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Lecture Outline – Ch. 46: Endocrine System
I.
Hormone overview
II. Hypothalamus &
Pituitary
III. Thyroid
IV. Parathyroid
V. Pancreas
VI. Ovaries &
VII. Adrenals
Testes
Hormones in Animals
Hormones influence growth, development, mood…
Hormones in Animals
Types of Glands:
1) Exocrine Glands:
• Release substances outside
the body via ducts
• Sweat glands
• Salivary glands
• Mammary glands
2) Endocrine Glands:
• Release substances within the body via bloodstream
• Ductless
Hormones in Animals
Hypothalamus
Pineal gland
Parathyroid glands (on posterior
surface of thyroid gland)
Pituitary gland
Heart
Thyroid gland
Kidneys
Thymus gland
Digestive tract
Adrenal glands
(one at each kidney)
Pancreas islet cells
Gonads
testis
ovary
Hormones in Animals
Hormones released in response to stimuli
Travel through the circulatory system to reach target cells
A cell is affected only if it has receptors specific to that hormone
Most hormones are controlled by negative feedback,
which inhibits further release
In a few cases, positive feedback is used to amplify
hormone levels
Hormones in Animals
General Classes of Hormones:
Hypothalamus & Pituitary
Hypothalamus:
• Region of brain
• Collection of
neurosecretory cells
• Make and store
peptide hormones
• Secretes to anterior
pituitary via portal system
Hypothalamus & Pituitary
Pituitary Gland:
hypothalamus
• Pea-sized gland;
hangs from hypothalamus
• Master regulation/
coordination center
• Controlled by hypothalamus:
• Release hormones
• Inhibit hormones
pituitary
(anterior
lobe)
pituitary
(posterior lobe)
Pituitary
Anterior Pituitary (adenohypophysis):
• True gland
• Releases hormones that affect other glands
•
•
•
•
Follicle-stimulating Hormone (FSH) - egg / sperm production
Luteinizing Hormone (LH) - sex hormone secretion
Thyroid-stimulating Hormone (TSH) - hormones from thyroid
Adrenocorticotropic Hormone (ACTH) - hormones from adrenal cortex
Indirect (stimulate other glands)
Direct (stimulate tissues)
• Prolactin - mammary gland development
• Melanocyte-stimulating Hormone (MSH) - synthesis of melanin (skin pigment)
• Growth Hormone (GH) - growth of body cells
Pituitary
Goiters are caused
by a lack of iodine
in the diet
Pituitary
“Tom Thumb”
(Charles Stratton)
Robert Wadlow
8’11”
Pituitary
Posterior Pituitary (Neurohypophysis):
• Extension of cells in hypothalamus
• Releases two hormones
hypothalamus
• Contains neurosecretory cells
with bodies in hypothalamus
• Antidiuretic Hormone (ADH)
• water conservation (kidneys)
• Oxytocin
• Contraction of uterus muscles
• “Milk letdown” reflex
• Maternal behaviors
pituitary
(posterior lobe)
Thyroid Gland
Thyroid:
• Wraps around the front of the larynx in the neck
• Regulates metabolism & growth
• Controlled by TSH from ant. pit. (Thyroid-Stimulating Hormone)
• Secretes Thyroxine
(T4 - Amino Acid Hormone):
• Iodine required for
T4 production
larynx
thyroid gland
esophagus
parathyroid
glands
trachea
Parathyroid Gland
Parathyroid:
• Imbedded in thyroid gland
• Regulates blood calcium levels
• Secretes Parathyroid
hormone (PTH)
larynx
low blood calcium
normal blood
calcium
release
PTH
calcium release
from bone
thyroid gland
esophagus
parathyroid
glands
trachea
Pancreas
Pancreas:
• Both exocrine and endocrine:
Exocrine = Digestive enzymes
(small intestine)
Endocrine = Hormones
regulating blood sugar
Insulin
Reduces blood sugar
(cells uptake glucose)
Glucagon
Increases blood sugar
(cells release glucose)
Type I Diabetes: lack β cells
Type II Diabetes: low #s
insulin receptors
Ovaries & Testes
Sex Organs:
1) Ovaries (Female):
• Estrogen / Progesterone
(steroid hormones)
2) Testes (Male):
• Testosterone (steroid hormone)
• Controlled by FSH and LH from ant. pit.
Follicle-stimulating Hormone
Luteinizing Hormone
• Functions:
• Early development (brain development)
• Puberty
• Menstrual cycle; pregnancy
Adrenal Glands
1) Adrenal Medulla (center of gland)
• Epinephrine (Adrenaline)/Norepinephrine (Amino acid hormones):
• Prepare for “fight or flight”
• Controlled by nervous system
adrenal gland
Adrenal medulla secretes
epinephrine and norepinephrine.
kidney
Adrenal Glands
2) Adrenal Cortex (outside of gland)
• Glucocorticoids (Steroid hormones)
• Released in stressful situations
• Controlled by ACTH (ant. pit.)
• Testosterone
adrenal gland
Adrenal cortex
glucocorticoids,
aldosterone, and
testosterone.
kidney
Congenital adrenal
hyperplasia (CAH)
Other Sources of Hormones
1) Most Cells in Body
• Prostaglandins (Fatty Acid Hormones): Ibuprofen
• Target = Nearby cells
• Function is varied (Inflammation; Uterine contractors)
2) Pineal Gland
• Melatonin (Amino Acid Hormone):
• Regulate sleep/wake cycle; reproductive cycle (non-humans)
3) Thymus
• Thymosin: Stimulates white blood cell production
4) Kidneys
• Erythropoietin: Regulates red blood cell production
Other Sources of Hormones
5) Adipose Cells:
• Leptin: Regulates body fat
Leptin tells body
how much fat is
stored and
decreases appetite
Link between
obesity and leptin
sensitivity
leptin-deficient mouse
normal mouse
Hypothalamus
produces ADH and oxytocin, regulatory
hormones for anterior pituitary
A Good Slide to Know 
Pineal gland
melatonin
Pituitary gland
anterior pituitary:
ACTH, TSH, GH, PRL, FSH, LH, and MSH
posterior pituitary:
releases oxytocin and ADH
Parathyroid glands (on posterior
surface of thyroid gland)
parathyroid hormone
Thyroid gland
thyroxine, calcitonin
Kidneys
erythropoietin
Thymus gland
(atrophies during adulthood)
Adrenal glands (one at each kidney)
medulla:
epinephrine, norepinephrine
cortex:
glucocorticoids (cortisol), aldosterone,
testosterone
Pancreas islet cells
insulin, glucagon
Gonads
testes (male):
androgens, especially testosterone
ovaries (female):
estrogens, progesterone
testis
ovary
Self-Check:
Pituitary
Anterior
Posterior
Kidney
Pancreas
Thyroid
Gonads
Adrenal
Medulla
Adrenal
Cortex
Thought Questions:
What allows animal movement in response to stimuli?
Lecture Outline – Ch.47: Muscular & Skeletal
I.
Skeletal Muscles
A. Structure
B. Contraction
C. Nerve Input
II. Skeletal Systems
III. Vertebrate Skeletons
A.
Support
B.
Protection
C.
Movement
D.
Joints
Muscular and skeletal systems
Muscles power
movement by
contracting
Bones provide
framework for
muscles
Muscles
Muscle Tissue (Muscle = “little mouse”):
• Exerts force by
contracting
Movement due to actin
microfilaments and
myosin strands
Slide past one another,
change cell shape
Transformation
Chemical energy (ATP)
Mechanical Energy
Muscles
Types of Muscle Tissue:
Skeletal Muscle
Cardiac Muscle
Smooth Muscle
Striated
Striated
Not Striated
Function
Skeletal
Movement
Pump Blood
Move Substances
Through Hollow Tubes
Control
Voluntary
Involuntary
Involuntary
Appearance
Skeletal Muscles
tendon (to bone)
connective tissue
nerve and
blood vessels
bundle of
muscle cells
Skeletal muscle
Muscle fiber
(muscle cell)
Myofibril
(contains thin sand thick
filaments)
• Humans > 700 unique skeletal muscles
• Muscle connected to bones by tendons
Skeletal Muscles
Cross section of fiber
muscle fiber
T tubules
sarcoplasmic
reticulum
myofibril
- Each muscle cell runs length
of muscle
plasma
membrane
- Multinucleate
- Made up of myofibrils
- Each myofibril surrounded by
Contractile cylinders of actin
sarcoplasmic reticulum
and myosin
- Fluid with high calcium levels
- T-tubules in plasma membrane relay signals
Skeletal Muscles
Myofibril sarcomere
myofibril
Z lines
thin filament
Myofibrils of “thick”
and “thin” filaments.
Each filament is made
of protein strands.
thick filament
Filaments arranged in sarcomeres
Separated by Z-lines of fibrous protein
Skeletal Muscles
Thick and thin filaments
thin filament
myosin heads
thick filament
(myosin)
troponin
accessory
proteins
tropomyosin
actin
Thick filaments: made mostly of myosin, have
small moveable “heads”
Thin filaments: primarily actin, have points to
which the myosin heads temporarily attach
Skeletal Muscles
thin filament
binding sites
myosin head
Each actin subunit has
binding site for myosin
head
thick filament
Contraction exposes binding
sites, allowing filaments to
bind to one another
ATP
ADP
Myosin heads then
repeatedly bend, pull,
release, and reattach
(using ATP-energy)
Skeletal Muscles
Sliding filaments shorten each sarcomere
Skeletal Muscles
Neuromuscular junctions between axons and fibers
All or nothing response:
Skeletal muscle excited
All sarcomeres respond
axon of motor neuron
synaptic terminal
synaptic vesicles
postsynaptic
membrane
Skeletal Muscles
Strength of Muscle Contraction  # of Fibers Stimulated
Motor Unit:
A single motor
neuron and all the
muscle fibers
innervated by it
Skeletal Muscles
Action potential travels through T-channels and opens
Ca++ channels in sarcoplasmic reticulum
These ions allow binding of thin and thick fibers
Ca++ is pumped back out after action potential ends
Unless you’re dead
Skeletal Muscles
You cannot add
muscle fibers
You can add more
myofibrils
bundle of
muscle cells
muscle
Muscle fiber Myofibril
(muscle cell)
Skeletal Muscles
Slow-twitch fibers:
Lots of myoglobin (provides O2) and mitochondria.
Fast-twitch fibers:
Less myoglobin and mitochondria
More able to use glycolysis to quickly produce ATP
Different people (& muscles) – different ratios of two fibers.
80% slow twitch
50% slow
50% fast
80% fast twitch
Skeletal System
A supporting framework for the body
Skeletal System
Hydrostatic skeleton
Fluid provides support
Muscles contract and move fluid
Skeletal System
Exoskeleton
Hard shells cover outside of body
Muscles contract and move frame
at joints
Skeletal System
Endoskeleton
Internal framework - least common
skeleton type
Muscles contract and move frame at
joints
Vertebrate Skeletons
Support body
Protect fragile organs
Allow movement
Produce blood cells
Store minerals
Transmit vibrations (hearing)
Vertebrate Skeletons
Bodily Support
Axial skeleton- main body axis
Appendicular skeleton- appendages and supporting structures
Vertebrate Skeletons
Protection
Skull- brain
Vertebral column- nerve cord
Ribcage – soft internal organs
Vertebrate Skeletons
Movement
Three skeletal connective tissues
Cartilage- tough, but flexible
Skeletal development
Cushioning joints
Ligaments- tough
Connect bones at joints
Bone- tough and rigid
bone
cartilage
Vertebrate Skeletons
Bone = hardened by deposits of calcium phosphate
Compact bone (exterior) is dense and strong
Spongy bone (interior) is lightweight and porous
cartilage
chondrocytes
osteon
spongy
bone
(contains
marrow)
collagen
matrix
compact
bone
osteocytes
capillary
central
canal
Vertebrate Skeletons
Blood cell production
Red blood cells, white
blood cells, platelets
Produced by bone marrow
Leukemia: cancer of the bone
marrow, leads to decreased
blood cells
Mineral storage
Bones store and release
calcium and phosphorous to
maintain constant
concentrations
Vertebrate Skeletons
Bone cells work together
Osteoclasts- bone dissolving cells
Dissolve cartilage
Osteoblasts- bone forming cells
Replace cartilage with bone
Osteocytes- mature bone cells
Cannot produce more bone,
but can remodel it
Vertebrate Skeletons
Bone remodeling
Can alter skeletal shape in response to use
Osteoclasts create channels invaded by
capillaries and osteoblasts to form
new bone
Osteoporosis is when activity of
osteoclasts outstrips osteoblasts
Normal bone section
Osteoporosis
Vertebrate Skeletons
Movement of bones
Joints are where two bones meet
Lubricated by cartilage
Attached by ligaments
Muscles are attached to bone on
either side of the joint
Attached by tendons
Ligaments
Origin - attachment to still bone
Insertion - attachment to moving
bone
Vertebrate Skeletons
Movement
Antagonistic muscle pairs pull the
bone in opposite directs when
they contract
Flexor muscle bends the joint
Extensor muscle straightens it
Vertebrate Skeletons
Joints
Immovable- joints do not move (skull)
Ball & Socket – rotational movement in all
directions (hip, shoulder)
Hinge – extend or retract an appendage in one
direction (knee)
Gliding – permit sliding of two surfaces (spine)
Combination – utilize more than one of above (jaw)
Lecture 11 Summary
1. Overview (Ch. 46)
Gland types
Classes of hormones
2. Hormones (Ch. 46)
Hypothalamus & Pituitary (anterior and posterior)
Thyroid & Parathyroid
Pancreas
Gonads
Adrenals
3. Muscles (Ch. 47)
Muscle cell types
Structure of muscles
Contraction/relaxation
4. Skeleton (Ch. 47)
Skeleton types
Cell types and building bone
- Joints and attachments