Transcript Ch. 23 & 24 Circulation and Respiration

Circulatory & Respiratory
Systems
Ch’s. 23 & 24
Three types of circulatory systems
found in the animal kingdom
Open and Closed Circulatory
Systems
• Two Types
1. open circulatory system
• there is no distinction between the circulating fluid (blood) and the
extracellular fluid of the body tissues (interstitial fluid or lymph)
• this fluid is called hemolymph
2. closed circulatory system
• the circulating fluid (blood) is always enclosed within blood vessels
that transport blood away from and back to a heart
• arteries carry blood away from the heart, and veins return blood to
the heart; blood passes from the arterial system to the venous
system in capillaries
• the pressure of the blood forces some fluid out of the capillary walls
– this fluid is called interstitial fluid
» some of it will return to the blood but some becomes lymph
and travels through the lymph vessels
Open and Closed Circulatory
Systems
• The functions of the circulatory system can be
divided into three areas
 transportation
• substances essential for cellular functions are transported by
the circulatory system
 regulation
• the cardiovascular system participates in temperature
regulation, such as by countercurrent heat exchange
 protection
• the circulatory system protects against injury and foreign
microbes or toxins introduced into the body
Architecture of the Vertebrate
Circulatory System
• The vertebrate circulatory system (also
known as the cardiovascular system) is
made up of three elements
 heart—a muscular pump that pushes blood
through the body
 blood vessels—a network of tubes through
which the blood moves
 blood—fluid that circulates through the
vessels
Architecture of the Vertebrate
Circulatory System
• Blood moves through the body in a cycle, from the heart,
through a system of vessels
 blood leaves the heart in arteries
 from the arteries, blood passes into smaller arterioles
 tiny vessels called capillaries connect arterioles to venules, or
small veins
 venules and then veins carry blood back to the heart
The capillary network connects
arteries with veins
Architecture of the Vertebrate
Circulatory System
• An artery is more than a simple pipe
 it needs to be able to expand with be strong against
the pressure caused by contraction of the heart
 for this reason, arteries have both elastic and smooth
muscle layers
• Arterioles differ from arteries in that they are
smaller in diameter and respond to nervous and
hormonal stimulation
 they can constrict or expand to affect blood flow
during periods of stress or body activity
The structure of blood vessels
Capillary Structure
Figure 29.4 (b) The structure of
blood vessels
Figure 29.5 Red blood cells within
a capillary
Structure of Veins
Figure 29.4 (c) The structure of
blood vessels
Figure 29.6 Veins and arteries
Figure 29.7
Flow of
blood
through
veins
The Lymphatic System: Recovering
Lost Fluid
• The cardiovascular
system is very leaky
 from capillary
exchange, the body
loses about 4 liters of
fluid each day
 to collect and recycle
this fluid, the body
uses a second
circulatory system
called the lymphatic
system
• the lymphatic system is
also a network of
vessels filled with a fluid
called lymph
• ultimately the lymph
reenters the
bloodstream through
veins in the neck
The human
lymphatic
system
The Lymphatic System: Recovering
Lost Fluid
• The lymphatic system has three important
functions
 it returns proteins to circulation
• if this protein remains in the tissues, it would cause swelling
or edema
 it transports fats absorbed from the intestine
 it aids in the body’s defense
• swellings along lymph vessels called lymph nodes and a
lymph organ called the spleen are where bacteria and dead
blood cells are destroyed
• the thymus produces white blood cells
Blood
• Blood plasma is a complex
solution of water with three
kind of substances dissolved
in it
 metabolites and wastes
• for example—glucose,
vitamins, hormones, wastes
 salts and ions
• the chief plasma ions are
sodium, chloride, and
bicarbonate
 proteins
• proteins help keep water in
the plasma
• other plasma proteins include
antibodies, globulins, and
fibrinogen
Blood
• Nearly half the volume of blood is
occupied by cells
 the three principal cell types are
• erythrocytes (red blood cells)
– the blood’s hematocrit is the fraction of the total volume
of the blood that is occupied by red blood cells
– in humans, the hematocrit is usually about 45%
• leukocytes (white blood cells)
• platelets (cell fragments)
Amphibian and Reptile Circulation
• The advent of lungs involved a major
change in the pattern of circulation
 after blood is pumped by the heart to the
lungs, it does not go directly to the tissues of
the body but instead returns to the heart
• pulmonary circulation goes to and from the heart
and lungs
• systemic circulation goes to and from the heart
and the rest of the body
Amphibian and Reptile Circulation
• The amphibian heart
has structural
features to prevent
the mixing of
deoxygenated from
the body with
oxygenated blood
from the lungs
 the atrium is divided
by a septum that
separates the blood
coming from the body
and from the lungs
Amphibian and Reptile Circulation
• Amphibians in water supplement the
oxygenation of their blood by obtaining
additional oxygen by diffusion across their skin
 this is called cutaneous respiration
• The reptilian heart is additionally specialized
 there is a partial septum in the ventricle
 the conus arteriosus has become incorporated into
the large arteries leaving the heart
Mammalian and Bird Circulation
• mammals, birds, and crocodiles have a
four-chambered heart with two complete
pumping circuits
 this increased efficiency of the double
circulation in mammals and birds may have
been important in the evolution of endothermy
• more efficient circulation is necessary to support
the high metabolic rate required
Mammalian and Bird Circulation
• In the mammalian heart,
 oxygen-rich blood returns from the lungs through pulmonary
veins to the left atrium of the heart and flows mostly passively
through the mitral valve into the left ventricle
 the thick-walled left ventricle contracts, sending oxygenated
blood through a large artery called the aorta and out to the body
• backflow of blood from the aorta is prevented by the aortic
semilunar valve
 blood travels through the body returns to the heart through the
vena cavae, which drain into the right atrium
 blood flows from the right atrium through the tricuspid valve to
the right ventricle
 the right ventricle contracts, pushing blood through the
pulmonary valve into pulmonary arteries that lead to the lungs
The heart and circulation of
mammals and birds
The heart and circulation of
mammals and birds
Respiratory Systems
• Respiration is the
uptake of oxygen and
the simultaneous release
of carbon dioxide
 most primitive animal
phyla obtain oxygen
directly from their
environments through
diffusion
 more advanced phyla
have specific respiratory
organs
• gills, tracheae, and lungs
Respiration in Terrestrial
Vertebrates
• Lungs are less efficient than gills because
new air that is inhaled mixes with old air
already in the lung
 but there is so much more oxygen in air than
in water
 the lungs of mammals possess on their inner
surface many small chambers called alveoli,
which greatly increases surface area for the
diffusion of oxygen
The Mammalian Respiratory
System
• In the mammalian respiratory system, air
passes in and out of the lungs, which are
housed in the thoracic cavity
• air is warmed and filtered as it flows through the
nasal cavity
• it passes next through the pharynx, then the larynx
(or voice box), then to the trachea, or windpipe.
• from there, air passes through several branchings
of bronchi in the lungs and then to the bronchioles
– the tissue of the lungs is divided into tiny air sacs called
alveoli; through these thin-walled cells, gas exchange
with the blood occurs
The human respiratory system
The Mammalian Respiratory
System
• The mammal respiratory apparatus is simple in
structure and functions as a one-cycle pump
 a diaphragm muscle separates the thoracic cavity
from the abdominal cavity
 each lung is covered by a thin, smooth membrane
called the pleural membrane
 this membrane adheres to another pleural membrane
lining the walls of the thoracic cavity, basically
coupling the lungs to the thoracic cavity
The Mammalian Respiratory
System
• Air is drawn into the lungs by the creation
of negative pressure
• The active pumping of air in and out is
called breathing
 during inhalation, muscular contraction
causes the chest cavity to expand
 during exhalation, the ribs and diaphragm
return to their original position
How breathing works
How Respiration Works: Gas
Exchange
• Oxygen moves through the circulatory system
carried by the protein hemoglobin
 hemoglobin molecules contain iron, which binds
oxygen in a reversible way
Figure 30.8
The
hemoglobin
molecule
How Respiration Works: Gas
Exchange
• Hemoglobin molecules act like little
sponges for oxygen
 at the high O2 levels that occur in the blood
supply at the lung, most hemoglobin
molecules carry a full load of O2
 in the tissues, the O2 levels are much lower,
so hemoglobin gives up its bound oxygen
 in the presence of CO2, the hemoglobin
assumes a different shape that give up its
oxygen more readily
How Respiration Works: Gas
Exchange
• CO2 must also be transported by the blood
 about 8% simply dissolves in the plasma
 20% is bound to hemoglobin but at a different site
than where O2 binds
 the remaining 72% diffuses into the red blood cells
• In order to maintain the gradient for CO2 to leave
the tissues and enter the plasma, the CO2 levels
in the plasma must be kept low
The Nature of Lung Cancer
• Smoking causes lung cancer
 the annual incidence of lung cancer is much
higher for smokers than for nonsmokers
 changes in the incidence of lung cancer have
mirrored changes in smoking habits
 many types of mutagens are found in
cigarette smoke that can damage genes
• the p53 gene is damaged in 70% of lung cancers
 smoking also leads to nicotine addiction