the circulatory system Flashcards
(152 cards)
1
Q
main function of the circulatory system?
A
2
Q
what are the components of the circulatory system?
A
3
Q
circulatory fluids are?
A
blood or hemolymph
4
Q
what’s the vascular system?
A
arteries, capillaries, veins
5
Q
what’s the propulsory organ of the circulatory system?
A
heart
6
Q
What determines the movement of circulatory fluid through an animal’s body?
A
7
Q
how can the unidirectional movement be assured?
A
presence of valves and/or septa
8
Q
what is hemodynamics?
A
- study of the physical principles governing the movement of blood within the circulatory system
- it examines factors such as
- blood pressure
- blood flow
- vascular resistance - Hemodynamics considers how these factors interact to maintain proper circulation throughout the body
- ensuring delivery of oxygen and nutrients to tissues and removal of waste products
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
10
Q
what vessel-types are there?
A
- arteries
- arterioles
- capillaries
- veins
11
Q
arteries
(number, special feature, functions)
A
- number: several hundred
- special features:
- thick, highly elastic walls
- large radii - functions:
- passageway from heart to organs
- serve as pressure reservoir
12
Q
arterioles
(number, special feature, functions)
A
- number: half a million
- special features:
- highly muscular, well innervated walls
- small radii - functions:
- primary resistance vessels
- determine distribution of cardiac output
13
Q
capillaries
(number, special feature, functions)
A
- number: ten billion
- special features:
- very thin walled
- large total cross-sectional area - functions:
- site of exchange
- determine distribution of extracellular fluid between plasma and interstitial fluid
14
Q
veins
(number, special feature, functions)
A
- number: several hundred
- special features:
- thin walled compared to arteries
- highly distensible
- large radii - functions:
- passageway to the heart from organs
- serve as blood reservoir
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
16
Q
describe the energy within the circulatory system
(4 steps)
A
- Potential Energy in the Heart
- heart contracts during systole
- generates pressure that pushes blood into the arteries
- pressure creates potential energy within the blood - 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 - 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 - 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
17
Q
high or low velocity after heart?
A
- high
- max pressure
- max velocity when potential energy becomes kinetic energy
18
Q
is the transversal area in the circulatory system constant?
A
no
19
Q
velocity, area and pressure from heart to capillaries?
A
- area increases
- velocity decreases
- pressure decreases
20
Q
what happens after the velocity decreases?
A
- pressure decreases
- probability of energy transformation to movement decreases
- diameter of vessel increases
21
Q
what’s the name of the process during the exchange in capillaries?
A
- diffusion
- passive
- using the gradient
- takes time
22
Q
why is the velocity so low in the capillaries?
A
- Gradient needs enough time to have the possibility to exchange oxygen, glucose, etc. with interstitial fluid
- passive diffusion with gradients
- active transport of e.g. glucose
- takes time because transporters are involved
- time to bind etc. - crucial because it allows sufficient time for the exchange
23
Q
why is high pressure in capillaries risky?
A
because there is not so much support of the walls
24
Q
from a microscopic view, is the movement of particles during capillary exchange quick or slow?
A
- quick
25
from a macroscopic view, is the movement of particles during capillary exchange quick or slow?
- slow
- that allows for sufficient time for the exchange of substances between the blood and the tissue fluid
26
how does the velocity develop after passing the capillaries?
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
27
is the pressure in the aorta, arteries and arterioles linear?
- no, with peaks
28
Why do pressure peaks occur in the aorta, arteries, and arterioles?
- pressure peaks occur due to heart activity
- with systolic pressure representing high peaks
- and diastolic pressure representing low peaks
29
Why do the pressure peaks disappear or decrease as blood flows through the capillaries?
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
30
Importance of Disappearing Pressure Peaks
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.
31
what is an open circulatory system?
32
what is a closed circulatory system?
33
what about the relationship of the volume and pressure of hemolymph and blood in open and closed circulatory systems?
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
34
besides these facts of closed circulatory system, what other features are there?
35
vasoconstriction?
- narrows blood vessels, increasing pressure inside the vessel
- mechanism: Constriction of vessel walls reduces vessel diameter, leading to increased pressure
36
vasodilation?
- opposite of vasoconstriction
- widens blood vessels, decreasing pressure inside the vessel
37
what does it mean, the high blood pressure allows ultrafiltration at the capillary level?
38
what are the functions of circulatory systems related to movement and erection?
39
overview: Arterial system
- property: pressure reservoir
40
what's important in definition of arterial system?
- 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
41
do fish have a large or short ventral aorta?
- a short one (possible due to fish heart structure)
- it's very elastic for regulating the blood flow that goes to the gills
42
what does a fish heart consist of?
- 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
43
structure of fish heart
- respiratory and systemic circulatory systems are NOT separated
- blood enters from right
- bulbus arteriosum is important for buffering pressure variations
44
blood pressure in fish
- 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
45
pericardium
1. Definition: Double-layered sac surrounding the heart.
2. Function: Protects the heart, anchors it in place, and prevents overfilling.
46
Pericardium in Fish
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.
47
Aortic Pressure Regulation in Fish
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.
48
overview: Venous system
- property: volume reservoir
49
why does the blood or hemolymph spend more time in veins than arteries?
- due to low velocity in veins
- therefor: lots of blood inside the veins
50
what helps the flow and movement in the veins?
- a muscle structure that contracts and squeezes the vein structure
- increases pressure
- increases flow
51
what problem comes due to squeezing the veins and how is it solved?
- 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)
52
how large are capillaries in diameter?
- 1mm long
- diameter: 3-10 micrometer
53
blood cells are usually 50 micrometer in diameter. how can they pass capillaries?
- 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)
54
capillary network overview
55
What are the two primary forces involved in the movement of substances across capillary walls?
- it's two forces that act in opposite directions
56
How do proteins retained in capillaries influence fluid movement?
Proteins retained in capillaries create a force that attracts water, known as the osmotic force.
57
What happens to the forces at the start of the capillary?
- 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
58
How do pressure dynamics change at the middle of the capillary?
- 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
59
What changes in pressure occur during capillary exchange?
- 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.
60
What problems can arise if interstitial fluid increases?
- 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.
61
How is constant interstitial fluid maintained?
- 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
What is the role of the lymphatic system in fluid balance?
- 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
Arrangement of vascular systems
1. single circulation
- e.g. fish
2. double circulation
- double secretion needs double entry
- division of vascular system
64
Why is high pressure in respiratory organs not desirable?
- 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
How is the structure of respiratory organs adapted to infusion?
- 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
What evolutionary significance does the distinction between systemic and pulmonary circulation have?
67
Why is a high-pressure systemic circulation beneficial?
- 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
What is the advantage of a low-pressure pulmonary circulation?
- 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
What distinguishes the heart muscle (myocardium) from skeletal muscle?
70
How does the activation of contraction differ between skeletal and cardiac muscles?
71
What is the role of gap junctions in cardiac muscle?
72
How does intrinsic activation function in the heart muscle?
73
Why is the heart muscle considered rich in muscle?
74
overview "heart"
75
squid- and octopus heart
76
How does the cardiovascular system of fish differ from that of octopuses and squids?
77
What challenges does the cardiovascular system of octopuses and squids face due to the distance between the heart and organs?
78
How does the cardiovascular system of octopuses adapt to maintain sufficient pressure?
79
What are peristaltic tubular hearts, and where are they found?
80
heart in hagfish (overview)
81
What additional structure aids venous return in the hagfish cardiovascular system?
82
How does the hagfish heart ensure the proper flow of blood?
83
What regulates the function of the hagfish heart?
84
What insights does the hagfish heart provide into vertebrate evolution?
85
What is the function of the caudal heart in hagfish?
86
Why is there a need for an auxiliary heart in hagfish?
87
How does the contraction of muscles in the caudal heart chambers affect blood flow?
88
What happens during relaxation of the caudal heart chambers?
89
evolution of the vertebrate heart
90
What challenges does the amphibian heart face regarding blood circulation?
91
How does the amphibian heart prevent the mixing of oxygen-rich and oxygen-poor blood?
92
How does the amphibian heart ensure functional separation of blood flow?
93
What mechanism aids in directing blood flow in the amphibian heart?
94
the reptilian circulation
95
ventricle of turtles
- 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
How does the reptilian heart facilitate circulation during diving?
- 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
Describe the structure and function of the reptilian heart
98
heart of estuarine crocodiles
- 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
How does the heart of a crocodile differ from other reptiles?
100
What adaptations does the crocodile heart have for diving?
101
cardiac cells of the mammalian heart
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
What are the key features of a mammalian heart?
103
What are the specialized cells present in the mammalian heart?
104
cardiac action potentials
- action potential in cardiac contractile cells differs
considerably from the action potential in cardiac autorhythmic cells
- prolonged plateau phase
105
Explain the action potential in cardiac cells.
106
How is the action potential generated in cardiac cells?
107
How does the action potential lead to muscle contraction in cardiac cells?
108
What mechanism triggers muscle contraction in cardiac cells?
109
Describe the process of muscle contraction in cardiac cells.
110
How does calcium contribute to muscle contraction in cardiac cells?
111
neurogenic hearts in decapods
112
cardiac output
113
control of circulation
114
arterial system
115
the nervous system
116
the autonomic nervous system
117
autonomic nervous system: cholinergic and adrenergic
118
How is the activation of the heart different in crustaceans?
119
Why is regulating heart activity important in animals?
120
How is pressure generated in the circulatory system?
121
How is blood pressure regulated in the body?
122
How is organ perfusion regulated in mammals?
123
How does the nervous system regulate heart activity?
124
What are the different receptor types involved in the autonomic nervous system?
125
Action Potential Propagation in Crustaceans
126
Cardiac Output
127
Control of Circulation
128
Arterial System
129
Nervous System
130
Autonomic Nervous System
131
Baroreflex in response to change in blood pressure: Afferent Pathways
132
Baroreflex in response to change in blood pressure: Efferent Pathways
In the case of a hypertensive episode
increase in parasympathetic activity
133
Baroreflex in response to change in blood pressure: Efferent Pathways
If blood pressure falls below normal
sympathetic nervous system is activated
134
Baroreflex in response to change in blood pressure: adrenergic receptors
135
What are baroreceptors, and where are they primarily located?
Baroreceptors are specialized pressure sensors sensitive to changes in blood pressure. They are primarily located in the aortic arch and the carotid sinus.
136
Describe the function of baroreceptors in the context of blood pressure regulation.
Baroreceptors detect alterations in blood pressure and initiate signals in response to maintain homeostasis.
137
What are the main areas where baroreceptors are found in mammals?
Baroreceptors are mainly located in the aortic arch and the carotid sinus.
138
What is the role of the parasympathetic nervous system in the baroreflex pathway?
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
How does the parasympathetic nervous system affect nodal cells in the heart?
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
What effect does sympathetic activation have on ventricular contraction?
Sympathetic activation increases the intensity of ventricular contraction, leading to an increase in stroke volume and cardiac output.
141
What is the response of the sympathetic nervous system in the baroreflex pathway?
The sympathetic nervous system causes vasoconstriction in arteries and veins, elevating blood pressure.
142
What are the types of adrenergic receptors involved in the baroreflex pathway?
The main types of adrenergic receptors involved are alpha1, alpha2, beta1, and beta2 receptors.
143
Describe the effects of noradrenaline on adrenergic receptors.
Noradrenaline can have both inhibitory and excitatory effects depending on the receptor type.
144
How do adrenergic receptors interact with epinephrine?
Some adrenergic receptors can interact with epinephrine, amplifying their effects.
145
What is the significance of the SA node in the heart's electrical conduction system?
The SA (sinoatrial) node serves as the primary pacemaker of the heart, initiating the electrical impulses that regulate heart rhythm.
146
How many nodes are typically found in the hearts of mammals, and what is their function?
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
Explain the coordination of signals between the SA node and other pacemakers in the heart.
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
What are the consequences of a dysfunction in the SA node?
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
How does acetylcholine affect nodal cells in the heart, and why is this important in the context of the baroreflex pathway?
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
Describe the physiological response to a hypertensive episode in terms of the baroreflex pathway.
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
What are the effects of sympathetic activation on arterial and venous vessels?
Sympathetic activation causes vasoconstriction in both arterial and venous vessels, increasing peripheral resistance and elevating blood pressure.
152
