Download Chapter 23 Circulation

Chapter 23 Circulation
Circulatory
Systems
The Human Cardiovascular
System and Heart
Internal transport systems
carry materials between
exchange surfaces and
body cells.
The heart pumps blood
through the pulmonary circuit
and the systemic circuit.
Structure and Function
of Blood Vessels
Blood flows through arteries to
capillaries, where exchange
occurs with body cells, and
returns to the heart in veins.
Structure and
Function of Blood
Red blood cells carry oxygen,
white blood cells fight infections,
and platelets function
in blood clotting.
Circulatory systems facilitate exchange
with all body tissues
 All cells must receive nutrients, exchange gases, and remove wastes.
 Diffusion alone is inadequate for large and complex bodies.
循環系統
 In most animals, circulatory systems facilitate these exchanges.
 An internal transport system assists diffusion by moving materials
between surfaces of the body and internal tissues.
胃循環腔
 A gastrovascular cavity in cnidarians and flatworms promotes
digestion and distributes substances.
 Most animals use a true circulatory system that consists of a
circulatory fluid (blood), muscular pump (heart), and set of tubes
(blood vessels) to carry the fluid.
Two circulatory systems
開放式循環系統
 Open circulatory systems are found in arthropods and many
molluscs and consist of
- a heart.
- open-ended vessels.
- blood that directly bathes the cells and functions as the
interstitial fluid.
閉鎖式循環系統
 Closed circulatory systems are found in vertebrates, earthworms,
squids, and octopuses and consist of
- a heart.
- vessels that confine blood, keeping it distinct from interstitial
fluid.
The open and closed circulatory systems
Tubular
heart
Pores
Capillary
beds
Artery
(O2-rich blood)
Arteriole
Venule
Vein
Gill
capillaries
Atrium
Artery
(O2-poor blood)
Ventricle
Heart
The heart and vessels
 The vertebrate
circulatory system is often called a 血管
心血管系統
cardiovascular system, including three types of vessels.
動脈
1. Arteries
carry blood away from the heart.
靜脈
2. Veins
return blood to the heart.
微血管
3. Capillaries convey blood between arteries and veins.
 The cardiovascular system of a fish includes a heart with
two main chambers:
心房
1. The心室
atrium receives blood from veins.
2. The ventricle pumps blood to gills via large arteries.
 These large arteries branch微血管
into
小動脈
arterioles that give rise to capillaries, the smallest blood vessels,
微血管床
which branch into networks called capillary beds.
小靜脈
 Capillaries converge into venules, which in turn converge into larger
靜脈
veins.
Vertebrate cardiovascular systems reflect evolution
 A two-chambered heart
- is characteristic of fish.
- pumps blood in a single circulation
in which blood moves
- from gill capillaries.
- to systemic capillaries.
- back to the heart.
Heart:
Ventricle
Atrium
Gill
capillaries
One atrium
One ventricle
Body
capillaries
The single circulation and two-chambered heart of a fish
 Land vertebrates have a double circulation consisting of a separate
- pulmonary circuit. 肺循環
- systemic circuit. 體循環
 Three-chambered hearts
- are found in amphibians, turtles, snakes, and lizards.
- consist of two atria and one undivided ventricle.
- this arrangement generally separates oxygen-poor and
oxygen-rich blood.
 Four-chambered hearts
- are found in crocodilians, birds, and mammals.
- consist of two atria and two ventricles.
- These two circuits do not mix oxygen-rich and oxygen-poor blood.
充氧血
缺氧血
Two atrium
Two ventricle
Two atrium
One ventricle
Lung and
skin capillaries
肺皮循環
Pulmocutaneous
circuit
Lung
capillaries
Pulmonary
circuit
Atrium
Atrium
Ventricle
Left
Right
Systemic
circuit
Atrium
Atrium
Ventricle
Ventricle
Right
Left
Systemic
circuit
Systemic
capillaries
The double circulation and three-chambered
heart of an amphibian
Systemic
capillaries
The double circulation and four-chambered
heart of a bird or mammal
The human cardiovascular system illustrates
the double circulation of mammals
 Blood flow through the double circulatory system of humans
- drains from the superior
vena cava (from the head and arms) or
上腔靜脈
inferior vena cava (from the lower trunk and legs) into the right
atrium.下腔靜脈
- moves out to the lungs via the pulmonary artery. 肺動脈
- returns to the left atrium through the pulmonary vein. 肺靜脈
- leaves the heart through the aorta.主動脈
The double circulation of the human cardiovascular system
8
Capillaries of
head, chest and
arms
Superior
vena cava
Pulmonary artery
Pulmonary artery
Aorta
9
Capillaries of
right lung
2
7
Capillaries
of left lung
2
3
4
10
4
Pulmonary vein
6
1
Right atrium
3
5
9
Pulmonary vein
Left atrium
Left ventricle
Right ventricle
Aorta
Inferior vena cava
Capillaries of
abdominal region
and legs
8
Blood flow through the human heart
To lung
To lung
Left atrium
Right atrium
From lung
From lung
半月瓣
房室瓣
Semilunar
valve
Semilunar
valve
半月瓣
Atrioventricular
房室瓣
(AV) valve
Atrioventricular
(AV) valve
三尖瓣 (Tricuspid valve)
二尖瓣 (Bicuspid valve)
僧帽瓣
Right
ventricle
Left
ventricle
The heart contracts and relaxes rhythmically
 The repeated
contraction and relaxation of pumping blood is called
心跳週期
the cardiac cycle. The cycle consists of two main phases.
舒張
 During diastole, blood flows
- from veins into heart chambers.
收縮
 During systole, blood flows
- from atria into ventricles.
心輸出量
 Cardiac output is the amount of blood pumped per minute from the
ventricles.
心跳率
 Heart rate is the number of heart beats per minute.
 Heart valves prevent the backflow of blood.
心雜音
 A heart murmur is a defect in one or more heart valves that
- permits a backflow of blood.
- reduces the cardiac output.
The cardiac cycle
Systole
Diastole
1 The heart
is relaxed.
The semilunar
valves are
closed.
2 The atria
contract.
0.1 sec
3 The ventricles
contract.
0.4 sec
0.3 sec
The AV
valves are
open.
The
semilunar
valves are
open.
The AV valves
are closed.
A cardiac cycle in a human with a heart rate of about 72 beats a minute
Cardiac output
Cardiac rate
X
Stroke volume
ll
Cardiac output
Cardiac sounds
lub-dup 心音
stethoscope
聽診器
Heart murmur
The SA node sets the tempo of the heartbeat
 The SA (sinoatrial) node 竇房結
- generates electrical signals in atria.
- sets the rate of heart contractions.
 The AV (atrioventricular) node 房室結
- relays these signals to the ventricles.
- causes ventricular contraction.
 An electrocardiogram (ECG) records electrical changes in the heart.
心電圖
 Heart rates normally adjust to body needs.
 Abnormal rhythms may occur in a heart attack.
 Automatic external defibrillators (AEDs) 自動體外去顫器
- shock the heart.
- reset the SA node.
- save thousands of lives.
1 Signals from the
SA node spread
through the atria.
SA node
(pacemaker)
2
Signals are
delayed at the
AV node.
AV node
3
Specialized muscle
fibers pass signals
to the heart apex.
4 Signals spread
throughout the
ventricles.
Specialized Purkinge fiber
muscle fibers
Right
atrium
Apex
ECG (EKG)
The sequence of electrical events in a heartbeat (top) and the corresponding electrocardiogram (bottom)
Artificial pacemaker
起搏器
心律調節器
Wire
leading
to SA node
Artificial
pacemaker
Heart
An artificial pacemaker implanted in the chest
Automatic external defibrillators (AEDs)
What is a heart attack?
 A heart attack 心臟病
- is damage or death of cardiac muscle.
- usually results from a blocked coronary artery.
心血管病變
 Cardiovascular diseases are disorders of the heart and blood
vessels. These include
中風
1. a stroke, death of brain tissue from blocked or ruptured arteries
in the head.
動脈粥狀硬化
2. atherosclerosis, in which fatty deposits in the walls of arteries
narrow the blood vessels and restrict blood flow.
Heart attack = Myocardial infarction
心肌梗塞
Superior
vena cava
Pulmonary
artery
Right coronary
artery
Aorta
Left coronary
artery
Blockage
Dead muscle
tissue
Blockage of a coronary artery, resulting in a heart attack
Stroke
缺血性中風
出血性中風
Atherosclerosis
Connective
tissue
Smooth
muscle
Fibrous connective
issue
Epithelium
Plaque
硬化斑
Atherosclerosis: a normal artery (left); an artery partially closed by plaque (right)
Angioplasty 血管成形術
氣球血管擴張手術
Balloon angioplasty
冠狀動脈支架放置
Stent (mesh tube) Implantation
The structure of blood vessels fits their functions
 Capillaries
- have thin walls consisting of a single layer of epithelial cells.
- are narrow, about as wide as one red blood cell.
- increase surface area for gas and fluid exchange with the interstitial
fluid.
 Arteries and veins
- are lined by a single layer of epithelial cells.
- have elastic fibers in an outer connective tissue layer that allows
these vessels to recoil after stretching.
- arteries contain a thick layer of smooth muscle in their walls that
can constrict and reduce blood flow.
- veins have one-way valves that restrict backward flow of blood.
Functions of blood vessels
Capillary
Red blood
cell
A capillary in smooth muscle tissue
Capillary
Interstitial
fluid
Diffusion of
molecules
Tissue
cell
Diffusion between blood and tissue cells
Structural relationships of blood vessels
Epithelium
Basal lamina
Capillary
Epithelium
Epithelium
Smooth
muscle
Connective
tissue
Artery
Arteriole
Valve
Smooth
muscle
Connective
tissue
Venule
Vein
Comparison of blood vessels
Blood pressure
血壓
 Blood pressure
- is the force blood exerts on vessel walls.
- depends on cardiac output and resistance of vessels to expansion.
- decreases as blood moves away from the heart.
 Blood pressure is
- highest in arteries.
- lowest in veins.
 Blood pressure is measured as
- systolic pressure - caused by ventricular contraction. 收縮壓
- diastolic pressure - low pressure between contractions. 舒張壓
Pressure
(mm Hg)
Blood pressure and velocity in the blood vessels
120
100
80
60
40
20
0
Systolic
pressure
Diastolic
pressure
Venae cavae
Veins
Venules
Capillaries
Arterioles
Arteries
50
40
30
20
10
0
Aorta
Velocity
(cm/sec)
Relative sizes and
numbers
of blood
vessels
Blood flow in a vein
 How does blood travel against gravity, up legs?
(1) Veins are squeezed by pressure from muscle contractions between
- two muscles.
- muscles and bone or skin.
Direction of
(2) One-way valves limit blood flow
blood flow
to one direction, toward the heart.
in vein
Valve
(open)
Contracting
skeletal
muscle
Valve
(closed)
Measuring blood pressure can reveal
cardiovascular problems
 A typical blood pressure for a healthy young adult is about 120/70.
Blood pressure is commonly measured using a sphygmomanometer.
 Hypertension is a serious cardiovascular problem in which blood
pressure is persistent at or above 140 systolic and/or 90 diastolic.
 Hypertension causes
- the heart to work harder, weakening the heart over time.
- increased plaque formation from tiny ruptures.
- increased risk of blood clot formation.
 Hypertension can contribute to
- heart attacks.
- strokes.
- kidney failure.
Measuring blood pressure
Typical blood
pressure:
120 systolic
70 diastolic
橡膠封套
Rubber cuff
inflated
with air
Artery
Pressure
in the cuff
above 120
Pressure
in the cuff
at 120
120
120
70
Sounds
audible
in the
stethoscope
Artery
closed
1
Pressure
in the cuff
at 70
2
3
Sounds
stop
4
Hypertension
Smooth muscle controls the distribution of blood
 Blood flow through capillaries is restricted by precapillary sphincters.
 By opening and closing these precapillary sphincters, blood flow to
particular regions can be increased or decreased.
 Only about 5–10% of capillaries are open at one time.
毛細血管前括約肌
Precapillary
sphincters
Arteriole
1
Thoroughfare
channel 直捷通路
Capillaries
Venule
Thoroughfare
channel
Arteriole
2 Sphincters are contracted.
Sphincters are relaxed.
The control of capillary blood flow by precapillary sphincters
Venule
Capillary structure and function
 Capillaries have very thin walls.
 Substances leave blood and enter interstitial fluid by
- diffusion.
- pressure-driven flow through clefts between epithelial cells.
 Blood pressure forces fluid out of capillaries at the arterial end.
 Osmotic pressure draws in fluid at the venous end.
Interstitial fluid
Capillary wall
Capillary lumen
Nucleus of
epithelial cell
Clefts between
the cells
Muscle cell
Fluid return via the lymphatic system
Tissue cells
Blood
pressure
Arterial
end
Interstitial
fluid
Osmotic
pressure
Venous
end
Net fluid movement
out of the capillary
Fluid enters a lymph vessel
The movement of fluid out of a capillary and into a lymph vessel
Blood consists of red and white blood cells
suspended in plasma
 Blood
consists of several types of cells suspended in a liquid called
血漿
plasma, which is about 90% water and contains many different
substances.
 Two classes of cells are suspended in blood plasma.
- Red blood cells or erythrocytes transport O2 bound to hemoglobin.
- White blood cells, or leukocytes,
- function inside and outside the circulatory system.
- fight infections and cancer.
嗜中性球
單核球
- monocytes and neutrophils are white blood cells called
吞噬細胞
phagocytes,
which engulf and digest bacteria and debris from our
own dead cells.
The composition of blood
Plasma (55%)
Constituent
Water
90%
Ions (blood electrolytes)
Sodium
Potassium
Calcium
Magnesium
Chloride
Bicarbonate
Plasma proteins
Cellular elements (45%)
Major functions
Cell type
Solvent for
carrying other
substances
Osmotic balance,
pH buffering, and
maintaining ion
concentration of
interstitial fluid
Osmotic balance
and pH buffering
Centrifuged
blood
sample
Number
per L (mm3) of blood)
Red blood cells
(erythrocytes)
White blood cells
(leukocytes)
5–6 million
Transport of
O2 and
some CO2
5,000–10,000
Defense
and immunity
20-25%
0.5-1%
Lymphocytes
Basophils
Fibrinogen
Clotting
Eosinophils
Immunoglobulins
(antibodies)
Defense
2-4%
Substances transported by blood
Nutrients (e.g., glucose, fatty acids, vitamins)
Waste products of metabolism
Respiratory gases (O2 and CO2)
Hormones
60-70%
Functions
phagocytes
Monocytes
Neutrophils
3-8%
Platelets
250,000–
400,000
(thrombocytes)
Megakaryocyte巨核細胞
Blood clotting
Anemia
貧血
 Anemia can be caused by low amounts of
- hemoglobin.血紅素
- red blood cells.
 Anemia causes fatigue due to lack of oxygen in tissues.
Erythropoietin
紅血球生成素
 The hormone erythropoietin (EPO)
regulates red blood cell production.
Erythropoietin in athletes
Some athletes artificially increase red blood cell production by
- training at high altitudes.
- injecting erythropoietin.
- withdrawing, storing, and then reinjecting their blood cells just
before a competition.
- abuse of these methods can lead to clotting, stroke, heart failure,
or even death.
Normal
EPO
Blood clots plug leaks when blood vessels are injured
 When a blood vessel is damaged
- platelets rapidly adhere to the exposed connective tissue and
a cluster of sticky platelets forms a plug.
- Clotting factors released from platelets and in the plasma help
trigger the conversion of the plasma protein fibrinogen to fibrin, a
纖維蛋白原
纖維蛋白
threadlike protein that helps form a clot that plugs the leak.
 Within an hour after a fibrin clot forms,
the platelets contract, pulling
the torn edges closer together.
 Chemicals released by platelets
also stimulate cell division in
smooth muscle and connective tissue,
initiating the healing process.
The blood-clotting process
纖維蛋白凝塊
血小板栓塞
1 Platelets adhere.
2 A platelet plug
forms.
3 A fibrin clot
forms.
Epithelium
Connective
tissue
Platelet
Platelet
plug
Fibrin clot
The blood-clotting process
Hemophilia
血友病
Stem cells offer a potential cure for blood cell diseases
 Multipotent stem cells多潛能性幹細胞
- are unspecialized.
- replace themselves throughout the life of an organism.
 Multipotent stem cells can differentiate into two main types of stem
cells.
- Lymphoid stem cells can in turn produce
two types of lymphocytes,
which function in the immune system.
- Myeloid stem cells can differentiate into
- erythrocytes.
multipotent stem cells
- other white blood cells.
unipotent stem cells
- platelets.
Leukemia
 Leukemia 白血病, 俗稱血癌
- is cancer of white blood cells.
- results in extra leukocytes
that do not function properly.
- is usually fatal unless treated.
 Leukemia may be treated by
- radiation.
- chemotherapy.
- the replacement of cancerous bone marrow
with healthy bone marrow
(or bone marrow stem cells).
Differentiation of blood cells from stem cells
Multipotent
stem cells
(in bone marrow)
Lymphoid
stem cells
Myeloid
stem cells
Basophils
Erythrocytes
Platelets
Lymphocytes
Monocytes
Eosinophils
Neutrophils