Exam One Flashcards
What does the endocrine system use to regulate the body?
Chemicals (hormones)
What are the basic functions of the endocrine system?
Maintaining homeostasis
Responds to stress
Growth and development
Sexual reproduction
How does the nervous system regulate the body?
Electrical impulses
What are endocrine glands?
Glands that secrete only hormones
Release hormones directly into the bloodstream
What are exocrine glands?
Glands that secrete sweat and oils
Produce secretions into a duct or outside the body
What are neurocrine glands?
Nervous tissues that produce a hormone
Hypothalamus
What are autocrines?
Hormones released locally into interstitial fluid and affect same type of cell they were released from
What are paracrines?
Hormones released locally and affects neighboring cells of different type
What are the true endocrine glands?
Pineal Anterior pituitary Thyroid Parathyroid Adrenal
What are the multiple function endocrine glands?
Hypothalamus Posterior pituitary Thymus Pancreas Ovaries Testes
What are the four classes of hormones?
Steroids
Proteins
Amino acids
Prostonoids
What is the process that must occur for steroids to be transported?
Bind to carrier protein
Pass through plasma membrane of cell
Bind to receptor inside the cell
Causes direct interaction on the cell
What are the four ways that steroids can be transported?
Cortisol - Cortisol Binding Globulin - Strong affinity
Testosterone/Estrodiol - TEBG - Strong affinity
Albumin - can bind to testosterone and estrodiol with weak affinity
Free hormone - circulates through blood alone
What are biologically active hormones?
Hormones that are able to be used right now
Free hormone and albumin
What are biologically inactive hormones?
Hormones that are unable to be used right now
TEBG and CBG
What is the mechanism of action for steroids?
- Steroid hormone diffuses through the plasma membrane and binds to an intracellular receptor
- Receptor-hormone complex enters the nucleus
- Receptor-hormone complex binds a specific DNA region
- Binding initiates transcription of the gene to mRNA
- The mRNA directs protein synthesis
What is the mechanism of action for amino acids?
- Hormone (first messenger) binds to receptor
- Receptor activates G protein
- G protein activates adenylate cyclase
- Adenylate cyclase converts ATP to cAMP (2nd messenger)
- cAMP activates protein kinases
How are hormones removed from blood?
Degrading enzymes
kidneys
liver
What is basal secretion?
General day to day hormone secretion
What is stimulatory secretion?
Secretion requires a stimulus
What is pulsatile stimulation?
Basal secretion when there are peaks throughout the day
What are the three types of endocrine gland stimulation?
Humoral
Neural
Hormonal
What is humoral stimulation?
Changing blood levels of ions and nutrients directly stimulate secretion
Calcium levels and parathyroid
What is neural stimulation?
Nerve fibers stimulate hormone release
What is hormonal stimulation?
Hormones stimulate other endocrine glands to release their hormones
What does target cell activation depend on?
Blood levels of hormone
Relative number of receptors on or in the cell
Affinity of binding between receptor and hormone
What is up-regulation?
Receptors become more sensitive due to low hormone levels
What is down regulation?
Receptors become less sensitive due to high hormone levels
What is permissiveness?
One hormone can not exert its effects without another hormone being present
What is synergism?
More than one hormone produces same effects on target cell
Amplification
What is antagonism?
One or more hormone oppose the action of another hormone
What is the difference between the anterior and posterior pituitary?
Anterior is true endocrine (adrenohypophysis)
Posterior is composed of nervous tissue (neurohypophysis)
What are the main parts of the posterior pituitary?
Hypothalamic-hypophyseal tract - neural connection of pituitary and hypothalamus
What is the function of ADH?
Causes urine retention
What are the main causes for the release of ADH?
Change is osmolality
Change in blood pressure
What are the different types of ADH receptors?
V2 receptors
V1a receptors
V1b receptors
Where are V2 receptors found?
Kidneys
Makes kidneys reabsorb water through aquaporin channels
Where are V1a receptors found?
Smooth muscle
Causes smooth muscle to contract in blood vessels to increase BP
Where are V1b receptors found?
Anterior pituitary
Cause release of ACTH
What are factors that increase ADH secretion?
Increases in osmolarity Decreases in fluid volume Periods of stress Nausea and vomiting Prolonged periods of standing Angiotensin 2
What are factors that decrease ADH secretion?
Decrease in osmolality
Increase in extracellular fluid volume
Alcohol - supresses hypothalamus
What is diabetes insipidus?
ADH deficiency due to hypothalamus or posterior pituitary damage
What are the functions of oxytocin?
Strong stimulation of uterine contraction
Hormonal trigger for milk ejection
Releases at time of ejaculation to contract muscles and push sperm out
Positive feedback
What hormones does the hypothalamus produce that regulate hormone production in the anterior pituitary?
GHRH - Growth hormone releasing hormone GHIH - Growth hormone inhibiting hormone TRH - Thyroid releasing hormone CRH - Corticotropin releasing hormone GnRH - Gonadotropin releasing hormone PIH - Prolactin inhibiting hormone
What are the three types of interaction that can occur at a target cell?
Permissiveness
Synergism
Antagonism
What are the two hormones that the hypothalamus makes?
Paracentricular nucleus - makes oxytocin
Supraoptic nucleus - makes ADH
What hormones does the anterior pituitary produce?
Growth hormone Prolactin Thyroid stimulating hormone Adrenocorticotropic hormone Follicle stimulating hormone Luteinizing hormone
What is a tropic hormone?
Hormone that controls the release of another hormone
What are the tropic hormones that the anterior pituitary produces?
Thyroid stimulating hormone
Adrenocorticotropic hormone
Follicle stimulating hormone
Luteinizing hormone
What cells in the anterior pituitary produce Growth hormone?
Somatotropic cells
What are the direct actions that growth hormone has?
Increases blood levels of fatty acids - encourages fatty acid use
Decrease rate of glucose uptake and metabolism
Causes glycogen breakdown and glucose release into blood
What are the indirect actions that growth hormone has?
Mediates growth via growth promoting proteins - insulin like growth factors
What do the insulin like growth factors stimulate?
Uptake of nutrition
Formation of collagen and deposition of bone matrix
How is growth hormone regulated?
Hypothalamus regulates growth hormone with GHRH and GRIH
What are the homeostatic imbalances of growth hormone?
Hypersecretion - In children results in gigantism - In adults results in acromegaly Hyposecretion - In children results in dwarfism
What are the effects of thyroid stimulating hormone?
Stimulates normal development and secretion of thyroid
What produces thyroid stimulating hormone?
Thyrotropic cells of the anterior pituitary
How is thyroid stimulating hormone regulated?
Thyroidtropin releasing hormone from hypothalamus
What are the effects of ACTH?
Stimulates adrenal cortex to release corticosteriods (cortisol)
What produces ACTH?
Corticotropic cells of anterior pituitary
How is ACTH regulated?
Triggerd by corticotropin-releasing hormone from hypothalamus
Internal and external factors such as stress, fever and hypoglycemia can alter CRH release
What are the ganodotropins?
Follicle-stimulating hormone
Luteinizing hormone
What are the effects of follicle-stimulating hormone?
Stimulate gamete production (sperm or egg)
What are the effects of luteinizing hormone?
Promotes prodcution of gonadal hormones
What produces ganodotropins?
Gonadotropic cells of anterior pituitary
How are ganodotropins regulated?
Triggered by GnRH from hypothalamus
Negative feedback mechanism
What are the effects of prolactin?
Stimulates milk production
How is prolactin regulated?
Controlled by prolactin inhibiting hormone (dopamine) from hypothalamus
What produces prolactin?
Secreted by prolactin cells of anterior pituitary
What are the two hormones that the thyroid releases?
Calcitonin
Thyroid hormone
What are the effects of thyroid hormone?
Has a calorigenic effect
Has a thermogenetic effect
Regulates growth and development
Helps maintain blood pressure
What are the two related compounds of thryroid hormone?
T4 - thyroxine ( 2 tyrosine and 4 iodine)
T3 - Triiodothyronine ( 2 tyrosine and 3 iodine)
What makes up colloid cells?
Thyroglobulin
What is the protein that transports MIT and DIT across the cell?
Megalin
What are the steps of T3 and T4 synthesis?
- Thyroglobulin is synthesized and discharged into the follicle lumen
- Iodide is trapped, transported into follicular cells
- Iodide is oxidized into iodine in colloid
- Iodine is attached to tyrosine, forming DIT and MIT
- Iodinated tyrosines are linked together to form T3 and T4
- Thyroglobulin colloid is endocytosed and combined with a lysosome
- Lysosomal enzymes cleave T4 and T3 from thyroglobulin, hormones diffuse into blood
How are T3 and T4 transported?
Thyroxine binding globulin - tightly bound
Transthyretin - transports to brain / CNS
Albumin - weak affinity
Free in blood
Which is more active T3 or T4?
T3 is about ten times more active than T4
What are the homeostatic imbalances of T3 and T4?
Hyposecretion - Myxedema in adults - Cretinism in infants Hypersecretion -Grave's disease
What are the effects of calcitonin?
Inhibits osteoclast activity and stimulates calcium uptake
Antagonist to parathyroid hormone
What is the function of parathyroid hormone?
Stimulates osteoclasts and releases calcium into the blood
What are the two divisions of the adrenal gland?
Medulla and Cortex
What hormones does the adrenal medulla produce?
Epinephrine and norepinephrine
What are the effects of epinephrine and norepinephrine?
Vasoconstriction to abdomen
Increased heart rate
Increased blood glucose levels
What are the three layers of the adrenal cortex and what are their hormones?
Zona Glomrulosa - aldosterone
Zona fasciculata and reticularis - Cortisol and androgens
What is the main hormone that the pineal gland produces?
Melatonin
What are the effects of melatonin?
Timing of sexual maturity
Day and night cycles
Rhythmic cycles (sleep, appetite, and body temp)
What are the different types of cells in the pancreas?
Acinar cells (exocrine cells)
Pancreatic islets (contains endocrine cells)
Alpha cells - produce glucagon
Beta cells - produce insulin
What are the effects of glucagon?
Main target is liver
Release of glucose into blood