Ch.6 The Endocrine System

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Adenaline: fight or flight response
epinephrine
Primary endocrine organs: primary function is to secrete hormones
ex. hypothalamus, pit. gld., pineal gland,thyroid gland, parathyroid, thymus, adrenal gland, pancreas, gonads, and placenta.
Secondary endocrine organs: the secretion of hormones is secondary to some other function

ex. heart, liver, stomach, S.I., Kidney, and skin.
Hypothalamus: releasing and release inhibiting hormones

regulate secretion of ant. pit. hormones
Pituitary gland: a pea sized structure that is connected to the hypothalamus by a thin stalk of tissue called the infundibulum
divided into 2 parts: ant. lobe & post. lobe
Anterior lobe of pit gland: adenohypophysis
secretes LH, FSH, GH, TSH, ACTH and prolactin (PRL).
Posterior lobe of pit gland: neurohypophysis
releases the hormones oxytocin and vasopressin (ADH) that are produced by hypothalamic neurons.
ADH (vassopressin): synthesized in the paraventricular nucleus
Oxytocin: Females: stimulates uterine contraction and milk ejection by mammary glands
Males: unknown
Neurohormones: hormones that are secreted by neurons instead of endocrine glands are called ______________.
Hypothalamus & Pituitary Gland Interactions: 1. Post. pit. derived from embryonic brain (nerve tissue).
2. Neurons extended from 2 sites in hypothalamus into tissue of post. pit.
3. Hormones produced in neurons move down axons to terminals (ends).
4. Stimulation of neurons causes release of hormones by exocytosis.
5. Hormones picked up by capillaries
(Hormones are made in the hypothalamus)
Post. Pituitary Hormones: 1. Antidiretic Hormone (ADH) vasopressin
2. Oxytocin
Antidiretic Hormone (ADH) vasopressin: regulates H2O excretion & B.P.
Hypothalamus & Ant. Pituitary hormones: 1. Neurons extend into base of hypothalamus & pit. stalk
2. End at a capillary in the pit. stalk
3. Portal veins extend from that capillary into Ant. pit. capillaries.
Release of Ant. pit. hormones: 1. Hypothalamus controls release of ant. pit. hormones by use of releasing hormones
2. Releasing hormones are produced by neurons picked up by portal veins, carried to ant. pit. capillaries, released into ant. pit.
3. Control release of 6 major peptide hormones.
Hormones: ________ exist in the blood for a short time before they are metabolized. ________ that bind to receptors often metabolize by the target cell itself.
Tropic hormones: A hormone that regulates the function of another endocrine organ.
Secreted by ant. pit. and hypothalamus
can be stimulating hormones or inhibiting hormones.
stimulating hormone: A tropic hormone that increases the secretion of another hormone
Inhibiting hormone: A tropic hormone that decreases the secretion of another hormone
Ant. Pit. Gland: GH
ACTH
FSH
Prolactin
LH
Growth hormones: Essential for growth
stimulates bone and soft tissue growth
reguates protein, lipid, and carbohydrate metabolism
Adrenocorticotropic Hormone (ACTH): Stimulates glucocorticoid secretion by the adrenal cortex
TSH: Stimulates the secretion of TH by the by thyroid gland.
Prolactin: Stimulates the development of breasts and milk secretion by the mammary glands
Follicles stimulating Hormones (FSH): Females: stimulates growth and development of ovarian follicles, estrogen secretion

Males: stimulates sperm production by the testis
Luteinizing hormone (LH): Females: stimulates ovulation, transformation of ovarian follicles into corpus luteum, and secretion of estrogen and progesterone

Males: stimulates testosterone secretion by the testis
Posterior pituitary gland: ADH
Oxytocin
ADH (antidiretic hormone)vassopressin: Decreases urine output by the kidneys

Promotes constriction of blood vessels (arterioles)
Pineal gland: Melatonin
Melatonin: Regulates biological rhythms according to day-night cycles
Thymus: Thymosin
Thymosin: Stimuates proliferation and function of T lymphocytes
Thyroid Gland: TH
Calcitonin
Thyroid hormone: T3 and T4

Increases metabolic reate of many tissues

Nessesary for normal development
Calcitonin: Promotes calcium deposition in bone
Lower blood calcium levels
Parathyroid glands: PTH
Parathyroid hormone: Promotes calcium release from bone, calcium absorption by intestine, and calcium reaborsption by kidney tubules

Raises blood calcium levels

Stimulates Vit. D synthesis
Adrenal Cortex: Mineralcorticoids
Glucocorticoids
Adrenogens
Mineralcorticoids: alderstone

stimulates sodium reabsorption and potassium secretion by kidney tubules
Glucocorticoids: cortisol
corticosterone

Promotes catabolism of proteins and fats

Raises blood glucose levels

Adapts the body to stress
Adrenogens: dehydroepiondrosterone
androstenedione

Promote sex drive
Adrenal medulla: Epinephrine
NE
Dopamine
Epinephrine: stimulates fight or flight responses
Pancreas: Insulin
Glucagon
Somatostatin
Insulin: Lowers blood glucose levels
Promotes protein, lipid, and glycogen synthesis
Glucagon: Raises blood glucose levels

Promotes glycogenolysis & glyconeogenosis
Somatostatin: Inhibits secretion of pancreatic hormones

Regulates digestion and absorption of nutrients by gastrointestinal system
Testes: Androgens(testosterone, androstenedione)
Ovaries: Estrogens
Progestins (progesterone)
Placenta (during pregnancy): Chorionic gonadotropin, estrogens, progesterone
Androgens(testosterone, androstenedione): Necessary for sperm production by testis

Promotes sex drive and development of secondary sex characteristics (face hair, deep voice...)
Estrogens: Necessary for follicular development

Promotes development of secondary sex characteristics (breasts, body fat distribution, etc.)
Progestins (progesterone): Promotes endometrial growth to prepare uterus for pregnancy
Chorionic gonadotropin, estrogens, progesterone: Maintain corpus luteum

Reinforces actions of hormones secreted by corpus luteum
Prolactin releasing hormone (PRH): stimulates the ant. pit. to release prolactin
Prolactin inhibiting hormone (PIH) (dopamine): inhibits the release of prolactin
Thyrotropin releasing hormone (TRH): Stimulates the release of thyroid stimulating hormone (TSH)
Corticotropin releasing hormone CRH: stimulates the release of adrenocorticotropic hormone (ACTH) by the ant. pit.
Growth hormone releasing hormone (GHRH): stimulates the secretion of GH by the ant. pit.
Growth hormone inhibiting hormone (GHIH): aka somatostatin

inhibits the secretion of GH by the ant. pit.
Gonadotropin releasing hormone (GnRH): stimulates the releas of both FSH and LH by the ant. pit.
Hypothalamic-pituitary portal system: Neurosecretory cells of the hypothalamus secrete tropic hormones into the hypothalamic-pituitary portal system. The tropic hormones travel to the ant. pit., where they effect release of ant. pit. hormones into the blood.
target cells: Factors influencing the magnitude of a _______ _____ response to a hormone include the types of receptors in the target cell & the concentration of free hormone in the blood.
1. the rate of hormone secretion 2. the amount of hormone transported bound to carrier proteins 3. The rate at which the hormone is metabolized.: What are the 3 factors of concentration of free hormone in the blood?
Faster rates: rate of secretion rises or falls
______ _____of secretion translate to greater conc. of hormone in blood & more the conc. of hormone bind to receptors on target cells.
neural signal humoral (bloodborne) signal: Endocrine cells alter secretion in response to 2 types of input:
Neural signals: directly regulate hormone secretion by the hypothalamus, post. pituitary, and adrenal gland, which can affect the secretion of other hormones.
Humoral signals: Control of Insulin release by blood glucose levels

Control of aldosterone release by blood potassium levels.
unbound: When hormones are transported by carrier proteins, only the conc. of _______ hormones affects the binding of hormone to receptor.
Carrier proteins: _______ ________ increase half life of hormones, so that they are present in the blood for a longer period, by decreasing the rate of the their metabolism.
lysosomes peptide: Inside the cell, the hormone is degraded by _________. _______ hormones can be metabolized by proteolytic enzymes that are present in the blood.
liver urine: Hormones can also be metabolized by enzymes in the ______. Breakdown products of these hormones can be excreted in the ______.
1. Steroids and thyroid hormones are transported in the blood bound to carrier proteins 2. Fat soluble steroids and thyroid hormones can be stored temporarily in fatty tissue.: Steroids & thyroid hormones are metabolized more slowly (have a longer half-life) than are peptides and amines for 2 reasons:
hypersecretion: In primary ___________, the blood levels of tropic hormones tend to be lower than normal due to the increased negative feedback from the hormone regulated by the tropic hormones.
hyposecretion: In primary ___________, the opposite pattern of hormone level occurs: TH levels are decreased, but TRH and TSH levels increase due to reduced neg. feedback.
acromegaly: a disease caused by an excess of GH secretion in adults, which causes the bones to thicken and organs to grow excessively.

ex. of hypersecretion
insulin dependent diabetes mellitus: hyposecretion

a disease caused by insuffient secretion of insulin from the B cells of the pancreas.
Too little insulin in blood, leads to inadequate use of glucose for energy.
receptors hormone: Cells have many types of ________ for hormones

A cell may be effected by more than 1 ________ type at the same time.
antagonist: If the effects of 2 hormones act in opposition to each other then they are termed __________ to each other.
additive: Hormone effects may be _________ when 2 hormones produce the same effect on a target cell. 2+2=4
synergistic: Hormone effects may be __________ if the combined effects of the 2 hormones is greater then the individual leffects produced by the hormones. 2+2=5
permissive: A hormone is said to be __________ if one hormone must be present for another hormone to act on the target cells.
hormone interactions: have many types of receptors for hormones
effected my more than 1 hormone type at the same time
antagonist
additive
synergistic
permissive

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