Exchange Systems in the Human Body

Exchange Systems in the Human Body

Exchange systemsExchange systemsEvery organism must exchange materials Every organism must exchange materials

(food, waste) with its environment.(food, waste) with its environment.Single-celled organisms employ osmosis & Single-celled organisms employ osmosis & diffusion.diffusion.

Multi-cellular organisms have groups of cells Multi-cellular organisms have groups of cells with with specialized functions = tissues: epithelial, specialized functions = tissues: epithelial, nerve, etc.nerve, etc.

Organs – groups of tissues with a special Organs – groups of tissues with a special purpose: heart, lung, blood, skin.purpose: heart, lung, blood, skin.

Organ systems – Organ systems – groups of organs groups of organs with a particular with a particular purpose: the cir- purpose: the cir- culatory system, culatory system,

respiratory system, respiratory system, urinary system, etc. urinary system, etc.

Skin (an organ) protects us.

Circulatory systemCirculatory systemEvery organism must exchange Every organism must exchange

materials with its environment.materials with its environment.Circulatory system con-Circulatory system con-

nects the organs of ex-nects the organs of ex-change (lungs, intes-change (lungs, intes-

tines, etc.) with tines, etc.) with the the body cells.body cells.

3 main components:3 main components:A circulatory fluid: A circulatory fluid:

(blood , (blood , hemolymph)hemolymph)

A set of tubes A set of tubes (blood vessels) (blood vessels)

A muscular pump A muscular pump (the heart) (the heart)

Circulatory systemCirculatory systemComplex animals have either open or Complex animals have either open or

closed circula-tory systems.closed circula-tory systems.In an open system blood bathes the In an open system blood bathes the organs directly.organs directly.

In a closed system, blood is confined to In a closed system, blood is confined to vessels.vessels.

Humans (all vertebrates) have this type Humans (all vertebrates) have this type of system.of system.

Diagram of the heartDiagram of the heart

Diagram of the heartDiagram of the heartCoronary arteries supply heart Coronary arteries supply heart

muscle with oxygen and nutrients.muscle with oxygen and nutrients.

Blockage of coronary arteries can starve the heart Blockage of coronary arteries can starve the heart and cause a heart attack.and cause a heart attack.

The action of the heartThe action of the heartThe four-chambered heartThe four-chambered heart

The two atria collect the blood, either The two atria collect the blood, either from the lungs from the lungs or from the rest of the or from the rest of the body.body.

The two ventricles pump the blood out The two ventricles pump the blood out of the heart.of the heart.

The action of the heartThe action of the heartHeart valves dictate a one-way flow of Heart valves dictate a one-way flow of

blood through the heart. blood through the heart. Atrioventricular valves Atrioventricular valves control flow from control flow from atria to ventricles.atria to ventricles.

Semilunar valves Semilunar valves control flow from control flow from ventricles into aorta & pulmonary artery.ventricles into aorta & pulmonary artery.

The action of the heartThe action of the heartHeart valves dictate a one-way flow of Heart valves dictate a one-way flow of

blood through the heart. blood through the heart. The back pressure of the heart beat The back pressure of the heart beat seals one valve seals one valve as the opposite as the opposite one is pushed opened.one is pushed opened.

The action of the heartThe action of the heartBlood begins its flow with the right Blood begins its flow with the right

ventricle pumping blood through the ventricle pumping blood through the pulmonary artery to the lungs.pulmonary artery to the lungs.

The action of the heartThe action of the heartIn the lungs, the blood loads OIn the lungs, the blood loads O22 and and

unloads COunloads CO22

Oxygen-rich blood from the lungs Oxygen-rich blood from the lungs enters the heart at enters the heart at the left atrium and the left atrium and is is pumped to the pumped to the body body tissues tissues by the left by the left ventricle.ventricle.

Blood returns to the Blood returns to the heart through the heart through the

right right atrium.atrium.

Control of the heartbeatControl of the heartbeatSome cardiac muscle cells can contract Some cardiac muscle cells can contract

without any signal from the nervous without any signal from the nervous system.system.

These contractions are controlled by a These contractions are controlled by a region of the region of the heart called the heart called the sinoatrial (SA) node, or pacemaker.sinoatrial (SA) node, or pacemaker.

The pacemaker sets The pacemaker sets the rate and timing the rate and timing

of of contractions. contractions.

Control of the heartbeatControl of the heartbeatMaintaining homeostasisMaintaining homeostasis

The pacemaker can monitor body The pacemaker can monitor body conditions and conditions and adjust the heart beat to adjust the heart beat to the body’s needs.the body’s needs.

The pacemaker also sends and receives The pacemaker also sends and receives signals to signals to and from the brain stem and from the brain stem (oldest part of brain).(oldest part of brain).

Within the medulla oblongata of the Within the medulla oblongata of the brain stem is the cardiac center.brain stem is the cardiac center.

Arteries, capillaries & veinsArteries, capillaries & veinsThe “infrastructure” of the circulatory The “infrastructure” of the circulatory

system is its network of blood vessels: system is its network of blood vessels: arteries, veins, capillaries.arteries, veins, capillaries.

All blood vessels are built of similar All blood vessels are built of similar tissues and have three similar layers.tissues and have three similar layers.

Arteries, capillaries & veinsArteries, capillaries & veinsArteries carry blood Arteries carry blood awayaway from the from the

heart.heart.Arteries have thicker walls that Arteries have thicker walls that accommodate the accommodate the high pressure of high pressure of blood pumped from the heartblood pumped from the heart

Arteries, capillaries & veinsArteries, capillaries & veinsVeins return blood from capillaries Veins return blood from capillaries to to

the heartthe heart..In the thinner-walled veins, blood flows In the thinner-walled veins, blood flows back to the back to the heart mainly as a result of heart mainly as a result of muscle actionmuscle action

Arteries, capillaries & veinsArteries, capillaries & veinsCapillaries are sites of chemical Capillaries are sites of chemical

exchange exchange between the between the blood blood and the fluid around cells.and the fluid around cells.

Arteries, capillaries & veinsArteries, capillaries & veinsSignals from the medulla Signals from the medulla

can constrict the walls of can constrict the walls of

capillaries to increase or capillaries to increase or restrict blood flow. restrict blood flow.

Ex: less blood to skin,Ex: less blood to skin,more to internal or-more to internal or-

gans when gans when the bodythe body is is too cold.too cold.

Blood compositionBlood compositionBlood is composed of plasma (55%), and Blood is composed of plasma (55%), and

solids (45%): erythrocytes, solids (45%): erythrocytes, leucocytes leucocytes (phagocytes (phagocytes

and lympho- and lympho- cytes), cytes),

and and platelets.platelets.

Blood compositionBlood compositionThe following are transported by the The following are transported by the

blood: nutrients, oxygen, carbon blood: nutrients, oxygen, carbon dioxide, dioxide,

hormones, hormones, antibodies, urea, antibodies, urea, and heat. and heat.

Exchange Systems in the Human Body

Exchange Systems in the Human Body

Respiratory systemRespiratory systemVentilation: any method of increasing Ventilation: any method of increasing

contact between the respiratory medium contact between the respiratory medium and the respiratory surface.and the respiratory surface.

The medium could be air (for humans) or The medium could be air (for humans) or water (fish).water (fish).

The respiratory surface The respiratory surface could be lungs, gills, etc.could be lungs, gills, etc.

Ventilation includes breath-Ventilation includes breath- ing, panting, gasping ing, panting, gasping

Hyperventilation: Hyperventilation: very fast breathing.very fast breathing.

Respiratory systemRespiratory systemGas exchange: the process of replacing Gas exchange: the process of replacing

one gas with another – to replace COone gas with another – to replace CO22 in in the cells or tissues with Othe cells or tissues with O22..

Follows the rules of physics: depends Follows the rules of physics: depends upon concen-upon concen- tration gradients, tration gradients, temperature, pH. temperature, pH.

Respiratory systemRespiratory systemA system of branching ducts conveys air to A system of branching ducts conveys air to

the lungs.the lungs.Air inhaled through the nostrils passes Air inhaled through the nostrils passes through the through the pharynx into the trachea, pharynx into the trachea, bronchi, bronchioles, and bronchi, bronchioles, and dead-end dead-end alveoli, where gas exchange occurs.alveoli, where gas exchange occurs.

The process that ventilates The process that ventilates the lungs is breathing, the the lungs is breathing, the

alternate alternate inhalation and inhalation and exhalation of air. exhalation of air.

Respiratory systemRespiratory systemA system of branching ducts conveys air to A system of branching ducts conveys air to

the lungs.the lungs.The trachea, bronchi, and larger The trachea, bronchi, and larger bronchioles have rings bronchioles have rings of cartilage for of cartilage for support.support.

Incision for tracheostomyIncision for tracheostomy

Respiratory systemRespiratory systemGoblet cells of the epithelial lining of Goblet cells of the epithelial lining of

trachea, bronchi, and bronchioles and of trachea, bronchi, and bronchioles and of the nose produce mucous, a viscous fluid the nose produce mucous, a viscous fluid that traps microbes and other particles.that traps microbes and other particles.

In these tissues, ciliated epithelial cells In these tissues, ciliated epithelial cells sweep mucus sweep mucus and trapped microbes and trapped microbes

upward, preventing upward, preventing microbes from microbes from

enter-enter- ing the ing the lungs.lungs.

Contraction of smooth Contraction of smooth muscle aids coughing.muscle aids coughing.

H: cilia (little hairs); I: epithelial cells; J: goblet cells make the mucous;K: smooth muscle.

H: cilia (little hairs); I: epithelial cells; J: goblet cells make the mucous;K: smooth muscle.

Respiratory systemRespiratory systemAlveolus: a dead-end, multi-lobed sac that Alveolus: a dead-end, multi-lobed sac that

constitutes the gas exchange surface of constitutes the gas exchange surface of the lungs. Features include:the lungs. Features include:

large total surface area (~75 mlarge total surface area (~75 m22),),

a wall consisting of a single layer a wall consisting of a single layer of flattened cells (easier of flattened cells (easier

diffusion),diffusion),

a film of moisture (gas is dissolved),a film of moisture (gas is dissolved),

a dense network of capillaries.a dense network of capillaries.

Respiratory systemRespiratory systemDraw and label (inset alveoli):Draw and label (inset alveoli):

Respiratory systemRespiratory systemMammals ventilate their lungs by negative Mammals ventilate their lungs by negative

pressure breathing, which pressure breathing, which pullspulls air into air into the lungs.the lungs.

Lung volume increases as the rib muscles Lung volume increases as the rib muscles (the inter-(the inter- costals) and the diaphragm costals) and the diaphragm contract.contract.

Respiratory systemRespiratory systemMammals ventilate their lungs by negative Mammals ventilate their lungs by negative

pressure breathing, which pressure breathing, which pullspulls air into air into the lungs. the lungs.

Normally we breathe using just the Normally we breathe using just the diaphragm.diaphragm.

The diaphragm tightens, pulls lungs The diaphragm tightens, pulls lungs down; air rushes in.down; air rushes in.

For a bigger breath we tighten For a bigger breath we tighten intercostals; they pull intercostals; they pull up, & even up, & even more air enters the lungs due to negative more air enters the lungs due to negative

pressure.pressure.

We breatheWe breathe9 to 20 times9 to 20 timesper minute.per minute.

We breatheWe breathe9 to 20 times9 to 20 timesper minute.per minute.

Respiratory systemRespiratory systemLung volumeLung volume::

Depends on many factors – Depends on many factors –

For a 135 lb male, the lungs hold ~6 For a 135 lb male, the lungs hold ~6 liters of airliters of air

Only ½ L is exchanged with each breath.Only ½ L is exchanged with each breath.

~4.8 liters of air can be forced out, ~4.8 liters of air can be forced out, leaving a leaving a residual of 1.2 L that can’t be residual of 1.2 L that can’t be forced out.forced out.

Exchange systemsExchange systemsEvery organism must exchange materials Every organism must exchange materials

with its environment.with its environment.Circulatory system con-Circulatory system con-

nects the organs of ex-nects the organs of ex-change (lungs, kidneys,change (lungs, kidneys,intestines, etc.) with intestines, etc.) with

the body cells. the body cells.

Homeostasis maintains Homeostasis maintains constant conditions constant conditions

within the body. within the body.

Exchange Systems in the Human Body

Exchange Systems in the Human Body

The Kidney

Urinary systemUrinary systemThe human body needs to eliminate waste The human body needs to eliminate waste

materialmaterialNot all food eaten is usable; ex. cell walls Not all food eaten is usable; ex. cell walls of plants.of plants.

We don’t have the We don’t have the enzymes to break enzymes to break

down down cellulose.cellulose.

Metabolism produces Metabolism produces toxic materials; toxic materials; ex. urea (dissolved ex. urea (dissolved in water it becomes in water it becomes urine – a waste of urine – a waste of

water that limits water that limits where we live). where we live).

Urinary systemUrinary systemOrgans of the urinary Organs of the urinary

system include the system include the kidneys, ureters, & kidneys, ureters, &

bladder. bladder.

Urinary systemUrinary systemOrgans of the urinary system include the Organs of the urinary system include the

kidneys.kidneys.Kidneys filter the blood to preserve a Kidneys filter the blood to preserve a proper water proper water and salt balance & to and salt balance & to remove toxic matter.remove toxic matter.

Urinary systemUrinary systemWithin the kidney, nephrons clean the Within the kidney, nephrons clean the

blood and regulate blood composition blood and regulate blood composition (homeostasis). (homeostasis).

A nephronA nephron

Urinary systemUrinary systemCleaning & regulation of blood occurs in Cleaning & regulation of blood occurs in

3 phases3 phasesFiltration: in the glomerulus excess Filtration: in the glomerulus excess water is removed – 125 ml of blood water is removed – 125 ml of blood filtered per minute.filtered per minute.

Urinary systemUrinary systemCleaning & regulation of blood occurs in Cleaning & regulation of blood occurs in

3 phases3 phasesReabsorption: capillaries around the Reabsorption: capillaries around the renal tubule recollect more or less renal tubule recollect more or less water, depending on condi-tions.water, depending on condi-tions.

Urinary systemUrinary systemCleaning & regulation of blood occurs in Cleaning & regulation of blood occurs in

3 phases3 phasesSecretion: cells in the renal tubule Secretion: cells in the renal tubule secrete positive ions or absorb secrete positive ions or absorb negative ions to maintain blood pH.negative ions to maintain blood pH.

Urinary systemUrinary systemThe pH of blood (how much The pH of blood (how much

acid is present) is acid is present) is ~7.35.~7.35.

The pH of urine averages The pH of urine averages 6.0; the urine is made 6.0; the urine is made

from the blood plasma from the blood plasma as it passes as it passes

through the through the kidney, kidney, and acid was and acid was removed.removed.The pH scale is based

on concentration; pH 6 has 10 times more acid than pH 7.

The pH scale is based on concentration; pH 6 has 10 times more acid than pH 7.