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Circulatory Systems: Transport & Thermoregulation in Open & Closed Systems, Lecture notes of Hydraulics

An in-depth exploration of the circulatory systems in various organisms, focusing on their functions, components, and designs. Topics include transportation of water, electrolytes, gases, nutrients, wastes, and chemical messengers; thermoregulation; and hydraulics. both open and closed circulatory systems, discussing their advantages and limitations.

Typology: Lecture notes

2021/2022

Uploaded on 09/27/2022

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Circulatory Systems
Heyer
Circulatory Systems
Circulatory Systems
Circulatory Systems
Functions:
Transportation
Water & electrolytes (salts)
Dissolved gases— O2 & CO2
Nutrients
Wastes
Chemical messengers
(hormones)
Defense (immune) systems
Repair (clotting) factors
Thermoregulation
Hydraulics
Cardiovascular
System
Lymphatic
System
Circulatory Systems
Ciliated Body Cavity
Open Circulatory System
Closed Circulatory System
Hemocoel
Size & System Development
Diffusion is sufficient for small
organisms w/ low volumes &
metabolic demands (e.g.
protozoans and micrometazoans).
Ciliated Body Cavity
Cnidarians & Platyhelmintheans
gastrovascular system
ciliated digestive cavity w/ branching extensions.
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Circulatory Circulatory SystemsSystems Circulatory^ Systems

Functions:

  • Transportation
    • Water & electrolytes (salts)
    • Dissolved gases— O 2 & CO 2
    • Nutrients
    • Wastes
    • Chemical messengers

(hormones)

  • Defense (immune) systems
  • Repair (clotting) factors
  • Thermoregulation
  • Hydraulics Cardiovascular System Lymphatic System

Circulatory Systems

  • Ciliated Body Cavity
    • Open Circulatory System
      • Closed Circulatory System

Hemocoel

Size & System Development

• Diffusion is sufficient for small

organisms w/ low volumes &

metabolic demands (e.g.

protozoans and micrometazoans).

Ciliated Body Cavity

Cnidarians & Platyhelmintheans

  • gastrovascular system
    • ciliated digestive cavity w/ branching extensions.
  • water vascular system
    • ciliated coelom w/ extensions

(dermal branchae

& tube feet)

for respiration.

  • Important

hydraulic functions

Echinoderms Vascular System Components

  • Four components are
      1. circulatory fluids
      1. vessels
      1. pump
      1. valves
  • Vasculature (vessels) may form open or

closed circulatory system

Open Circulatory Systems

  • In arthropods & most molluscs.
  • 4-part system - what are those parts?
  • circulatory fluids mix w/ interstial fluids of

body cavity.

  • Hence, “blood” is called hemolymph. Open Circulatory Systems
  • Dorsal heart pumps

hemolymph out

vessels into body

cavity (= hemocoel )

  • Hemocoel partially

compartmentalized

into sinuses

  • Hemolymph returns

to heart via ostia or

veins.

Open Circulatory Systems

Dorsal Vessel as Pump

  • Whole dorsal vessel

may act as a tubular

heart

  • Insects
  • Specific region

specialized into a heart

  • Crustaceans &

Molluscs

  • Hemolymph pulled from

hemocoel by veins to

gills to heart to arteries

to hemocoel

Limitations of Open Systems

  • Difficult to regulate different perfusion of

different tissues.

  • Great for small body plans; not so great for

big bodies with variable metabolic activities.

  • How can it be enhanced for large bodies?

Closed Circulatory Systems in Vertebrates

  • Crocodilians, Birds &

Mammals

  • 4-chambered heart
    • 2 atria/2 ventricles
  • Double circuit :
      1. Pulmonary circuit: blood flows from heart to lungs only
      1. Systemic circuit: repressurized blood flows from heart to systemic vessels
  • No mixing of deoxygenated + oxygenated blood
  • Pulmonary & systemic circuits are pressurized differently
  • 10x more efficient systemic oxygenation Closed Circulatory Systems in Vertebrates - Crocodilians - 4-chambered heart - 2 atria/2 ventricles - Double circuit : - 1. Pulmonary circuit: blood flows from heart to lungs only - 2. Systemic circuit: repressurized blood flows from heart to systemic vessels - Shunt to divert pulmonary to

systemic flow when

underwater

Review of Designs Mammalian Cardiovascular System

  • Two circuits, each with its own 2-chamber pump
    • Different pressure
    • Same flow rate Mammalian Cardiovascular System
  • Pulmonary circuit:
  • Right pump Æ lungs Æ left pump

q Deoxygenated systemic blood

fills right A&V

q Right A&V contract pushing

deoxygenated blood through

pulmonary artery to lungs

q Release CO 2 q Take up O 2

q Oxygenated blood from lungs

flows through pulmonary veins

to left atrium

Mammalian Cardiovascular System

  • Systemic circuit:
  • Left pump Æ body Æ right pump

q Oxygenated pulmonary blood

fills left A&V

q Left A&V contract pushing

oxygenated blood through

aorta to branching major

arteries to all other body

organs

q Release O 2 q Take up CO 2

q Deoxygenated blood from

body tissues flows through

branches of veins converging

on vena cava to right atrium

The Pump

  • For any pump to function, it needs

two components:

1. Constriction (stroke) chamber

Øchamber volume fi ↑pressure

fi move fluid

2. Valves

fi direct fluid flow direction

Human Heart Anatomy

  • Diagrams show

heart from front

  • Viewer’s “right” is

heart’s “left”

  • Enclosed in fluid-

filled sac behind

sternum

Human heart in chest cavity

Cardiac Contractions

  1. Sinus node (pacemaker) fires
  2. Signal spreads across atria
  3. Cardiac muscle in atria contract
  4. Signal reaches AV node; travels down Bundle of HIS to apex of heart
  5. Signal spreads across venticles
  6. Cardiac muscle in venticles contract - Arteries – carry blood away from the heart - Arterioles – smaller branches of arteries - Capillaries – thin, microscopic, with porous walls - Venules – smaller branches that converge into veins - Veins – carry blood back to heart The Vessels Artery Vein SEM (^100) μm Endothelium Artery Smooth muscle Connective tissue Capillary Basal lamina Endothelium Smooth muscle Connective tissue Valve Vein Arteriole (^) Venule Red blood cell Capillary 15 μm LM Vessel Structure & Function
  • Arteries: blood away from heart
  • Thick-walled and elastic to withstand higher pressure
  • Smooth muscle in arteriole walls regulate selective blood flow
  • Veins: blood toward heart
  • Thin, compliant walls
  • Internal valves prevent backflow
  • Capillaries: thin-walled and highly branched
  • Only vessels exchanging with tissue fluids!
  • Walls only 1 cell thick to maximize diffusion rates
  • Not permeable to blood cells & proteins; permeable to water and other solutes (^) Fig. 42. Poisseuille’s Law

The Hagen-Poiseuille Equation:

  • Flow rate = f = ( Dy p)( p r^4 )/(8L h )

where

ßDyp= pressure difference

ß r = radius

ßh = fluid viscosity

ßL = length of tube

  • NOTE: Df proportional with Dr^4!
  • Fluids not returned to

capillaries goes to

lymphatics

  • 85-90% fluid returned to blood circulation
  • 10-15% taken up by lymphatic capillaries Capillary exchange Lymphatic System
  • Recaptures lost

fluids & proteins

  • Interstitial fluids

filtered through

lymphoid tissues

and monitored by

immune system

  • Fluids return to CV

system in vena cava

Lymph node Fluid Flow in Veins — both Cardiovascular & Lymphatic Systems

  • Fluids pumped by “skeletal muscle pumps”
  • Valves prevent backflow

The composition of blood

Blood: Liquid Tissue

Cells Suspended in Plasma

Blood Structure and Function

“Formed Elements” — cells and cell-derivatives

Since erythrocytes and thrombocytes lose their nuclei,

they are no longer truly cells.

  • Erythrocytes (red blood cells)
    • Carry oxygen
  • Leukocytes (white blood cells)
    • Defense/clean up
  • Thrombocytes (platelets)
    • Blood clotting

Plasma

  • 90% H 2 O
  • 7–9% protein Human blood smear ClottingClotting
  • • Leukemia victims lack plateletsLeukemia victims lack platelets
  • •^ HemophiliacsHemophiliacs lacklack^ clottingclotting factors.factors.

PlateletesPlateletes

ClottingClotting FactorsFactors

ProthrombinProthrombin ThrombinThrombin

FibrinogenFibrinogen FibrinFibrin