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Santovito > the circulatory system > Flashcards

the circulatory system Flashcards

1
Q

main function of the circulatory system?

A
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2
Q

what are the components of the circulatory system?

A
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3
Q

circulatory fluids are?

A

blood or hemolymph

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4
Q

what’s the vascular system?

A

arteries, capillaries, veins

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5
Q

what’s the propulsory organ of the circulatory system?

A

heart

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6
Q

What determines the movement of circulatory fluid through an animal’s body?

A
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7
Q

how can the unidirectional movement be assured?

A

presence of valves and/or septa

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8
Q

what is hemodynamics?

A
  1. study of the physical principles governing the movement of blood within the circulatory system
  2. it examines factors such as
    - blood pressure
    - blood flow
    - vascular resistance
  3. Hemodynamics considers how these factors interact to maintain proper circulation throughout the body
  4. ensuring delivery of oxygen and nutrients to tissues and removal of waste products
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9
Q

what’s the volumetric flow rate (Q)?

A
  • the volume of circulatory fluid that is set in motion in the unit of time
  • directly proportional to the pressure difference
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10
Q

what vessel-types are there?

A
  1. arteries
  2. arterioles
  3. capillaries
  4. veins
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11
Q

arteries
(number, special feature, functions)

A
  1. number: several hundred
  2. special features:
    - thick, highly elastic walls
    - large radii
  3. functions:
    - passageway from heart to organs
    - serve as pressure reservoir
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12
Q

arterioles
(number, special feature, functions)

A
  1. number: half a million
  2. special features:
    - highly muscular, well innervated walls
    - small radii
  3. functions:
    - primary resistance vessels
    - determine distribution of cardiac output
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13
Q

capillaries
(number, special feature, functions)

A
  1. number: ten billion
  2. special features:
    - very thin walled
    - large total cross-sectional area
  3. functions:
    - site of exchange
    - determine distribution of extracellular fluid between plasma and interstitial fluid
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14
Q

veins
(number, special feature, functions)

A
  1. number: several hundred
  2. special features:
    - thin walled compared to arteries
    - highly distensible
    - large radii
  3. functions:
    - passageway to the heart from organs
    - serve as blood reservoir
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15
Q

in the circulatory system, how is the potential energy transformed to kinetic energy?

A
  • potential energy is transformed into kinetic energy as blood moves through the blood vessels
  • transformationdue to the pressure generated by the heart as it pumps blood into the arteries
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16
Q

describe the energy within the circulatory system
(4 steps)

A
  1. Potential Energy in the Heart
    - heart contracts during systole
    - generates pressure that pushes blood into the arteries
    - pressure creates potential energy within the blood
  2. Conversion to Kinetic Energy:
    - blood moves from the arteries to smaller arterioles and then to capillaries
    - the pressure gradually decreases
    - kinetic energy of the blood increases as it accelerates through narrower vessels due to the conservation of mass and the principle of fluid dynamics
  3. Blood Flow:
    - kinetic energy of the blood allows it to flow through the circulatory system
    - delivering oxygen and nutrients to tissues and organs
    - while removing waste products
    - blood flow driven by the pressure difference between the arteries and veins
    - also driven by the pumping action of the heart
  4. Return to Potential Energy:
    - as blood moves through the capillaries and into the veins, its kinetic energy decreases as it encounters increasing resistance to flow
    - decrease in kinetic energy is associated with a decrease in pressure
    - when blood returns to the heart, it has largely transitioned back to potential energy
    - ready to be pumped out again during the next cardiac cycle
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17
Q

high or low velocity after heart?

A
  • high
  • max pressure
  • max velocity when potential energy becomes kinetic energy
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18
Q

is the transversal area in the circulatory system constant?

A

no

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19
Q

velocity, area and pressure from heart to capillaries?

A
  • area increases
  • velocity decreases
  • pressure decreases
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20
Q

what happens after the velocity decreases?

A
  1. pressure decreases
  2. probability of energy transformation to movement decreases
  3. diameter of vessel increases
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21
Q

what’s the name of the process during the exchange in capillaries?

A
  • diffusion
  • passive
  • using the gradient
  • takes time
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22
Q

why is the velocity so low in the capillaries?

A
  1. Gradient needs enough time to have the possibility to exchange oxygen, glucose, etc. with interstitial fluid
  2. passive diffusion with gradients
  3. active transport of e.g. glucose
    - takes time because transporters are involved
    - time to bind etc.
  4. crucial because it allows sufficient time for the exchange
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23
Q

why is high pressure in capillaries risky?

A

because there is not so much support of the walls

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24
Q

from a microscopic view, is the movement of particles during capillary exchange quick or slow?

A
  • quick
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25
Q

from a macroscopic view, is the movement of particles during capillary exchange quick or slow?

A
  • slow
  • that allows for sufficient time for the exchange of substances between the blood and the tissue fluid
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26
Q

how does the velocity develop after passing the capillaries?

A

velocity increases
1. Decrease in cross-sectional area leads to increase in velocity because vessel diameter increases
2. Decrease in total-vascular resistance
- larger blood vessels have less resistance due to their larger lumens and fewer branches
- moves quicker in larger vessels
3. Smooth muscle contraction
- veins contain smooth muscle in their walls
- can contract or relax to regulate blood flow
- when smooth muscle contracts, it can squeeze blood forward, contributing to an increase in velocity
4. Gravity and Muscular Pump
- contribute to an increase in blood velocity as it moves from the lower extremities back towards the heart
5. One-Way Valves
- prevents back flow
- unidirectional

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27
Q

is the pressure in the aorta, arteries and arterioles linear?

A
  • no, with peaks
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28
Q

Why do pressure peaks occur in the aorta, arteries, and arterioles?

A
  • pressure peaks occur due to heart activity
  • with systolic pressure representing high peaks
  • and diastolic pressure representing low peaks
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29
Q

Why do the pressure peaks disappear or decrease as blood flows through the capillaries?

A

Pressure peaks disappear or decrease due to the properties of capillary walls
- capillaries have thin, compliant walls
- can expand to accommodate the incoming blood volume during systole and recoil during diastole
- elastic recoil helps to dampen pressure fluctuations, resulting in a smoother flow of blood through the capillaries
- Diameter Changes: Capillaries undergo vasomotion, altering diameter to dissipate pressure
- Energy Dissipation: Blood flow through resistance vessels dissipates energy, smoothing pressure peaks

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30
Q

Importance of Disappearing Pressure Peaks

A
  1. Capillary Function: Ensures constant flow and low pressure for efficient exchange.
  2. Elastic Components: Capillary walls have elastic properties aiding pressure regulation.
  3. Tissue Health: Steady flow in capillaries supports nutrient and waste exchange for tissue health.
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31
Q

what is an open circulatory system?

A
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32
Q

what is a closed circulatory system?

A
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33
Q

what about the relationship of the volume and pressure of hemolymph and blood in open and closed circulatory systems?

A
  1. open
    - high hemolymph volume
    - space available for hemolymph in whole body
    - low hemolymph pressure
  2. closed
    - low blood volume
    - space available for blood only in vessels
    - high blood pressure
    - allows a flow under long distances
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34
Q

besides these facts of closed circulatory system, what other features are there?

A
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35
Q

vasoconstriction?

A
  • narrows blood vessels, increasing pressure inside the vessel
  • mechanism: Constriction of vessel walls reduces vessel diameter, leading to increased pressure
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36
Q

vasodilation?

A
  • opposite of vasoconstriction
  • widens blood vessels, decreasing pressure inside the vessel
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37
Q

what does it mean, the high blood pressure allows ultrafiltration at the capillary level?

A
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38
Q

what are the functions of circulatory systems related to movement and erection?

A
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39
Q

overview: Arterial system

A
  • property: pressure reservoir
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40
Q

what’s important in definition of arterial system?

A
  • the position: from heart to tissue
  • wrong would be O2-rich blood
    why?
  • e.g. pulmonary arterie brings O2-poor blood from heart to tissue
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41
Q

do fish have a large or short ventral aorta?

A
  • a short one (possible due to fish heart structure)
  • it’s very elastic for regulating the blood flow that goes to the gills
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42
Q

what does a fish heart consist of?

A
  • venous sinus (collects deoxygenated blood from various parts of the body and transports it back to the heart; often serve as large reservoirs for venous blood)
  • atrium
  • ventricle
  • bulbus arteriosum
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43
Q

structure of fish heart

A
  • respiratory and systemic circulatory systems are NOT separated
  • blood enters from right
  • bulbus arteriosum is important for buffering pressure variations
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44
Q

blood pressure in fish

A
  • pericardium is a double-walled sac that surrounds the heart and the roots of the great vessels
  • Ventricular systole is the phase of the cardiac cycle during which the ventricles contract and pump blood out of the heart
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45
Q

pericardium

A
  1. Definition: Double-layered sac surrounding the heart.
  2. Function: Protects the heart, anchors it in place, and prevents overfilling.
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46
Q

Pericardium in Fish

A
  1. Description: Pericardium is semi-rigid in fish.
  2. Function: Maintains negative pressure lower than atrial pressure.
  3. Purpose: Facilitates rapid filling during ventricular systole.
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47
Q

Aortic Pressure Regulation in Fish

A
  1. Description: Difference in aortic pressure between ventricular systole and diastole is limited.
  2. Mechanism: High elasticity of the bulbs arteriosum.
  3. Importance: Ensures efficient circulation and prevents excessive pressure fluctuations.
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48
Q

overview: Venous system

A
  • property: volume reservoir
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49
Q

why does the blood or hemolymph spend more time in veins than arteries?

A
  • due to low velocity in veins
  • therefor: lots of blood inside the veins
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50
Q

what helps the flow and movement in the veins?

A
  • a muscle structure that contracts and squeezes the vein structure
  • increases pressure
  • increases flow
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51
Q

what problem comes due to squeezing the veins and how is it solved?

A
  • problem: two directions of flow when squeezing
  • solved by valves
  • Valves opening and closing is mechanical
  • Opening through pushing due to increase of pressure
  • Closed valve: closed due to increase of pressure after valve structure
  • It’s a mechanical movement (both)
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52
Q

how large are capillaries in diameter?

A
  • 1mm long
  • diameter: 3-10 micrometer
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53
Q

blood cells are usually 50 micrometer in diameter. how can they pass capillaries?

A
  • blood cells deformation allow the flow through capillaries
  • Important is the structure of capillaries: no vessel constriction in capillaries
  • The capillary wall is made up of a single layer of endothelial cells resting on a basement membrane (collagen and glucosaminoglycans)
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54
Q

capillary network overview

A
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55
Q

What are the two primary forces involved in the movement of substances across capillary walls?

A
  • it’s two forces that act in opposite directions
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56
Q

How do proteins retained in capillaries influence fluid movement?

A

Proteins retained in capillaries create a force that attracts water, known as the osmotic force.

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57
Q

What happens to the forces at the start of the capillary?

A
  • At the start of the capillary, there is a significant outward pressure (blood pressure) and osmotic pressure.
  • The combination favors blood pressure, with the sum of pressures being 11 mm Hg, thus favoring exit from the capillary.
  • Substances must enter the interstitial fluid to reach different cells afterwards
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58
Q

How do pressure dynamics change at the middle of the capillary?

A
  • At the middle of the capillary, decreasing volume leads to decreasing pressure.
  • Although transfer stops, the process continues.
  • Osmotic pressure remains constant
  • while blood pressure decreases.
  • The sum now favors osmotic pressure, at 9 mm Hg, directing substances from interstitial fluid into the capillary
  • e.g., uptake of CO2 produced by cells
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59
Q

What changes in pressure occur during capillary exchange?

A
  • Initially, there is an outward pressure of 11 mm Hg
  • followed by an inward pressure of 9 mm Hg.
  • It’s important to note that the amount leaving is not equal to what returns inside.
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60
Q

What problems can arise if interstitial fluid increases?

A
  • Increased interstitial fluid leads to inflation, as substances transfer through it via simple diffusion.
  • The increased fluid increases transfer time, necessitating the maintenance of a constant amount of interstitial fluid.
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61
Q

How is constant interstitial fluid maintained?

A
  • The lymphatic system
  • serves as an accessory system
  • limiting the interstitial fluid amount
  • Vessels within the lymphatic system can receive water and solutes from the interstitial fluid
  • allowing the extra fluid to reenter the circulatory system.
62
Q

What is the role of the lymphatic system in fluid balance?

A
  • The lymphatic system plays a crucial role in regulating interstitial fluid volume.
  • It limits the amount of interstitial fluid and recaptures excess liquid, returning it to the circulatory system.
63
Q

Arrangement of vascular systems

A
  1. single circulation
    - e.g. fish
  2. double circulation
    - double secretion needs double entry
    - division of vascular system
64
Q

Why is high pressure in respiratory organs not desirable?

A
  • The structure of respiratory organs is very simple
  • it’s lacking multiple cell layers to withstand strong pressure
  • Thus, high pressure could potentially damage or disrupt their function.
65
Q

How is the structure of respiratory organs adapted to infusion?

A
  • Respiratory organs have a simple structure with a low number of cell layers, - which facilitates infusion.
  • This adaptation is essential for efficient gas exchange.
66
Q

What evolutionary significance does the distinction between systemic and pulmonary circulation have?

A
67
Q

Why is a high-pressure systemic circulation beneficial?

A
  • A high-pressure systemic circulation allows a high flow rate to reach tissues
  • even those far from the heart, and against gravity
  • This is crucial for delivering oxygen and nutrients to various tissues efficiently.
68
Q

What is the advantage of a low-pressure pulmonary circulation?

A
  • A low-pressure pulmonary circulation facilitates a low flow rate
  • which is optimal for effective gas exchange.
  • This ensures that the exchange of oxygen and carbon dioxide in the lungs occurs efficiently
69
Q

What distinguishes the heart muscle (myocardium) from skeletal muscle?

A
70
Q

How does the activation of contraction differ between skeletal and cardiac muscles?

A
71
Q

What is the role of gap junctions in cardiac muscle?

A
72
Q

How does intrinsic activation function in the heart muscle?

A
73
Q

Why is the heart muscle considered rich in muscle?

A
74
Q

overview “heart”

A
75
Q

squid- and octopus heart

A
76
Q

How does the cardiovascular system of fish differ from that of octopuses and squids?

A
77
Q

What challenges does the cardiovascular system of octopuses and squids face due to the distance between the heart and organs?

A
78
Q

How does the cardiovascular system of octopuses adapt to maintain sufficient pressure?

A
79
Q

What are peristaltic tubular hearts, and where are they found?

A
80
Q

heart in hagfish (overview)

A
81
Q

What additional structure aids venous return in the hagfish cardiovascular system?

A
82
Q

How does the hagfish heart ensure the proper flow of blood?

A
83
Q

What regulates the function of the hagfish heart?

A
84
Q

What insights does the hagfish heart provide into vertebrate evolution?

A
85
Q

What is the function of the caudal heart in hagfish?

A
86
Q

Why is there a need for an auxiliary heart in hagfish?

A
87
Q

How does the contraction of muscles in the caudal heart chambers affect blood flow?

A
88
Q

What happens during relaxation of the caudal heart chambers?

A
89
Q

evolution of the vertebrate heart

A
90
Q

What challenges does the amphibian heart face regarding blood circulation?

A
91
Q

How does the amphibian heart prevent the mixing of oxygen-rich and oxygen-poor blood?

A
92
Q

How does the amphibian heart ensure functional separation of blood flow?

A
93
Q

What mechanism aids in directing blood flow in the amphibian heart?

A
94
Q

the reptilian circulation

A
95
Q

ventricle of turtles

A
  • 3 interconnected internal sub chambers
    1. cavum venosum
    2. cavum pulmonale
    3. cavum arteriosum
  • cavum venosum and cavum pulmonale are separated by partial septum
  • cavum arteriosum connected to the cavum venosum by intercaval canal
  • 3 large arteries come out of the ventricle
    1. pulmonary artery
    2. right systemic arch
    3. left systemic arch
  • during a dive lungs can be bypassed by diversion of systemic venous blood directly back into the systemic circuit
  • that’s called “right-to-left shunting”
96
Q

How does the reptilian heart facilitate circulation during diving?

A
  • During diving, reptiles redirect blood flow to either ventilation or diving.
  • This adaptation allows reptiles to continue circulation even when underwater.
  • The absence of complete separation between the right and left sides of the heart enables this functional separation.
97
Q

Describe the structure and function of the reptilian heart

A
98
Q

heart of estuarine crocodiles

A
  • complete separation of atria and ventricles by septa
  • with clear division between systemic and pulmonary circulation
  • they have 2 systemic aortas arising from each ventricle
  • they are connected by the “foramen of Panizza”
  • during ventilation: right aorta closed by valve
  • but: foramen allows blood flow also into the left aortic arch
  • during dive: lungs can be bypassed by the right aorta
  • because pulmonary artery is closed by the “cog-teeth valve”
  • foramen allows blood flow also in aortic arch
99
Q

How does the heart of a crocodile differ from other reptiles?

A
100
Q

What adaptations does the crocodile heart have for diving?

A
101
Q

cardiac cells of the mammalian heart

A
  1. myocetes in
    - sinoatrial node
    - atrioventricular node
  2. myocetes in
    - inner surface of ventricle walls
    - bundles of His
    - Purkinje fibers
  3. myocetes
    - making up most of the myocardium
102
Q

What are the key features of a mammalian heart?

A
103
Q

What are the specialized cells present in the mammalian heart?

A
104
Q

cardiac action potentials

A
  • action potential in cardiac contractile cells differs
    considerably from the action potential in cardiac autorhythmic cells
  • prolonged plateau phase
105
Q

Explain the action potential in cardiac cells.

A
106
Q

How is the action potential generated in cardiac cells?

A
107
Q

How does the action potential lead to muscle contraction in cardiac cells?

A
108
Q

What mechanism triggers muscle contraction in cardiac cells?

A
109
Q

Describe the process of muscle contraction in cardiac cells.

A
110
Q

How does calcium contribute to muscle contraction in cardiac cells?

A
111
Q

neurogenic hearts in decapods

A
112
Q

cardiac output

A
113
Q

control of circulation

A
114
Q

arterial system

A
115
Q

the nervous system

A
116
Q

the autonomic nervous system

A
117
Q

autonomic nervous system: cholinergic and adrenergic

A
118
Q

How is the activation of the heart different in crustaceans?

A
119
Q

Why is regulating heart activity important in animals?

A
120
Q

How is pressure generated in the circulatory system?

A
121
Q

How is blood pressure regulated in the body?

A
122
Q

How is organ perfusion regulated in mammals?

A
123
Q

How does the nervous system regulate heart activity?

A
124
Q

What are the different receptor types involved in the autonomic nervous system?

A
125
Q

Action Potential Propagation in Crustaceans

A
126
Q

Cardiac Output

A
127
Q

Control of Circulation

A
128
Q

Arterial System

A
129
Q

Nervous System

A
130
Q

Autonomic Nervous System

A
131
Q

Baroreflex in response to change in blood pressure: Afferent Pathways

A
132
Q

Baroreflex in response to change in blood pressure: Efferent Pathways

In the case of a hypertensive episode

A

increase in parasympathetic activity

133
Q

Baroreflex in response to change in blood pressure: Efferent Pathways

If blood pressure falls below normal

A

sympathetic nervous system is activated

134
Q

Baroreflex in response to change in blood pressure: adrenergic receptors

A
135
Q

What are baroreceptors, and where are they primarily located?

A

Baroreceptors are specialized pressure sensors sensitive to changes in blood pressure. They are primarily located in the aortic arch and the carotid sinus.

136
Q

Describe the function of baroreceptors in the context of blood pressure regulation.

A

Baroreceptors detect alterations in blood pressure and initiate signals in response to maintain homeostasis.

137
Q

What are the main areas where baroreceptors are found in mammals?

A

Baroreceptors are mainly located in the aortic arch and the carotid sinus.

138
Q

What is the role of the parasympathetic nervous system in the baroreflex pathway?

A

The parasympathetic nervous system is activated in response to signals from baroreceptors. It leads to a decrease in heart rate, thereby reducing cardiac output.

139
Q

How does the parasympathetic nervous system affect nodal cells in the heart?

A

Parasympathetic activation influences nodal cells, resulting in alterations in heart rate. It inhibits the release of acetylcholine by the vagus nerve, allowing for an increase in heart rate.

140
Q

What effect does sympathetic activation have on ventricular contraction?

A

Sympathetic activation increases the intensity of ventricular contraction, leading to an increase in stroke volume and cardiac output.

141
Q

What is the response of the sympathetic nervous system in the baroreflex pathway?

A

The sympathetic nervous system causes vasoconstriction in arteries and veins, elevating blood pressure.

142
Q

What are the types of adrenergic receptors involved in the baroreflex pathway?

A

The main types of adrenergic receptors involved are alpha1, alpha2, beta1, and beta2 receptors.

143
Q

Describe the effects of noradrenaline on adrenergic receptors.

A

Noradrenaline can have both inhibitory and excitatory effects depending on the receptor type.

144
Q

How do adrenergic receptors interact with epinephrine?

A

Some adrenergic receptors can interact with epinephrine, amplifying their effects.

145
Q

What is the significance of the SA node in the heart’s electrical conduction system?

A

The SA (sinoatrial) node serves as the primary pacemaker of the heart, initiating the electrical impulses that regulate heart rhythm.

146
Q

How many nodes are typically found in the hearts of mammals, and what is their function?

A

Mammalian hearts typically have two nodes: the SA node and the AV (atrioventricular) node. These nodes serve as backup pacemakers, ensuring the continuation of the heart’s electrical activity if the SA node fails.

147
Q

Explain the coordination of signals between the SA node and other pacemakers in the heart.

A

The SA node generates electrical impulses at a higher frequency than other pacemakers. If both SA and secondary pacemakers are active, the signals are not summed up; rather, the SA node’s signal dominates, masking the lower-frequency signals.

148
Q

What are the consequences of a dysfunction in the SA node?

A

Dysfunction in the SA node can lead to a decrease in heart rate and cardiac output, potentially impacting essential physiological functions such as circulation and organ perfusion.

149
Q

How does acetylcholine affect nodal cells in the heart, and why is this important in the context of the baroreflex pathway?

A

Acetylcholine, released by the parasympathetic nervous system, opens potassium channels in nodal cells, leading to hyperpolarization and a decrease in heart rate. This mechanism is crucial for modulating heart rate in response to changes in blood pressure.

150
Q

Describe the physiological response to a hypertensive episode in terms of the baroreflex pathway.

A

During a hypertensive episode, baroreceptors detect elevated blood pressure, leading to activation of the parasympathetic nervous system. This results in a decrease in heart rate and cardiac output, helping to restore blood pressure to normal levels.

151
Q

What are the effects of sympathetic activation on arterial and venous vessels?

A

Sympathetic activation causes vasoconstriction in both arterial and venous vessels, increasing peripheral resistance and elevating blood pressure.

152
Q
A

Santovito (6 decks)

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