Transcript 42.1 Circulatory systems link exchange surfaces with cells

42.1 Circulatory systems link
exchange surfaces with cells
throughout the body
By: Ethan Wright
Overview
• Gases are needed by organism
▫ Excreted as waste
• Dilema:
▫ Multicellular organisms cannot happen directly
 Specialized systems required
Solution one
• Body Shape
▫ Facilitates direct diffusion
▫ Hydras, jellies, and other cnidarians
 Diploblastic
 Allows for diffusion for all cells
Circulatory System (Solution 2)
• 3 Components:
▫ Fluid
▫ Interconnecting vessels
▫ Pump
Open Circulatory System
• Fluid bathes organs directly
▫ Circulatory fluid = hemolymph
Closed System
• Circulatory fluid = blood
• Confined to vessels
• Advantages:
▫ High blood pressure
▫ Delivery of O2
▫ Regulation of blood flow to organs
Cardiovascular System
• Arteries
▫ Carry blood away from heart
 Arterioles
 Branches of arteries
• Capillaries
▫ Microscopic vessels
 Converge into – venules  veins 
heart
Circulation
• Atria – receive blood
• Ventricles – pump blood
• Single Circulation – blood passes through heart once in
each complete circuit
• Double Circulation – one circuit, oxygen-poor blood goes
to capillary beds (gas exchange tissues)
▫ 2nd circuit delivers oxygen-rich blood to body
Single vs. Double Circulation
42.2 Coordinated cycles of heart contraction
drive double circulation in mammals
• Cardiac cycle
▫ Systole – contraction phase
▫ Diastole – relaxation phase
• 2 determining factors of cardiac output:
▫ Heart rate
▫ Stroke volume
Maintaining Heart Rhythm
• Heart beats independently (no nerve signals)
• Sinoatrial (SA) node
▫ Pacemaker of heart
▫ cluster of autorhythmic cells
 Generate electrical
impulses (gap junctions)
• Atrioventricular (AV) node
Concept 42.3: Patterns of blood
pressure and flow reflect the
structure and arrangement of blood
vessels
Grace Castro
Blood Vessels
• Capillaries
• Arteries
• Veins
• Central lumen and endothelium
Vein
LM
Artery
Red blood cells
100 m
Valve
Basal lamina
Endothelium
Endothelium
Smooth
muscle
Connective
tissue
Capillary
Smooth
muscle
Connective
tissue
Artery
Vein
Capillary
15 m
Red blood cell
Venule
LM
Arteriole
Blood Flow Velocity
• Capillary beds: slowest velocity
▫ High resistance and large cross-sectional area
▫ Essential for blood transfer with interstitial fluid
Area (cm2)
Velocity
(cm/sec)
50
40
30
20
10
0
Pressure
(mm Hg)
5,000
4,000
3,000
2,000
1,000
0
120
100
80
60
40
20
0
Systolic
pressure
Diastolic
pressure
Blood Pressure
• Blood flows from high pressure to low
pressure
• Pressure on exerted on wall of vessels
• Becomes smaller in capillaries- reduced
space resists the flow
• Systolic pressure: arteries during ventricular
systole
• Diastolic pressure : arteries during diastole
© 2011 Pearson Education, Inc.
Regulation of Blood Pressure
• Signals cause contraction or relaxation
• Vasoconstriction contraction of smooth
muscle in arteriole walls
• Vasodilation is the relaxation of smooth
muscles in the arterioles
Blood Pressure and Gravity
• Animals with longer necks require greater
systolic pressure
• Blood is pumped through veins:
▫ Rhythmic contraction of smooth muscles
▫ Contraction of skeletal muscles during exercise
▫ Change in pressure within thoracic cavity during
inhalation
• Valves prevent backflow of blood
Direction of blood flow
in vein (toward heart)
Valve (open)
Skeletal muscle
Valve (closed)
Mechanisms to Regulate Blood Flow in
Capillaries
•
•
•
•
Blood amount varies in capillary sites
Contraction of smooth muscle layer
Precapillary sphincters
Regulated by nerve impulses, hormones, and
other chemicals
Precapillary
sphincters
Thoroughfare
channel
Arteriole
(a) Sphincters relaxed
Arteriole
(b) Sphincters contracted
Capillaries
Venule
Venule
Figure 42.15
INTERSTITIAL
FLUID
Net fluid movement out
Body cell
Blood
pressure
Osmotic
pressure
Arterial end
of capillary
Direction of blood flow
Venous end
of capillary
Fluid Return
• Lymphatic system
• Lymph reenters circulation at the venous end of
the capillary bed and indirectly through the
lymphatic system
• Valves prevent backflow of fluid
• Lymph nodes: filled with white blood cells
Concept 42.4: Blood components
contribute to exchange,
transport, and defense
• open circulation, the fluid that is pumped comes
into direct contact with all cells
• The closed circulatory systems of vertebrates
contain blood
• Blood consists of several kinds of cells
suspended in a liquid matrix called plasma
• The cellular elements occupy about 45% of the
volume of blood
• Blood plasma is about 90% water
• inorganic salts in the form of dissolved ions,
sometimes called electrolytes
• plasma proteins, which influence blood pH,
osmotic pressure, and viscosity
• plasma proteins function in lipid transport,
immunity, and blood clotting
• Suspended in blood plasma are two types of cells
▫ Red blood cells (erythrocytes) transport oxygen
O2
▫ White blood cells (leukocytes) function in
defense
• Platelets, a third cellular element, are
fragments of cells that are involved in clotting
▫ Have no nuclei
erythrocytes
• They contain hemoglobin, the iron-containing
protein that transports O2
▫
Sickle-cell is caused by abnormal hemoglobin that forms aggregates: rupture
blood vessels
• Each molecule of hemoglobin binds up to four
molecules of O2
• In mammals, mature erythrocytes lack nuclei
and mitochondria
▫ Anaerobic respiration
Leukocytes
• There are five major types of white blood cells,
or leukocytes: monocytes, neutrophils,
basophils, eosinophils, and lymphocytes
• They function in defense by phagocytizing
bacteria and debris or by producing antibodies
• They are found both in and outside of the
circulatory system
Blood Clotting
• Coagulation is the formation of a solid clot
from liquid blood
• A cascade of complex reactions converts
inactive fibrinogen to fibrin, forming a clot
• A blood clot formed within a blood vessel
is called a thrombus and can block blood
flow
• The
cellular
of blood wear
Stem
Cells
andelements
the Replacement
of
out and
are being replaced constantly
Cellular
Elements
• Erythrocytes, leukocytes, and platelets
develop from a common source of
stem cells in the marrow of bones
• The hormone erythropoietin (EPO)
stimulates erythrocyte production
when O2 delivery is low
Cardiovascular diseases
• Cholesterol, a steroid, helps maintain membrane fluidity
• Low-density lipoprotein (LDL) delivers cholesterol
to cells for membrane production
• High-density lipoprotein (HDL) scavenges
cholesterol for return to the liver
• Risk for heart disease increases with a high LDL to HDL
ratio
• Inflammation
• heart attack is the death of cardiac muscle tissue
resulting from blockage of one or more coronary
arteries
• stroke is the death of nervous tissue in the brain,
usually resulting from rupture or blockage of
arteries in the head
• Hypertension, or high blood pressure, promotes
atherosclerosis and increases the risk of heart
attack and stroke
• atherosclerosis, is caused by the buildup of
plaque deposits within arteries
42.5
An Overview by Griffin Schroeter
Main Idea
Gas Exchange Occurs Across Specialized
Respiratory Surfaces
Gas Exchange
• The uptake of molecular O2 from the
environment and the discharge of CO2 to the
environment
• Partial Pressure
▫ The pressure exerted by a particular gas in a
mixture of gases.
▫ Calculated by multiplying the pressure that the
gas mixture exerts and the fraction of the mixture
represented by a particular gas.
Predicting Gas Flow
• A gas always diffuses from a region of higher
partial pressure to a region of lower partial
pressure
• Air is more conductive to gas exchange than
water because air has a higher O2 content, lower
density, and lower viscosity
What is a specialized respiratory
• For adequate diffusion of O2 and CO2 between
surface?
air/water and an animal’s cells requires large,
moist respiratory surfaces
• Gills, Tracheal system, Lungs
Gills
• Outfoldings of the body surface specialized for
gas exchange in water. The effectiveness by some
gills, including those of fishes, is increased by
ventilation and countercurrent exchange
between blood and water
• Ventilation- movement of the respiratory
medium over the respiratory surface
• Countercurrent Exchange- the exchange of a
substance or heat between two fluids flowing in
opposite directions
Tracheal Systems
• Found in insects
• A system consisting of tiny, branching tubes that
penetrate the body, bringing O2 directly to the
cells
Lungs
• Spiders, land snails, and most terrestrial
vertebrates have internal lungs
▫ Lungs are localized respiratory organs
▫ The size and complexity of the lungs correlate with
the organism’s metabolic rate
Mammalian Respiratory Systems
Branch of
pulmonary vein
(oxygen-rich
blood)
Terminal
bronchiole
Nasal
cavity
Pharynx
Left
lung
Larynx
(Esophagus)
Trachea
Right lung
Branch of
pulmonary artery
(oxygen-poor
blood)
Alveoli
50 m
Capillaries
Bronchus
Bronchiole
Diaphragm
(Heart)
Dense capillary bed
enveloping alveoli (SEM
Mammalian Respiratory System
• Trachea- the windpipe
• Bronchi- the leading to each lung(singular: Bronchus)
• Bronchioles- fine tubes branching off of the
bronchi
• Alveoli- air sacs clustered at the tips of the
tiniest bronchioles. Gas exchange occurs here