Transcript Villi: Structure and Fun!(ction)

Villi: Structure and
Fun!(ction)
By: Guinea McGinnis, Reese’s
Reser, Pikachu Bui, Tiny Garcia
How it works

The lining of the small intestine is characterized by numerous
circular folds called “plicae circulares.” The plicae are lined with
fingerlike villi. From a cross-sectional view, the villus contains a
network of capillaries which surround a specialized lymphatic vessel
known as a lacteal. The epithelium of an intestinal villus consists of
columnar cells which are covered with microvilli. This succession of
folds and projections increases the surface of the intestinal lining for
efficient absorption. Carbohydrates are absorbed by the villi and
then enter the capillary. Fat molecules are digested and absorbed
into the epithelial cells of the villus. The fats are formed into clusters
called chylomicrons which pass into the lacteal. Lymph carries
chylomicrons away from the villus. Proteins are broken down first
into peptides, then into amino acids. These are absorbed into the
villi, then into the capillary.
What it looks like
Magic School Bus
 http://www.youtube.com/watch?v=zJieJ3_
R2Do
 (3:48)
Neuron Anatomy and Neural
Communication
Neurons
Dendrites
Cell Body
Myelin
Sheath
Axon of another
neuron
Axon
Dendrites of
another neuron
Neural Anatomy
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Dendrite
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the bushy, branching extensions of a
neuron that receive messages and
conduct impulses toward the cell body
Axon
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the extension of a neuron, ending in
branching terminal fibers, through which
messages are sent to other neurons or to
muscles or glands
Neural Anatomy and
communication
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Synapse
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junction between the axon tip of the sending
neuron and the dendrite or cell body of the
receiving neuron
tiny gap at this junction is called the synaptic
gap or cleft
Synapse movie
Specific Parts: The Neuron
Structure
Specific Parts: The Neuron
Function
1.
3.
2.
Neurons = 3 functions: Reception, Conduction, Transmission
Action Potential
When dendrites stimulated, the delicate
balance is altered
Membrane breaks down
Positively charged ions rush in
(depolarization)
Charge = less negative
Causes release of chemicals from
terminal buttons
Relay Race
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Action Potential starts at dendrite
 Through cell body
 Down Axon
 Axon Terminals
• How does it get to the next cell’s dendrites?
• Neurons don’t touch
 Synapse = millionth inch gap
 In synapse = vesicles w/ neurotransmitters
• Chemical messengers that transmit info
Communication
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Impulse releases
neurotransmitter from
vesicles
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Neurotransmitter
enters synaptic gap
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Neurotransmitter
binds to receptors on
the receiving neuron
Myelin Sheath
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Fatty material made by glial cells
Insulates the axon
Allows for rapid movement of
electrical impulses along axon
Nodes of Ranvier: gaps in myelin sheath
where action potentials are transmitted
Multiple sclerosis is a breakdown of
myelin sheath
Speed of neural impulse Ranges from 2 –
200+ mph
Myelinization clip
Myelin conduction clip
Neurotransmitters
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chemical messengers that traverse the
synaptic gaps between neurons
when released by the sending neuron,
neurotransmitters travel across the
synapse and bind to receptor sites on
the receiving neuron, thereby
influencing whether it will generate a
neural impulse
Neurotransmitters (>60)
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Acetylcholine (ACh)
st substance identified as NT
 1
 Links motor neurons and muscles (contract or relax)
• e.g. curare vs black widow spider
 Also involved in memory, learning, sleep, dreaming
(acetylcholine movie)
Endorphins (the brain’s own morphine)
 1973 injected rats with morphine
 Bound like NTs
 Brain had receptors for exogenous substance?
• Brain must produce its own morphine
• Released during pain and discomfort
Artery
White blood cells
Platelets
Red blood cells
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RBC Structure And Function
Have no organelles or nuclei
 Hemoglobin – oxygen
carrying protein
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Each RBC has about 280
million hemoglobin
molecules
Biconcave shape – 30%
more surface area
• Deliver O2
• Remove metabolic wastes
• Maintain temperature, pH, and fluid volume
• Protection from blood loss- platelets
• Prevent infection- antibodies and WBC
• Transport hormones
Erythrocytes
Erythrocytes – Red Blood Cells
(RBCs)
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Oxygen-transporting cells
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Most numerous of the formed elements
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7.5 µm in diameter (diameter of capillary 8 – 10µm)
Females: 4.3 – 5.2 million cells/cubic millimeter
Males: 5.2 – 5.8 million cells/cubic millimeter
Made in the red bone marrow in long bones,
cranial bones, ribs, sternum, and vertebrae
 Average lifespan 100 – 120 days
Erythrocyte7.5m in dia
 Anucleate- so can't reproduce; however, repro
in red bone marrow
 Hematopoiesis- production of RBC
 Function- transport respiratory gases
 Hemoglobin- quaternary structure, 2  chains
and 2  chains
 Lack mitochondria. Why?
 1 RBC contains 280 million hemoglobin
molecules
 Men- 5 million cells/mm3
 Women- 4.5 million cells/mm3
 Life span 100-120 days and then destroyed in
spleen (RBC graveyard)
Blood Cell Production
Leukocytes – White Blood Cells
(WBCs)
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Protect the body from infectious microorganisms
4,800 – 11,000/cubic millimeter
Function outside the bloodstream in loose
connective tissue
Diapedesis – circulating leukocytes leave the
capillaries
WBCs have a nucleus and are larger than RBCs
Most produced in bone marrow
Lifespan of 12 hours to several years
Leukocytes – White Blood Cells (WBCs)
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Two types of
leukocytes
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Granulocytes
Agranulocytes
Differential WBC
Count
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Never
Let
Monkeys
Eat
Bananas
Figure 17.5
White Blood Cells
Type Of White Blood
Cells
% By Volume Of WBC
Description
Function
Neutrophils
60 – 70 %
Nucleus has many
interconnected lobes; blue
granules
Phagocytize and destory
bacteria; most numerous
WBC
Eosinophils
2–4%
Nucleus has bilobed nuclei;
red or yellow granules
containing digestive
enzymes
Play a role in ending allergic
reactions
<1%
Bilobed nuclei hidden by
large purple granules full of
chemical mediators of
inflammation
Function in inflammation
medication; similar in
function to mast cells
20 – 25 %
Dense, purple staining,
round nucleus; little
cytoplasm
the most important cells of
the immune system;
effective in fighting infectious
organisms; act against a
specific foreign molecule
(antigen)
4–8%
Largest leukocyte; kidney
shaped nucleus
Transform into
macrophages; phagocytic
cells
Basophils
Lymphocytes (B Cells
and T Cells)
Monocytes
Granulocytes
 Neutrophils
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– most numerous WBC
Phagocytize and destroy bacteria
Nucleus – has two to six lobes
Granules pick up acidic and basic stains
Figure 17.4a
Granulocytes
 Eosinophils
– compose 1 – 4% of all
WBCs
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Play roles in ending allergic reactions,
parasitic infections
Figure 17.4b
Granulocytes
 Basophils
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– about 0.5% of all leukocytes
Nucleus – usually two lobes
Granules secrete histamines
Function in inflammation mediation, similar in
function to mast cells
Agranulocytes
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Lymphocytes – compose 20 – 45% of WBCs
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The most important cells of the immune system
Nucleus – stains dark purple
Effective in fighting infectious organisms
Act against a specific foreign molecule (antigen)
Two main classes of lymphocyte
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T cells – attack foreign cells directly
B cells – multiply to become plasma cells that secrete
antibodies
Figure 17.4d
Agranulocytes
 Monocytes
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– compose 4–8% of WBCs
The largest leukocytes
Nucleus – kidney shaped
Transform into macrophages
• Phagocytic cells
Figure 17.4e
A rod cell (upper) and a cone cell
From which direction would light come?
 Retina
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Several
layers of
Rods
Cones
cells in inner
More abundant Less abundant
surface of
choroid
Center of
Periphery of
Contains
retina
retina
photorecepto
Black & White
Color
rs - Rods &
Poor definition High resolution
Cones
Night Vision
Daytime
Muscle Tissue
 Alternating
contraction and
relaxation of cells
 Chemical
energy
changed into
mechanical
energy
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3 Types of Muscle Tissue
 Skeletal
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muscle
attaches to bone, skin or fascia
striated with light & dark bands visible with
scope
voluntary control of contraction & relaxation
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3 Types of Muscle Tissue
 Cardiac
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muscle
striated in appearance
involuntary control
autorhythmic because of built in pacemaker
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3 Types of Muscle Tissue
 Smooth
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muscle
attached to hair follicles in skin
in walls of hollow organs -- blood vessels & GI
nonstriated in appearance
involuntary
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Functions of Muscle Tissue
 Producing
body movements
 Stabilizing body positions
 Regulating organ volumes
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bands of smooth muscle called sphincters
 Movement
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blood, lymph, urine, air, food and fluids, sperm
 Producing

of substances within the body
heat
involuntary contractions of skeletal muscle
(shivering)
44
Connective Tissue
Components
45
Nerve and Blood Supply
 Each
skeletal muscle is supplied by a nerve,
artery and two veins.
 Each motor neuron supplies multiple muscle
cells (neuromuscular junction)
 Each muscle cell is supplied by one motor
neuron terminal branch and is in contact with
one or two capillaries.
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nerve fibers & capillaries are found in the
endomysium between individual cells
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Fusion of Myoblasts into Muscle Fibers
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Every mature muscle cell developed from 100
myoblasts that fuse together in the fetus.
(multinucleated)
 Mature muscle cells can not divide
 Muscle growth is a result of cellular enlargement &
not cell division
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Two Types of Smooth Muscle
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Visceral (single-unit)
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in the walls of hollow
viscera & small BV
autorhythmic
gap junctions cause
fibers to contract in
unison
Multiunit
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individual fibers with
own motor neuron
ending
found in large arteries,
large airways, arrector
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Excitation - Contraction Coupling
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All the steps that occur from the muscle action
potential reaching the T tubule to contraction of the
muscle fiber.
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