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Endocrine glands
- ductless
- secrete hormones
- cells acted on by hormones are target cells
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Target organ cell
receptor on a cell that a hormone targets
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Second messenger mechanism
- 1. hormone communicates with target organ cell
- 2. another molecule is released within the organ to cause cells within the organ to perform a function
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Which homeostatic mechanism is usually used by hormones
negative feedback loop
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What are prostaglandins
- aka tissue hormones
- produced in organ tissue and then diffuses to other cells within that organ tissue
- doesn't meet teh definition of a hormone
- diffuse a short distance
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Pituitary gland
- broken into 2 parts
- 1. anterior pituatary gland (adenohypophysis): glandular
- 2. posterior pituatary gland (neurohypophysis): nervous
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Anterior pituatary gland
- controls thyroid gland, adrenal cortex, ovarian follicles, corpus luteum
- secretes:
- thyroid-stimulating hormone (TSH)
- adrenocorticotropic hormone (ACTH)
- follicle-stimulating hormone (FSH)
- luteininzing hormone (LH)
- growth hormone (GH)
- prolactin
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Thyroid-stimulating hormone (TSH)
- ANTERIOR PITUITARY GLAND HORMONE
- stimulates the thyroid gland to secrete thyroid hormone
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adrenocorticotripic hormone (ACTH)
- ANTERIOR PITUITARY GLAND HORMONE
- stimulates the adrenal cortex
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follicle stimulating hormone (FSH)
- ANTERIOR PITUITARY GLAND HORMONE
- stimulates ovarian follicles to start growing and secrete estrogen
- stimulates males to produce sperm
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luteinizing hormone (LH)
- ANTERIOR PITUITARY GLAND HORMONE
- causes ovulation
- stimulates corpus luteum tor produce progesterone
- stimulates testes to secrete testosterone
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growth hormone (GH)
- ANTERIOR PITUITARY GLAND HORMONE
- increases blood glucose levels
- increases fat breakdown (catabolism)
- increases tissue growth
- hypersecretion causes... gigantism (adolescent), acromegaly (adult)
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prolactin
- ANTERIOR PITUITARY GLAND HORMONE
- aka lactogenic hormone
- stimulates breast tissue for lactation during pregnancy
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Posterior pituitary gland hormones (neurohypophysis)
- antidiuretic hormone (ADH)
- oxytocin (OT)
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antidiuretic hormone (ADH)
- POSTERIOR PITUITARY GLAND HORMONE
- created by hypothalamus, stored in neurohypophysis
- causes kidney to reabsorb more water; decreases urine output
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oxytocin (OT)
- POSTERIOR PITUITARY GLAND HORMONE
- stimulates uterine contraction
- causes "milk letdown" into ducts within breast tissue
- created by hypothalamus
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diabetes insipidus
- hyposecretion of ADH
- excessive urination causes extreme thirst, dehydration and electrolyte imbalance
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hypothalamus
- creates ADH and oxytocin then sends it to the posterior pituitary gland for storage and secretion
- creates releasing and inhibititing hormones which control the anterior pituitary glands secretions
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releasing and inhibiting hormones
- produced by the hypothalamus
- cause the release or inhibition of anterior pituatary gland hormones
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thyroid gland
- secretes thyroxine (t4), triiodothyronine (t3) and calcitonin
- stores thyroid hormones in a colloid compound
- stimulates metabolism
- regulates blood calcium levels
- secretions regulated by the hypothalamus
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thyroxine(t4) and triiodothyronine (t3)
- thyroid hormones
- stimulate cellular metabolism
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calcitonin
- thyroid hormone
- decreases blood calcium levels
- inhibits osteoclasts from breaking down bone
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cretinism
- hyposecretion of thyroid hormones
- low metabolism, retarded growth and sexual development, and mental retardation
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myxedema
- adult hypothyroidism
- lessened mental and physical vigor, weight gain, hair loss, baggy eyes
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parathyroid glands
- located at the back of the thyroid
- secretes parathyroid hormone which increase blood calcium
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parathyroid hormone
- stimulates osteoclasts to break down bone
- increases blood calcium levels
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adrenal glands
- separated into 2 glands; adrenal cortex and adrenal medulla
- secretes corticoids and adrenaline
- works with sympathetic nervous system to prolong the "fight or flight" response
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adrenal cortex
- 3 layers which secrete corticoids
- outer zone secretes mineralcorticoids
- middle zone secretes glucocorticoids
- inner zone secretes androgens (sex hormones)
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mineralcorticoids
- secreted from the outter layer of the adrenal cortex
- corticoid hormone
- maintain mineral salts within the body
- aldosterone is the main one; increase blood sodium and decrease blood potassium
- decreases urine output
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glucocorticoids
- secreted by the middle layer of the adrenal cortex
- coriticoid hormone
- increases blood glucose levels
- has an antiimunity, antiallergy effect (decreasese antibodies)
- released during stressful moments
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adrenal medulla
- inner portion of the adrenal cortex
- releases epinephrine and norepinephrine
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Cushing syndrome
- hypersecretion of glucocorticoids
- moonface and buffalo hump are symptoms
- elevated blood sugar and frequent infections (glucocorticoids suppress antibodies and increase blood sugar)
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virilizing tumor
- tumor within the inner zone of the adrenal cortex
- excess androgens are usually released which cause male secondary characterisitics (facial hair, body hair, muscle mass)
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Addison's disease
- hyposecretion of adrenal cortex hormones
- JFK had it
- muscle weakness, reduced blood sugar, loss of appetite and weight
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pancreatic islets / islets of langerhans
- alpha cells secrete glucagon
- beta cells secrete insulin
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corpus luteum
secretes progesterone
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thymus
- secretes thymosin which develops the immune system
- located within the mediastinum
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Placenta
- secretes chorionic gonadotropins
- makes estrogen and progesterone
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pineal gland
- aka third eye
- secretes melatoninin
- melatonin secretion affected by night and day
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melatoninin
- inhibits tropic hormones that affect ovaries
- regulates onset of puberty and menstrual cycle
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