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QOD:
What are the functions of the
digestive system?
The Digestive System
Functions
Breaks down food into smallest
components for absorption into blood
– Proteins 
– Carbohydrates 
– Lipids 
Types
– Mechanical
– Chemical
Structures
Alimentary Canal
– Mouth
– Esophagus
– Stomach
– Intestines
Accessory Organs
– Pancreas
– Liver
– Gall bladder
The Digestive
System
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Your Mouth
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The Mouth
Mechanical digestion
– Teeth
– Tongue
Chemical digestion
– Salivary glands
– Salivary amylase
Esophagus
Digestion type?
Connects mouth to
stomach
– Peristalsis
Stomach
Structure: J-shaped pouch
– Cardiac sphinctor
– Pyloric Sphinctor
Mechanical digestion
– Smooth muscle
Chemical digestion
– Pepsin
Stomach
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The Small Intestines
First job: Chemical digestion with aid of
accessory organs
Pancreas
– Pancreatic amylase
– Trypsin
– Pancreatic lipase
– Nuclease
Liver/Gall Bladder
– Bile
Pancreas
& Liver
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Small Intestines Continued
Enzymes of the small intestines
– Maltase
– Sucrase
– Lactase
– Peptidase
– Nuclease
Small Intestines – Job 2
Structure: 3 main parts
– Duodenum
– Jejunum
– Ileum
Job 2 of Small Intestines: Absorption
Longest organ: about 6m
Contains villi
– Villi contain microvilli
Villi
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Large Intestines
Structure:
– Cecum
– Ascending Colon
– Transverse colon
– Descending colon
– Rectum and anus
Function:
– Re-absorption of water
– Synthesis of vitamins B and K
The Circulatory System
I. Function and Structure
Function:
– To send materials around your body through
the blood stream
Structures:
– Heart
– Blood vessels
– Blood
II. The Heart
Composed entirely of muscle
Pericardium
Myocardium
Right and Left side separated by the septum
Four chambers:
– Atria (Atrium)
– Ventricles
More Heart structures
Valves – prevent back-flow of blood
–
–
–
–
Tricuspid
Bicuspid/Mitral valve
Pulmonary valve
Aortic valve
III. Blood vessels
Arteries
– Arterioles
Veins
– Venules
Capillaries
IV. Circulation
Pulmonary circulation
Systemic circulation
– Coronary circulation
– Renal circulation
– Hepatic portal circulation
V. Pulmonary circulation
Oxygen-poor blood returns to the heart
through Superior vena cava and Inferior
vena cava  right atrium
Right atrium contracts: blood  tricuspid
valve  right ventricle
Ventricle contracts: blood pulmonary
valve  pulmonary arteries
Pulmonary circulation - continued
Blood taken to lungs to pick up oxygen and
drop off carbon dioxide
Oxygen rich blood returns to heart through
pulmonary veins  left atrium
Atrium contracts: blood  bicuspid valve 
left ventricle
•Ventricle contracts: blood  aortic
valve  aorta  systemic circulation
Pulmonary Circulation
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V. The Heartbeat
When a single cardiac muscle fiber is
stimulated, all fibers are stimulated and
network contracts as a unit
Impulse generated by sinoatrial node
– Cluster of cells in right atrium
– Called the “pacemaker”
– Generates atrial contraction
– Maintains rhythm of the heart beat
Heartbeat…continued
Signal from S-A node picked up by
atrioventricular node.
– Cluster of cells in the walls of the ventricles
– Generates ventricular contraction
Pacemaker
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VI. Blood Pressure
Force of blood on the walls of the arteries
Measured with a sphygmomanometer
Measurements:
– Systolic
– Diastolic
VII. Disorders of the Circulatory
System
Artherosclerosis
– Fatty deposits build up on walls of arteries
– Can obstruct flow of blood
– Can form clots
– Can lead to high blood pressure, stroke, or
heart attack
High blood pressure:
– Heart has to work harder
– Can weaken heart and blood vessels
Heart attack
– Blockage in coronary arteries deprives heart tissue of
oxygen
– Can lead to heart tissue death
Stroke
– Blockage in arteries in brain (clots), depriving brain of
oxygen
– Can lead to brain tissue death
The Respiratory System
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I. Structures and Function
Structure:
– Pharynx, Trachea, bronchi, alveoli, lungs
Function:
– Gas exchange: take in air and exchange
oxygen for carbon dioxide
II. Pathway of Air
Air is taken in through mouth and nose to
– Pharynx, passes the epiglottis to
– Larynx to
– Trachea to
– Bronchi to
– Bronchioles to
– Alveoli
Air Into Lungs
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III. Cleaning Air
Respiratory tract is lined with ciliated cells
that secrete mucus
– Mucus traps dirt/dust
– Cilia move dirt to your throat to be expelled or
swallowed
IV. Alveoli and Gas Exchange
Alveoli: air sacs in lungs where gas
exchange takes place
– Lie next to bed of capillaries
– Oxygen diffuses from alveoli into blood
– Carbon dioxide diffuses from blood into alveoli
Aveoli
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V. Mechanics of Breathing
Breathing is controlled by the diaphragm
– Inhale: Diaphragm contracts and flattens. Rib
cage rises. Chest expands
– Exhale: Diaphragm relaxes and becomes
dome-shaped. Rib cage lowers and chest
contracts.
– Creates a vacuum effect
Breathing
VI. Control of Breathing
Control center: medulla oblongata
– Part of brain stem
– Contains respiratory center
– Responds to carbon dioxide levels in blood
– Sends nerve impulses to diaphragm
The Urinary System
Kidneys
Removes
– Urea
– Mineral salts
– Water
Structure
– Cortex
– Medulla
– Renal pelvis
– Renal arteries/veins
Kidneys
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The Nephron
Functional unit of the kidneys
Structures:
– Bowman’s capsule
– Glomerulus
– Renal tubule
Proximal convoluted tubule
Loop of Henle
Distal convoluted tubule
Filtrates blood by nutrient exchange
Nephron
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Filtration, Reabsorption and
Secretion
Filtration
– Materials forced out of blood into Bowman’s capsule
– Out: water, urea glucose, vitamins, salts
Reabsorption
– Active transport of needed materials out of filtrate
back into blood (Water, Glucose, Minerals
– Mostly in proximal convoluted tubule
Secretion
– Some materials added to filtrate in distal convoluted
tubule
Formation of Urine
Urine formed from remaining material in
distal convoluted tubule
Urine from several nephrons flow into
collecting duct
More water reabsorbed here
Loop of Henle promotes reabsorption of
water
Elimination of Urine
From collecting ducts
 Ureter
 Urinary bladder
 Urethra
The Nervous System
I. Structure and Function
Function:
– To communicate messages throughout your
body using impulses
Structures:
– Neurons are the basic unit of the nervous
system
II. The Neuron
Three categories of neurons
– Sensory
– Motor
– Interneurons
III. Parts of a Typical Neuron
Dendrites
Cell body
– Nucleus
Axon
– Axonal hillock
– Myelin sheath
– Nodes of Ranvier
Axon terminals (endings)
– Synaptic end bulbs
Fig. 9.04
IV. Relaying an Impulse
Receptors in skin sense a stimulus
Sensory neurons transmit the message
Message is interpreted by the brain
Brain sends a response through motor
neurons
Motor neurons relay that message to
muscles to act in response
V. Neurons at Rest
High K+ ions inside the cell, high Na+ ions
outside cell
Na+/K+ pump maintains this difference
Outside of the membrane has a positive
charge, inside has a negative charge
Called a polarized membrane
VI. Impulse Transmission
Membrane at rest is polarized
– High K+ ions inside cell
– High Na+ outside cell
– Na+/K+ pump
– Positive charge outside the cell
– Negative charge inside the cell
A stimulation sets off an action potential
– Na+ gates open and it rushes inside cell
This depolarizes the cell (brings it close to neutral charge)
– After a delay, Na+ gates close and K+ gates open and
K+ rushes out
This repolarizes cell to send cell back to rest.
– This action is propagated down the neuron
The Impulse…animated.
VII. The Synapse
Synapse – the junction between neurons
When an impulse reaches the end of one
neuron:
– Neurotransmitters are released from vessicles
inside the synaptic end bulbs
– NT’s “jump” from one neuron to the next,
stimulating an action potential down that
neuron
The Synapse…animated!
VIII. Divisions of the Nervous
System
Central Nervous System
Peripheral Nervous System
– Somatic Nervous system
– Autonomic Nervous System
Sympathetic Nervous System
Parasympathetic Nervous System
IX. The CNS
Control Center of body
Coordinates all body activities
Include brain and spinal cord
X. The Brain
Cerebrum
– Separated into two hemispheres, connected
by bundles of nerves
– Outer portion = cerebral cortex
– Responsible for higher thinking, memory,
reasoning, speaking, etc.
Cerebellum
– Located in back
– Responsible for coordination, balance and
posture
Brain Stem
– Located under cerebrum
– Connects brain to spinal cord
3 parts to brain stem
– Medulla oblongata: Breathing and heart rate
– Pons
– Midbrain
XI. The PNS
Somatic Nervous System
– Responsible for voluntary movements
Autonomic nervous system
– Responsible for involuntary movements
Divisions of the Autonomic NS
Sympathetic
– Controls internal structures in times of stress
(“Fight or Flight” response)
– Releases epinephrine and norepinephrine
Parasympathetic
– Controls body at times of rest