Download Endocrine System

Endocrine System
Function
-Regulates and integrates bodily
functions by secreting hormones
-Coupling w/nervous system,
regulates internal environment in
response to external environment
-Coordinates long-term growth,
development, & reproduction
Bozeman Endocrine System
Endocrine glands (overview)
Thymus gland
Thymopoietin, thymosin
• Promote maturation of
white
blood cells
Adrenal gland (one on each kidney)
Adrenal cortex
Glucocorticoids (cortisol,
corticosterone,cortisone)
• Stimulate glucose synthesis and
conservation
• Inhibit the inflammatory response
Mineralocorticoids (aldosterone)
• Increase sodium reabsorption by
kidneys
• Increase potassium excretion by
kidneys
Gonadocorticoids (androgens,
estrogens)
• Insignificant effects in adulthood,
relative to secretion by gonads
Adrenal medulla
Epinephrine
• Fight-or-flight response to stress
Norepinephrine
• Fight-or-flight response to stress
Pineal gland
Melatonin
• Reduces jet lag and promotes sleep
Parathyroid glands (two of four)
Parathyroid hormone (PTH)
• Increases blood levels of calcium
Stomach
Heart
Kidney
Pancreas
Glucagon
• Increases blood glucose level
Insulin
• Decreases blood glucose level
Testis (one of a pair)
Androgens (testosterone)
• Develop male secondary sex
characteristics
Thyroid gland
Thyroid hormone (TH)
• Regulates metabolism and heat
production
• Promotes development and function
of nervous, muscular, skeletal, and
reproductive systems
Calcitonin (CT)
• Decreases blood levels of calcium
and phosphate
Small intestine
Uterus (contains the
placenta when pregnant)
Ovary (one of a pair)
Estrogens and progesterone
• Develop female secondary sex
characteristics
2) Pineal gland
-releases Melatonin
-circadian rhythms (based on
photic & nocturnal periods)
Pineal Gland: "The Third Eye"
1) Pituitary gland “Master Gland”
-controlled by the hypothalamus
(Anterior lobe) (“FLAT PEGG”)
-releases Follicle-Stimulating Hormone (FSH) = stimulates production
of gametes & stimulates ovaries to produce estrogen
- releases Luteinizing Hormone (LH) = stimulates ovulation &
stimulates testicles to produce testosterone
-releases Adrenocorticotropic Hormone (ACTH) = stimulates adrenal
glands
-releases Thyroid-Stimulating Hormone (TSH) = stimulates release of
thyroid gland
-releases Prolactin (PRL) = stimulates production of breast milk
-releases Endorphins= natural pain and stress fighters
-releases Growth Hormone (GH) = stimulates growth
-releases Gonadotropic Hormones = stimulates gonads
Khan Academy: Hypothalamus/Pituitary Gland
(Posterior lobe) (“AO”)
-releases Antidiuretic (ADH) = reabsorption of H2O by kidneys
-releases Oxytocin = stimulates uterine contractions
3) Thyroid gland
-releases thyroid hormones (TH):
thyroxine (T4) & triiodothyronine (T3)
-increase metabolic rates; regulates
growth & development
Opening
to
trachea
Larynx
-releases calcitonin: important in bone remodeling
-decreases levels of calcium & phosphates
in blood
Thyroid gland
Parathyroid
glands
Trachea
T3/T4
Front view
Back view
(a) The thyroid gland lies over the trachea, just below the larynx.
4) Parathyroid glands
-Four glands embedded w/in thyroid
gland
-releases Parathyroid Hormone (PTH):
important in bone remodeling
(opposite response of calcitonin)
-increases calcium levels in blood
Calcitonin (thyroid) vs. PTH (parathyroid)
5) Thymus gland
-releases thymosins
-stimulates production of T- cells
-couples as a lymphatic organ
-crucial for immunity
Importance of Thyroid Gland
7) Pancreas
-releases Glucagon
-raises blood glucose levels
-releases Insulin
-decreases blood glucose levels
Sugar Homeostasis
Type 1/Type 2 Diabetes
6) Adrenal glands
•
Adrenal cortex: releases steroid hormones
-releases Glucocorticoids – class of hormones
(cortisol): response to stress and low blood sugar
-increases blood glucose levels
-anti-inflammatory
-releases Mineralocorticoids-class of hormones
(aldosterone): regulates the balance of water and
electrolytes; plays a role in blood pressure
-stimulates reabsorption of Na+ &
excretion of K+ (kidneys)
•
Adrenal Medulla
-releases Epinephrine (also known as adrenaline)
& Norepinephrine (neurotransmitter/hormone)
-stimulates sympathetic nervous system
(flight/fight response)
Function of Adrenal Glands
8) Gonads
•
Testicles
-releases Androgens (Testosterone)
-enhances male characteristics
•
Ovaries
-releases Estrogens & Progesterone
-enhances female characteristics
Function of the Gonads
Steroid based hormones
Step 1: The
steroid hormone
diffuses through
the plasma
membrane of
the target cell.
Steroid hormone
Protein based hormones
Extracellular fluid
Plasma membrane
of target cell
(lipid bilayer)
Step 7: Enzymes
alter the activity
of the cell.
Step 2: The
steroid hormone
binds to a receptor
in the cytoplasm.
Cytoplasm
Receptor
Nuclear
envelope
Nuclear
pore
Step 6: Proteins,
including enzymes,
are synthesized.
Step 5: Certain
genes are activated.
Step 3: The hormonereceptor complex
enters the nucleus.
Step 4: The hormonereceptor complex
binds to DNA.
Nucleus
Hormone mechanisms
Hormones secreted from other
organs/tissues
• Erythropoietin
-low blood oxygen levels elicits the
kidney to secrete
-stimulates RBC formation in bone
marrow
• Leptin
-protein hormone from adipose tissue
-acts on hypothalamus, signaling
satiation from a meal ”stop eating”
• Prostaglandins
-lipid molecules that are locally acting
hormones
-diverse functions related to injury and
illness
- inflammatory responses
- blood flow, formation of blood
clots and induction of
childbirth contractions