Transcript Chapter 5 Gases

Chapter 36
Circulation
Sections 1-7
Albia Dugger • Miami Dade College
36.2 The Nature of Blood Circulation
• A circulatory system distributes materials throughout the
vertebrate body (and some invertebrates)
• It includes one or more hearts (muscular pumps) that propel
fluid through vessels extending through the body
Open and Closed Circulatory Systems
• Open circulatory system (arthropods, mollusks)
• A heart pumps hemolymph into open-ended vessels
• Hemolymph leaves the vessels and mixes with interstitial
fluid
• Closed circulatory system (annelids, vertebrates)
• A heart pumps blood through a continuous series of
vessels
• Materials diffuse across the walls of the smallest-diameter
blood vessels
aorta
pump
heart
spaces or
cavities
in body
tissues
dorsal blood vessel
pump
large-diameter
blood vessels
(rapid flow)
large-diameter
blood vessels
(rapid flow)
gut cavity
capillary bed (many small vessels
that serve as a diffusion zone)
ventral blood
vessels
two of five
hearts
Figure 36-2a p628
ANIMATED FIGURE: Types of circulatory
systems
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Evolution of Vertebrate Circulation
• Fishes
• Heart with two chambers
• Single circuit of circulation
• Amphibians
• Heart with three chambers
• Two partially separated circuits
• Birds and mammals
• Heart with four chambers
• Two fully separate circuits
gill capillaries
heart:
ventricle
atrium
capillaries of body
Figure 36-3a p629
Systemic
Circuit
Pulmonary
Circuit
lungs
left
atrium
right
atrium
ventricle
rest of body
Figure 36-3b p629
Systemic
Circuit
Pulmonary
Circuit
lungs
left
atrium
right
atrium
right ventricle
left ventricle
rest of body
Figure 36-3c p629
Circulation in Birds and Mammals
• The four-chambered heart has two separate halves, each with
an atrium and a ventricle
• Each half pumps blood in a separate circuit
• Pulmonary circuit: Blood flows from right half of heart, to
lungs (gains oxygen), to left half of heart
• Systemic circuit: Blood flows from left half of heart, to
body (loses oxygen), to right half of heart
Take-Home Message: How do animals
distribute substances to body cells?
• Most animals have a circulatory system that speeds the
distribution of substances through the body.
• Some invertebrates have an open circulatory system, other
invertebrates and all vertebrates have a closed circulatory
system, in which blood always remains enclosed within the
heart or blood vessels.
Take-Home Message: (cont.)
• Fish have a one-circuit circulatory system. All other
vertebrates have a short pulmonary circuit that carries blood
to and from the lungs, and a longer systemic circuit that
moves blood to and from the body’s other tissues.
• A four-chambered heart evolved independently in birds and
mammals. Such a heart allows strong contraction of one
ventricle to speed blood through the systemic circuit, while a
weaker contraction of the other ventricle
36.3 Human Cardiovascular System
• The term “cardiovascular” comes from the Greek kardia (for
heart) and Latin vasculum (vessel)
• Each circuit includes a network of blood vessels that carries
blood from the heart to small vessels where exchanges occur
and then back to the heart
Blood Vessels
• The ventricles force blood through a series of vessels:
• Arteries carry blood from ventricles to arterioles
• Arterioles control blood distribution to capillaries
• Capillaries exchange substances
• Venules collect blood from capillaries
• Veins deliver blood back to heart
Jugular Veins
Carotid Arteries
Ascending Aorta
Superior Vena Cava
Pulmonary Arteries
Pulmonary Veins
Coronary Arteries
Hepatic Veins
Brachial Arteries
Renal Veins
Renal Arteries
Inferior Vena Cava
Abdominal Aorta
Iliac Veins
Iliac Arteries
Femoral Veins
Femoral Arteries
Figure 36-4 p630
The Pulmonary Circuit
• The pulmonary circuit carries blood to and from the lungs
• Oxygen-poor blood is pumped from the right ventricle into
pulmonary arteries
• As blood flows through pulmonary capillaries, it picks up
oxygen and gives up carbon dioxide.
• Oxygen-rich blood returns through pulmonary veins to the left
atrium
The Pulmonary Circuit
right pulmonary artery
capillaries
of right
lung
capillary bed
of right lung
pulmonary
trunk
from
systemic
circuit
heart
a Pulmonary Circuit
left pulmonary artery
capillary bed
of left lung
to systemic
circuit
pulmonary
veins
capillaries
of left
lung
The Systemic Circuit
• The systemic circuit carries blood to and from the body
• The left ventricle pumps blood into the aorta
• Arteries and arterioles carry blood to various body parts
• Blood gives up oxygen and picks up carbon dioxide as it flows
through capillaries
• Oxygen-poor blood returns through venules and veins to the
right atrium
Hepatic Blood Flow
• Most blood moving through the systemic circuit flows through
only one capillary bed
• Blood that passes through capillaries in the small intestine
flows through the hepatic portal vein to capillaries in the liver
• The liver stores some absorbed glucose as glycogen, and
breaks down some absorbed toxins, including alcohol
capillaries of head,
neck, upper trunk, arms
aorta
to pulmonary
circuit
from
pulmonary
circuit
heart
capillaries of organs
in the thoracic cavity
capillaries
of the liver
capillaries of
the intestines
B Systemic Circuit
capillaries of other abdominal
organs, lower trunk, legs
Figure 36-5b p631
Take-Home Message: What are the two circuits
of the human cardiovascular system?
• The pulmonary circuit carries oxygen-poor blood from the
heart through the pulmonary arteries to arterioles and then
capillaries in the lungs. Pulmonary veins return oxygenated
blood to the heart.
• The systemic circuit carries oxygenated blood from the heart
out the aorta, through branching arteries and to capillaries
throughout the body. It returns oxygen-poor blood to the heart
by way of venules and veins.
• Most blood in the systemic circuit passes through one
capillary bed, but blood that flows through capillaries in the
intestines also flows through capillaries in the liver.
36.4 Components and Functions of Blood
• Vertebrate blood carries oxygen, nutrients, and other solutes
to cells, and carries away their metabolic wastes and
secretions, including hormones
• Blood also carries cells and proteins that protect and repair
tissues
• In birds and mammals, shifts in the distribution of blood flow
help maintain a constant body temperature
Blood Volume and Composition
• An average adult human has about 5 liters (10 pints) of blood
• Blood’s fluid portion is plasma
• Blood cells and platelets form in bone marrow and are
transported in plasma
Plasma
• Plasma is mostly water with hundreds of different plasma
proteins dissolved in it
• Some plasma proteins transport lipids and fat-soluble
vitamins; others have a role in blood clotting or immunity
• Some gases and nutrients such as sugars, amino acids, and
vitamins are dissolved in plasma
Blood Cells
• Red blood cells (erythrocytes)
• Contain hemoglobin that carries oxygen from lungs to
tissues
• Quantified in a cell count
• White blood cells (leukocytes)
• Defend the body from pathogens
• Neutrophils, basophils, eosinophils, monocytes, and
lymphocytes (B and T cells)
Platelets
• Platelets are fragments of megakaryocytes
• After a platelet forms, it lasts five to nine days
• When activated, it releases substances needed for blood
clotting
Components of Human Blood
Cellular Components of Mammalian Blood
hematopoietic stem cells
in red bone marrow
myeloid stem cell
red blood cell
precursor
granulocyte
precursor
lymphoid stem cell
monocyte
precursor
megakaryocytes
platelets
red blood cells neutrophils eosinophils basophils
(erythrocytes)
monocytes B lymphocytes T lymphocytes
(immature
(mature in
(mature in
phagocytes) bone marrow)
thymus)
Take-Home Message: What are the
components and functions of human blood?
• Blood consists mainly of plasma, a protein-rich fluid that
carries wastes, gases, and nutrients.
• Blood cells and platelets form in bone marrow and are
transported in plasma. Red blood cells contain hemoglobin
that carries oxygen from lungs to tissues. White cells help
defend the body from pathogens. Platelets are cell fragments
involved in clotting.
36.5 Hemostasis
• Hemostasis is a three-phase process that stops blood loss,
constructs a framework for repairs:
• Damaged vessel constricts
• Platelets accumulate
• Cascading enzyme reactions involving plasma proteins
cause clot formation
Three-Phase Process of Hemostasis
Take-Home Message:
How does the body halt bleeding?
• The vessel constricts, platelets accumulate, and cascading
enzyme reactions involving protein components of plasma
cause clot formation.
36.6 Blood Typing
• Blood type
• Genetically determined differences in molecules on the
surface of red blood cells
• Agglutination
• Clumping of foreign cells by plasma proteins
• When blood of incompatible types mixes, the immune
system attacks the unfamiliar molecules
ABO Blood Typing
• ABO blood typing analyzes variations in one type of glycolipid
on the surface of red blood cells
• Blood type O has neither A nor B – the immune system treats
both type A and type B cells as foreign
• Blood type O is a universal donor
• Blood type AB can receive blood from any donor
ABO Blood Types
Mixing ABO Blood Types
Rh Blood Typing
• Rh blood typing is based on the presence or absence of the
Rh protein
• An Rh- mother may develop Rh+ antibodies if blood from an
Rh+ child enters her bloodstream during childbirth
• These antibodies may attack the red blood cells of the next
Rh+ fetus
Rh–
Rh+
Rh+
markers
on the red
blood cells
of a fetus
fetus
Figure 36-10a p635
anti-Rh+
antibody
molecules
any
subsequent
Rh+ fetus
Figure 36-10b p635
Take-Home Message:
What is a blood type?
• Blood type refers to the kind of surface molecules on red
blood cells. Genes determine which form of these molecules
an individual has.
• When blood of incompatible types mixes, the immune system
attacks the unfamiliar molecules, with results that can be fatal.
36.7 The Human Heart
• The heart is a durable, muscular pump that contracts in
response to its own spontaneous action potentials
• A sac of connective tissue (pericardium) surrounds the heart
muscle (myocardium)
• Endothelium lines heart chambers and blood vessels
The Human Heart
• Each side of the human heart contains two chambers:
• An atrium that receives blood from veins
• A ventricle that pumps blood into arteries
• Heart valves keep blood moving in one direction:
• AV valves separate atria and ventricles
• Semilunar valves separate ventricles and arteries
Major Blood Vessels
• Two veins deliver deoxygenated blood to the right atrium:
• The superior vena cava from upper regions
• The inferior vena cava from lower regions
• The right ventricle pumps blood into two pulmonary arteries,
each leading to one lung
• Oxygenated blood returns to the left atrium via pulmonary
veins, and is pumped out of the left ventricle into the aorta
right lung left lung
superior vena cava
(flow from head, arms)
aorta (to body)
trunk of pulmonary
arteries (to lungs)
pulmonary valve
(closed)
pericardium
diaphragm
aortic valve
(closed)
right pulmonary
veins (from lungs)
left pulmonary
veins (from lungs)
Right Atrium
Left Atrium
right AV valve
(open)
left AV valve
(open)
Left Ventricle
Right Ventricle
cardiac muscle
inferior vena cava
(from trunk, legs)
septum
Figure 36-11 p636
superior vena cava
(flow from head, arms)
aorta (to body)
trunk of pulmonary
arteries (to lungs)
pulmonary valve
(closed)
aortic valve (closed)
right pulmonary
veins (from lungs)
left pulmonary
veins (from lungs)
Right Atrium
Left Atrium
right AV valve
(open)
left AV valve
(open)
Right Ventricle
Left Ventricle
inferior vena cava
(from trunk, legs)
cardiac muscle
septum
C Cutaway view, showing the heart’s internal organization. Arrows indicate
the path taken by oxygenated (red) and oxygen-poor (blue) blood.
Stepped Art
Figure 36-11 p636
The Cardiac Cycle
• In the cardiac cycle, heart muscle alternates between
diastole (relaxation) and systole (contraction)
• Blood collects in atria
• AV valves open, blood flows into ventricles
• Contraction of ventricles drives blood circulation
• Ventricles contract with a wringing motion from bottom to
top
1
Relaxed atria fill.
Fluid pressure opens
AV valves and blood
flows into the relaxed
ventricles.
As blood flows
into the arteries,
pressure in the
ventricles
declines and the
aortic and
pulmonary
valves close.
4
Contracting
atrial squeeze
more blood into
the still-relaxed
ventricles.
2
Ventricles
start contracting
and rising
pressure pushes
AV valves shut. A
further rise in
pressure opens
aortic and
pulmonary
valves.
3
Stepped Art
Figure 36-12a p637
Setting the Pace for Contraction
• The sinoatrial (SA) node in the wall of the right atrium, is the
cardiac pacemaker – it generates about 70 action potentials
per minute
• Gap junctions between adjacent cells allow action potentials
generated by the SA node to spread across the atria
• The signal spreads from the SA node to the atrioventricular
(AV) node, then to junctional fibers in the septum, so the
heart contracts from the bottom up
SA node
(cardiac
pacemaker)
AV node
conducting
fibers
Figure 36-13 p637
Take-Home Message: How does heart
structure relate to its function?
• The four-chambered heart is a muscular pump partitioned into
two halves, each with an atrium and a ventricle. Forceful
contraction of the ventricles provides the driving force for
blood circulation.
• The SA node is the cardiac pacemaker. Its spontaneous,
rhythmic signals make cardiac muscle cells of the heart wall
contract in a coordinated fashion.
36.8 Blood Vessel Structure and Function
• Contracting ventricles put pressure on the blood, forcing it
through a series of vessels that vary in their structure.
• Arteries have thick walls containing smooth muscle reinforced
with elastic connective tissue
• When a ventricle contracts, artery walls to bulge and spring
back, creating a pulse
Blood Vessel Structure and Function
• Blood flows from arteries into arterioles
• In the systemic circuit, the distribution of blood to particular
body parts is adjusted by altering the diameter of arterioles
• Smooth muscle that rings each arteriole responds to signals
from the autonomic nervous system, and to chemical signals
• Sympathetic stimulation causes vasodilation of arterioles in
the extremities and vasoconstriction of arterioles of the gut
Blood Vessel Structure and Function
• A capillary is a cylinder of endothelial cells, one cell thick,
wrapped in basement membrane – its narrow diameter
facilitate exchanges between blood and interstitial fluid
• Blood flows from capillaries into venules, which empty Into
veins
• Veins are large-diameter, low-resistance vessels that convey
blood to the heart – many veins have flaplike valves that help
prevent backflow
from
the heart
to
the heart
valve
endothelium
smooth muscle
connective tissue
capillary network
B
Arteriole
D
Venule
endothelium
A Artery
C Capillary
E Vein
Figure 36-14 p638
Take-Home Message: How do blood vessels
differ in structure and function?
• Arteries are thick-walled, large-diameter vessels. Stretching
and recoil of arteries helps keep blood moving.
• Smooth muscle in the wall of arterioles allows adjustments to
blood flow in the systemic circuit.
• Capillaries are narrow tubes of epithelial cells. They are the
site of exchanges with interstitial fluid.
• Veins have valves that prevent backflow.
36.9 Blood Pressure
• Blood pressure is the pressure exerted by blood on the walls
of blood vessels
• Blood pressure is highest in arteries, then declines throughout
a cardiovascular circuit
Change in Blood Pressure
through the Systemic Circuit.
Systolic and Diastolic Pressure
• Systolic pressure, the highest pressure of a cardiac cycle,
occurs as contracting ventricles force blood into arteries
• Diastolic pressure, the lowest blood pressure of a cardiac
cycle, occurs when ventricles are relaxed
• Blood pressure is measured in millimeters of mercury (mm
Hg), and is written as systolic /diastolic
• Normal blood pressure is about 120/80 mm Hg
Controlling Blood Pressure
• Blood pressure depends on total blood volume, how much
blood the ventricles pump (cardiac output), and whether
arterioles are constricted or dilated
• Receptors in the aorta and carotid arteries monitor blood
pressure and send signals to the medulla, which regulates
cardiac output and arteriole diameter
• Inability to regulate blood pressure can result in hypertension,
in which resting blood pressure remains above 140/90
Take-Home Message: How is blood pressure
recorded and regulated?
• Blood pressure is the fluid pressure exerted against a vessel
wall. It is recorded as systolic/diastolic pressure.
• Adjustments to arteriole diameter, cardiac output, and blood
volume regulate blood pressure.
36.10 Mechanisms of Capillary Exchange
• Capillary beds are diffusion zones, where blood exchanges
substances with interstitial fluid
• As blood flows through a circuit, it moves fastest through
arteries, and slowest in capillaries
• Slow flow through capillaries enhances the rate of exchanges
between the blood and interstitial fluid
Substance Exchange
• To move between the blood and interstitial fluid, a substance
must cross a capillary wall
• Oxygen, CO2 , and small lipid-soluble molecules diffuse
across endothelial cells of a capillary
• Some larger molecules enter endothelial cells by endocytosis,
diffuse through, then enter interstitial fluid by exocytosis
Fluid Exchange
• Higher blood pressure at the arterial end of a capillary bed
forces fluid out between cells
• At the venous end of the capillary, interstitial fluid enters the
capillaries by osmotic pressure
• Normally, there is a small net outward flow of fluid
• The lymphatic system returns fluid to the blood
Fluid Movement at a Capillary Bed
blood to
venule
high pressure causes
outward flow
blood
from
arteriole
inward-directed
osmotic movement
cells of
tissue
Take-Home Message: How do blood and
interstitial fluid exchange materials?
• Small molecules cross cells of a capillary by diffusion and
larger ones move across by exocytosis.
• Fluid rich in oxygen and nutrients also leaks out between cells
of the capillary wall.
36.11 Venous Function
• Veins are the body’s largest blood reservoir
• Skeletal muscle activity helps move blood at low pressure
through veins and back to the heart
• Valves in veins help prevent backflow
• Contractions of smooth muscle inside vein walls helps force
blood toward the heart
venous valve
Figure 36-18 p641
blood flow to heart
valve
open
valve
closed
valve
closed
valve
closed
Figure 36-19a p641
Take-Home Message:
What are the functions of veins?
• Veins are the body’s main blood reservoir. The amount of
blood in the veins changes depending on activity level.
• Blood pressure in veins is low. One-way valves, activity of
skeletal muscle, and respiratory muscle action all help move
the blood toward the heart.
Take-Home Message:
What factors impair circulatory function?
• Altered blood cell number or quality can alter blood’s ability to
carry out its functions.
• Atherosclerosis and hypertension raise the risk of heart attack
and stroke.
• Problems with the cardiac pacemaker cause arrhythmias.
Take-Home Message: What are the functions
of the lymphatic system?
• The lymph vascular system consists of tubes that collect and
deliver excess water and solutes from interstitial fluid to blood.
It also carries absorbed fats to the blood, and delivers disease
agents to lymph nodes.
• The system’s lymphoid organs, including lymph nodes, have
specific roles in body defenses.