Chapter 7b Transport Systems in Animals

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Chapter 7b- Transport Systems in Animals

• As discussed, organisms need to exchange
  materials with the environment (food and needed
  materials must come in, wastes must be taken
  out).
• - Unicellular organisms use vacuoles to bring
  materials in and out (example Paramecium)
• - Simple multicellulars that are a few cells
  total, or few cells thick, have sac-like body
  plans. Fluid materials are brought in and about
  the animal without a need for specific vessels
  or channels (examples Sponges, Hydra
  cnidarians, planarians flatworms)
• - More complex organisms (many cells thick) need
  a circulatory system. The sac-like body plan is
  insufficient. This is particularly more
  important in terrestrial environments, and on
  land the challenges of exchanging materials with
  the environment are more complicated.
• Most circulatory systems involve the movement of
  body fluids in and out of the body, and
  distribute them to all cells of the body. A
  pumping mechanism is needed (one or more hearts),
  and also blood vessels and blood. The types of
  materials that travel thru the circulatory system
  include
• - Nutritive materials, after having been
  digested (broken down)
• - Waste materials, that are processed in
  excretory systems but that are brought from each
  cell via the circulatory system.
• - Gases (O2, CO2), after being exchanged via a
  respiratory system
• - Hormones and other substances involved in
  regulation/control

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Some examples of transport systems
Circulatory systems with hearts
No circulatory system
(Unicellular) Uses vacuoles
Closed circulatory system with blood vessels
(Multicellular, 2 cells thick) Sac-like body plan
Open circulatory system with no blood or vessels
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Open vs Closed circulatory systems

• Both types involve a pumping structure (heart)
• The main differences lie in whether there are
• 1) Blood A fluid material that is distinct
  from other intercellular fluids.
• 2) Specific vessels (vessels, veins, arteries,
  capillaries) through which blood flows.
• Open circulatory system (usually with long,
  tubular heart)
• - Arthropods (insects arachnids,
  crustaceans-shrimp, crabs centipeds/millipeds)
• - Distribution of O2 occurs thru small ducts
  through the body
• - Generally, suitable only for animals up to a
  relatively small size
• Closed circulatory system (with one or more
  hearts)
• - More complex animals
• - Blood travels faster
• - Distribution of O2 occurs through the
  circulatory systems vessels
• - A requirement of larger, active animals.

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Circulation in vertebrates

• Circulatory system cardiovascular system
  heart(s) blood vessels blood
• The heart in vertebrates is multi-chambered
  (several chambers), but the number of chambers is
  not the same in all animals.
• Vertebrate heart chambers
• - Atria (singular atrium) - Receive blood
  returning to the heart
• - Ventricles - Pump blood out of the heart.
• Vertebrate heart blood vessels
• 1) arteries - carry blood away from the heart,
  to organs in the body.
• 2) capillaries The network of microscopic
  vessels that branch out of arteries to
  infiltrate every tissue.
• Chemical exchange (including gas exchange)
  between the blood and tissues occurs in
  capillaries. After that, capillaries rejoin into
  veins.
• 3) Veins carry blood to the heart.
• Large vessels are called arteries or veins
  depending on the direction of flow (away from, or
  to the heart), and not depending on whether is
  oxygenated or non-oxygenated blood.

(artery)
Atrium entrance Venter belly
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Vertebrate circulation - Fish
Crocodilians, birds, mammals. 4 (2A, 2V)
Fish 2(1A, 1V)
Amphibians, most reptilians (turtles, snakes,
lizards). 3 (2A, 1V)

• Closed circulatory systems and increased
  complexity are needed for achieving larger body
  size, higher levels of activity and the resulting
  increased cell respiration.
• Fish 2-chambered heart (1 Atrium, 1 Ventricle)
• - Ventricle ? gills (picks O2, gives off CO2) ?
  digestive system (picks nutrients) ? other
  tissues of body ? back to heart (atrium)
• - Blood does not return to heart after it gets
  aerated at gills, but goes direct to the body (1
  pump system). Thus blood goes sluggishly (low
  pressure), but fish offset this limitation by
  being very efficient at getting O2 in gills and
  into the blood.

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Vertebrate circulation Amphibiansreptilians
(part)
Crocodilians, birds, mammals. 4 (2A, 2V)
Fish 2(1A, 1V)
Amphibians, most reptilians (turtles, snakes,
lizards). 3 (2A, 1V)

• Amphibians and most reptilians 3 chambers (2
  Atria, 1 Ventricle)
• Ventricle ? artery w/ 2 branches
• 1st- to lungs skin (picks O2) ? returns to
  heart thru veins
• 2nd- to all organs except lungs ? returns to
  heart thru veins
• There are 2 pumps (2 pumpings) Double
  circulation the first when the blood is first
  sent ending in capillaries, the second after it
  has been in capillaries and is to return to the
  heart.
• Some mixing of oxygenated and non-oxigenated
  blood takes place because there is only one
  ventricle. Because of this, these animals tire
  easily, but actually they make up for it by being
  able to obtain additional O2 through their skin
  (without lung intervention).

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Vertebrate circulation Crocodilians, birds,
mammals
Crocodilians, birds, mammals. 4 (2A, 2V)
Fish 2(1A, 1V)

• Crocodilians, birds, mammals 4 chambers (2A, 2V
  RA, LA, RV, LV)
• Double circulation Oxygenated and de-oxygenated
  blood are kept separate. In effect, is as if
  there were 2 hearts (the right heart, and the
  left heart).
• Right heart receives blood from the tissues
  (de-oxygenated) and sends it to the lungs for
  oxygenation. From the lungs, the O2-rich blood
  returns to the Left heart to be pumped to the
  body tissues.
• These vertebrates, particularly birds and mammals
  are active, maintain constant and elevated body
  tissues and have high levels of metabolism
  (physical and mental activity). The
  high-efficiency, high-pressure double circulation
  is thought to be a necessary adaptation for these
  demands.

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The human heart

• 1- Superior inferior vena cava (bring
  deoxygenated blood from body)
• 2- Right atrium with pacemaker
• 3- RA/RV valve pass into right ventricle
• 4- right ventricle
• 56- Pulmonary arteries to left/right lungs (push
  out blood to be oxygenated in lungs)
• 7- Pulmonary veins bring blood back from lungs
• 8- Left atrium
• 9- LA/LV valve (Mitral valve)
• 10- Left ventricle propels blood to the aorta
• 11- Aorta (artery)- delivers oxygenated blood to
  body tissues.

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The human cardiac cycle

• Cardiac cycle Each sequence of muscle
  contraction (Systole) relaxation (Diastole).
  All chambers (RA, RV, LA, LV) go through them.
• Atria relaxed and filling (receiving blood from
  body RA or from lungs LA), ventricles are
  relaxed (in diastole)
• Blood forces AV valves open, and ventricles start
  to fill. Atria contract (atrial systole) pushing
  rest of blood to ventricles.
• Ventricles contract (ventricular systole) causing
  AV valves to close and pressure increases. Valves
  to aorta and to pulmonary artery open and blood
  flows out of the heart. Then the ventricles relax
  (ventricular diastole), and the cycle begins
  again.
• Why are ventricles thicker and more powerful than
  atria? Why is the left ventricle more muscular
  than the right ?

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Helpful review of the human heart
From lungs
from From body

• Left Atrium (in, send next door)
• Receives O2-blood from lungs by
• Pulmonary veins (left, right)
• sends O2-blood to left ventricle
• Little muscle needed

Right Atrium (in, send next door) -receives
de-ox blood from body (vena cava inf.
superior) -sends de-ox blood to right
ventricle - Little muscle needed

• Left ventricle (in, away)
• Receive O2-blood from left atrium
• Sends (pumps hard) O2-blood to
• Body via artery aorta
• - Most muscular of all (sends farthest)

• Right Ventricle (in, away)
• Receives de-ox blood from
• Right atrium
• -Sends (pumps hard) de-ox blood
• to lungs by L, R pulmonary arteries
• -More muscle to send to lungs

to lungs
to all body
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Cardiac muscle contraction

• Heart muscle cardiac muscle (involuntary)
• Body muscles - Skeletalstriated muscle
  (voluntary)
• organs except heart Smooth muscle (involuntary)
  
• Contraction requires Energy (ATP) whether is
  voluntary or involuntary. 2 proteins play a role
  in contraction of all muscles
• Actin (thin protein filaments), and myosin
  (thicker protein filaments)
• Z-lines are protein anchors. Actin filaments are
  attached to Z-lines.
• During contraction, myosin filaments walk and
  pull along the actin filaments, narrowing the
  gap between rows of actin filaments. The entire
  unit contracts.

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Early observations on blood flow

• People did not know there were different vessels
  with different functions (arteries, veins,
  capillaries). The understanding was that
• - blood was pumped from the heart and went to
  the body via vessels
• - blood returned through the same vessels
• - Blood flow was as the tides on the shore
• William Harvey (England, 17th century) discovered
  that
• - There was no ebb and flow as on the shore.
• - Blood runs all the time (he proposed blood
  circulates like a river with no end (moves all
  the time)
• - He saw that an utensil (or blood itself) could
  only flow in one direction through the vessels,
  because there were flaps of tissue (valves)
  that allowed only one way movement.
• - He concluded that there had to be 2 different
  sets of vessels One for blood to go out of the
  heart towards the body (arteries), and another
  for blood to return to the heart (veins).

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Vein artery structure making blood flow

• Large vessel structure from inside out (veins
  arteries)
• 1) Endothelium-internal lining (1 cell tick)
• 2) Middle layer- Smooth muscle elastic fibers
• Arteries - very thick muscle
• - operate under high pressure
• Veins - thinner wall overall
• - much less muscle
• - operate under less pressure
• 3) Outer layer -connective tissue elastic
  fibers
• ____________________________________
• The muscle layer of arteries expands/contracts
  during the cardiac cycle
• - Heart contracts (systole)?forces blood into
  arteries w/ high pressure?arteries walls
  stretch.
• - Heart relaxes (diastole)?stretched arteries
  walls contract?blood is pushed along, maintains
  pressure

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Maintaining Blood pressure
Blood pressure Measure of the force per unit
area with which blood pushes against the walls of
the blood vessels. - Usually measured at the
artery on the upper arm, with an sphygnometer. -
Normal pressure in a young adult at rest is about
120/80 (120 mm Hg when the ventricles are
contracting systolic pressure), and 80 mm Hg
when the ventricles relax (diastolic pressure)

• Veins have valves (flaps of tissue) that allow
  only a one-way blood flow thru them. Arteries do
  not have valves. Damaged vein valves allow
  backflow (example varicose veins)
• Blood pressure is maintained by various physical
  features of the organs involved, and various
  regulatory processes and controlling substances
• - Physical features The cardiac cycle
  (contraction/relaxation), the valves in veins,
  skeletal muscle pressing on vessels, gravity
  helps blood returning from the head region)
• - Regulatory processes
• - Hormones in nervous, excretory and
  circulatory systems
• - Sensory inputs emotions (flushing, getting
  pale), sexual arousal (body parts filling with
  blood)
• - Chemical inputs, particularly CO2, ions in
  blood tissues
• Hypertension Consistently higher readings of
  blood pressure, present in over 20 of adults in
  the USA. Makes heart work harder than normal can
  damage vessels and result in stroke (heart
  attacks) can result in atherosclerosis
  (hardening of vessel walls)

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So wheres my blood?
During moderate exercise

• Tissues that are most important for specific
  activities or physical exercise receive generally
  larger blood flow at all times, but also during
  specific activities during short term periods.
• Contraction of the smooth tissue layer in the
  walls of blood vessels reduces blood flow through
  specific organs.

Resting (normal) conditions
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Common heart /circulatory problems

• Cardiovascular diseases
• Some caused by poor health/habits Faulty heart
• valves, and some strokes may be related to
  these
• conditions.
• Some may have at least partial genetic
• basis, such as Familial hypercholesterolimia
• Abnormally high levels of blood cholesterol (a
  lipid)
• that accumulates inside arteries, blocking them
• and leading to heart attacks.

A replacement, artificial, mechanical-type heart
valve.
A stroke (heart attack) A blood vessel (artery)
has clogged somewhere on the body,
exerting backpressure on the heart. An artery
on The heart may then rupture.
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Composition of blood- 1) Erythrocytes

• Materials in the blood of vertebrates
• 1) Erythrocytes (red blood cells),
• 2) Leukocytes (white blood cells)
• 3) Platelets (small clotting agents),
• 4) Plasma (the fluid media)
• 1) Erythrocytes (red blood cells, RBC)
  transport O2 contained in a protein called
  hemoglobin, which consists of 4 subunits, each
  made of an iron (Fe) suspended in a molecule
  called heme group.
• - Fe in hemoglobin binds with oxygen in O2-rich
  areas (the lungs), carries them in the blood, and
  releases in O2-poor areas (ends of
  capillariestissues and cells)
• - Some animals dont have hemoglobin, but other
  substances that do the same job. All vertebrates
  have hemoglobin.
• - RBCs are produced constantly because the live
  only 120 days.
• - dont reproduce while in the blood
• - produced in the marrow of bones
  (regulated by a hormone in kidneys)
• - Mature erythrocytes in human and other
  mammals dont have a nucleus. In frogs and
  other animals they do.

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2) Leukocytes 3) Plasma

• 2) Leukocytes (WBC) Defend the body against
  invading organisms such as bacteria. There are
  several types
• - Macrophagues Surround bacteria and other
  foreign foreign cells and absorb them, thus
  eliminating them as a threat.
• - Foreign cells are incorporated eaten by
  endocytosis.
• - When there is an infection, WBC numbers in
  the blood increase greatly (the body is
  fighting the disease).
• - The Pus often seen in infected tissues is
  a thick opaque, usually yellowish white fluid
  matter formed by suppuration, composed partly of
  leukocytes, tissue debris, and microorganisms
• 3) Plasma Provides a liquid media for the
  blood cells to travel in and for carrying other
  materials. Plasma consists of water, proteins,
  aminoacids, sugar and other particles.
• Plasma serves as
• - Carries most of the CO2 waste from cell
  respiration throughout the body.
• - Absorves nutrients from the intestine
  after digestion, carrying them to the rest of the
  cells of the body.
• - Carries hormones from various glands, for
  example
• Insulin Maintains proper levels of blood
  sugar
• - Carries various dissolved ions that help
  regulate the balance between blood and the
  intercellular fluid, and others that maintain a
  proper blood pH.
• - Levels of ions in intercellular fluid
  depend of levels in the plasma. These ions
  regulate the operation of nerves and muscles.
  The organs that control proper levels of these
  ions (electrolytes) are the kidneys.

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4) Platelets (clotting coagulating agents)

• 4) Platelets Small bodies that interact with a
  protein in blood to cause clotting when there is
  an injury.
• - They help stop blood from running out
  continuously through a wound (coagulation of
  blood)
• - Platelets become sticky and attract other
  platelets forming a plug that seals the wound.
• - They release enzymes that interact with
  clotting factors in the blood (proteins),
  beginning an enzymatic chain that involves the
  changing of fibrinogen (a soluble plasma protein)
  to an insoluble form called fibrin. Fibrin
  strands make a network where platelets stick,
  forming a blood clot.

1) Enzyme cascade? enzyme Agent X forms 2) Agent
X Calcium ions (Ca2)? protein prothrombin
changes to thrombin 3) Thrombin an enzyme ?
soluble protein fibrinogen changes to insoluble
fibrin. 4) Fibrin attracts materials making a
clot (plug)
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The Lymphatic system

• The lymphatic system is an additional network of
  tubules that carry lymph through the body.
• Lymph consists of
• - specialized cells
• - water
• - large proteins
• - salts, other substances, and intercellular
  materials
• Lymph picks up intercellular materials and brings
  them into the lymphatic vessels.
• The lymphatic system does not have a pump (a
  heart). Thus, the flow is slow, and depends
  largely on muscle contractions on other muscles
  of the body, that push lymph through the
  lymphatic system.