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Endocrine System Jade Mellin - Period 3 - Coggle Diagram
Endocrine System
Jade Mellin - Period 3
Major Functions of the Endocrine System
Hormonal Communication
Hormones = chemical messengers
Travel through bloodstream
Bind to specific receptors on target cells
Only target cells respond
Regulation of Homeostasis
Maintains stable internal conditions:
Blood glucose
Body temperature
pH balance
Fluid balance
Growth & Development
Controlled by growth hormone (GH)
Affects:
Bone growth
Muscle development
Works with thyroid hormones
Metabolism Control
Regulates how body uses energy
Thyroid hormones increase metabolic rate
Affects:
ATP production
Oxygen consumption
Reproduction
Controls puberty and sexual development
Regulates menstrual cycle & sperm production
Hormones involved:
Estrogen
Progesterone
Testosterone
Stress Response
Short-term: adrenaline (fight or flight)
Long-term: cortisol
Maintains survival under stress
Brain Region
Hypothalamus
Link between nervous & endocrine systems
Produces releasing & inhibiting hormones
Controls pituitary gland
Maintains:
Temperature
Hunger
Thirst
Pituitary Gland
Anterior Pituitary
GH → growth
TSH → stimulates thyroid
ACTH → stimulates adrenal cortex
FSH & LH → control reproduction
Prolactin → milk production
Posterior Pituitary
ADH → water balance (kidneys)
Oxytocin → childbirth & bonding
Pineal Gland
Produces melatonin
Controls circadian rhythm (sleep-wake cycle)
Neck Region
Thyroid Gland
Hormones:
T3 (triiodothyronine)
T4 (thyroxine)
Function:
Increases metabolism
Regulates energy use
Requires iodine
Parathyroid Glands
Hormone: PTH
Function:
Raises blood calcium
Targets:
Bones (release calcium)
Kidneys (reabsorb calcium)
Abdominal Region
Adrenal Glands
Adrenal Medulla
Epinephrine (adrenaline)
Norepinephrine
Rapid stress response
Adrenal Cortex
Cortisol → long-term stress, metabolism
Aldosterone → regulates salt & water balance
Pancreas (Islets of Langerhans)
Insulin → lowers blood glucose
Glucagon → raises blood glucose
Maintains glucose homeostasis
Reproductive Organs
Ovaries
Estrogen → female traits
Progesterone → maintains pregnancy
Testes
Testosterone → male traits, sperm production
Hormones + Function + Target Organs
Insulin
Function: decreases blood glucose
Target: liver, muscle, fat cells
Mechanism: increases glucose uptake
Glucagon
Function: increases blood glucose
Target: liver
Mechanism: glycogen → glucose
ADH
Function: water reabsorption
Target: kidneys
Prevents dehydration
Cortisol
Function: stress adaptation
Target: many tissues
Increases blood sugar
Thyroid hormones (T3/T4)
Function: increase metabolism
Target: most body cells
Steroid vs Non-Steroid Hormones
Steroid Hormones
Lipid-based (from cholesterol)
Diffuse through cell membrane
Bind to receptors inside nucleus
Directly affect gene expression
Slow response but long-lasting
Examples:
Cortisol
Estrogen
Testosterone
Progesterone
Non-Steroid Hormones
Protein-based
Cannot enter cell
Bind to membrane receptors
Use second messenger system (cAMP)
Fast response but short-lived
Examples:
Insulin
Epinephrine
Growth hormone
ADH
Homeostatic Mechanisms
Negative Feedback Loop (MOST IMPORTANT)
Hormone release stops when levels normalize
Example: Thyroid Regulation
Hypothalamus → TRH
Pituitary → TSH
Thyroid → T3/T4
High T3/T4 → inhibits TRH & TSH
Positive Feedback Loop (RARE)
Example: Oxytocin in childbirth
Contractions → oxytocin release
More oxytocin → stronger contractions
Continues until birth
Endocrine Glands:
Endocrine Disorders
Diabetes
Type 1
Cause: autoimmune destruction of pancreatic beta cells
Hormone issue: little to no insulin production
Effect: glucose stays in bloodstream
Type 2
Cause: insulin resistance
Hormone issue: body doesn’t respond to insulin properly
Symptoms (both types)
High blood sugar
Frequent urination
Excess thirst
Fatigue
Target organs affected
Blood vessels, kidneys, eyes, nerves
Hyperthyroidism
Effects
Increased metabolism
Rapid heart rate
Weight loss
Nervousness/anxiety
Cause
overactive thyroid gland
Hormone issue: excess T3 and T4
Hypothyroidism
Cause
underactive thyroid
Hormone issue: low T3 and T4
Effects
Slow metabolism
Weight gain
Fatigue
Cold intolerance
Gigantism
Cause
excess growth hormone in childhood
Hormone issue: too much GH before growth plates close
Effects
Abnormally tall height
Enlarged bones and tissues
Dwarfism
Cause
lack of growth hormone
Hormone issue: too little GH
Effects
Short stature
Normal body proportions