Transcript 11 - Circulation & Gas Exchange Sum13

1
Lecture 11 Outline (Ch. 42)
I.
II.
III.
IV.
V.
Circulatory Systems
Human Heart
Blood, Vessels, & Lymph
Cardiovascular disorders
Respiration in different
organisms
VI. Methods – bulk flow
vs. diffusion
VII. Gas exchange and partial pressures
VIII. Inhalation/exhalation
IX. Brain control
X. Respiratory problems
XI. Preparation for next lecture
2
Circulation Overview
Circulation carries energy,
dissolved gasses, wastes
•
•
Connects individual cells in
distant parts of body
Requirements
– Blood – fluid for transport
– Blood vessels – channels for
transport
– Heart – pump for circulation
3
Circulation Overview
Circulatory systems are open or closed
•
•
Open- bathes organs in a hemocoel
Closed- direct vessel connections to organs
Heart
Hemolymph in sinuses
surrounding organs
Pores
Heart
Blood
Interstitial
fluid
Small branch vessels
In each organ
Dorsal vessel
(main heart)
Tubular heart
(a) An open circulatory system
Auxiliary hearts
Ventral vessels
(b) A closed circulatory system
4
Circulation Overview
Vertebrates have a closed circulatory system
•
•
More efficient
– Blood is 5 – 10% of body volume
– Flow is more rapid, pressure is higher
Multifunctional
– Transport dissolved gasses
– Distribute nutrients & hormones
– Transport waste
– Thermoregulation
– Circulate immunodefenses
Arteries – away from heart,
Veins – toward heart
5
The Vertebrate Heart
Atrium empties into ventricle
•
Set of
muscular
chambers
Ventricle pumps blood out
of heart  moves to gill
capillaries: gas exchange
•
Atria collect
blood
Ventricles
send blood
through body
From gills, blood collects
and moves to body
capillaries  gas exchange
The heart
has
evolved
From body, blood returns
to heart, swimming helps
propel blood
•
•
Single circulation
6
The Vertebrate Heart
2 atria empty into 1 ventricle
Ridge or incomplete septum
divides ventricle
Can shunt blood from lungs
to body when under water
From body, blood returns
to right atrium
Double circulation –
pulmocutaneous circuit
and systemic circuit
7
The Vertebrate Heart
2 atria empty into 2 ventricles
Complete septum – right side receives
oxygen poor blood from body – sends to lungs
Endotherms need to deliver 10X as much
dissolved gasses and nutrients/waste as same
size ectotherms!
Double circulation – pulmonary circuit and
systemic circuit
8
Heart
4-chambered heart: A closer look
•
2 pumps
•
•
Right: deoxygenated blood
Left: oxygenated blood
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Heart
•
Right atrium receives deO2 blood from veins
– Superior vena cava
– Inferior vena cava
Right ventricle pumps
deO2 blood to lungs
through pulmonary
arteries
Pumps into right ventricle
10
Heart
•
Oxygenated blood returns to left atrium from lungs via
pulmonary veins
Oxygenated blood
pumped to body
through aorta
Pumps into left ventricle
11
Heart
Keeping blood moving
•
•
•
Heart valves maintain oneway flow
Atrioventricular valves
– Between atria &
ventricles
Semilunar valves
– Between ventricles &
arteries
12
Which of the following regions contains
OXYGENATED blood?
1.
2.
3.
4.
5.
Pulmonary arteries
Right ventricle
Pulmonary veins
Superior vena cava
Inferior vena cava
Heart
The Cardiac Cycle
14
Heart
The Cardiac Cycle & Blood Pressure
•
•
Normal blood pressure ~120/70
Systolic
– Ventricular contractions
(higher pressure)
Diastolic
– Period between contractions
(lower pressure)
sphygmomanometer
• “Lub-dup” sounds heard with stethoscope
– Lub – AV valves closing
– Dup – closing of semilunar valves
15
Heart
Cardiac muscle contracts
•
Present only in the heart
Cells linked by
intercalated discs
Prevents strong contractions
from tearing muscle
Allows rapid spread of
electrical signal for
simultaneous
regional
contraction
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Heart
Keeping blood moving
•
•
•
Pacemaker cells initiate and
coordinate contractions
Sinoatrial (SA) node
– Primary pacemaker
– Stimulates atrial
contractions
Atrioventricular (AV) node
– Delayed impulse received
from SA node
– Ventricular contraction
after atrial contractions
have filled them with
blood (delay ~0.1 sec)
17
Blood
Plasma
•
•
Primarily water
Dissolved proteins and electrolytes
Blood
•
•
Plasma fluid
Cells
– Red blood cells – transport
– White blood cells – defense
– Platelets – clotting
18
Blood
Red blood cells: Erythrocytes
•
•
•
Most abundant blood cells (over 99%)
Transport O2 and CO2
Iron-based hemoglobin protein binds to O2 and
transports from areas of high concentration to
low concentration
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Blood
Erythrocytes are short-lived
•
•
•
•
Formed in bone marrow
Lack nuclei (cannot divide or make proteins)
Dead cells are removed by liver and spleen
– Iron is recycled, although some is excreted
Number of erythrocytes
maintained by negative
feedback
20
If an athlete injected erythropoietin (EPO),
would this help their performance?
1.
2.
3.
4.
5.
No – EPO decreases hemoglobin
Yes – EPO increases red blood cell number
No – EPO increases blood cell destruction
Yes – EPO decreases carbon dioxide levels
No – EPO is unrelated to athletic performance
Blood
White blood cells: leukocytes
•
•
Less than 1% of blood cells
Disease defense
–
–
–
–
–
Consume foreign
particles
(macrophages)
Produce antibodies
(lymphocytes)
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Blood
Platelets
•
•
•
Cellular fragments
aid blood clotting
Ruptured cells and
platelets work
together to produce
substances that plug
damaged vessels
Scabs are platelets
embedded in web of
fibrin proteins
23
Blood is carried in
vessels
24
Artery
Vein
SEM
Valve
100 µm
Basal lamina
Endothelium
Smooth
muscle
Connective
tissue
Endothelium
Smooth
muscle
Capillary
Connective
tissue
Artery
Vein
Capillary
15 µm
Red blood cell
Venule
LM
Arteriole
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Blood Vessels
Arteries
Arterioles
Arteries
• Carry blood away from heart
• Thick-walled:
Heart
Capillaries
• Smooth muscle/elastic fibers
• Withstand high pressure
Veins
Venules
26
Blood Vessels
Arteries
Arterioles
Arterioles
• Control distribution of blood flow
• Smooth muscle expands / contracts
• Under hormone / NS control
Capillaries
Heart
Veins
Venules
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Blood Vessels
•
•
•
•
Arterioles
Contract walls: redirects blood to heart and muscles
when needed (stress, exercise, cold)
Relax walls: brings more blood to skin capillaries to
dissipate excess heat
Precapillary sphincters control blood flow to
capillaries
28
Blood Vessels
Arteries
Arterioles
Capillaries
• Nutrients/waste exchanged with cells:
• Vessel wall one-cell thick
• Blood flow very slow
Capillaries
Heart
• Materials exit/enter via diffusion
Veins
Venules
29
Blood Vessels
Capillaries connect & exchange
•
•
Tiny vessels
Connect arterioles and venules
•
Interstitial fluid leaks from plasma in
capillaries and provides cells with means of
exchange
30
Blood Vessels
Arteries
Arterioles
Venules & Veins
• Carry blood towards the heart
Heart
Capillaries
• Thin-walled; large diameter
• One-way to prevent backflow
Veins
Venules
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Blood Vessels
Skeletal Muscle Pump:
Vein Valve:
32
Blood Vessels
Varicose veins occur if the vein valves become inefficient
33
What is a correct difference
between veins and arteries?
1.
2.
3.
4.
5.
Arteries carry blood toward the heart
Veins have thicker walls
Arteries carry higher pressure blood
Veins lack valves
Arteries always carry oxygenated blood
Blood Vessels
Cardiovascular Disorders:
• Leading cause of death in the United States
1) Hypertension = High blood pressure
•  Resistance in vessels =  work for heart
2) Atherosclerosis = Deposits (plaques) collect in vessels
Connective
tissue
Smooth
muscle
Endothelium
Plaque
35
(a) Normal artery
50 µm (b) Partly clogged artery
250 µm
The lymphatic system
•
•
Coordinates with circulatory system
Includes: lymph nodes, vessels,
and glands
–
–
–
•
Returns fluid to
bloodstream
–
•
Tonsils
contain lots of lymphocytes
Thymus
matures white blood cells
Spleen
filters blood
Lymph capillaries reabsorb
interstitial fluid
Bodily defense
–
Contain white blood cells
in nodes
36
Lymph
Elephantiasis
Condition caused by
parasitic worm
infection of the
lymphatic system.
Symptoms most
common in legs and
genitals
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Lymph
Lymphatic
vessels
•
Narrow, thinwalled
•
Cellular
openings act as
one-way valves
•
Dead-end in
tissues, collect
materials flow
back to larger
blood vessels
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Thought Question:
If you are an athlete who trains at high elevations, what
happens if you compete at a lower elevation?
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Overview
Living things process energy
• They need oxygen for this - Why?
40
Overview
Cellular respiration uses O2 and produces CO2
•
C6H12O6 + O2  CO2
+ H2O + ATP energy
•
Breathing –
respiration
supports this
process by
exchanging gasses
Cell
41
Gas Exchange Systems
Respiratory systems enable gas
exchange
• Bulk flow
– Fluids move in bulk
– Air/water move to respiratory
surface
– Blood moves through
vessels
• Diffusion
– Individual molecules move
down concentration
gradients
– Gas exchange across
respiratory surface
– Gas exchange in tissues
42
Gas Exchange Systems
•
Aquatic gas exchange
Gills
• Elaborately folded ( surface area)
• Contain capillary beds
• Gill size inversely related to [O2]
• Large gills = low [O2]
43
Gas Exchange Systems
•
Dissolved O2 is < 1%
of water (21% of air)
•
Countercurrent
exchange increases
efficiency
Fish Efficiency
44
Gas Exchange Systems
Terrestrial respiration
•
Internal
– Stay moist &
supported
•
Insects have tracheae
– Air enters/exits
through spiracles
– Branching channels
(trachioles) allow gas
exchange with cells
45
Gas Exchange Systems
Vertebrate respiration
•
Terrestrial use of lungs
–
•
Evolved from accessory
respiratory organs of
freshwater fish
Amphibians are weird
–
–
–
Remain tied to water
Larval gills to adult lungs
Moist skin transfers
gasses
46
Gas Exchange Systems
Reptiles & Mammals use lungs exclusively
•
•
Lack permeable skin
Lungs are more efficient
– Especially birds!
47
Mammals
Human Respiration
•
•
•
Air enters through nose
and mouth to pharynx
Travels through larynx
(voice box)
Epiglottis directs travel
48
On to the lungs
•
•
•
•
Trachea 
Bronchi 
Bronchioles
 Alveoli
•
•
•
Human Respiration
Air is warmed & cleaned
•
•
Dust & bacteria trapped by mucus
Swept up and out by cilia
Microscopic chambers provide
enormous surface area
Surfactant keeps surface moist
Association with capillaries
– Diffusion of gasses
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Lungs
Diffusion
•
Blood arrives from
pulmonary artery
•
Low in O2
– Higher concentration in
air diffuses into blood
High in CO2
– Higher concentration in
blood diffuses into air
•
O2
CO2
50
Human Respiration
• Gas exchange is
driven by differences
in pressures
• Blood from body with
low O2, has a partial
oxygen pressure
(PO2) of ~40 mm Hg
• By contrast, the PO2
in the alveoli is about
100 mm Hg
• Blood leaving lungs,
thus, normally
contains a PO2 of
~100 mm
51
Where is the partial pressure of oxygen lowest?
1.
2.
3.
4.
Systemic veins and pulmonary arteries
Pulmonary veins and pulmonary arteries
Systemic veins and systemic arteries
Pulmonary veins and systemic arteries
Transport of gasses
CO2 Transport
•
•
•
CO2 binds
hemoglobin loosely
Dissolved in plasma
Combines with H20
to form bicarbonate
(HCO3-)
–
More CO2 = lower pH
The Bohr Effect:
Hemoglobin binds more tightly to O2 when pH is
increased and loosely when pH is decreased
53
Transport of gasses
O2 Transport
•
Binds to hemoglobin
– Removes O2 from
plasma solution
– Increases
concentration
gradient; favors
diffusion from air
CO binds more tightly to
hemoglobin than O2
Prevents O2 transport
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Breathing Mechanisms
• Outside lung covered by
the visceral pleural
membrane
• Inner wall of thoracic cavity
lined with parietal pleural
membrane
• Space between called the
pleural cavity
– Thin space w fluid
– Causes 2 membranes
to adhere
– Lungs move with
thoracic cavity
Breathing Mechanisms
• Inhalation:
Contraction of
intercostal
muscles
expands rib
cage
Contraction of
diaphragm
expands the
volume of
thorax and
lungs
• Thoracic cavity expands, produces negative pressure
which draws air into the lungs
56
Which would increase air intake?
1.
2.
3.
4.
relaxing diaphragm and intercostal muscles
relaxing diaphragm, contracting intercostal muscles
contracting diaphragm and intercostal muscles
contracting diaphragm, relaxing intercostal muscles
Breathing Mechanisms
Breathing is involuntary
•
•
Controlled by respiratory
center of the brain
Adjusts breath rate & volume
based on sensory input
– Maintain a constant
concentration of CO2
58
Respiratory Problems
• Chronic obstructive pulmonary disease (COPD)
– Any disorder obstructs airflow on a long-term basis
Asthma
•
Smooth muscle irritated
& constricts or spasms,
increased mucus
Infection
Bronchitis & Pneumonia
•
•
•
Inflammations of respiratory passages & lungs
Increase in mucus production, decrease in cilia
Causes include bacteria, viruses, fungi, & parasites
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Respiratory Problems
Emphysema
•
Alveoli rupture or become brittle creating larger but
fewer alveoli
•
Reduces surface
area available for
gas exchange
•
Labored and
difficult breathing
•
80-90% of deaths
linked with
smoking
60
Respiratory Problems
Tuberculosis
•
Bacteria attack and cause lesions on lung tissue
61
Things To Do After Lecture 11…
Reading and Preparation:
1.
Re-read today’s lecture, highlight all vocabulary you do not
understand, and look up terms.
2.
Ch. 42 Self-Quiz: #1, 2, 3, 5, 6, (correct answers in back of book)
3.
Read chapter 42, focus on material covered in lecture (terms,
concepts, and figures!)
4.
Skim next lecture.
“HOMEWORK” (NOT COLLECTED – but things to think about for studying):
1.
Compare and contrast veins and arteries in terms of structure and
function.
2.
Diagram the path blood takes from the body, to the heart and lungs,
back to the body.
3.
Explain in detail how oxygen is carried in the bloodstream and
exchanged in the lungs and at cells.
4.
Describe at least four diseases/disorders of the respiratory system.