Podcast
Questions and Answers
What neurotransmitter is primarily responsible for increasing heart rate through sympathetic stimulation?
What neurotransmitter is primarily responsible for increasing heart rate through sympathetic stimulation?
What effect does the activation of GIRK (Kir3) K+ channels have on heart rate?
What effect does the activation of GIRK (Kir3) K+ channels have on heart rate?
Which ion channels are affected during an increase in heart rate?
Which ion channels are affected during an increase in heart rate?
What role does acetylcholine play in heart rate regulation?
What role does acetylcholine play in heart rate regulation?
Signup and view all the answers
Which pathological condition can lead to decreased activity of the If current in the heart?
Which pathological condition can lead to decreased activity of the If current in the heart?
Signup and view all the answers
What is the overall effect of norepinephrine and epinephrine on heart rate?
What is the overall effect of norepinephrine and epinephrine on heart rate?
Signup and view all the answers
The vagus nerve primarily influences heart rate via which mechanism?
The vagus nerve primarily influences heart rate via which mechanism?
Signup and view all the answers
What happens to the frequency of action potentials during an increase in heart rate?
What happens to the frequency of action potentials during an increase in heart rate?
Signup and view all the answers
What is the formula for calculating cardiac output (CO)?
What is the formula for calculating cardiac output (CO)?
Signup and view all the answers
How is stroke volume (SV) defined?
How is stroke volume (SV) defined?
Signup and view all the answers
Which factors can modify cardiac output?
Which factors can modify cardiac output?
Signup and view all the answers
What is the role of total peripheral resistance (TPR) in maintaining mean arterial pressure (MAP)?
What is the role of total peripheral resistance (TPR) in maintaining mean arterial pressure (MAP)?
Signup and view all the answers
What condition is associated with an abnormally low heart rate?
What condition is associated with an abnormally low heart rate?
Signup and view all the answers
Which part of the nervous system primarily modulates heart rate?
Which part of the nervous system primarily modulates heart rate?
Signup and view all the answers
Which of the following mechanisms would likely increase heart rate?
Which of the following mechanisms would likely increase heart rate?
Signup and view all the answers
What effect does the Gi pathway have on heart rate regulation?
What effect does the Gi pathway have on heart rate regulation?
Signup and view all the answers
Which circulatory system type is found in earthworms?
Which circulatory system type is found in earthworms?
Signup and view all the answers
What is the primary function of capillaries in the circulatory system?
What is the primary function of capillaries in the circulatory system?
Signup and view all the answers
How do the circulatory systems of air-breathing tetrapods differ from those of water-breathing fish?
How do the circulatory systems of air-breathing tetrapods differ from those of water-breathing fish?
Signup and view all the answers
What characterizes the circulatory system in insects?
What characterizes the circulatory system in insects?
Signup and view all the answers
What is a function of the tunica media in blood vessels?
What is a function of the tunica media in blood vessels?
Signup and view all the answers
Which type of blood vessel typically contains one-way valves?
Which type of blood vessel typically contains one-way valves?
Signup and view all the answers
What distinguishes a sinusoids capillary from other capillary types?
What distinguishes a sinusoids capillary from other capillary types?
Signup and view all the answers
What is the role of the pulmonary circuit in vertebrates?
What is the role of the pulmonary circuit in vertebrates?
Signup and view all the answers
What feature is unique to the circulatory system of cephalopods?
What feature is unique to the circulatory system of cephalopods?
Signup and view all the answers
Which layer of blood vessels is involved with the exchange of materials?
Which layer of blood vessels is involved with the exchange of materials?
Signup and view all the answers
What type of blood pressure is typically observed in water-breathing fish?
What type of blood pressure is typically observed in water-breathing fish?
Signup and view all the answers
What circulatory pattern do amphibians and reptiles share?
What circulatory pattern do amphibians and reptiles share?
Signup and view all the answers
What is the term for the small vessels where gas and nutrient exchange occurs?
What is the term for the small vessels where gas and nutrient exchange occurs?
Signup and view all the answers
What is the primary function of the ostia in the heart of decapod crustaceans?
What is the primary function of the ostia in the heart of decapod crustaceans?
Signup and view all the answers
Which type of myocardium is primarily found in mammals, birds, and reptiles?
Which type of myocardium is primarily found in mammals, birds, and reptiles?
Signup and view all the answers
In the cardiac cycle of fish, what role do the valves play?
In the cardiac cycle of fish, what role do the valves play?
Signup and view all the answers
What is a key feature of non-crocodilian reptile hearts?
What is a key feature of non-crocodilian reptile hearts?
Signup and view all the answers
How does the left ventricle compare to the right ventricle in mammals?
How does the left ventricle compare to the right ventricle in mammals?
Signup and view all the answers
During which phase of the cardiac cycle do the atria contract?
During which phase of the cardiac cycle do the atria contract?
Signup and view all the answers
What mechanism allows reptiles to shunt blood away from the pulmonary circuit?
What mechanism allows reptiles to shunt blood away from the pulmonary circuit?
Signup and view all the answers
What best describes the blood flow through capillaries?
What best describes the blood flow through capillaries?
Signup and view all the answers
What is the primary driving force for blood flow according to the law of bulk flow?
What is the primary driving force for blood flow according to the law of bulk flow?
Signup and view all the answers
What distinguishes the cardiac cycle in mammals from that in amphibians?
What distinguishes the cardiac cycle in mammals from that in amphibians?
Signup and view all the answers
What is the role of the bulbus arteriosus in fish hearts?
What is the role of the bulbus arteriosus in fish hearts?
Signup and view all the answers
What is the effect of vasoconstriction on blood flow?
What is the effect of vasoconstriction on blood flow?
Signup and view all the answers
Which layer of vertebrate hearts is responsible for facilitating contraction?
Which layer of vertebrate hearts is responsible for facilitating contraction?
Signup and view all the answers
What is the result of the spontaneous rhythmic depolarization in arthropod cardiac ganglia?
What is the result of the spontaneous rhythmic depolarization in arthropod cardiac ganglia?
Signup and view all the answers
What distinguishes the left and right ventricles in the mammalian heart?
What distinguishes the left and right ventricles in the mammalian heart?
Signup and view all the answers
What effect does hyperpolarization of pacemaker cells have on the frequency of action potentials?
What effect does hyperpolarization of pacemaker cells have on the frequency of action potentials?
Signup and view all the answers
Which phase of the action potential in cardiomyocytes corresponds to the refractory period?
Which phase of the action potential in cardiomyocytes corresponds to the refractory period?
Signup and view all the answers
What role do L-type calcium channels play during the action potential of cardiomyocytes?
What role do L-type calcium channels play during the action potential of cardiomyocytes?
Signup and view all the answers
What is the primary purpose of the cardiac output calculation?
What is the primary purpose of the cardiac output calculation?
Signup and view all the answers
Which of the following factors can modify cardiac output?
Which of the following factors can modify cardiac output?
Signup and view all the answers
What leads to the Frank-Starling effect?
What leads to the Frank-Starling effect?
Signup and view all the answers
What does the P wave in an ECG represent?
What does the P wave in an ECG represent?
Signup and view all the answers
Which type of cells in the conducting pathways are responsible for spreading action potentials rapidly?
Which type of cells in the conducting pathways are responsible for spreading action potentials rapidly?
Signup and view all the answers
What happens to the heart rate during parasympathetic influence?
What happens to the heart rate during parasympathetic influence?
Signup and view all the answers
What causes the increase in cytoplasmic calcium concentration during cardiomyocyte action potentials?
What causes the increase in cytoplasmic calcium concentration during cardiomyocyte action potentials?
Signup and view all the answers
What is the relationship defined by stroke volume?
What is the relationship defined by stroke volume?
Signup and view all the answers
Which segment of the ECG corresponds to the plateau phase of the ventricular action potential?
Which segment of the ECG corresponds to the plateau phase of the ventricular action potential?
Signup and view all the answers
What is the primary regulatory mechanism of heart rate during exercise?
What is the primary regulatory mechanism of heart rate during exercise?
Signup and view all the answers
Study Notes
Annelids
- Annelids have open and closed circulatory systems
- Tube worms have an open circulatory system
- Earthworms have a closed circulatory system
- Earthworms use peristalsis (muscle contractions) to move blood through vessels
Molluscs
- Molluscs have open and closed circulatory systems
- All molluscs have hearts and some blood vessels
- Most molluscs have open circulatory systems
- Only cephalopods (squids, octopuses, and cuttlefish) have closed circulatory systems
Arthropods - Crustaceans
- Crustaceans have open circulatory systems
- Circulatory systems become more complex in larger animals
- Small sinuses function as vessels in crustaceans
- Some crustaceans have control over the distribution of hemolymph flow in the body
Arthropods - Insects
- Insects have a relatively simple open circulatory system
- Insects have multiple, contractile "hearts" along the dorsal vessel
- Insects use a tracheal system for the majority of gas transport
Vertebrates
- All vertebrates have a closed circulatory system
- The heart contracts to increase pressure in the chambers
- Blood flows away from the heart in arteries
- Arteries branch into smaller arteries, which branch into arterioles
- Blood flows from arterioles into capillaries
- Capillaries are where diffusion of molecules between blood and interstitial fluid occurs
- Capillaries coalesce to form venules
- Venules coalesce to form veins
- Veins carry blood to the heart
Vertebrate Blood Vessels
- A complex wall surrounds a central lumen within blood vessels
- The wall is composed of up to three layers: tunica intima, tunica media, and tunica externa
- The thickness of the wall varies among vessels
- Veins have one-way valves and arteries do not
Capillaries
- Capillaries lack tunica media and tunica externa
- There are three types of capillaries: continuous, fenestrated, and sinusoidal
- Continuous capillaries have cells held together by tight junctions, found in skin and muscle, and the CNS (blood brain barrier)
- Fenestrated capillaries have cells that contain pores, specialized for exchange, found in kidneys, endocrine organs, and the intestine
- Sinusoidal capillaries have few tight junctions which makes them the most porous type for exchange of large proteins, found in liver and bone marrow
Circulatory Patterns of Vertebrates
- All vertebrates have a closed circulatory system
- Water-breathing fish have a single circuit
- Air-breathing tetrapods (amphibians, reptiles, birds, and mammals) have two circuits: pulmonary and systemic
- The pulmonary circuit is on the right side of the heart and pumps blood to the lungs
- The systemic circuit is on the left side of the heart and pumps blood to the body
- Water-breathing fish have a systolic pressure of 30-45 mm Hg, resulting in lower metabolic rates and oxygen consumption, resulting in lower blood pressure
- Mammals have a systolic pressure of 120-180 mm Hg, resulting in higher metabolic rates and oxygen consumption, resulting in higher blood pressure
Amphibians and Reptiles
- Amphibians and reptiles have hearts that are only partially divided
- Amphibians and reptiles have two atria and one ventricle
- Amphibians have a three-chambered heart (frog), and lizards have a five-chambered heart
- Blood from both atria flow into the ventricle in amphibians and reptiles
- Oxygenated and deoxygenated blood can mix in amphibians and reptiles, except for crocodiles which have a four-chambered heart
- Oxygenated and deoxygenated blood are kept fairly separate by a mechanism that is not completely understood in amphibians and reptiles
- The ventricle pumps blood into the pulmonary and systemic circuits in amphibians and reptiles
- Blood can be diverted between the pulmonary and systemic circuits in amphibians and reptiles
Summary
- The circulatory system is composed of three components: a pump, tubes, and fluid
- There are two types of circulatory systems: open and closed
- Blood contains three main components: plasma, red blood cells, and white blood cells
- There are three types of blood vessels: arteries, veins, and capillaries
- There are two circuits in the circulatory system: pulmonary and systemic
Arthropod Heart
- The arthropod heart pumps hemolymph out via arteries.
- Hemolymph returns to the heart through ostia (holes) during diastole.
- Valves in the ostia regulate the flow of hemolymph.
- Ligaments suspend the heart.
- The heart is neurogenic, meaning it contracts in response to signals from the nervous system.
Cardiac Cycle in Arthropods
- Neurons in the cardiac ganglion undergo spontaneous rhythmic depolarization.
- Cardiomyocytes contract, decreasing the heart's volume and increasing pressure.
- Valves in the ostia close as pressure increases, forcing hemolymph out via arteries.
- Stretched ligaments pull apart the heart walls, increasing volume and decreasing pressure.
- Valves in the ostia open, allowing hemolymph to be sucked into the heart.
Vertebrate Hearts
- Vertebrate hearts have complex walls with different parts:
-
Pericardium: A sac of connective tissue surrounding the heart.
- It has outer (parietal) and inner (visceral) layers, with lubricating fluid between them.
-
Epicardium: The inner layer of the pericardium, continuous with connective tissue on the heart.
- Contains nerves regulating the heart and coronary arteries.
- Myocardium: The layer of heart muscle cells (cardiomyocytes).
- Endocardium: The innermost layer of connective tissue covered by endothelial cells (endothelium).
-
Pericardium: A sac of connective tissue surrounding the heart.
Myocardium
- Myocardium exists in two forms:
- Compact: Tightly packed cells arranged in a regular pattern.
- Spongy: A meshwork of loosely connected cells.
- The relative proportions of compact and spongy myocardium vary between species.
- Mammals, birds, and reptiles have mostly compact myocardium.
- Fish and amphibians have mostly spongy myocardium, arranged as trabeculae that extend into the chambers.
Fish Hearts
- Fish hearts have two chambers and two other compartments arranged in series:
- Sinus venosus
- Atrium
- Ventricle
- Bulbus arteriosus (non-contractile)
Cardiac Cycle in Fish
- The atrium and ventricle contract serially.
- Valves are passive, opening and closing due to pressure differences.
- The non-contractile bulbus arteriosus acts as a volume and pressure reservoir.
Amphibian Hearts
- Amphibian hearts have three chambers:
- Two atria
- One ventricle
- Trabeculae in the ventricle help prevent mixing of oxygenated and deoxygenated blood.
- A spiral fold in the conus arteriosus directs deoxygenated blood to the pulmocutaneous circuit and oxygenated blood to the systemic circuit.
Non-Crocodilian Reptile Hearts
- Non-crocodilian reptiles have five-chambered hearts with two atria and three interconnected ventricular compartments:
- Cavum venosum: Leads to systemic aortas.
- Cavum pulmonale: Leads to the pulmonary artery.
- Cavum arteriosum.
Shunting in Reptile Hearts
- Reptiles can shunt blood to bypass either the pulmonary or systemic circuits.
- Right-to-left shunt: Deoxygenated blood bypasses the pulmonary circuit and enters the systemic circuit, occurring during breath-holding.
- Left-to-right shunt: Oxygenated blood reenters the pulmonary circuit, aiding oxygen delivery to the myocardium.
Crocodilian Reptile Hearts
- Crocodilian reptiles have four-chambered hearts with two atria and two ventricles, with complete separation of the chambers.
Birds and Mammals
- Birds and mammals have four chambers:
- Two atria: Thin-walled.
- Two ventricles: Thick-walled, with the left ventricle thicker than the right.
- The ventricles are separated by the intraventricular septum.
Valves in Bird and Mammalian Hearts
-
Atrioventricular (AV) valves: Located between the atria and ventricles.
- Tricuspid valve: On the right side.
- Bicuspid or mitral valve: On the left side.
-
Semilunar valves: Located between the ventricles and arteries.
- Aortic valve: Between the left ventricle and aorta.
- Pulmonary valve: Between the right ventricle and pulmonary artery.
Cardiac Cycle
- The cardiac cycle is the pumping action of the heart, with two phases:
- Systole: Contraction, forcing blood into or out of a chamber.
- Diastole: Relaxation, allowing blood to enter the heart.
Mammalian Cardiac Cycle
- The atria and ventricles alternate systole and diastole.
- The two atria contract simultaneously, followed by a slight pause.
- The two ventricles contract simultaneously.
- Atria and ventricles relax while the heart fills with blood.
Ventricular Pressure
- The left ventricle contracts more forcefully, developing higher pressure.
- The resistance in the pulmonary circuit is low due to high capillary density, resulting in lower pressure required to pump blood through it.
- This low pressure protects the delicate blood vessels of the lungs.
Mean Arterial Pressure (MAP)
- The average arterial pressure in the aorta over time.
- MAP = 2/3 diastolic pressure + 1/3 systolic pressure
Blood Velocity
- Flow (Q): The volume of fluid transferred per unit time.
- Velocity: The distance traveled per unit time.
- Blood velocity = Q/A (A = cross-sectional area of the vessels).
- Velocity is inversely proportional to total cross-sectional area.
- The large cross-sectional area of capillaries leads to slow velocity, allowing for more diffusion.
Vasoconstriction and Flow Resistance
- The Law of Bulk Flow: Q = ΔP/R (Q = flow, ΔP = pressure drop, R = resistance).
- Poiseuille's equation: Q = ΔPπr⁴ / (8Lη) (L = length of tube, η = viscosity, r = radius).
- Small changes in radius significantly impact resistance and flow.
Factors Enhancing Diffusion Across Capillaries
- Fick's Law of Diffusion: Diffusion Rate = ΔC * A * D / ΔX (ΔC = concentration gradient, A = surface area, D = diffusion coefficient, ΔX = distance).
- Capillaries facilitate diffusion due to:
- Thin capillary walls.
- The capillary diameter being slightly larger than a RBC.
- Slow blood velocity.
Increasing Heart Rate
- Norepinephrine (from sympathetic neurons) and epinephrine (from the adrenal medulla) increase heart rate.
- They open more pacemaker (funny), Ca²⁺, and Kv channels, increasing the rate of depolarization, repolarization, and action potential frequency.
Decreasing Heart Rate
- Acetylcholine (from parasympathetic neurons in the vagus nerve) decreases heart rate.
- It activates GIRK (Kir3) K⁺ channels, slowing the heart rate.
- It also inhibits cAMP and PKA activity, reducing If current and Cav/Kv channel activity.
Summary
- The text explores the structure of the heart, focusing on the differences between arthropod, fish, amphibian, reptile, bird, and mammal hearts.
- The cardiac cycle is detailed for each type, explaining how blood flow is directed and regulated.
- The text discusses blood pressure, the factors influencing it, and how it is affected by vasoconstriction and vasodilation.
- The importance of capillaries in facilitating diffusion is highlighted.
- Finally, the text explains how the nervous system regulates heart rate through the sympathetic and parasympathetic nervous systems.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
Animal Physiology Midterm 2 prep
