Chapter 17 - The Endocrine System Flashcards
Endocrinology
The study of hormones and endocrine glands
Endocrine System Overview
Series of ductless glands that secrete hormones
Hormones travel to regions of the body and signal physiological responses
Cooperates with nervous system
-nervous = faster activity
-endocrine = slower response but effect usually lasts longer
Endocrine organs and hormones = system
Exocrine
Have ducts Secrete onto body surface or into cavity Secretions travel directly onto target Secretions are usually fluids, lubricants, enzymes ex. sweat, salivary, mucous
Endocrine Glands
DUCTLESS
Secrete hormones
Function is regulation, homeostasis
Hormones dumped right into bloodstream, act on target cells
Endocrine Organs Classifications
Pure Endocrine organs
Endocrine organs belonging to other body systems
Other
Pure endocrine organs
Pituitary gland Pineal gland Thyroid gland Parathyroid glands Adrenal gland
Endocrine organs belonging to other body systems
Pancreas
Thymus
Gonads
Hypothalamus
Other Endocrine organs
Organs that can also secrete hormones
Heart
Digestive Tract
Hormone classes
Amino acid (protein) Steroid (lipid)
Hormone Action
Circulate through bloodstream and affect only the target cells (have receptors)
Hormones themselves are just triggers
How hormones control secretion
Humoral stimuli
Neural stimuli
Hormonal stimuli
Feedback loops (Negative and Positive)
Humoral Stimuli
Respond to changing levels of ions/nutrients in blood
ex. parathyroid gland
Neural stimuli
Respond to nervous system
ex. adrenal medlla
Hormonal stimuli
Respond to hormones from other glands
ex. hypothalamus
Negative Feedback loop
More hormone secreted if levels drop
Positive Feedback loop
More hormone secreted if levels increase
Pituitary Gland (hypophysis)
9 major hormones, from 2 different portions all are protein hormones
Small, round structure
Hangs on stalk below hypothalamus; stalk is called infundibulum
2 separate glands, anterior (adenohypophysis) and posterior (neurohypophysis)
-Adnohypophysis is controlled by hypothalamus, which secretes peptide hormones (releasing factors) that signal the hormone release (inhibiting factors can also be released).
The hypothalamus controls the adenohypophysis, which controls the thyroid gland, adrenal cortex, and gonads
Adenohypophysis
Anterior pituitary gland, ventral portion under hypothalamus
Secrete: hormones that regulate growth and secretion of other glands, tissues (called TROPIC hormones/stimulating hormones)
ex. GH, MSH, FSH, LH, TSH, ACTH, Prolactin
Target: other endocrine glands (thyroid, adrenal, gonads)
The hypothalamus controls the adenohypophysis, which controls the thyroid gland, adrenal cortex, and gonads
Effect: Generally stimulates tissue growth and gland secretion, essential for growth, development, maturation
Growth Hormone (GH)
Regulates growth of all body cells, promotes cell division
Melanocyte stimulating hormone (MSH)
Causes darkening of skin by stimulating melanin
Follicle Stimulating Hormone (FSH)
In females, it regulates monthly development of follicle and egg and secretion of estrogen
In males, it stimulates testes to create sperm
Luteinizing hormone (LH)
Works together with FSH
In females, helps bring about ovulation, formation of progesterone
In males, it stimulates testosterone development and secretion
Thyroid stimulating hormone (TSH; thyrotropin)
Regulates thyroid gland, but hypothalamus also partially controls
Adrenocorticotropic hormone (ACTH)
Promotes functioning of adrenal cortex
Prolactin
Secreted in both males and females, but functions more in females after birth-responsible for milk production
Neurohypophysis
Posterior pituitary gland; dorsal, is considered part of the brain - has nervous tissue
Secretes: ADH & Oxytocin
ADH
Antidiuretic hormone, or vasopressin
Kidney = helps to retain water (decrease urine flow)
Blood vessels = constricts (increases BP)