads to increased ACTH which stimulates growth of adrenal cortex. results in accumulation of cortisol precursors which can be converted to testosterone
Diabetes Mellitus
Insulin imbalance. 3 symptoms:
1) Polyuria: Increased urine
2) Polydipsia: Increased thirst
3) Polyphagia: Increased hunger
Type I Diabetes
No insulin production; not early onset, but usually found in children. If not treated, body will think its starving because it has no energy, leading to increased stress hormones. Stress hormones increasingly tries to put glucose in body leading to sugar shock
Type II Diabetes
Insufficient insulin and/or receptors
Hypoglycemia
Low blood glucose. Hyper insulinism. Results in tremors and weakness
Seasonal affective disorder
Increase melatonin output; occurs when daylight cycle is too short. Depressed during the winter. treatment is full-spectrum phototherapy
Aging effects of hormones
Ovaries: Significantly less produced during menopause
Testosterone: Less as aging but very gradual
Growth hormone: Less as aging; Decreased muscle mass and higher likelihood to fall if not working muscles
Thyroid hormone: Less as aging; Metabolic rate and caloric need decreases leading to increased weight gain
Parathyroid hormone: May stay steady or increases as aging; Takes increased amount of Ca2+ from bone; Osteoporosis in especially women 65+
Adrenals: More fibrous with age
Insulin: Decreases with age, receptor sensitivity decreases as age; no way to decrease glucose in blood, so elderly stays more hyper than younger person (sugar rush)
Anemia
Low oxygen carrying capability in blood
Hemorrhagic: Lack of ability to clot
Hemolytic: Blood cells destroyed faster than it can be replaced
Aplastic: Body stops producing new blood cells; bone marrow damage
Iron deficiency: Not enough healthy RBCs to carry O2; treatment: eat iron rich food
Pernicious: Decrease in RBCs because body cant absorb B-12; cannot eat iron rich foods; B-12 must be injected
Sickle cell: RBCs break down and die early leaving shortage of healthy RBCs; not flexible and cannot fit through capillaries or blood vessels
Thalassemia
Less O2 carrying protein (hemoglobin) and fewer red blood cells than normal
Polycythemia
Make blood thick so it cannot move throughout body; Increase in red blood cells; Doping in athletes
