Lecture 10: Principles Of Fluid Flow In Vertebrates

Question 1

What are the advantages of a closed circulatory system?

Answer 1

1. Closed systems can generate higher pressures, blood flows more rapidly through vessels than interstitial space -> therefore quicker nutrient and waste transport
2. Resistance in blood vessels can be changed -> blood flow can be more tightly regulated and more easily redirected to specific tissues
3. Cellular elements and transport molecules kept within vessels (eg hemoglobin)

Question 2

Three types of pumps used in circulatory systems

Answer 2

Contractile chamber: muscles can be inside or outside the chamber
External pump: skeletal muscles push contents through
Peristaltic pump: rhythmic waves of contraction move along he blood vessel

Question 3

What are the 4 types of fluid?

Answer 3

Hemolymph- fluid that circulates within an open circulatory system (single ECF compartment)
Blood- fluid that circulates within a closed circulatory system (plasma and cells)
Interstitial fluid: extracellular fluid that directly bathes the tissues
Lymph: fluid that circulates in the secondary system of vertebrates called the lymphatic system

Question 4

Common features of vertebrate circulatory systems

Answer 4

• closed circulatory system
• general plan involves two or more contractile chambers of myocardial tissue, with valves to ensure unidirectional blood flow
• two or more heart chambers
• progressive increase in separation of blood flow to gas exchange organs and blood flow to rest of body

Question 5

All vertebrates hearts generate force through conaction of myocardial tissue. What are the 2 different types of myocardium

Answer 5

1. Spongy: mesh work of loosely connected cells

2. Compact: tightly packed cells arranged in a regular pattern

Question 6

The number of heart chambers has increased during vertebrate evolution.

Answer 6

Vertebrates heart evolved from two chambers in fish to three in amphibians and reptiles and four in crocodilians, mammals, and birds.
A three chambered heart evolved in order to separate oxygenated and deoxygenated blood increasing respiratory efficiency

Question 7

What are the advantages of of separate pulmonary and systemic circulations

Answer 7

1) oxygenated and deoxygenated blood cannot mix- meaning systemic blood always receives blood with highest oxygen content
2) maximizes respiratory gas exchange
3) pulmonary and systemic circuits can operate under different pressures
All together an improved respiratory and cardiovascular efficiency

Question 8

What are the other two changes in the cardiovascular system.

1) specialized electrical conduction
2) myocardial cell replication

Answer 8

1) specialized electrical conduction:
- pacemaker cells present very early in evolution-> rhythmic activity
2) myocardial cell replication
- the ability to efficiently replace lost myocardial cells in adulthood disappeared around the appearance of warm bloodedness

Question 9

Part 2 fluid mechanics

Blood is divided into two portions what are they and what do they consist of?

Answer 9

Blood is divided up into a plasma portion and a cellular portion

1. Plasma is the water component, containing ions, organic solutes and proteins
2. Cellular components are produced from stem cells in the Bone marrow

Question 10

Electrical activity of the heart: how does The beat start?

Answer 10

-cardiac cycle involves rhythmic contraction of heart chambers in response to electrical activity (depolarization)
-depolarization is initiated in the sinoatrial node
-depolarization then spreads
1) across the atria then..
2) to ventricles via the atrioventricular node
Refer to slide 13 lecture 11

Question 11

What is the electrocardiogram used for?

Answer 11

Electrocardiography monitors the electrical activity of the heart

Question 12

Increase in heart rate is called?

Decrease in heart rate is called?

Answer 12

Decrease is bradycardia

Increase is tachycardia

Question 13

Principles of fluid flow part 3

What are the 2 determinants of fluid flow?

Answer 13

1. Pressure gradient
2. Resistance ie
   - tube length
   - tube radius
   - fluid viscosity
   - flow pattern

Question 14

What are the components of a circulatory system?

Answer 14

Circulatory system move fluids by generating pressure on one part of the circuit
Fluid flows through the body from high pressure to Low pressure
Circulatory systems need three main components:
-pump
-system of tubes
-fluid

Question 15

What is the differences in open circulatory systems and closed?

Answer 15

Open:
-circulatory fluid comes in direct contact with the tissues in spaces called sinuses

Closed circulatory system:

• circulatory fluid stays within blood vessels
• circulatory fluid does not make direct contact with tissues
• extracellular fluid separated into plasma and interstitial fluid compartments

Question 16

The number if heart chambers has increased during vertebrate evolution. Explain

Answer 16

Vertebrates hearts are the first to have two chambers
Vertebrates heart evolved from 2 chambers in fish to 3 in amphibians and reptiles and 4 in crocodilians, mammals and birds

Question 17

Fish heart and circulation

Answer 17

Heart:
-first group to develop a multi chambered heart
-focal gas exchange (gills) requires more efficient circulatory systems working at higher pressures
Two chambers allows separate collection and pumping of blood
-have mostly spongy myocardium

Circulation:

• ventricles are located ventral to atrium (gravity helps blood flow)
• most pressure from ventricular contraction dissipated passing through gills (high resistance)
• blood flowing to tissues is at relatively low pressure

Question 18

Lungfish heart and circulatory syste

Answer 18

Heart:
Three-chambered heart (2 atria, one ventricle)
-partial separation of oxygenated and deoxygenated blood increasing respiratory efficiency.
-has mostly spongy myocardium

Circulation:
First separation of pulmonary (lungs) and systemic (body) circulations
-not complete separation of oxygen rich and oxygen poor blood, but there is very little mixing.

Question 19

Amphibian heart and circulation:

Answer 19

Heart:

• three chambered heart (2 atria, one ventricle)
• oxygenated blood from the lungs to left atrium, deoxygenated blood to right atrium
• two types of blood enter a single ventricle, but surprisingly little mixing
• mostly spongy myocardium

Circulation:

• partially separated pulmonary and systemic circuits
• gas exchange occurs at skin
• only the pulmonary circuit has a separate venous return to heart

Question 20

Reptile hearts and circulation

Answer 20

Heart:

• Three chambered heart (2 atria, one ventricle)
• but complex ventricular structure (3 sub chambers divided by muscular ridges)
• ridges separate flow of oxygenated and deoxygenated blood
• mostly compact myocardium

Circulations:

• left aorta takes oxygenated blood from left ventricle to body, right aorta takes blood from both ventricles to body
• blood is diverted from lungs into systemic circuit when not breathing

Question 21

Crocodilians heart and circulation:

Answer 21

Heart:

• 4 chambered heart
• blood bypasses lungs when animal is submerged (pulmonary pressure increases, opens valve)

Circulation:
Bypasses circuit to miss the lungs if animal is submerged

Question 22

Avian and mammalian circulations and heart:

Answer 22

Heart:

• 4 chambered hearts with valves to prevent back flow of blood
• atria are thin walls, ventricles are thick walled
• complete seperation of oxygenated and deoxygenated blood
• very different pressures in pulmonary and systemic circuits
• compact myocardium

Question 23

What are 2 more evolutionary changes in cardiovascular system

Answer 23

1) specialised electrical conduction
- pacemaker cells
2) myocardial cell replication
- the ability to efficiently replace lost myocardial cells in adulthood disappeared around warm blooded ness
- mammals cannot generate significant numbers of her ventricular myocytes after birth

Question 24

During the cardiac cycle, blood moves from ->

Answer 24

Inferior and superior vena cava veins - right atrium - right ventricle -pulmonary artery -lungs- pulmonary vein - left atrium - left ventricle - aorta