UNIT 2 - B 3.2 - Transport Flashcards
What do capillaries receive blood from?
arterioles
What are arterioles?
the smallest type of arteries
What does an arteriole branch into within body tissues?
a capillary bed
What is a capillary bed?
a network of capillaries that all receive blood from the same arteriole
What does a single capillary bed drain its blood into?
a venule
What is a venule?
the smallest type of vein
What happens to the pressure and velocity of blood that enters a capillary bed?
much of it is lost
Why do blood cells line up in single file within a capillary bed?
because the lumen of each capillary is only large enough to accommodate one cell at a time
What is each capillary composed of?
a single-cell thickness of inner tissue and a single-cell thickness of outer tissue
What are the layers of capillaries permeable to?
many different substances
Why is no cell in the body far from a capillary?
because the total surface area and extensive branching of capillary beds is high
What is highly vascular tissue?
metabolically active tissues in the body that are expecially enriched with capillary beds
What are capillaries that are said to be fenestrated?
capillary beds that are designed to be more permeable to substances than a typical capillary
What makes certain capillaries fenestrated?
they have fenestrations which are small slits/openings
What do fenestrations do in capillaries?
they allow relatively large molecules to enter/exit the blood and allow increased movement of all molecules in a given period of time
How are capillaries adapted to their function?
having a small inside diameter, being thin walled, being permeable, having a large surface area, having fenestrations (only some)
What is an artery?
a vessel which receives blood from the heart and takes it to a capillary bed
What is a vein?
a vessel that receives blood from a capillary bed and takes it back to the heart
what is the reason for arteries being lined with a thick layer of smooth muscle and elastic fibres?
becasue they receive blood directly from the heart and the blood is under relatively high pressure
How do lumens of arteries compare to lumens of veins in size?
they are relatively small
How much pressure does the blood which veins receive from capillary beds have?
low amount
What is the reason for veins being thin walled and having large lumen?
because they carry slow-moving blood
What happens when the heart contracts?
a surge of blood enters an artery and its branches
Which kind of muscle do arteries have a thick lyer of?
smooth muscle
What is the smooth muscle on arteries controlled by?
the autonomic nervous system (ANS)
What kind of functions does the ANS control?
functions that are necessary but not controlled consciously
What does the smooth muscle do to the arteries to help regulate blood pressure?
it changes the lumen diameter of the arteries
In addition to smooth muscle, what does the wall of each artery contain?
the protein elastin and collagen
What permits arteries to withstand the high blood pressure of each blood surge and keep blood moving continuously?
The muscular and elastic tissues
What happens with the elastin and collgen fibres when blood is pumped into an artery?
they are stretched
What does the elastin and collagen fibres being stretched allow?
the artery to accommodate the increased pressure
What happens after the blood surge has passed?
the elastic fibres recoil and provide further pressure, propelling the blood forwards within the artery
What is your pulse/heart rate?
a measurement of the number of times your heart beats in a minute
What are the two possible locations where one can measure their heart rate?
the carotid artery (neck) or the radial artery (wrist)
How do veins account for the lost pressure and velocity of blood after going through a capillary bed?
they have thin walls and a larger internal diameter
What is the unidirectional flow of the relatively slow-moving blood in veins aided by?
internal valves that help prevent backflow of blood, and the thin walls of veins are easily compressed by surrounding muscles
what are coronary arteries?
the arteries that supply blood to cardiac muscle
What is plaque in the lumen of arteries?
a build-up of cholesterol and other substances
what is an occlusion?
the restriction in blood flow caused by plaque in coronary arteries
What do plants rely on to bring water and dissolved minerals up from the roots?
a tension force generated by transpiration
What does the loss of water by transpiration cause?
water to be pulled through the cell walls of nearby xylem tissue by capillary action
What does water being pulled up cell walls of xylem tissue create?
tension at the upper end of each xylem tube
What does the tension at the upper end of the xylem tubes result in?
water movement up the xylem and the entire column of water moves up because of cohesion
What is the cohesion-tension theory?
the upwards movement of water with dissolved minerals in xylem
What lines the dead xylem tubes cell walls for strength?
lignin
What does lignin provide for xylem?
resistance to collapse
How does lignin provide resistance to collapse?
because of the tension created by transpiration
What allows unobstructed water flow upwards in xylem?
the partial or total lack of cell walls between adjoining cells of the xylem tubes
What do xylem have that allows the easy flow of water in and out as needed?
small pits
What is the function of epidermis tissue in a dicotyledonous stem?
prevents water loss and provides protection from microorganisms
What is the function of cortex tissue?
sometimes stores food reserves
What is cortex tissue?
a layer of unspecialized cells
what is the function of xylem?
bring water up from roots
what is the function of phloem in a dicotyledonous stem?
transport carbs, usually from leaves to other parts of the plant
What is the function of a vascular bundle in a dicotyledonous stem?
contains multiple vessels of both xylem and phloem
What tissues are in dicotyledonous stem and root?
epidermis, cortex, xylem, phloem, vascular bundle
What is the function of epidermis tissue in dicotyledonous root?
grows root hairs that increase the surface area for water uptake
What are phloem in dicotyledonous root?
transport tubes that receive sugars from leaves
What is a vascular bundle in dicotyledonous root?
the area in the centre of the root containing xylem and phloem
What is needed in order for cells to chemically exchange substances with blood?
a fluid between the cells and blood
What is tissue fluid?
the fluid between cells and blood
How is tissue fluid constantly renewed?
by being released from the side of a capillary bed closest to the arteriole
What is pressure filtration?
the release of tissue fluid
What allows tissue fluid to drain back into capillaries?
the lower pressure of the capillary bed near the venule
Why is the chemical makeup of blood plasma and tissue fluid similar?
because of the largely unregulated passage of substances through very porous capillary membranes and gaps under arteriole pressure
Why do red blood cells and large proteins not exit the capillaries?
because they are too large to exit the capillary walls
What is urea?
waste production of amino acid metabolism
Where is the concentration of potassium ions higher?
in cytoplasm compared to tissue fluid
Where is the concentration of sodium ions higher?
in tissue fluid compared to cytoplasm
What are lymphatic capillaries?
small tubes which tissue fluid that does not re-enter the venous side of the capillary bed enters
How are lymphatic capillaries able to facilitate easy movement of water and solutes?
because they are thin-walled and contain gaps between adjoining cells
What is lymph?
fluid that enters lymphatic capillaries
What does the collection of tissue fluid in lymph vessels prevent?
fluid build-up around body cells
How are lymph vessels similar to veins?
they also have internal valves to keep fluid moving in one direction, they rely on skeletal muscle contractions to squeeze the vessels and they join together into larger and larger lymph ducts
Where do lymph ducts eventually take lymph fluid back so that it can become part of the blood plasma again?
to veins
What are the two chambers in fish heart for?
one for receiving blood, the other for pumping blood out
What happens when the blood is pumped out in fish?
it is sent to the gills for oxygen and carbon dioxide exchange
What happens after the reoxygenated blood is collected from the gill capillaries in fish?
it goes to capillary beds in body tissues
What happens once the blood is deoxygenated in fish?
it gets sent back to the heart to be pumped to the gills
What is the limitation of the circulatory pattern in fish?
the loss of blood pressure when the blood is within the capillaries of the gills
What does a four-chambre heart allow mammals to use?
a double circulation pattern
What is the pulmonary circulation?
blood being pumped to capillaries in the lungs for reoxygenation
what is the systemic circulation?
blood returning to the heart and being pumped out to capillaries in body tissues to supply oxygen where it is needed
What does the additional trip to the heart with the use of double circulation allow?
the blood pressure to be restored
What does the right side of the mammalian heart do?
sends blood to and from the lung capillaries (pulmonary circulation)
What does the left side of the mammalian heart do?
sends blood to and from body tissues (systemic circulation)
What is the advantage of having two circulation routes in a mammalian heart?
both lung and body capillaries can receive blood from arteries and arterioles allowing pressure filtration to occur in all capillaries
What do the heart’s adaptations ensure?
that both atria contract simultaneously, followed by both ventricles contracting simultaneously
What do the four heart valves ensure?
that there is only a one-way flow of the blood
What are some of the heart’s adaptations for efficient blood flow?
cardiac muscle, a pacemaker, atria, ventricles, atrioventricular valves, semilunar valves, septum, coronary vessel
What is cardiac muscle?
a highly vascular tissue making up the heart muscle
Where is cardiac muscle especially thick?
in the ventricles of the heart
Why is the cardiac muscle making up the wall of the left ventricle the thickest?
because it pumps bloot out to locations in the whole body
What is a pacemaker also known as?
the sinoatrial node/SA node
What does the sinoatrial node do?
its an area of specialized cells in the right atrium that generates a spontaneous electrical impulse to start each heartbeat
What are atria?
thin muscular chambers of the heart
What are atria designed to do?
receive low pressure blood from capillaries of the lungs or body tissues by large veins entering the heart
Where do atria send blood to?
the ventricles
What are ventricles?
thick muscular chambers
What do ventricles do?
pump blood out under pressure to the lungs or body tissues
Where are atrioventricular valves located?
between the atria and ventricles
What do atrioventricular valves do?
close each heart cycle to prevent any backflow of blood into the atria
What do semilunar valves do?
close after the surge of blood into the pulmonary artery or aorta to prevent backflow of blood into ventricles
What is the septum?
a wall of muscular and fibrous tissue
What does the septum do?
separates the right side of the heart from the left side
What do coronary vessels do?
provides oxygenated blood to the heart muscle
What is the cardiac cycle?
a series of events, referred to as one heartbeat
What is the frequency of the cardiac cycle?
a person’s heart rate
What happens when a chamber of the heart contracts?
there is an increase in pressure on the blood within the chamber and the blood leaves the chamber through any available opening
What are the events that happen when a chamber of the heart contracts called?
systole
When is the cardiac muscle of a chamber in the heart relaxed?
when the chamber is not undergoing systole
What is it called when a chamber of the heart is not undergoing systole?
diastole
Why could you say that both atria undergo systole at the same time?
because both atria contract at the same time
When do both ventricles undergo systole simultaneously?
only a fraction of a second after atrial systole
Where is the SA node located?
in the thin muscle wall of the right atrium
Although cardiac muscle is capable of spontaneous contractions without stimulation from the nervous system, what can it not control?
the timing of the reactions
What does the SA node provide to regulate contractions?
an electrical stimulation
What is your resting heart rate also called?
your myogenic
What does the action potentials from the SA node result in?
the thin-walled atria undergoing systole
What group of cells does the SA node action potential also reach?
the atrioventricular node/AV node
Where is the AV node located?
in the right atrium, in the septum between the right and left atria
How long does the AV node delay after receiving the impulse from the SA node?
about 0.1 seconds
What does the AV node do after receiving the impulse and delaying for the 0.1 seconds?
sends out its own action potentials that spread out to both ventricles
What is there in order to get the action potentials to reach all of the muscle cells in the ventricles efficiently?
a system of conducting fibres that begin at the AV node and then travel down the septum between the two ventricles
Where do the branches of the conducting fibres spread out into?
the thick cardiac muscle tissue of the ventricles
What does the reception of the impulse from the conducting fibres result in?
both ventricles undergoing systole simultaneously
What is an electrocardiogram (ECG)?
a graph plotted in real time, with electrical activity from the SA and AV nodes plotted on the y-axis and time on the x-axis
What are electrical leads placed in a variety of places on the skin measuring for an ECG?
the small voltage given off by the SA and AV nodes of the heart
What is every repeating pattern on an ECG a representation of?
one cardiac cycle
How can roots create a low water potential?
by the active transport or diffusion of mineral ions into cells
What happens with water after mineral ions are transported into cells of roots?
water will follow by osmosis
What happens to the mineral ions after entering root cells?
they can diffuse or be actively transported across the epidermis and cortex of the root until the minerals reach the xylem tubes in the centre of the root
Why will water always follow mineral ions by osmosis?
because the presence of mineral ions creates an area of low water potential
What is allowed as water always follows mineral ions by osmosis in plants?
the water can enter the xylem and can create a positive fluid pressure pushing the column of water upwards
What is the fluid of phloem called?
sap
What is sap rich in?
sugars
What principle is the direction of sap movement based on?
the movement from a source to a sink
What is a source in terms of sap movement?
a plant organ that is a net producer of sugar, either by photosynthesis or the hydrolysis of stored starch
Why are leaves the primary sugar sources?
because they are responsable for photosynthesis
What is a sink in terms of sap movement?
a plant organ that uses or stores sugars
What are examples of sugar sinks?
roots, buds, stems, seeds and fruits
What are the two types of cells of phloem?
phloem sieve tubes and companion cells
What are individual phloem sieve tube cells connected to one another by to form sieve tube elements?
porous sieve plates
What do sieve tube elements need to stay alive?
the numerous metabolic activities of companion cells
Why do sieve tube elements not contain a nucleus and many other cell organelles?
because they are designed to be nearly empty
Why are sieve tube elements designed to be nearly empty?
to serve their function as vessels carrying a fluid
What are plasmodesmata?
connections between companion cells and sieve tube elements
What is the purpose of plasmodesmata?
to allow the cytoplasm of the tube cells to be shared and they are the orgin of the proteins and ATP needed by the specialized sieve tube elements
Where does sap travel between the two types of phloem cells?
through the tube-like area of the sieve tube elements where the plasma membrane and cytoplasm are reduced
What is the movement of sap within the sieve tube elements called?
translocation
Why does translocation occur?
because a water pressure is created at the source
Where does the water pressure at the source in plants begin?
at any portion of the plant that has sugars that need to be transported elsewhere
How is sugar transported into sieve tube elements?
companion cells in the source actively transport sugar molecules in, and the sugars pass through the plasmodesmata into the sieve tube elements in that area
Why does the movement of sugars into an area of sieve tube elements create an area of low water potential?
because of the high number of solutes
Which area in plants has the higher water potential?
the xylem
Which area of plants has the lower water potential?
phloem
What does the influx of water into the sieve tube elements result in?
the cell expanding outwards because of the increased pressure
Where will water go along the tube?
wherever there is the lowest pressure
What will be the area with the lowest pressure in plants?
wherever sugars are being downloaded out of the sieve tube elements into companion cells and then into an area where the sugar is needed for energy or storage
