RESPIRATORY, CIRCULATORY, and RESPIRATORY, CIRCULATORY, and EXCRETION SYSTEMEXCRETION SYSTEM

A.A. The Respiratory SystemThe Respiratory System

I.I. Passageways and LungsPassageways and Lungs Your respiratory system is made of a Your respiratory system is made of a

pair of lungs and a series of pathways pair of lungs and a series of pathways (nasal passageway, throat, windpipe, (nasal passageway, throat, windpipe, and bronchi)and bronchi)

Respiration is the process of gas Respiration is the process of gas exchangeexchange

Respiration includes all of the Respiration includes all of the mechanisms involved in getting oxygen mechanisms involved in getting oxygen (O(O22) to the cells of your body and ) to the cells of your body and getting rid of carbon dioxide (COgetting rid of carbon dioxide (CO22))

Respiratory System Respiratory System ComponentsComponents

The path air takesThe path air takes The first step of respiration is taking air into The first step of respiration is taking air into

your body through your nose or mouth.your body through your nose or mouth.

Air flows into the pharynx, or throat, passes Air flows into the pharynx, or throat, passes the epiglottis, and moves through the larynx.the epiglottis, and moves through the larynx.

It then travels down the windpipe, or It then travels down the windpipe, or trachea, which leads to the bronchi into the trachea, which leads to the bronchi into the lungs.lungs.

Reminder:Reminder: When you swallow food, the When you swallow food, the epiglottis covers the entrance to the trachea, epiglottis covers the entrance to the trachea, which prevents food from getting into the air which prevents food from getting into the air passages.passages.

Cleaning dirty airCleaning dirty air To prevent foreign particles from reaching To prevent foreign particles from reaching

the lungs, the nasal cavity, trachea, and the lungs, the nasal cavity, trachea, and bronchi are lined with ciliated cells that bronchi are lined with ciliated cells that secrete mucus.secrete mucus.

The cilia constantly beat upward in the The cilia constantly beat upward in the direction of your throat, where foreign direction of your throat, where foreign material can be swallowed or expelled by material can be swallowed or expelled by coughing or sneezing.coughing or sneezing.

Alveoli: The place of gas exchangeAlveoli: The place of gas exchange Each bronchus branches into bronchioles, Each bronchus branches into bronchioles,

which in turn branch into numerous which in turn branch into numerous microscopic tubules that eventually open microscopic tubules that eventually open into thousands of thin-walled sacs called into thousands of thin-walled sacs called alveoli.alveoli.

Alveoli:Alveoli: sacs in the lungs where oxygen sacs in the lungs where oxygen diffuses into the blood and carbon dioxide diffuses into the blood and carbon dioxide diffuses into the airdiffuses into the air

The clusters of alveoli are surrounded by The clusters of alveoli are surrounded by networks of tiny blood vessels (capillaries).networks of tiny blood vessels (capillaries).

AlveoliAlveoli

Blood in the capillaries have come from the Blood in the capillaries have come from the cells of the body and contains wastes from cells of the body and contains wastes from cellular respiration.cellular respiration.

Diffusion of gases takes place easily because Diffusion of gases takes place easily because the wall of each alveolus, and the walls of the the wall of each alveolus, and the walls of the capillaries, are only one cell thick.capillaries, are only one cell thick.

External respiration involves the exchange of External respiration involves the exchange of oxygen or carbon dioxide between the air in oxygen or carbon dioxide between the air in the alveoli and the blood that circulates the alveoli and the blood that circulates through the walls of the alveoli.through the walls of the alveoli.

Gas Exchange in AlveoliGas Exchange in Alveoli

Blood transport of gasesBlood transport of gases Once oxygen from the air diffuses into the blood Once oxygen from the air diffuses into the blood

vessels surrounding the alveoli, it is pumped by vessels surrounding the alveoli, it is pumped by the heart to the body cells, where it is used for the heart to the body cells, where it is used for cellular respiration.cellular respiration.

Carbon dioxide (waste product of cellular Carbon dioxide (waste product of cellular respiration) diffuses into the blood, which is respiration) diffuses into the blood, which is carried back to the lungs.carried back to the lungs.

The blood that comes to the alveoli from the The blood that comes to the alveoli from the body’s cells is high in carbon dioxide and low in body’s cells is high in carbon dioxide and low in oxygen.oxygen.

Carbon dioxide from the body diffuses from the Carbon dioxide from the body diffuses from the blood into the air spaces in the alveoli.blood into the air spaces in the alveoli.

During exhalation (breathing out), carbon dioxide During exhalation (breathing out), carbon dioxide is removed from your body and at the same time is removed from your body and at the same time oxygen diffuses from the air in the alveoli into the oxygen diffuses from the air in the alveoli into the blood, making the blood rich in oxygen.blood, making the blood rich in oxygen.

Transport of GasesTransport of Gases

II.II. The Mechanics of BreathingThe Mechanics of Breathing The action of your diaphragm and the muscles The action of your diaphragm and the muscles

between your ribs enable you to breathe in and between your ribs enable you to breathe in and out.out.

When you inhale, the muscles between your When you inhale, the muscles between your ribs contract, and your rib cage rises and at the ribs contract, and your rib cage rises and at the same time, the diaphragm muscle contracts, same time, the diaphragm muscle contracts, becomes flattened, and moves lower in the becomes flattened, and moves lower in the chest cavity.chest cavity.

These actions increase the space in the chest These actions increase the space in the chest cavity, which creates a slight vacuum.cavity, which creates a slight vacuum.

Air rushes into your lungs because the air Air rushes into your lungs because the air pressure outside your body is greater than the pressure outside your body is greater than the air pressure inside your lungs.air pressure inside your lungs.

When you exhale, the muscles between When you exhale, the muscles between your ribs relax, and your ribs drop down in your ribs relax, and your ribs drop down in the chest cavity, and your diaphragm the chest cavity, and your diaphragm relaxes, returning to its resting position.relaxes, returning to its resting position.

The relaxation of these muscles decreases The relaxation of these muscles decreases the volume of the chest cavity and forces the volume of the chest cavity and forces most of the air out of the alveoli.most of the air out of the alveoli.

The alveoli still contain a small amount of The alveoli still contain a small amount of air after you exhale.air after you exhale.

Breathing In and OutBreathing In and Out

III.III. Control of RespirationControl of Respiration Breathing is usually an involuntary process.Breathing is usually an involuntary process.

It is partially controlled by an internal feedback It is partially controlled by an internal feedback mechanism that involves signals being sent to mechanism that involves signals being sent to the medulla oblongata (maintains homeostasis) the medulla oblongata (maintains homeostasis) about the chemistry of your blood.about the chemistry of your blood.

It responds to higher levels of carbon dioxide in It responds to higher levels of carbon dioxide in your blood by sending nerve signals to the rib your blood by sending nerve signals to the rib muscles and diaphragm.muscles and diaphragm.

The nerve signals cause these muscles to The nerve signals cause these muscles to contract, and you inhale.contract, and you inhale.

When breathing becomes more rapid, a more When breathing becomes more rapid, a more rapid exchange of gases between air and blood rapid exchange of gases between air and blood occurs.occurs.

B.B. The Circulatory SystemThe Circulatory System

I.I. Your Blood: Fluid TransportYour Blood: Fluid Transport Your blood is composed of fluid, cells, and Your blood is composed of fluid, cells, and

fragments of cells.fragments of cells.

The fluid portion of your blood is called plasma.The fluid portion of your blood is called plasma.

Plasma:Plasma: fluid portion of the blood that makes fluid portion of the blood that makes up about 55 percent of total volume of the up about 55 percent of total volume of the blood and contains proteins.blood and contains proteins.

Plasma transports red blood cells, white blood Plasma transports red blood cells, white blood cells, platelets, nutrients, enzymes, hormones, cells, platelets, nutrients, enzymes, hormones, gases, and inorganic salts.gases, and inorganic salts.

PlasmaPlasma

Red blood cells: Oxygen CarriersRed blood cells: Oxygen Carriers Red blood cells are disk-shaped cells that carry Red blood cells are disk-shaped cells that carry

oxygen to body cells.oxygen to body cells.

Red blood cells make up 44 percent of the total Red blood cells make up 44 percent of the total volume of your blood, and are produced in the red volume of your blood, and are produced in the red bone marrow of your ribs, humerus, femur, bone marrow of your ribs, humerus, femur, sternum, and other long bone.sternum, and other long bone.

Red blood cells remain active in the blood stream Red blood cells remain active in the blood stream for about 120 days, and then they break down for about 120 days, and then they break down and are removed as waste.and are removed as waste.

Old red blood cells are destroyed in your spleen, Old red blood cells are destroyed in your spleen, and organ of your lymphatic system, and in your and organ of your lymphatic system, and in your liver.liver.

Red blood cells do not have a nucleus.Red blood cells do not have a nucleus.

Red Blood CellsRed Blood Cells

Oxygen in the bloodOxygen in the blood Red blood cells have an iron-containing protein Red blood cells have an iron-containing protein

molecule called hemoglobin.molecule called hemoglobin.

HemoglobinHemoglobin: iron-containing protein molecule in : iron-containing protein molecule in red blood cells that bind to oxygen and carries it red blood cells that bind to oxygen and carries it form the lungs to the body’s cellsform the lungs to the body’s cells

Oxygen becomes loosely bound to the Oxygen becomes loosely bound to the hemoglobin in blood cells that have entered the hemoglobin in blood cells that have entered the lungs.lungs.

These oxygenated blood cells carry oxygen form These oxygenated blood cells carry oxygen form the lungs to the body’s cells.the lungs to the body’s cells.

As blood passes through body tissues with low As blood passes through body tissues with low oxygen concentrations, oxygen is released from oxygen concentrations, oxygen is released from the hemoglobin and diffuses into the tissues.the hemoglobin and diffuses into the tissues.

HemoglobinHemoglobin

Carbon dioxide in the bloodCarbon dioxide in the blood Hemoglobin carries some carbon dioxide as Hemoglobin carries some carbon dioxide as

well as oxygen.well as oxygen.

Once cellular respiration is completed by Once cellular respiration is completed by your cells, wastes in the form of carbon your cells, wastes in the form of carbon dioxide diffuse into the blood and are dioxide diffuse into the blood and are carried in the bloodstream to the lungs.carried in the bloodstream to the lungs.

About 70 percent of this carbon dioxide About 70 percent of this carbon dioxide combines with water in the blood plasma to combines with water in the blood plasma to form bicarbonate.form bicarbonate.

The remaining 30 percent travels back to The remaining 30 percent travels back to the lungs dissolved in the plasma or the lungs dissolved in the plasma or attached to hemoglobin molecules that attached to hemoglobin molecules that have already released their oxygen into the have already released their oxygen into the tissues.tissues.

White blood cells: Infection fightersWhite blood cells: Infection fighters White blood cells major role in your body is White blood cells major role in your body is

protecting your body from foreign protecting your body from foreign substances and from microscopic substances and from microscopic organisms that cause disease.organisms that cause disease.

White blood cells make up only one percent White blood cells make up only one percent of the total volume of your blood cells.of the total volume of your blood cells.

Blood clottingBlood clotting Your blood contains small cell fragments Your blood contains small cell fragments

called platelets, which help your blood clot called platelets, which help your blood clot after an injury.after an injury.

Platelets help link together a stick network Platelets help link together a stick network of protein fibers called fibrin, which forms a of protein fibers called fibrin, which forms a web over the wound that traps escaping web over the wound that traps escaping blood cells.blood cells.

Platelets are produced from cells in bone Platelets are produced from cells in bone marrow and have a short life span.marrow and have a short life span.

They are removed from the blood by the They are removed from the blood by the spleen and liver after only about one week.spleen and liver after only about one week.

Blood Clotting/PlateletsBlood Clotting/Platelets

II.II. ABO Blood GroupsABO Blood Groups There are four human blood groups: A, B, There are four human blood groups: A, B,

AB, and O.AB, and O.

You inherited the characteristics of one You inherited the characteristics of one of these blood groups from your parents.of these blood groups from your parents.

Blood type is used to describe the blood Blood type is used to describe the blood group to which a person belongs.group to which a person belongs.

Blood surface antigens determine blood Blood surface antigens determine blood groupgroup Differences in blood groups are due to the Differences in blood groups are due to the

presence or absence of proteins, called presence or absence of proteins, called antigens, on the membranes of red blood antigens, on the membranes of red blood cells.cells.

Antigens:Antigens: foreign substances that foreign substances that stimulate an immune response in the bodystimulate an immune response in the body

Blood plasma contains proteins, called Blood plasma contains proteins, called antibodies that are shaped to correspond antibodies that are shaped to correspond with the different blood surface antigens.with the different blood surface antigens.

Antibodies:Antibodies: proteins in the blood plasma proteins in the blood plasma produced in reaction to antigens that react produced in reaction to antigens that react with and disable antigens.with and disable antigens.

Blood Antigens and Blood Antigens and AntibodiesAntibodies

The antibody in the blood plasma reacts The antibody in the blood plasma reacts with its matching antigen on red blood cells with its matching antigen on red blood cells if they are brought into contact with one if they are brought into contact with one another.another.

This reaction results in clumped blood cells This reaction results in clumped blood cells that can no longer function.that can no longer function.

Each blood group contains antibodies for Each blood group contains antibodies for the blood surface antigens found only in the the blood surface antigens found only in the other blood groups, not for antigens found other blood groups, not for antigens found on its own red blood cells.on its own red blood cells.

When an antigen-antibody reaction occurs, When an antigen-antibody reaction occurs, it results in your blood clumping.it results in your blood clumping.

Clumped blood cells can not carry oxygen Clumped blood cells can not carry oxygen or nutrients to body cells which results in or nutrients to body cells which results in cells dying.cells dying.

Blood ClumpingBlood Clumping

Rh factorRh factor Another characteristic of red blood cells Another characteristic of red blood cells

involves the presence or absence of an involves the presence or absence of an antigen called Rh (Rhesus factor).antigen called Rh (Rhesus factor).

Rh factor is an inherited characteristic.Rh factor is an inherited characteristic.

People are Rh positive (Rh+) if they have People are Rh positive (Rh+) if they have the Rh antigen factor on their red blood the Rh antigen factor on their red blood cells, and they are Rh negative (Rh-) if they cells, and they are Rh negative (Rh-) if they do not have the Rh antigen factor on their do not have the Rh antigen factor on their blood.blood.

Rh factor can cause complication in some Rh factor can cause complication in some pregnancies.pregnancies.

If an Rh- mother becomes pregnant with If an Rh- mother becomes pregnant with an Rh+ baby, after birth, the mother will an Rh+ baby, after birth, the mother will make anti-Rh+ antibodies, and if the make anti-Rh+ antibodies, and if the mother becomes pregnant again, these mother becomes pregnant again, these antibodies can cross the placenta.antibodies can cross the placenta.

If the new baby is Rh+, the anti-Rh+ If the new baby is Rh+, the anti-Rh+ antibodies from the mother will destroy red antibodies from the mother will destroy red blood cells in the fetus.blood cells in the fetus.

This can be prevented if the mother is This can be prevented if the mother is given a substance that prevents the given a substance that prevents the production of Rh antibodies in her blood, production of Rh antibodies in her blood, so that the next fetus will not be in danger.so that the next fetus will not be in danger.

Rh FactorRh Factor

III.III. Your Blood Vessels: Pathways of Your Blood Vessels: Pathways of CirculationCirculation

The three main types of blood vessels The three main types of blood vessels are: arteries, capillaries, and veins.are: arteries, capillaries, and veins.

Arteries Arteries are large, thick-walled, are large, thick-walled, muscular, elastic blood vessels that muscular, elastic blood vessels that carry blood away from the heart.carry blood away from the heart.

The blood that the arteries carry is The blood that the arteries carry is under great pressure.under great pressure.

As the heart contracts, it pushes blood As the heart contracts, it pushes blood through the arteries and they slightly through the arteries and they slightly expand.expand.

As the heart relaxes, the artery shrinks a As the heart relaxes, the artery shrinks a bit, which helps push the blood forward.bit, which helps push the blood forward.

ArteriesArteries

Arteries Veins

After the arteries branch off from the heart, they After the arteries branch off from the heart, they divide into smaller arteries that, in turn, divide into divide into smaller arteries that, in turn, divide into even smaller vessels called arterioles.even smaller vessels called arterioles.

Arterioles enter tissues, were they branch into the Arterioles enter tissues, were they branch into the smallest blood vessels, the capillaries.smallest blood vessels, the capillaries.

CapillariesCapillaries are microscopic blood vessels with are microscopic blood vessels with walls that are only one cell thick.walls that are only one cell thick.

These blood vessels are so tiny that red blood cells These blood vessels are so tiny that red blood cells must move through them in a single file.must move through them in a single file.

Capillaries form a dense network that reaches Capillaries form a dense network that reaches virtually every cell in the body.virtually every cell in the body.

Thin capillary walls enable nutrients and gases to Thin capillary walls enable nutrients and gases to diffuse easily between blood cells and surrounding diffuse easily between blood cells and surrounding tissue cells.tissue cells.

CapillariesCapillaries

As blood leaves the tissues, the capillaries join to As blood leaves the tissues, the capillaries join to form slightly larger vessels called venules.form slightly larger vessels called venules.

The venules merge to form The venules merge to form veinsveins, the large blood , the large blood vessels that carry blood from the tissues back vessels that carry blood from the tissues back toward the heart.toward the heart.

In some veins, especially those in your arm and In some veins, especially those in your arm and legs, blood travels uphill against gravity.legs, blood travels uphill against gravity.

These veins are equipped with valves that prevent These veins are equipped with valves that prevent blood from flowing backward.blood from flowing backward.

When the skeletal muscles contract, the top valves When the skeletal muscles contract, the top valves open, and the blood is forced toward the heart.open, and the blood is forced toward the heart.

When the skeletal muscles relax, the top valves When the skeletal muscles relax, the top valves close to prevent blood from flowing backward, close to prevent blood from flowing backward, away for the heart.away for the heart.

VeinsVeins

IV.IV. Your Heart: The Vital PumpYour Heart: The Vital Pump The main function of the heart is to keep The main function of the heart is to keep

blood moving constantly throughout the blood moving constantly throughout the body.body.

The heart is a large organ made of The heart is a large organ made of cardiac muscle cells that are rich in cardiac muscle cells that are rich in energy-producing mitochondria.energy-producing mitochondria.

All mammalian hearts have four All mammalian hearts have four chambers.chambers.

The two upper chambers of the heart are The two upper chambers of the heart are the atria.the atria.

The two lower chambers of the heart are The two lower chambers of the heart are the ventricles.the ventricles.

HeartHeart

The walls of each atrium are thinner and The walls of each atrium are thinner and less muscular than those of each ventricle.less muscular than those of each ventricle.

Each atrium pumps blood into the Each atrium pumps blood into the corresponding ventricle.corresponding ventricle.

The left ventricle pumps blood to the entire The left ventricle pumps blood to the entire body, so its muscles are thicker than those body, so its muscles are thicker than those of the right ventricle, which pumps blood of the right ventricle, which pumps blood to the lungs.to the lungs.

Due to the different task that each Due to the different task that each ventricle performs your heart is lopsided.ventricle performs your heart is lopsided.

Blood’s path through the heartBlood’s path through the heart Blood enters the heart through the atria and Blood enters the heart through the atria and

leaves it through the ventricles.leaves it through the ventricles.

Both atria fill up with blood at the same time.Both atria fill up with blood at the same time.

The right atrium receives oxygen-poor blood The right atrium receives oxygen-poor blood from the head and body through two large from the head and body through two large veins called the venae cavae.veins called the venae cavae.

The left atrium receives oxygen-rich blood The left atrium receives oxygen-rich blood from the lungs through four pulmonary veins.from the lungs through four pulmonary veins.

The pulmonary veins are the only veins that The pulmonary veins are the only veins that carry blood rich in oxygen.carry blood rich in oxygen.

After both atria have filled with blood, the After both atria have filled with blood, the two atria then contract, pushing the blood two atria then contract, pushing the blood down into the two ventricles.down into the two ventricles.

Between the atria and ventricle are one-Between the atria and ventricle are one-way valves that keep blood from flowing way valves that keep blood from flowing back into the atria.back into the atria.

After both ventricles have filled with After both ventricles have filled with blood, the both contract simultaneously.blood, the both contract simultaneously.

When the right ventricle contracts, it When the right ventricle contracts, it pushes the oxygen-poor blood from the pushes the oxygen-poor blood from the right ventricle out of the heart and toward right ventricle out of the heart and toward the lungs through the pulmonary arteries.the lungs through the pulmonary arteries.

The pulmonary arteries are the only The pulmonary arteries are the only arteries that carry oxygen-poor blood.arteries that carry oxygen-poor blood.

At the same time, the left ventricle At the same time, the left ventricle forcefully pushes oxygen-rich blood from forcefully pushes oxygen-rich blood from the left ventricle out of the heart through the left ventricle out of the heart through the aorta to the arteries of the body.the aorta to the arteries of the body.

Between the ventricles and the arteries are Between the ventricles and the arteries are also one-way valves that keep blood from also one-way valves that keep blood from flowing back into the ventricles.flowing back into the ventricles.

The aorta is the largest blood vessel in the The aorta is the largest blood vessel in the body.body.

The Drop of Blood StoryThe Drop of Blood Story1.1. Blood drop coming back form the body through Blood drop coming back form the body through

a vena cava.a vena cava.

2.2. The drop travels first into the right atrium.The drop travels first into the right atrium.

3.3. Then travels into the right ventricle.Then travels into the right ventricle.

4.4. Then travels through a pulmonary artery to one Then travels through a pulmonary artery to one of the lungs.of the lungs.

5.5. In lungs, the blood drop releases carbon dioxide In lungs, the blood drop releases carbon dioxide and picks up oxygen.and picks up oxygen.

6.6. Then drop moves through the pulmonary vein to Then drop moves through the pulmonary vein to the left atrium.the left atrium.

7.7. Then drop moves into the left ventricle and Then drop moves into the left ventricle and finally out the body through the aorta.finally out the body through the aorta.

Blood through the HeartBlood through the Heart

Heartbeat regulationHeartbeat regulation Each time the heart beats, a surge of blood Each time the heart beats, a surge of blood

flows from the left ventricle into the aorta flows from the left ventricle into the aorta and then into the arteries.and then into the arteries.

The radial artery in the arm and carotid The radial artery in the arm and carotid arteries near the jaw are fairly close to the arteries near the jaw are fairly close to the surface of the body, a surge of blood can surface of the body, a surge of blood can be felt as it moves through them.be felt as it moves through them.

This surge of blood through an artery is This surge of blood through an artery is called a pulse.called a pulse.

Pulse:Pulse: surge of blood through an artery surge of blood through an artery that can be felt on the surface of the body.that can be felt on the surface of the body.

Radial Artery and Carotid Radial Artery and Carotid ArteriesArteries

The heart rate is set by the pacemaker, a The heart rate is set by the pacemaker, a bundle of nerve cells located at the top of bundle of nerve cells located at the top of the right atrium.the right atrium.

This pacemaker generates an electrical This pacemaker generates an electrical impulse that spreads over both atria.impulse that spreads over both atria.

This impulse signals the two atria to This impulse signals the two atria to contract at almost the same time.contract at almost the same time.

The impulse also triggers a second set of The impulse also triggers a second set of cells at the base of the right atrium to cells at the base of the right atrium to send the same electrical impulse over the send the same electrical impulse over the ventricles, causing them to contract.ventricles, causing them to contract.

Heart PacemakerHeart Pacemaker

These electrical signals can be measured These electrical signals can be measured and recorded by a machine called and and recorded by a machine called and electrocardiograph which produces an electrocardiograph which produces an electrocardiogram (ECG).electrocardiogram (ECG).

The ECG is used in diagnosing abnormal The ECG is used in diagnosing abnormal heart rhythms or patterns.heart rhythms or patterns.

Blood PressureBlood Pressure A pulse beat represents the pressure that A pulse beat represents the pressure that

blood exerts as it pushes against the walls of blood exerts as it pushes against the walls of an artery.an artery.

Blood pressure is the force that the blood Blood pressure is the force that the blood exerts on the blood vessels.exerts on the blood vessels.

Blood pressure rises sharply when the Blood pressure rises sharply when the ventricles contract, pushing blood through the ventricles contract, pushing blood through the arteries.arteries.

The high pressure is called systolic pressure.The high pressure is called systolic pressure.

Blood pressure then drops dramatically as the Blood pressure then drops dramatically as the ventricles relax.ventricles relax.

The lowest pressure occurs just before the The lowest pressure occurs just before the ventricles contract again and is called the ventricles contract again and is called the diastolic pressure.diastolic pressure.

Control of the heartControl of the heart The medulla oblongata regulates the rate The medulla oblongata regulates the rate

of the pacemaker, speeding or slowing its of the pacemaker, speeding or slowing its nerve impulses.nerve impulses.

If the heart beats too fast, sensory cells in If the heart beats too fast, sensory cells in arteries near the heart become stretched.arteries near the heart become stretched.

Through the nervous system, these cells Through the nervous system, these cells send a signal to the medulla oblongata, send a signal to the medulla oblongata, which in turn sends signal that slow the which in turn sends signal that slow the pacemaker.pacemaker.

If the heart slows down too much, blood If the heart slows down too much, blood pressure in the arteries drops, signaling the pressure in the arteries drops, signaling the medulla oblongata to speed up the medulla oblongata to speed up the pacemaker and increase the heart rate.pacemaker and increase the heart rate.

C.C. The Urinary SystemThe Urinary System

I.I. Kidneys: Structure and FunctionKidneys: Structure and Function The urinary system is made up of two kidneys, a The urinary system is made up of two kidneys, a

pair of ureters, urinary bladder, and the urethra.pair of ureters, urinary bladder, and the urethra.

The kidneys filter the blood to remove wastes The kidneys filter the blood to remove wastes from it, thus maintaining the homeostasis of from it, thus maintaining the homeostasis of body fluids.body fluids.

Your kidneys are located just above the waist, Your kidneys are located just above the waist, behind the stomach.behind the stomach.

One kidney lies on each side of the spine, One kidney lies on each side of the spine, partially surrounded by ribs.partially surrounded by ribs.

Each kidney is connected to a tube called a Each kidney is connected to a tube called a ureter, which leads to the urinary bladder.ureter, which leads to the urinary bladder.

Urinary SystemUrinary System

Ureter:Ureter: tube that transports urine form tube that transports urine form each kidney to the urinary bladdereach kidney to the urinary bladder

The urinary bladder is a smooth muscle The urinary bladder is a smooth muscle bag that stores a solution of wastes until it bag that stores a solution of wastes until it is expelled.is expelled.

Nephron: The unit of the KidneyNephron: The unit of the Kidney Each kidney is made up of about one Each kidney is made up of about one

million tiny filters.million tiny filters.

The kidneys remove impurities from the The kidneys remove impurities from the blood.blood.

Each filtering unit of the kidney is called a Each filtering unit of the kidney is called a nephron.nephron.

Blood entering a nephron carries wastes Blood entering a nephron carries wastes produced by body cells.produced by body cells.

NephronNephron

As blood enters the nephron, it is under high As blood enters the nephron, it is under high pressure and immediately flows into a bed of pressure and immediately flows into a bed of capillaries called the glomerulus.capillaries called the glomerulus.

The high pressure causes water, glucose, The high pressure causes water, glucose, vitamins, amino acids, protein waste products vitamins, amino acids, protein waste products (urea), salts, and ions from the blood to pass (urea), salts, and ions from the blood to pass out of the capillaries into a part of the out of the capillaries into a part of the nephron called the Bowman’s capsule.nephron called the Bowman’s capsule.

Blood cells and most proteins are too large to Blood cells and most proteins are too large to pass through the walls of the capillary, so pass through the walls of the capillary, so these components stay within the blood these components stay within the blood vessels.vessels.

The liquid forced into the Bowman’s capsule The liquid forced into the Bowman’s capsule passes through a narrow, U-shaped tubule.passes through a narrow, U-shaped tubule.

As the liquid moves along the tubule, most As the liquid moves along the tubule, most of the ions and water, and all of the of the ions and water, and all of the glucose and amino acids, are reabsorbed glucose and amino acids, are reabsorbed into the bloodstream, which this helps into the bloodstream, which this helps maintain homeostasis.maintain homeostasis.

Small molecules and water move back into Small molecules and water move back into the capillaries by diffusion.the capillaries by diffusion.

Other molecules and ions move back into Other molecules and ions move back into the capillaries by active transport.the capillaries by active transport.

The formation of urineThe formation of urine The liquid that remains in the tubules The liquid that remains in the tubules

(waste molecules and excess water and (waste molecules and excess water and ions) is urine.ions) is urine.

You produce about 2 liters of urine a day.You produce about 2 liters of urine a day.

This waste fluid flows out of the kidneys, This waste fluid flows out of the kidneys, through the ureter, and into the urinary through the ureter, and into the urinary bladder, where it may be stored.bladder, where it may be stored.

Urine passes form the urinary bladder out Urine passes form the urinary bladder out of the body through a tube called the of the body through a tube called the urethra.urethra.

The Urinary System and HomeostasisThe Urinary System and Homeostasis The major waste products of cells are nitrogenous The major waste products of cells are nitrogenous

wastes, which come from the breakdown of wastes, which come from the breakdown of proteins.proteins.

These wastes include ammonia and urea.These wastes include ammonia and urea. Both compounds are toxic to the body and must be Both compounds are toxic to the body and must be

removed from the blood regularly.removed from the blood regularly. In addition to removing these wastes, the kidneys In addition to removing these wastes, the kidneys

control the level of sodium in blood by removing control the level of sodium in blood by removing and reabsorbing sodium ions which helps control and reabsorbing sodium ions which helps control the osmotic pressure of the blood.the osmotic pressure of the blood.

The kidneys also regulate the pH of blood by The kidneys also regulate the pH of blood by filtering out hydrogen ions and allowing filtering out hydrogen ions and allowing bicarbonate to be reabsorbed back into the blood.bicarbonate to be reabsorbed back into the blood.

Glucose is a sugar that is not usually filtered out of Glucose is a sugar that is not usually filtered out of the blood by the kidneys.the blood by the kidneys.

Individuals who have the disease known as Individuals who have the disease known as diabetes have excess levels of glucose in their diabetes have excess levels of glucose in their blood.blood.