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Lecture Presentation by Patty Bostwick-Taylor
Florence-Darlington Technical College
Chapter 9
The Endocrine System
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Education, Inc.
Introduction
Hormone and Target Cells
Steroids and Non-Steroids
HW: Read / Take notes from text p.308-310
Complete WB 184
Endocrine System
Endocrine vs Nervous Cell Communication
Nervous vs. Endocrine System
Nervous vs. Endocrine System
Communication:
Electrical impulses
Neurotransmitters
Reaction time
1-10 msec
Stops immediately
Effects
Specific organs
Hormones
Seconds – days
Response lingers
Often entire body
Endocrine System Anatomy
Endocrine glands secrete into blood, lymph
Exocrine glands secrete into ducts
Major Endocrine Organs
Many glands are purely endocrine
Anterior pituitary, thyroid, adrenals, parathyroids
Some glands are mixed glands
endocrine and exocrine functions
pancreas, ovaries, testes
Endocrine System Functions
Regulate metabolic processes
Controls rate of chemical reactions
Helps transport across membranes
Helps regulate water & electrolytes
Regulates glucose and calcium concentrations
Reproduction, development, growth
Mobilization of body defenses
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Endocrine Hormones
Produced by specialized cells (endocrine glands)
Blood transfers hormones to target sites
Hormones regulate activity of other cells
Turns genes on / off
The Chemistry of Hormones (2 types)
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Hormones are classified chemically as
Amino acid–based (non-steroids):
Proteins
Peptides
Amines
Steroids—made from cholesterol
Hormone Action
Hormones alter cellular activity.
Typically, one or more occurs:
1. Membrane permeability or electrical state changes
2. Synthesis of proteins (often enzymes)
3. Enzyme activation or inactivation
4. Stimulation of mitosis (cell division)
5. Promotes cell to secrete substance
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Hormone Action
Hormones affect only certain tissues / organs
(target cells / target organs)
Hormone binding to receptor alters cellular activity
Target cells must have specific protein receptors
On cell membrane OR Inside the cell
Non-Steroid Cell Communication
Second-Messenger System (Nonsteroid Hormone Action)
1. Hormone (1st messenger) binds to membrane receptor
2. Activated receptor sets off a series of reactions
Activates an enzyme
3. Enzyme catalyzes a reaction
Activates second-messenger molecule (cyclic AMP, Ca2+)
4. Additional intracellular changes promote cellular response
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Figure 9.1b Mechanisms of hormone action.
Nonsteroid hormone action
Plasmamembraneof target cell
Receptorprotein
Nonsteroidhormone (firstmessenger)
Cytoplasm
Enzyme
ATP
cAMPSecondmessenger
1
2
3
4
Slide 5
Effect on cellular function
Steroid Cell Communication
Direct Gene Activation (Steroid Hormone Action)
1. Steroid hormones diffuse through plasma membrane
2. Steroid hormones bind to a receptor protein
In the cytoplasm OR
In the nucleus
3. Steroid hormones enter the nucleus
4. Hormone-receptor complex binds DNA
5. Activates genes
6. New proteins are made
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Figure 9.1a Mechanisms of hormone action.
Steroidhormone
Cytoplasm Nucleus
Receptorprotein
Hormone-receptorcomplex
DNA
mRNA
Newprotein
Plasmamembraneof targetcell
1
(a) Steroid hormone action
2
3
4
5
6
Slide 1
3 Ways to Stimulate Endocrine Glands
Neural
Hormonal
Humoral
Feedback Mechanisms
Negative
Positive
HW: Read / take notes from text p.310-312
Complete Feedback Mechanisms packet
1. Hormonal 2. Neural 3. Humoral
Endocrine Gland Stimuli
Three categories of stimuli that activate endocrine glands
Hormonal Stimuli of Endocrine Glands
Most common stimulus
Endocrine organs are activated by other hormones
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Hormonal – gland secretion
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Hormonal stimulus
The hypothalamus secretes
hormones that… Hypothalamus
1
…stimulate
the anterior
pituitary
gland to
secrete
hormones
that…
Anteriorpituitarygland
Thyroidgland
Adrenalcortex
Gonad(testis)
…stimulate other endocrine
glands to secrete hormones
2
3
Neural Stimuli of Endocrine Glands
Nerve impulses stimulate hormone release
Under sympathetic nervous system control (mostly)
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Figure 9.2c Endocrine gland stimuli.
Neural stimulus
Sympathetic fiber stimulates
adrenal medulla cells
CNS (spinal cord)
Sympathetic fibers
1
2
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Figure 9.2c Endocrine gland stimuli.
Neural stimulus
Adrenal medulla
cells secrete epinephrine
and norepinephrine
1
2
Neural Stimuli Results inRelease of Epinephrine
Increase cardiac output
Dilate coronary blood vessels
Increase muscle contraction
Increase mental alertness
Increase glycogen
Increase blood sugar
Humoral Stimuli of Endocrine Glands
Blood levels of certain ions and nutrients stimulate
hormone release
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Humoral stimulus
Capillary blood contains lowconcentration of Ca2+, whichstimulates…
Capillary
(low Ca2+
in blood)
Thyroid gland(posterior view)
Parathyroid
glands
Parathyroid
glandsPTH
…secretion of parathyroid
hormone (PTH) by parathyroid
glands)
1
2
Regulation of Calcium Ion Concentration in Blood
Control of Hormone Release:Negative Feedback Mechanism (usually)
Hormone levels maintained by negative feedback
What triggers the release of more hormone?
A stimulus
Low hormone levels in the blood
What stops the release of hormones?
Hormone reaches appropriate level in the blood
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Negative Feedback Mechanism
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Negative Feedback Mechanism
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Master Controls of the Endocrine System
Hypothalamus
Pituitary GlandPosterior Pituitary Gland (2 hormones)
HW: Read / Take notes from text p. 310-312
Pituitary Gland and Hypothalamus
Pituitary Gland and Hypothalamus
Pituitary gland is the size of a pea
Hangs by a stalk from the hypothalamus
Protected by the sphenoid bone
Has two functional lobes
Anterior pituitary—glandular tissue
Posterior pituitary—nervous tissue
Called the “master endocrine gland”
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Pituitary Gland and Hypothalamus
Hypothalamus makes two hormones:
antidiuretic hormone (ADH)
oxytocin
Neurosecretory cells bring
hormones to posterior pituitary
Posterior pituitary is a storage site
Venous drainage
ADH Oxytocin
Arterial blood supply
Posterior Pituitary Stores Hormones
When stimulated
Releases ADH
Releases Oxytocin
Posterior Pituitary - ADH
Antidiuretic hormone (ADH) Prevents dehydration Inhibits urine production (diuresis)
Promotes water reabsorption by the kidneys
Alcohol inhibits ADH secretion Therefore increases water loss
Large amounts of ADH vasoconstriction of arterioles increases blood pressure ADH is also known as vasopressin
ADH hyposecretion results in Diabetes insipidus
Posterior Pituitary - Oxytocin
Oxytocin
Stimulates contractions of the uterus
during labor
sexual relations
breastfeeding
Causes milk ejection (let-down reflex) in a breastfeeding woman
Increases sense of calmness
Pitocin: synthetic oxytocin
Used to induce labor
Used post labor to stop bleeding
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Venous drainage
ADH Oxytocin
Arterial blood supply
Posterior Pituitary
When stimulated
Releases ADH
Prevents water loss
Releases Oxytocin
Uterine contractions
Milk let-down
Increases calmness
Kidney Mammary glandsUterine muscles
Pituitary Gland and Hypothalamus
Hypothalamus produces releasing / inhibiting hormones
These hormones are released into portal circulation,
which connects hypothalamus to anterior pituitary
Hypothalamus also makes two hormones: oxytocin and
antidiuretic hormone
Carried to posterior pituitary via neurosecretory cells for
storage
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Master Controls of the Endocrine System
Hypothalamus
Pituitary GlandAnterior Pituitary Gland (6 hormones)
HW: Read / Take notes from text p.315-317
Complete WB 181-183
Pituitary Gland and Hypothalamus
Hormones of the Anterior Pituitary
Six anterior pituitary hormones
Hormonal control
All amino acid-based hormones
Regulated by negative feedback (mostly)
Two affect non-endocrine targets:
1. Growth hormone
Bones
Muscles
2. Prolactin
Breast – milk production in females
Unknown function in males
Growth Hormone
General metabolic hormone
Causes amino acids to be built into proteins
Causes fats to be broken down for a source of energy
Plays a role in determining final body size
Growth of skeletal muscles
Growth of long bones
Growth Hormone Disorders
Pituitary dwarfism
hyposecretion of GH
during childhood
Gigantism
hypersecretion of GH
during childhood
Acromegaly
hypersecretion of GH in adulthood
continued growth of hand, feet, and facial bones
Prolactin (PRL)
In females, stimulates and maintains milk production
(after childbirth)
Positive feedback
Function in males is unknown
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Figure 9.5 Hormones of the anterior pituitary and their major target organs.
Mammary
glands
Prolactin (PRL)Bones and muscles
Growth hormone (GH)
Anterior pituitary
Hypothalamus
Hormones of the Anterior Pituitary
Four are tropic hormones
stimulate other endocrine glands to release hormones
1. Thyroid-stimulating hormone (TSH)
2. Adrenocorticotropic hormone (ACTH)
3. Follicle-stimulating hormone (FSH)
4. Luteinizing hormone (LH)
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Hormones of the Anterior Pituitary
Adrenocorticotropic hormone (ACTH)
Regulates endocrine activity of the adrenal cortex
Thyroid-stimulating hormone (TSH)
Influences growth and activity of the thyroid gland
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© 2015 Pearson Education, Inc.
Figure 9.5 Hormones of the anterior pituitary and their major target organs.
Adrenocorticotropic
hormone (ACTH)
Adrenal cortexThyroid stimulating
hormone (TSH)
Thyroid
Hypothalamus
Hormones of the Anterior Pituitary
Gonadotropic hormones
Regulate hormonal activity of the gonads
Follicle-stimulating hormone (FSH)
Stimulates follicle development in ovaries
Stimulates sperm development in testes
Luteinizing hormone (LH)
Triggers ovulation of an egg in females
Stimulates testosterone production in males
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Figure 9.5 Hormones of the anterior pituitary and their major target organs.
Follicle-stimulating
hormone (FSH)
and luteinizing
hormone (LH)
Testes or ovaries
Hypothalamus
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Figure 9.5 Hormones of the anterior pituitary and their major target organs.
Posterior pituitary
Adrenocorticotropic
hormone (ACTH)
Adrenal cortexThyrotropic
hormone (TH)
Thyroid
Follicle-stimulating
hormone (FSH)
and luteinizing
hormone (LH)
Testes or ovaries
Mammary
glands
Prolactin (PRL)Bones and muscles
Growth hormone (GH)
Hypophyseal
portal system
Anterior pituitary
Releasing hormones
secreted into portal
circulation
Hypothalamus
Control of Metabolism and Ca2+ ion concentration
Thyroid (3 hormones)Hormonal stimuliHumoral stimuli
Parathyroid (1 hormone)Humoral stimuli
HW: Read / Take notes from text p. 317-320
Copy Figure 9.10 into notes
Thyroid Gland
Found at the base of the throat
Consists of two lobes and a connecting isthmus
Produces two hormones:
1. Thyroid hormone (T3 and T4)
2. Calcitonin
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Figure 9.7a The thyroid gland.
Isthmus of
thyroid gland
Thyroid
cartilage
Common
carotid artery
Trachea
Brachiocephalic
artery
Aorta
(a) Gross anatomy of the thyroid gland, anterior view
Epiglottis
Left subclavian
artery
Left lobe of
thyroid gland
Thyroid Hormone (1 functional hormone)
Major metabolic hormone
Controls rate of oxidation of glucose
Chemical energy (ATP)
Body heat
Composed of two iodine-containing hormones
Thyroxine (T4)
Triiodothyronine (T3)
converts to T4 at target cells
Needed for tissue growth and development© 2015 Pearson
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© 2015 Pearson Education, Inc.
Figure 9.7b The thyroid gland.
(b) Photomicrograph of thyroid gland
follicles (380×)
Parafollicular cells
Colloid-filled
follicles Follicle cells
Thyroid Gland
Thyroid hormone disorders
Goiters
Thyroid gland enlarges because of lack of iodine
Salt is iodized to prevent goiters
Cretinism
Caused by hyposecretion of thyroxine
Results in dwarfism during childhood
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Thyroid Gland
Thyroid hormone disorders
Myxedema
Caused by hypothyroidism in adults
Results in physical and mental sluggishness
Graves’ disease
Caused by hyperthyroidism
Results in increased metabolism, heat intolerance,
rapid heartbeat, weight loss, and exophthalmos
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Thyroid Gland
Calcitonin
Decreases blood calcium levels
Causes calcium deposition on bone
Antagonistic to parathyroid hormone
Disorder: Calcinosis
– calcification of soft tissue
Parathyroid Glands
On the posterior of the thyroid
Parathyroid hormone (PTH)
Stimulates osteoclasts
remove calcium from bone
Hypercalcemic hormone ( blood calcium levels)
Stimulates the kidneys and intestine
absorb more calcium
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Figure 9.10 Hormonal controls of ionic calcium levels in the blood.
Parathyroid
glands
Thyroid
gland
Parathyroid
glands release
parathyroid
hormone (PTH).PTH
Stimulus
Falling blood
Ca2+ levels
BALANCE
Calcitonin
stimulates
calcium salt
deposit in bone.
Thyroid gland
releases calcitonin.
Calcitonin
BALANCE
Stimulus:
Rising blood
Ca2+ levels
Osteoclasts
degrade bone
matrix and release
Ca2+ into blood.
Calcium homeostasis of blood:
9–11 mg/100 ml
Adrenal Gland (2-in-1)
Adrenal Cortex (3 groups of hormones)
Hormonal stimuli
Humoral stimuli
Adrenal Medulla (2 hormones)
Neural stimuli
HW: Read / Take notes from text p. 319-323
Study all glands / hormones covered so far.
Adrenal Glands
Sit on top of the kidneys
Two regions:
Adrenal cortex – hormonal / humoral control
produces 3 corticosteroids
Mineralocorticoids
Glucocorticoids
Sex hormones
Adrenal medulla – neural control
inner neural tissue region
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Figure 9.11 Microscopic structure of the adrenal gland.
Kidney
Adrenal
gland
Adrenal gland• Medulla
• Cortex
Kidney
Cortex
Medulla
Adrenal
cortex
Adrenal
medulla
Sex hormone–
secreting area
Glucocorticoid-
secreting area
Mineralocorticoid-
secreting area
Capsule
Adrenal Cortex Hormones
Mineralocorticoids (mainly aldosterone)
Produced in outer adrenal cortex
Target organ: kidney
Regulate sodium and potassium ion levels in blood
Regulate water and electrolyte balance
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Aldosterone
Increases blood pressure by regulating kidney function
Causes kidney to
Reabsorb sodium
Reabsorb water
Secrete potassium
Release stimulated by:
Humoral stimulation – level of K+ ions in blood
Hormonal stimulation (ACTH – stress hormone)
Inhibited by atrial natriuretic peptide (ANP)
Heart-produced hormone when blood pressure is high
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Figure 9.12 Major mechanisms controlling aldosterone release from the adrenal cortex.
Kidney
Decreased Na+ or
increased K+ in
blood
Decreasedblood volumeand/or bloodpressure
Stress
Hypothalamus
Corticotropin-releasinghormone
Anterior pituitary
ACTH
Increasedblood pressureor blood volume
HeartReninIndirectstimulatingeffect viaangiotensin
Angiotensin II
Atrial natriureticpeptide (ANP)
Inhibitory
effect
Directstimulatingeffect
Mineralocorticoid-producing part ofadrenal cortex
Enhanced secretionof aldosterone targetskidney tubules
Increased absorptionof Na+ and water;increased K+ excretion
Increased blood volume andblood pressure
Glucocorticoids
Cortisone and cortisol
Produced by middle layer of adrenal cortex
Promote normal cell metabolism
Increases blood glucose levels (hyperglycemic)
Helps resist long-term stressors
Anti-inflammatory properties
Released in response to increased ACTH in blood
(hormonal stimulus)
Sex Hormones
Androgens (male sex hormones, ex. testosterone)
Some estrogens produced (female sex hormone)
Produced in the inner layer of the adrenal cortex
Small amounts are made throughout life
Role in male development:
Testes formation (early regulation)
Spermatogenesis
Inhibition of fat deposition
Enlargement of skeletal muscle cells
Sex Hormones – Effects of Testosterone
Adrenal Medulla Hormones
Produces two similar hormones: (catecholamines)
1. Epinephrine (adrenaline)
2. Norepinephrine (noradrenaline)
“Fight or Flight” Hormones
Prepare the body to deal with short-term stress
Increases:
heart rate
blood pressure
blood glucose levels
Dilates small passageways of lungs
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Cortex
Medulla
Adrenal
medulla
Sex hormone
Secreting cells
Glucocorticoid
Secreting cells
Mineralocorticoid
Secreting cells
Capsule
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Figure 9.13 Roles of the hypothalamus, adrenal medulla, and adrenal cortex in the stress response.
Hypothalamus
Short term More prolonged
Spinal cord
Nerve impulses
PreganglionicsympatheticfibersAdrenal
medulla
Short-term stress response
Catecholamines(epinephrine andnorepinephrine)
1.2.3.
4.5.
6.
Increased heart rateIncreased blood pressureLiver converts glycogento glucose and releasesglucose to bloodDilation of bronchiolesChanges in blood flowpatterns, leading toincreased alertness anddecreased digestive andkidney activityIncreased metabolic rate
Stress
Releasing hormones
Corticotropic cells of
anterior pituitary
ACTHAdrenal
cortex
Mineralocorticoids Glucocorticoids
Long-term stress response
1.
2.
Retention of sodiumand water by kidneysIncreased bloodvolume and bloodpressure
1.
2.
3.
Proteins and fatsconverted toglucose or brokendown for energyIncreased bloodsugarSuppression ofimmune system
Regulation of Blood Glucose Levels
Pancreas (hidden Islets of Langerhans)
Pancreatic Islets (2 hormones)
Humoral stimuli
Beta cells
Alpha cells
HW: Read / Take notes from text p. 323-325
Complete Blood Glucose handout.
Pancreatic Islets
Pancreas
Located in the abdomen, close to stomach
Mixed gland, with both endocrine and exocrine
functions
The pancreatic islets produce hormones
Insulin—produced by beta cells
Glucagon—produced by alpha cells
These hormones are antagonists that maintain blood
sugar homeostasis
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Figure 9.14a Pancreatic tissue.
Stomach
Pancreas
(a)
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Figure 9.14c Pancreatic tissue.
(c)
Cord of beta (𝛃) cells
secreting insulin into
capillaries
Capillaries
Exocrine
cells of
pancreas
Alpha (𝛂)
cells
Pancreatic Islets
Insulin
Released when blood glucose levels are high
Increases the rate of glucose uptake and metabolism
by body cells
Glucagon
Released when blood glucose levels are low
Stimulates the liver to release glucose to blood, thus
increasing blood glucose levels
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BioFlix™: Homeostasis
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Figure 9.15 Regulation of blood glucose levels by a negative feedback mechanism involving pancreatic hormones.
Stimulus
Bloodglucose level(e.g., aftereating fourjelly doughnuts) Stimulus
Blood glucoselevel (e.g., afterskipping a meal)
Insulin
Pancreas
Tissue cells
Glucose Glycogen
Uptake of glucose fromblood is enhanced inmost body cells
Blood glucosefalls to homeostaticset point; stimulusfor insulin releasediminishes
Liver takes upglucose and storesas glycogen
Insulin-secreting cellsof the pancreas activated;release insulin into theblood
Elevated bloodsugar level
Blood glucose risesto homeostaticset point; stimulusfor glucagonrelease diminishes
Liver breaksdown glycogenstores andreleases glucoseto the blood
Glucose Glycogen
LiverGlucagon
Low blood sugar level
Glucagon-releasingcells of pancreasactivated; releaseglucagon into blood
Diabetes mellitus
Occurs in the absence of insulin
Blood sugar levels increase dramatically
Blood glucose is lost in the urine; water follows
Three cardinal signs:
1. Polyuria
production of abnormally large volumes of dilute urine.
2. Polydipsia
excessive thirst
3. Polyphagia
excessive hunger
Oral Glucose Tolerance Test
Pineal Gland (1 hormone)
Neural stimuli
Thymus (1 hormone)
Humoral stimuli
Gonads (endocrine function same as adrenal cortex)
Testes (1 group, 1 main hormone)
Ovaries (2 groups)
Placenta (3 hormones)
HW: Read / Take notes from text p. 325-330
Study all glands and hormones. Complete WB 185-187, 189
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Figure 9.3 Location of the major endocrine organs of the body.
Pineal gland
Hypothalamus
Pituitary gland
Thyroid gland
Parathyroid glands
Thymus
Adrenal glands
Pancreas
Ovary (female)
Testis (male)
Pineal GlandLocated in the middle of the brain
Stimulated by light
Secretes melatonin
Helps establish the body’s sleep/wake cycles
Establishes biological rhythms
Coordinates fertility hormones in humans
Circadian Rhythms
Thymus Gland
Located posterior to the sternum
Largest in infants and children
Produces thymosin
Matures some types of white blood cells
Important in developing the immune system
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Gonads
Ovaries
Produce eggs
Produce two groups of steroid hormones:
1. Estrogens
2. Progesterone
Testes
Produce sperm
Produce androgens
Ex. testosterone
Hormones of the Ovaries
Estrogens
Development of secondary female characteristics
Mature female reproductive organs
Progesterone
Helps in the implantation of an embryo in the uterus
Helps prepare breasts for lactation
In combination, progesterone and estrogens
Promote breast development
Regulate menstrual cycle
Hormones of the Testes
Produce several androgens
Testosterone is the most important androgen
Responsible for male secondary sex characteristics
Promotes growth
Promotes maturation of male reproductive system
Required for sperm cell production
Testosterone levels – Optimal vs. Low(exaggerated illustration)
Placenta
Hormones maintain pregnancy
Progesterone
hCG (human chorionic gonadotropin)
Estrogen
Some hormones help during childbirth
Endocrine System Videos as Review
Endocrine System Video Support
Hormone song https://www.youtube.com/watch?v=UqEgTUlG8FU
Watch the following videos to review the endocrine system, hormones and gland functions.
CC Endocrine system part 1 – A&P
https://www.youtube.com/watch?v=eWHH9je2zG4
CC Endocrine system part 2 – A&P
https://www.youtube.com/watch?v=SCV_m91mN-Q
CC Endocrine system – Biology
https://www.youtube.com/watch?v=WVrlHH14q3o