Biologie van Dieren Deeltoets 2
Chapter 42: Circulation and Gas exchange
℗42.1
> Gas exchange:
o Organisms exchange substances (CO2, O2) with their environment, gaining the O2 requires every cell
in the body.
o Doing this via diffusion takes too long. Solution:
- Body size/shape that keeps all cells in direct contact with the environment (cnidarians, flatworms)
- a Circulatory system
> Gastrovascular cavity:
o Cnidarians lack a circulatory system, instead they have a gastrovascular cavity.
o Fluid from the environment bathes the outside of the organism and the inside of the cavity. Since the
body wall is 2 cells thick, gases can exchange via diffusion.
o a flat body optimizes diffusion, by increasing surface area and minimizing diffusion distances.
> Circulatory system:
o Minimizes distances that substances must diffuse to enter a cell.
o A circulatory system has 3 basic components:
- a circulatory fluid (blood)
- set of interconnecting vessels
- a muscular pump (heart)
o The circulatory system carries oxygen-rich blood to all parts of the body.
o Variation in circulatory systems:
- open/closed systems
- number of circuits in the body
- pumps differ in structure and orginazation
> Open and closed circulatory systems:
o Arthropods and most molluscs have an open circulatory system.
o In an open circulatory system the circulatory fluid bathes organs directly.
o In these animals the circulatory fluid, called Hemolymph, is also the interstitial fluid that bathes body
cells.
o In a closed circulatory system blood is confined in vessels. These vessels branch out and infiltrate the
organs.
o Chemical exchange: blood->interstitial fluid->cells
o Annelids, cephalopods and all vertebrates have closed circulatory systems.
o Benefits of an open system:
- less energy costly than a closed system.
- can serve additional functions (helps spiders extend their legs)
o Benefits of a closed system:
- relatively high blood pressure, enables effective O2 delivery in larger animals.
- can regulate the distribution of blood to organs
,> Orginazation of circulatory systems:
o The closed system of humans is often called cardiovascular system.
o Arteries, veins and capillaries are the 3 main types of blood vessels, blood flows in one direction.
o Arteries carry blood away from the heart to organs.
o Within organs, arteries branch out to smaller arterioles.
o Capillaries are microscopic vessels with thin walls.
o Capillary bed: network of capillaries
o Capillaries converge into venules, venules converge into veins.
o Veins carry blood back to the heart.
o Heart->Arteries->arterioles->capillaries->venules->veins->Heart
o The hearts of all vertebrates contain 2 or more chambers.
o The chamber that receives blood entering the heart is called atrium.
o The chamber that pumps blood out of the heart is called ventricle.
> Single circulation: (fish, rays, sharks)
o Single circulation characteristics:
- the blood passes through the heart once in each complete circuit.
- blood that leaves the heart passes through 2 capillary beds before entering the heart again.
o Blood pressure drops substantially after passing through a capillary bed.
> Double circulation: (amphibians, reptiles, mammals)
o Double circulation characteristics:
- the blood passes through the heart twice in each complete circuit.
o Pulmonary circuit: delivers oxygen-poor blood towards the lungs.
o If the pulmonary circuit involves the lungs and the skin, it is called pulmocutaneous circuit.
o Systemic circuit: blood flow through organs and back to heart.
℗ 42.2
> Mammilian heart:
o Cardiac cycle: one complete sequence of pumping and filling of the heart.
o The contraction phase is called systole.
o The relaxation phase is called diastole.
o Cardiac output: volume of blood each ventricle pumps per minute.
o 2 factors determine cardiac output:
- heart rate (beats per minute)
- stroke volume (amount of blood pumped by a ventricle in a beat)
o Valves prevent backflow of blood.
o Atrioventricular valve lies between atrium and ventricle.
o Semilunar valve are located at the 2 exits of the heart.
o Heart murmur: abnormal sound created by a defective valve.
o Sinoatrial node: sets the rate and timing at which all cardiac muscle contracts.
o SA node generates electric impulses that spread to all cardiac muscles.
o These impulses can also spread to the skin, which are used to graph an ElectroCardioGram.
, o Pathway of impulse from SA node:
-impulse moves through the atria wall, which causes the atria to contract
- during this contraction, impulses move to the Atrioventricular node (right atrium wall): here the
impulse is delayed by 0.1s.
- the impulse is then sent to the heart apex and ventricular walls, this is done by muscle fibers called
bundle branches and Purkinje fibers.
o Influences to the SA node:
- physiological cues (walking, sitting)
- hormones (adrenaline)
- body temperature (the higher your temperature, the faster your heart rate becomes.)
℗ 42.3
> Blood vessel:
o Blood vessels contain a central lumen lined with endothelium (single layer, flat).
o The smooth surface reduces resistance to the flow of blood.
o The walls of arteries are thick and strong, made for high blood pressure. It also has elastic recoil to
help maintain the high pressure.
o Hormones control the smooth muscle, dilation and constriction.
o Veins have a lower blood pressure, which is why their walls are not as thick.
o Blood flow velocity in the capillaries slows down, enhancing diffusion of substances.
o Arterial blood pressure is highest during systolic pressure: when the heart contracts during ventricular
systole.
> Regulation of blood pressure:
o When the smooth muscles contracts the arterioles narrow, vasoconstriction, increasing blood
pressure.
o When the smooth muscles relax the arterioles widen, vasodilation, decreasing blood pressure.
o NO (nitric oxide) is an inducer of vasodilation.
o Endothelin is an inducer of vasoconstriction.
o Gravity also has a significant effect on blood pressure.
o Capillaries lose fluid (lymph) and blood protein, which is later returned to the blood via the lymphatic
system.
o Along lymph vessels are lymph nodes: plays a role in the body’s defense by filtering the lymph.
o Lymph nodes are also filled with white blood cells.
℗ 42.4
> Blood components:
o Vertebrate blood is a connective tissue consisting of cells suspended in plasma(55% of blood
composition).
o The blood cells, protein and ions in the plasma function in:
- Osmotic regulation
- Transport
- Defense
Chapter 42: Circulation and Gas exchange
℗42.1
> Gas exchange:
o Organisms exchange substances (CO2, O2) with their environment, gaining the O2 requires every cell
in the body.
o Doing this via diffusion takes too long. Solution:
- Body size/shape that keeps all cells in direct contact with the environment (cnidarians, flatworms)
- a Circulatory system
> Gastrovascular cavity:
o Cnidarians lack a circulatory system, instead they have a gastrovascular cavity.
o Fluid from the environment bathes the outside of the organism and the inside of the cavity. Since the
body wall is 2 cells thick, gases can exchange via diffusion.
o a flat body optimizes diffusion, by increasing surface area and minimizing diffusion distances.
> Circulatory system:
o Minimizes distances that substances must diffuse to enter a cell.
o A circulatory system has 3 basic components:
- a circulatory fluid (blood)
- set of interconnecting vessels
- a muscular pump (heart)
o The circulatory system carries oxygen-rich blood to all parts of the body.
o Variation in circulatory systems:
- open/closed systems
- number of circuits in the body
- pumps differ in structure and orginazation
> Open and closed circulatory systems:
o Arthropods and most molluscs have an open circulatory system.
o In an open circulatory system the circulatory fluid bathes organs directly.
o In these animals the circulatory fluid, called Hemolymph, is also the interstitial fluid that bathes body
cells.
o In a closed circulatory system blood is confined in vessels. These vessels branch out and infiltrate the
organs.
o Chemical exchange: blood->interstitial fluid->cells
o Annelids, cephalopods and all vertebrates have closed circulatory systems.
o Benefits of an open system:
- less energy costly than a closed system.
- can serve additional functions (helps spiders extend their legs)
o Benefits of a closed system:
- relatively high blood pressure, enables effective O2 delivery in larger animals.
- can regulate the distribution of blood to organs
,> Orginazation of circulatory systems:
o The closed system of humans is often called cardiovascular system.
o Arteries, veins and capillaries are the 3 main types of blood vessels, blood flows in one direction.
o Arteries carry blood away from the heart to organs.
o Within organs, arteries branch out to smaller arterioles.
o Capillaries are microscopic vessels with thin walls.
o Capillary bed: network of capillaries
o Capillaries converge into venules, venules converge into veins.
o Veins carry blood back to the heart.
o Heart->Arteries->arterioles->capillaries->venules->veins->Heart
o The hearts of all vertebrates contain 2 or more chambers.
o The chamber that receives blood entering the heart is called atrium.
o The chamber that pumps blood out of the heart is called ventricle.
> Single circulation: (fish, rays, sharks)
o Single circulation characteristics:
- the blood passes through the heart once in each complete circuit.
- blood that leaves the heart passes through 2 capillary beds before entering the heart again.
o Blood pressure drops substantially after passing through a capillary bed.
> Double circulation: (amphibians, reptiles, mammals)
o Double circulation characteristics:
- the blood passes through the heart twice in each complete circuit.
o Pulmonary circuit: delivers oxygen-poor blood towards the lungs.
o If the pulmonary circuit involves the lungs and the skin, it is called pulmocutaneous circuit.
o Systemic circuit: blood flow through organs and back to heart.
℗ 42.2
> Mammilian heart:
o Cardiac cycle: one complete sequence of pumping and filling of the heart.
o The contraction phase is called systole.
o The relaxation phase is called diastole.
o Cardiac output: volume of blood each ventricle pumps per minute.
o 2 factors determine cardiac output:
- heart rate (beats per minute)
- stroke volume (amount of blood pumped by a ventricle in a beat)
o Valves prevent backflow of blood.
o Atrioventricular valve lies between atrium and ventricle.
o Semilunar valve are located at the 2 exits of the heart.
o Heart murmur: abnormal sound created by a defective valve.
o Sinoatrial node: sets the rate and timing at which all cardiac muscle contracts.
o SA node generates electric impulses that spread to all cardiac muscles.
o These impulses can also spread to the skin, which are used to graph an ElectroCardioGram.
, o Pathway of impulse from SA node:
-impulse moves through the atria wall, which causes the atria to contract
- during this contraction, impulses move to the Atrioventricular node (right atrium wall): here the
impulse is delayed by 0.1s.
- the impulse is then sent to the heart apex and ventricular walls, this is done by muscle fibers called
bundle branches and Purkinje fibers.
o Influences to the SA node:
- physiological cues (walking, sitting)
- hormones (adrenaline)
- body temperature (the higher your temperature, the faster your heart rate becomes.)
℗ 42.3
> Blood vessel:
o Blood vessels contain a central lumen lined with endothelium (single layer, flat).
o The smooth surface reduces resistance to the flow of blood.
o The walls of arteries are thick and strong, made for high blood pressure. It also has elastic recoil to
help maintain the high pressure.
o Hormones control the smooth muscle, dilation and constriction.
o Veins have a lower blood pressure, which is why their walls are not as thick.
o Blood flow velocity in the capillaries slows down, enhancing diffusion of substances.
o Arterial blood pressure is highest during systolic pressure: when the heart contracts during ventricular
systole.
> Regulation of blood pressure:
o When the smooth muscles contracts the arterioles narrow, vasoconstriction, increasing blood
pressure.
o When the smooth muscles relax the arterioles widen, vasodilation, decreasing blood pressure.
o NO (nitric oxide) is an inducer of vasodilation.
o Endothelin is an inducer of vasoconstriction.
o Gravity also has a significant effect on blood pressure.
o Capillaries lose fluid (lymph) and blood protein, which is later returned to the blood via the lymphatic
system.
o Along lymph vessels are lymph nodes: plays a role in the body’s defense by filtering the lymph.
o Lymph nodes are also filled with white blood cells.
℗ 42.4
> Blood components:
o Vertebrate blood is a connective tissue consisting of cells suspended in plasma(55% of blood
composition).
o The blood cells, protein and ions in the plasma function in:
- Osmotic regulation
- Transport
- Defense
