Download Unit 7_Endocrine System

Activating Strategy- chapter 9
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Create a Venn Diagram: Compare & Contrast the
endocrine and nervous systems? Use the terms below:
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FAST-ACTING vs. SLOW-ACTING
Released into blood
Produce hormones as chemical messenger
Use neurotransmitters as messengers
Transmit nervous impulses via action potential
Acts on effector organs/gland
Stimulates glands
Control bodily functions
Bind receptors
2nd messenger vs. 1st messenger
The
Endocrin
e System
EQ:
How does the
endocrine
system help
regulate bodily
functions?
GPS
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SAP3. Students will assess the integration and
coordination of body functions and their
dependence on the endocrine and nervous
systems to regulate physiological activities.
a. Interpret interactions among hormones, senses,
and nerves which make possible the coordination of
functions of the body.
c. Describe how the body perceives internal and
external stimuli and responds to maintain a stable
internal environment, as it relates to biofeedback.
Endocrine
Organs
The Endocrine System
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2nd-messenger system of the body (NS is 1st
messenger system)
Response: Slow acting vs. NS which is fast-acting
Uses chemical messengers (hormones) that are
released into the blood
Hormones control several major processes:
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Reproduction
Growth & development
Mobilization of body defenses
Maintenance of homeostasis
Regulation of metabolism
Hormone Overview
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Hormones are produced by specialized cells
Cells secrete hormones into extracellular
fluids
Blood transfers hormones to target sites
These hormones regulate the activity of other
cells
The Chemistry of Hormones
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Hormones are classified chemically as
1.
Amino acid–based, which includes:
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2.
3.
Proteins
Peptides
Amines
Steroids—made from cholesterol
Prostaglandins—made from highly active lipids
Mechanisms of Hormone Action
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Hormones affect only certain tissues or
organs (target cells or target organs)
Target cells must have specific protein
receptors
Hormone-binding alters cellular activity
Effects Caused by Hormones
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Changes in plasma membrane permeability
or electrical state, i.e. makes membrane
permeable to sodium.
Synthesis of proteins, such as enzymes.
Activation or inactivation of enzymes.
Stimulation of mitosis.
Promotes secretion of material from vesicles
of cell.
The Chemistry of Hormones
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Two mechanisms in which hormones act
1.
2.
Direct gene activation- (make new protein)
2nd-messenger system
Direct Gene Activation
(Steroid Hormone Action)
Nucleus
1.
2.
3.
4.
5.
Steroid
Hormone diffuses through hormone
the plasma membrane of
target cells
Enter the nucleus
Bind to a specific protein
within the nucleus
Bind to specific sites on
the cell’s DNA
Activate genes that result
in synthesis of new
proteins
Cytoplasm
Receptor
protein
Hormonereceptor
complex
Plasma
membrane
of target
cell
New
protein
DNA
mRNA
Second-Messenger System
(Nonsteroid Hormone Action)
Cytoplasm
1.
2.
3.
4.
Hormone binds to a
membrane receptor, but
does not enter the cell
Sets off a series of
reactions that activates
an enzyme
Enzyme catalyzes a rxn
that produces a 2ndmessenger molecule
It oversees additional
intracellular changes to
promote a specific
response
Nonsteroid
hormone (1st
messenger)
Enzyme
ATP
cAMP 2nd
messenger
Receptor
protein
Plasma
membrane
of target cell
Effect on cellular
function,
such as glycogen
breakdown
Control of Hormone Release
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Hormone levels in the blood are mostly
maintained by negative feedback
A stimulus or low hormone levels in the blood
triggers the release of more hormone
Hormone release stops once an appropriate
level in the blood is reached
Stimulus is either HORMONAL, HUMERAL
or NEURAL.
Hormonal Stimuli of Endocrine
Glands
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Most common stimuli
Endocrine glands are activated by other
hormones
Examples:
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Anterior pituitary hormones
Hormonal Stimuli of Endocrine
Glands
Figure 9.2a
Humoral Stimuli of Endocrine
Glands
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Changing blood levels of certain ions
stimulate hormone release
Humoral indicates various body fluids such
as blood and bile
Examples:
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Parathyroid hormone (stimulated by blood Ca2+
levels)
Calcitonin (stimulated by blood Ca2+ levels)
Insulin (stimulated by blood glucose levels)
Humoral Stimuli of Endocrine
Glands
Figure 9.2b
Neural Stimuli of Endocrine
Glands
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Nerve impulses stimulate hormone release
Most are under the control of the sympathetic
nervous system (SNS)
Ex). the release of neutotransmitters (NT)
like norepinephrine (NEpi) & epinephrine
(Epi) by the adrenal medulla
Neural Stimuli of Endocrine
Glands
Figure 9.2c
Major Endocrine Organs
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Pituitary gland
Thyroid gland
Parathyroid glands
Adrenal glands
Pineal gland
Thymus gland
Pancreas
Gonads (Ovaries and Testes)
Hypothalamus
Location of Major Endrocrine Organs
Figure 9.3
Endocrine
Organs
Major Endocrine Glands and Hormones
Table 9.1 (1 of 4)
Major Endocrine Glands and Hormones
Table 9.1 (2 of 4)
Major Endocrine Glands and Hormones
Table 9.1 (3 of 4)
Major Endocrine Glands and Hormones
Table 9.1 (4 of 4)
A. Pituitary Gland
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Size of a pea
Hangs by a stalk from the hypothalamus in
the brain
Protected by the sphenoid bone
Has two functional lobes:
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Anterior pituitary—glandular tissue
Posterior pituitary—nervous tissue
Often called the “master endocrine gland”
Hormones of the Anterior
Pituitary
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Six anterior pituitary hormones
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Two affect non-endocrine targets
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Growth hormone (GH)
Prolactin (PRL)
4 stimulate other endocrine glands (tropic hormones)
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Thyroid-stimulating hormone (thyrotropic hormone)- (TSH)
Adrenocorticotropic hormone (ACTH)
2 gonadotropic hormones- follicle-stimulating hormone (FSH)
& leutenizing hormone (LH).
Hormones of the Anterior
Pituitary
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Characteristics of all anterior pituitary
hormones
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Proteins (or peptides)
Act through 2nd-messenger systems
Regulated by hormonal stimuli, mostly negative
feedback
Hormones of the Anterior Pituitary
Figure 9.4
Hormones of the Anterior
Pituitary
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Growth hormone (GH)
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General metabolic hormone
Affects muscular & skeletal system mostly: Major
effects are on growth of skeletal muscles, long
bones & joints.
Plays a role in determining final body size
Causes amino acids to be built into proteins
Causes fats to be broken down for a source of
energy
Hormones of the Anterior
Pituitary
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Growth hormone (GH) disorders
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Pituitary dwarfism results from hyposecretion of
GH during childhood
Gigantism results from hypersecretion of GH
during childhood
Acromegaly results from hypersecretion of GH
during adulthood
Hormones of the Anterior
Pituitary
Gigantism
Figure 9.5a
Hormones of the Anterior
Pituitary
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Prolactin (PRL):
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Adrenocorticotropic hormone (ACTH):
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Target: mammary glands
Stimulates & maintains milk production following childbirth
Function in males is unknown
Target: adrenal cortex
Regulates endocrine activity of the adrenal cortex
Thyroid-stimulating hormone (TSH):
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Target: Thyroid gland
Influences growth & activity of the thyroid gland
Hormones of the Anterior
Pituitary
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Gonadotropic hormones
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Target: gonads (testes, ovaries)
Regulate hormonal activity of the gonads
1.
Follicle-stimulating hormone (FSH)
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2.
Stimulates follicle development in ovaries (oogenesis)
Stimulates sperm development in testes
(spermatogenesis)
Luteinizing hormone (LH)
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Triggers ovulation of an egg in females
Stimulates testosterone production in males
Pituitary–Hypothalamus
Relationship
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Hormonal release is regulated by releasing &
inhibiting hormones produced by the hypothalamus
Hypothalamus produces two hormones:
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These hormones are transported to & stored in the
posterior pituitary
1.
2.
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Oxytocin
Antidiuretic hormone (ADH)
The posterior pituitary is not strictly an endocrine
gland, but does release hormones
Hormones of the Posterior Pituitary
1.
Oxytocin
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2.
Target: Mammary glands, uterine muscles
Stimulates contractions of the uterus during labor, sexual
relations, and breastfeeding by positive feedback
Causes milk ejection in a nursing woman
Antidiuretic hormone (ADH)/ vasopressin
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Target: kidney
Inhibits urine production by promoting water reabsorption
by the kidneys
In large amounts, causes vasoconstriction leading to
increased blood pressure
Hormones of the Posterior Pituitary
Figure 9.6
Pituitary Control
B. Thyroid Gland
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Found at the base of
the throat
Produces two
hormones
1.
2.
Thyroid hormone (TH)
Calcitonin
Thyroid Gland
1.
Thyroid hormone
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Major metabolic hormone
Composed of two active iodine-containing
hormones
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Thyroxine (T4)—secreted by thyroid follicles
Triiodothyronine (T3)—conversion of T4 at target
tissues
Thyroid Gland
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Thyroid hormone disorders
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Goiters
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Thyroid gland enlarges
due to lack of iodine
Salt is iodized to prevent
goiters
Cretinism
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Caused by hyposecretion
of thyroxine
Results in dwarfism during
childhood
Thyroid Gland
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Thyroid hormone disorders
(continued)
– Myxedema
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Caused by
hypothyroidism in
adults
Results in physical and
mental sluggishness
Graves’ disease
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Caused by
hyperthyroidism
Results in increased
metabolism, heat
intolerance, rapid
heartbeat, weight loss,
and exophthalmos
Thyroid Gland
2. Calcitonin
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Decreases blood
calcium levels by
causing its deposition
on bone.
Antagonistic to
parathyroid hormone
(PTH), meaning it has
an opposite effect.
C. Parathyroid Glands
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4 tiny masses on the posterior of the thyroid
Secrete parathyroid hormone (PTH):
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Increases blood Ca2+ levels
Stimulate osteoclasts in bones to break down
bone & release Ca2+ into the blood
Stimulate the kidneys & intestine to absorb more
Ca2+ to be placed back into the blood
Draw This: Hormonal
Regulation of Calcium in Blood
Calcitonin
stimulates
calcium salt
deposit
in bone
Calcitonin
Thyroid gland
releases
calcitonin
Thyroid
gland
Rising
blood
Ca2+
levels
Calcium homeostasis of blood
9–11 mg/100 ml
Falling
blood
Ca2+
levels
Thyroid
gland
Osteoclasts
degrade bone
matrix and release
Ca2+ into blood
Parathyroid
glands
PTH
Parathyroid
glands release
parathyroid
Figure
hormone (PTH)
9.10, step 11
D. Adrenal Glands
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Sit on top of the kidneys
Two regions:
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1. Adrenal cortex—outer glandular region has
three layers
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Mineralocorticoids secreting area- Zona glomerulosa
Glucocorticoids secreting area- Zona fasciculata
Sex hormones secreting area- Zona reticularis
2. Adrenal medulla—inner neural tissue regionsecretes epinepherine and norepinepherine
Hormones of the Adrenal
Cortex
Figure 9.11
Hormones of the Adrenal
Cortex
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Mineralocorticoids (mainly aldosterone)
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Produced in outer layer
Regulate mineral content in blood
Regulate water & electrolyte balance
Target organ:kidney
Production stimulated by renin & aldosterone
Production inhibited by atrial natriuretic peptide
(ANP); ANP is produced & released by the heart.
Hormones of the Adrenal Cortex
Figure 9.12
Hormones of the Adrenal Cortex
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Glucocorticoids (including cortisone &
cortisol)
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Produced in the middle layer
Promote normal cell metabolism
Help resist long-term stressors
Released in response to increased blood levels of
ACTH
Roles of the Hypothalamus and
Adrenal Glands in the Stress Response
Short term
More prolonged
Stress
Hypothalamus
Nerve impulses
Releasing hormone
Corticotropic cells of
anterior pituitary
Spinal cord
Preganglionic
sympathetic
fibers
ACTH
Adrenal
cortex
Adrenal
medulla
Mineralocorticoids
Short-term
stress response
Catecholamines
(epinephrine and
norepinephrine)
1. Increased heart rate
2. Increased blood pressure
3. Liver converts glycogen to
glucose and releases glucose
to blood
4. Dilation of bronchioles
5. Changes in blood flow
patterns, leading to increased
alertness and decreased
digestive and kidney activity
6. Increased metabolic rate
Glucocorticoids
Long-term stress response
1. Retention of sodium
and water by kidneys
2. Increased blood
volume and blood
pressure
1. Proteins and fats
converted to glucose
or broken down for
energy
2. Increased blood
sugar
3. Suppression of
immune system
Figure 9.13
Hormones of the Adrenal
Cortex
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Sex hormones
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Produced in the inner layer
Small amounts are made throughout life
Mostly androgens (male sex hormones/
testosterone) are made but some estrogens
(female sex hormones) are also formed
D. Adrenal Glands
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Adrenal cortex disorders
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Addison’s disease
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Results from hyposecretion of all adrenal cortex
hormones
Bronze skin tone, muscles are weak, burnout,
susceptibility to infection
Hyperaldosteronism
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May result from an ACTH-releasing tumor
Excess water and sodium are retained leading to high
blood pressure and edema (water-retention/ fluid
buildup)
D. Adrenal Glands
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Adrenal cortex disorders
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Cushing’s syndrome
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Results from a tumor in the middle cortical area of the
adrenal cortex
“Moon face,” “buffalo hump” on the upper back, high
blood pressure, hyperglycemia, weakening of bones,
depression
Masculinization
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Results from hypersecretion of sex hormones
Beard and male distribution of hair growth
D. Hormones of the Adrenal Medulla
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Produces two similar hormones/
neurotransmitters: (catecholamines)
1.
2.
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Epinephrine (Epi)-A.K.A adrenaline
Norepinephrine (NEpi)- A.K.A- noradrenaline
These hormones prepare the body to deal
with short-term stress (“fight or flight”) by:
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Increasing heart rate, blood pressure, blood
glucose levels
Dilating small passageways of lungs
Hormones of the Adrenal
Cortex
Figure 9.11
E. Pancreas (Pancreatic Islets)
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Controls how the body uses glucose (sugar)
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The pancreas is a mixed gland & has both
endocrine & exocrine functions
The pancreatic islets produce hormones:
1.
2.
Insulin— takes glu from blood; ↓ blood glu lvls
Glucagon— puts glu back in blood; ↑ glu lvls.
These hormones are antagonists (opposites) that
maintain blood sugar homeostasis
Pancreas
Pancreatic Islets
Figure 9.14a–b
Insulin-secreting
cells of the pancreas
activated; release
insulin into the
blood
Elevated
blood sugar
levels
Stimulus:
rising blood
glucose levels
(e.g., after
eating four
jelly doughnuts)
Uptake of glucose
from blood is enhanced in most
body cells
Liver takes up
glucose and stores
it as glycogen
Homeostasis: Normal blood glucose
levels (90 mg/100ml)
Blood glucose
levels decline
to set point;
stimulus for
insulin release
diminishes
Stimulus:
declining blood
glucose levels
(e.g., after
skipping a meal)
Low blood
sugar levels
Rising blood
glucose levels
return blood sugar
to homeostatic set
point; stimulus for
glucagon release
diminishes
Liver breaks down
glycogen stores and
releases glucose to
the blood
Glucagon-releasing
cells of pancreas
activated;
release glucagon
into blood; target
is the liver
Figure 9.15
F. Pineal Gland
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Found on the epithalamus of the
diencephalon of the brain
Secretes melatonin
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Helps establish the body’s wake/ sleep cycles
Believed to coordinate the hormones of fertility in
humans
Act as an antioxidant to help restore cells when u
sleep
G. Thymus Gland
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Located posterior to the sternum
Largest in infants & children; often atrophy in
adults.
Produces thymosin
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Matures some types of white blood cells
Important in developing the immune system to
fight infections by helping the body recognize &
reject germs
H. Gonads
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Ovaries
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Produce eggs
Produce two groups of steroid hormone
1.
2.
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Estrogens
Progesterone
Testes
1.
2.
Produce sperm
Produce androgens, such as testosterone
H. Hormones of the Ovaries
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Estrogens
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Stimulate the development of 2° female sex
characteristics
Mature female reproductive organs
With progesterone, estrogens also
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Promote breast development
Regulate menstrual cycle
H. Hormones of the Ovaries
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Progesterone
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Acts with estrogen to bring about the menstrual
cycle
Helps in the implantation of an embryo in the
uterus
Helps prepare breasts for lactation
H. Hormones of the Testes
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Produce several androgens (male sex
hormones)
Testosterone is the most important androgen
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Responsible for adult male 2° sex characteristics
Promotes growth & maturation of male
reproductive system
Required for sperm cell production
(spermatogenesis)
H. Endocrine Function of the
Placenta
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Produces hormones that maintain the
pregnancy
Some hormones play a part in the delivery of
the baby
Produces human chorionic gonadotropin
(hCG) in addition to estrogen, progesterone,
and other hormones
I. Other Hormone-Producing
Tissues and Organs
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Parts of the small intestine
Parts of the stomach
Kidneys
Heart
Many other areas have scattered endocrine
cells
I. Other Hormone-Producing
Tissues and Organs
Table 9.2 (1 of 2)
I. Other Hormone-Producing
Tissues and Organs
Table 9.2 (2 of 2)
J. Developmental Aspects of
the Endocrine System
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Most endocrine organs operate smoothly
until old age
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Menopause is brought about by lack of efficiency
of the ovaries
Problems associated with reduced estrogen are
common
GH production declines with age
Many endocrine glands decrease output with age