Origins As A Field Of Study
For the very first humans, knowledge about plant and animal meant the difference between life or death. As a result, cumulative knowledge about species, behaviour and anatomy were passed down for many generations.
However, the most significant development in biological knowledge came when humans transitioned from hunters and foragers to farmers, cultivating crops and perfecting agriculture.
Traditions of medicine, collective knowledge from physicians, works of prominent historical figures such as Aristotle eventually coalesced into the field of study we know today as biology.
The most significant revolutions in biology came during the 19th century, with a host of discoveries and technological innovations.
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Flow Of Blood Through Single Vessels
Poiseuille’s law for a viscous fluid quantifies the relationship among the volumetric flow of blood through a blood vessel, modeled as a circular cylindrical tube, the geometric properties of the tube and the flow properties of the blood. Poiseuille’s law is usually expressed as:
The average velocity of blood through a vessel can also be expressed in terms of the above factors. Conservation of flow leads to the conclusion that volumetric flow is equal to the product of average velocity, v, and the cross-sectional area of the vessel, a2:
For a Newtonian fluid flowing through a vessel or tube of circular cross-section, the radial dependence of velocity is described as parabolic due to the quadratic dependence of velocity on radial position, r:
Structure And Function Of The Microcirculation
The microcirculation deserves special attention since it is across the walls of these vessels that the exchange of oxygen, among other substances, takes place . Furthermore, the arterioles, also known as the resistance vessels, are the primary site for control of blood flow. Thus, the blood vessels of the microcirculation play important roles in both the convective and diffusive transport of oxygen. These blood vessels are classified as arterioles, capillaries and venules and vary in diameter from about 100200 m for the largest arterioles and venules down to about 5 m for capillaries. In terms of their structure, all these vessels possess an inner layer of endothelial cells. In addition, the arterioles have a circumferential layer of vascular smooth muscle with which they can control blood flow and its distribution within organs. Venules typically have thinner layers of smooth muscle.
The primary function of the circulatory system is to exchange substances between blood and tissue, and these exchange processes take place in the microcirculation. The classes of vessels playing a role there are the arterioles , capillaries and venules . The amount of flow through the capillaries appears to be regulated to maintain adequate tissue oxygenation. The regulation of blood flow appears to be accomplished by the coordination of several different mechanisms which affect the flow of blood through precapillary vessels.
Types Of Circulatory Systems
The information below was adapted from OpenStax Biology 40.1
The circulatory system is the primary method used to transport nutrients and gases through the body. Simple diffusion allows some water, nutrient, waste, and gas exchange in animals that are only a few cell layers thick; however, bulk flow is the only method by which the entire body of larger, more complex organisms is accessed.
Mechanisms Of Local Regulation
Two major mechanisms have been proposed to account for the local regulatory phenomena described above: the myogenic mechanism and the metabolic mechanism. Although these mechanisms appear to act independently, the expression of each mechanism varies among tissues and some combination of each one is probably operative, depending on the particular intervention, i.e., altered perfusion pressure, flow or tissue activity.
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Transcapillary Exchange Of Solutes
The transport mechanism of passive diffusion is a rapid and efficient mode of molecular exchange over the small distances between the blood supply and tissue cells. Fick’s first law of diffusion describes the net rate of transfer of a substance from a location of high concentration to one of lower concentration:
In regard to the permeability characteristics of the capillary wall, the wall is composed of a single layer of endothelial cells about l m thick. For lipid-soluble substances , the entire wall surface is available for diffusion. For water-soluble substances , there are small aqueous pathways equivalent to cylindrical pores 80 to 90 Å in diameter through which they may pass. Total pore area is about 1/1000 of the surface area of a typical capillary. The permeability of the wall to a particular substance depends upon the relative size of the substance and the pore .
Functions And Types Of Blood Vessels
The blood from the heart is carried through the body by a complex network of blood vessels. Arteries take blood away from the heart. The main artery is the aorta that branches into major arteries that take blood to different limbs and organs. These major arteries include the carotid artery that takes blood to the brain, the brachial arteries that take blood to the arms, and the thoracic artery that takes blood to the thorax and then into the hepatic, renal, and gastric arteries for the liver, kidney, and stomach, respectively. The iliac artery takes blood to the lower limbs. The major arteries diverge into minor arteries, and then smaller vessels called arterioles, to reach more deeply into the muscles and organs of the body.
The major human arteries and veins are shown.
Arteries and veins consist of three layers: an outer tunica externa, a middle tunica media, and an inner tunica intima. Capillaries consist of a single layer of epithelial cells, the tunica intima.
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What Is Internal Transport In Biology
5/5internal transportcellsseen here
When internal transportation is mentioned in the field of logistics and warehousing, it refers to the relocation of goods within the warehouse. Internal transportation is only a small part of the larger process of material handling, but it is the part during which the goods are most vulnerable.
Secondly, what is the transport system in humans? The human circulatory system functions to transport blood and oxygen from the lungs to the various tissues of the body. The heart pumps the blood throughout the body. The components of the human circulatory system include the heart, blood, red and white blood cells, platelets, and the lymphatic system.
Accordingly, what is transport system in biology?
Simple definition of a transport system in biology: A transport system is a means by which materials are moved from an exchange surface or exchange surfaces to cells* located throughout the organism.
What are the 4 types of circulation?
Types of circulation. There are three types of circulation found within humans. Systemic circulation, pulmonary circulation and portal circulation.
What Type Of Protein Is Aquaporin
Aquaporins are integral membrane proteins that serve as channels in the transfer of water, and in some cases, small solutes across the membrane. They are conserved in bacteria, plants, and animals. Structural analyses of the molecules have revealed the presence of a pore in the center of each aquaporin molecule.
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What Is A Transporter In Biology
In biology, transport refers to the act or the means by which a molecule or ion is moved across the cell membrane or via the bloodstream. This type of transport requires expenditure of energy and the assistance of proteins .
Beside above, what is the difference between a channel and a transporter? Transporters and channels are considered to operate in a different way. A channel is like an open door in the membrane, whereas transporters are likened to sliding doors with swipe card access.
Considering this, what are the 3 types of membrane transport?
There are three main kinds of passive transport – Diffusion, Osmosis and Facilitated Diffusion.
What is the function of a transporter protein?
Transport proteins act as doors to the cell, helping certain molecules pass back and forth across the plasma membrane, which surrounds every living cell. In passive transport molecules move from an area of high concentration to an area of low concentration.
What 3 Molecules Cannot Easily Pass Through The Membrane
Small uncharged polar molecules, such as H2O, also can diffuse through membranes, but larger uncharged polar molecules, such as glucose, cannot. Charged molecules, such as ions, are unable to diffuse through a phospholipid bilayer regardless of size; even H+ ions cannot cross a lipid bilayer by free diffusion.
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Factors That Affect Diffusion
Molecules move constantly in a random manner, at a rate that depends on their mass, their environment, and the amount of thermal energy they possess, which in turn is a function of temperature. This movement accounts for the diffusion of molecules through whatever medium in which they are localized. A substance will tend to move into any space available to it until it is evenly distributed throughout it. After a substance has diffused completely through a space, removing its concentration gradient, molecules will still move around in the space, but there will be no;net movement of the number of molecules from one area to another. This lack of a concentration gradient in which there is no net movement of a substance is known as dynamic equilibrium. While diffusion will go forward in the presence of a concentration gradient of a substance, several factors affect the rate of diffusion.
Origin Of The Term Biology
Before the term biology was adapted, other terms existed which described the study of plants and animals. For instance, the term Natural History was used to explain animals, plants fungi and other lifeforms in their natural environment.
Furthermore, it was observational rather than an experimental field of study. Hence, a person who would study natural history is termed as a natural historian or a naturalist. Other terms that came before biology included Natural Theology and Natural philosophy.
The term Biology, in the modern sense, was introduced through the works of Michael Christoph Hanow in 1766. However, it was introduced independently four more times through the works of Thomas Beddoes , Karl Friedrich Burdach , Gottfried Reinhold Treviranus and Jean-Baptiste Lamarck .
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A Closed Circulatory System;
- Found in vertebrates and annelids where the blood is confined;within blood vessels and does not come into direct contact with;tissues.
- The heart undergoes contraction and relaxation .
- When the ventricular muscles contract, the cuspid valves close preventing backflow of blood into auricles.
- The volume of the ventricles decreases while pressure increases.
- This forces blood out of the heart to the lungs through semi-lunar;valves and pulmonary artery, and to the body tissues via semi-lunar;valve and aorta respectively.
- At the same time the atria are filled with blood.
- The left ventricle has thicker muscles than the right ventricle, and;pumps blood for a longer distance to the tissues.
- When ventricular muscles relax, the volume of each ventricle;increases while pressure decreases.
- Contractions of atria force the bicuspid and tricuspid valves to open;allowing deoxygenated blood from right atrium into right ventricle;which oxygenated blood flows from left atrium into the left ventricle.
- Semi-lunar valves close preventing the backflow of blood into;ventricles.
- The slight contractions of atria force the , blood flow into ventricles.
- antibodies, some enzymes suspended cells.
The functions of plasma include:
Circulatory System Variation In Animals
The circulatory system varies from simple systems in invertebrates to more complex systems in vertebrates. The simplest animals, such as the sponges and rotifers , do not need a circulatory system because diffusion allows adequate exchange of water, nutrients, and waste, as well as dissolved gases. Organisms that are more complex but still only have two layers of cells in their body plan, such as jellies and comb jellies also use diffusion through their epidermis and internally through the gastrovascular compartment. Both their internal and external tissues are bathed in an aqueous environment and exchange fluids by diffusion on both sides. Exchange of fluids is assisted by the pulsing of the jellyfish body.
Simple animals consisting of a single cell layer such as the sponge or only a few cell layers such as the jellyfish do not have a circulatory system. Instead, gases, nutrients, and wastes are exchanged by diffusion.
In amphibians, reptiles, birds, and mammals, blood flow is directed in two circuits: one through the lungs and back to the heart, which is called pulmonary circulation, and the other throughout the rest of the body and its organs including the brain . In amphibians, gas exchange also occurs through the skin during pulmonary circulation and is referred to as pulmocutaneous circulation.
This video gives an overview of the different types of circulatory systems in different types of animals:
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Which Process Is Characterized By The Movement
The process that is characterized by the movement of particles from the area of high concentration to the area of low concentration across the plasma membrane without the use of energy is called PASSIVE TRANSPORT. The rate at which active transport occur usually depend on the permeability of the cell membrane.
Chapter 2the Circulatory System And Oxygen Transport
The cardiovascular or circulatory system is designed to ensure the survival of all cells of the body at every moment and it does this by maintaining the immediate chemical environment of each cell in the body at a composition appropriate for that cell’s normal function. The term homeostasis is used to denote the approximate constancy of the internal environment .
First consider the simple hypothetical case of a single spherical cell suspended in a large , well-stirred volume of aqueous medium in equilibrium with room air and containing other nutrients. Oxygen availability is often a limiting factor for cell survival, and it is generally supplied to a cell by passive diffusion. As oxygen molecules diffuse into the cell, they are consumed, so that there is a progressive fall in oxygen concentration from the surface of the cell to the lowest concentration which occurs at the center of the cell. For a spherical cell with a typicaldiffusion coefficient for oxygen and an oxygen consumption of resting skeletal muscle , the critical size which is just adequately supplied with oxygen from the surrounding medium is about 1 mm. Thus, we find that diffusion puts an upper limit on the size of cells in regard to their need for oxygen.
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What Is Diffusion Boundary In Biology
diffusion boundarydiffusionDiffusion boundarydiffusion
Diffusion is the net passive movement of particles from a region in which they are in higher concentration to regions of lower concentration. It continues until the concentration of substances is uniform throughout.
Secondly, what is the short definition of diffusion? Diffusion is the movement of a fluid from an area of higher concentration to an area of lower concentration. Diffusion is a result of the kinetic properties of particles of matter. The term “diffusion” comes from the Latin word diffundere, which means “to spread out.”
Additionally, where does diffusion occur biology?
Diffusion is when molecules of a liquid or gas move from a high concentrated area to a lower concentrated area.
What are the 3 types of diffusion?
The three main kinds of passive transport are diffusion,osmosis, and facilitated diffusion. Diffusion is the movement of molecules from an area of high concentration of the molecules to an area with a lower concentration.
External Compression Inlet Installation
In the case of simpler all-external compression inlets, like those on the Concorde M0;=;2 supersonic transport, internal ramps are extended by an actuator thereby decreasing the throat area for the reduced mass flow requirement in supersonic cruise as shown in Fig. 9.19. The ramps at the throat do not meet, but instead form a gap for excess air to bleed from the throat and be bypassed to the exhaust nozzle. There is an additional door which may be opened to bleed off excess air, as might be expected when operating at high Mach number and relatively low engine rpm. The bleed bypass to the nozzle shown in Fig. 9.19 adds weight to the engine as well as forming a channel for coupling exhaust nozzle pressure disturbances to the inlet because the bypass flow is subsonic. The three-shock inlet provides good pressure recovery, over 90%, at the cruise flight Mach number M0;=;2.
Fig. 9.19. An external three shock compression inlet in supersonic flight showing reduced throat area, throat bleed with bypass to the exhaust nozzle, and flap door open for bleeding excess mass flow.
At subsonic speeds typical of cruise, the throat area is increased by retracting the ramps, as shown in Fig. 9.20. This permits efficient operation at high subsonic speeds where A0;=;A1. However, at takeoff and low subsonic Mach numbers, where A0;>;A1 the flap door is opened inward to provide additional flow area needed during high thrust situations like takeoff and climb.
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Which Best Describes The Difference Between Osmosis And Diffusion
Osmosis: Osmosis is the movement of solvent particles across a semipermeable membrane from a dilute solution into a concentrated solution. Diffusion: Diffusion is the movement of particles from an area of higher concentration to lower concentration. The overall effect is to equalize concentration throughout the medium.
Regulation Of Blood Flow
Since the convective supply of oxygen depends directly on blood flow, the regulation of tissue oxygenation depends critically on the regulation of blood flow. The cardiovascular system controls blood flow to individual organs by maintaining the input pressure to each organ within narrow limits by the mechanisms designed to regulate arterial pressure and by allowing each organ to adjust its vascular resistance to blood flow to an appropriate value. The cardiac output is distributed among the various organs according to their respective resistances so that flow in an organ is given by: