B3.2 Flashcards
Transport
Blood Vessels
What are Arterioles?
- The ‘small arteries’ that connect the larger arteries and the many thin capillaries. They move blood away from the heart, are thinner & the pressure and speed is lower in them.
Note that: Arteries are very thick vessels the blood moves through at high pressue (however actual gas exchange occurs in capillaries which are thin).
Blood Vessels
Capillary Beds?
- A network of capillaries (the thin blood vessels that cover all tissues from which gas exchange occurs).
- All capillaries recieve blood from the same arteriole –> millions of both.
Blood Vessels
Venules?
- The smallest of veins –> used for capillaries in a singular capillary bed to drain their now deoxygenated blood into.
- Many venules then connect to a vein which carries that blood back to the heart to be pumped to the lungs for gas exchange.
Blood Vessels
Fenestrations?
- Small slits/ openeings that allow tissue fluid containing larger substances (e.g., glucose) to enter & exit the capillaries.
- An adaptation for some capillaries to make them more permeable.
- Found in the kidneys & intestines (organs specialized for material exchange.)
Blood Vessels
Coronary Ateries?
- Arteries that branch off the aorta delivering oxygen rich blood directly from the lungs to the heart muscle.
- Necessary because the heart is made of thick cardiac muscle which is always active, and thus has a high energy demand, rate of cellular resp, and thus high oxygen demand.
Blood Vessels
Occlusion?
- When the layer of plaque (build up of cholesterol & other lipids inside the lumen inside of the arteries) is so thick it intereferes with the blood flow.
Blood Vessels
Necessity of Highly Vascular Tisse
- Highly vascular tissue – tissues that have more capillary beds. (Organs & Sensory organs.)
- Some areas of the body with great O2 demand require more capillary beds to increase the O2 trasnport –> better support their needs for high rates of cell resp.
Blood Vessels
Structural Adaptations of Arteries
NEED: To withstand high pressure: as arteries carry blood away from heart.
ADAPTATION: Thicker wall made of three layers.
1. Tunica media (made of smooth muslce).
2. Collagen fibre.
3. Elastic tissue –> gives the flexability to withstand pressure changes & apply extra force to push blood forward.
Blood Vessels
Structural Adaptations of Veins
NEED: Prevent potential backflow of blood due to lack of force.
Note: Blood’s no longer at high pressure, thus veins have thinner walls with wider lumen (greater SA:V)
ADAPTATION: Valves made up of cup shaped flaps, so if blood tries to reverse direction, they prevent it by closing.
Blood Vessels
Structural Adapations of Capillaries
NEED: Fast diffusion, thin (one cell), small diameter/ high SA:V ratio.
ADAPTATION:
1. Fenstrations: allowing for greater permeability for nurtrients and hormones.
2. Basement membrane: retains red blood cells and proteins.
Blood Vessels
Pulse Rates at Radial (wrist) and Carotid (neck) Arteries.
- Pulse rate is a measure of how many heart beats per minute. –> feeling the pressure of the expanding elastic artery.
- Carotid artery is in your neck (either side of traches) –> closer to heartm stronger pressure.
- Radial artery is in your wrist –> thin skin, little muscle or fat.
Blood Vessels
Complications from Coronary Artery Occlusion
- Vessel becomes occluded by plaque, often 2. The plaque ruptures due to high pressure, worsened by hypertension.
- Clot forms at rupture site = occlusion, pain (angina).
- If blockage becomes complete (total blockage) the blood supply becomes insufficient, tissue can be damaged, and the resulting disease could be Coronary heart disease. If blood can’t get to heart –> HEART ATTACK.
The Mammalian Heart
What is Tissue Fluid?
- The fluid between individual cells that make up the tissue of our organs, bathes the individual cells.
- Located outside the blood vessles and amongst body cells, it’s released as blood plasma that’s squeezed out of the arterioles as they pump blood into the arterioles.
- Tissue fluid then allows for easier material exchange at capillaries and then a lot of it is reabsorbed into the venules to become blood plasma again.
The Mammalian Heart
Pressure Filtration?
Note: When an arteriole branches off into capillaries, there’s high pressure at the end of it, causing gaps between the cells of the capillary wall that allows for fluid from the blood plasma to flow through to create tissue fluid.
* The pushing out of this tissue fluid is pressure filtration.
* Pressure being lower at venule allows fluid to move back in, following conc. gradient.
The Mamalian Heart
Lymphatic Capillaries?
- Thin walled vessels with gaps between cells, allowing for easy fluid uptake and prevent fluid build up around body tissues.
- Lympathic capillaries adress the tissue fluid that doesn’t re-enter at the venule.
- Capillaries accumulate into lympth vessels -> also lymph nodes throughout that help filter the lympth for pathogens.
The Mamalian Heart
Pulmonary Circulation?
- One of two circulatory systems, which has its vessels and chambers for the transport of blood between the heart and lungs.
- Includes pulmonary artery, pulmonar vein, right ventricle and left atrium.
The Mamalian Heart
Systemic Circulation?
- The other half of the double circulatory system, which transports blood to and from the organs (body SYSTEMS) and the heart.
- Inlcudes vena cara, aorta, right atrium, left ventricle .
The Mamalian Heart
Septum?
- The thick wall of muscular & fiborous tissue that seperates right and left sides of the heart.
- Important, as right side of heart contains deoxygenated blood still to go to the lungs, while the left side contains oxygenated blood.
- Also, the conc. gradients in lungs wouldn’t be ideal for gas exchange.
The Mamalian Heart
Valves?
- Ensure blood flows in a single direction, responding to signals and pressure changes (cardiac cycle) to open.
- Total of 4 valves in the heart.
- There’s two between the atria and ventricles and two between ventricles and vessels leaving the heart.
The Mamalian Heart
Exchange between Tissue Fluids and Cells
- When tissue fluid is squeezed out at the arterioles –> contains gasses, water glucose other substances.
- RBCs and proteins are too large to squeeze through, so stay in plasma.
- Membrances of cells are less porous, so instead of squeezing through, they have to move through passive/active transport.
- Passive –> moves with conc. gradients, moves glucose and gasses.
The Mamalian Heart
Lymph Vessel vs Veins
Lymph Vessel –> similarly thin walls and valves (like veins), ensuring way flow. They collect together into larger vessels called lymph ducts.
* However, lymph capillaries (smallest lympathic vessel) contains gaps between cells that help in fluid reabsorption.
The Mamalian Heart
Single Circulation vs Double Circulation
- Singular (Fish): Hearts have two chambers, one recieves blood the other pumps blood. Blood is oxgyenated in the gills and goes straight to the tissues, meaning blood losses a lot of its pressure by then.
- Double (Mammals): Hearts have four chambers, where Oxygenated blood returns from lungs to the heart, where it’s then pumped at high pressure to tissues.
The Mamalian Heart
Atria vs Ventricle
- Two upper chambers –> Atria (plural), two Atriums (single).
* They have thinner muscular walls as they pump blood but only to Ventricles.
* They recieve blood –> right atria from the body, left atria from the lungs. - Two bottom chambers –> Ventricles.
* Recieve blood from atria, then use their mucular walls to pump blood to nearby lungs.
* Left atrium (largely muscular walls) pumps blood to entire body.
The Mamalian Heart
Atrioventricular vs Semilunar Valves
Atrioventricular valves:
* Located between the atria and ventricles
* Include the tricupsid valve on the right side of the heart and the mitral valve on the left side of the heart.
* Prevent backflow into the atria.
Semilunar valves:
* Located between the ventricles and the vessels.
* Pump blood in to prevent backflow into the ventricles.
* The pulmonary valve seperatres the right ventricle and pulmonary artery.
* The aortic valve speratres the left ventricle and the aorta.
The Mamalian Heart
The Flow of Blood through the Heart (12 steps)
- Vena Cara
- Right Atria
- Tricupsid Valve
- Right Ventricle
- Pulmonary Valve
- Pulmonary Artery
INTO THE LUNGS - Pulmonary Veins
- Left Atria
- Mitral Valve
- Left Ventricle
- Aortic Valve
- Aorta
INTO THE BODY
The Cardiac Cycle
What is the Cardiac Cycle?
The series of events commonly referred to “one heart beat”.
* Includes 2 heart muscle contractions:
1. Pushing blood from atria into ventricles.
2. Pushing blood from ventricles out of the heart.
* This pair of contractoins occur fractions of a second apart.
The Cardiac Cycle
Sinoatrial Node?
- The (SA node) pacemaker, an area modifiied cardiac muscle cells in the right atrium that can generate a spontaneous electrical impulse to initiate a heartbeat.
- The electrical signal travels to all cells in left and right atria, so cells all contract together, causing both atrias to contract.
- Fires consistently –> ‘resting’ heartrate.
The Cardiac Cycle
Atrioventricular Node?
- The (AV node) is at the bottom of the right atrium, and is reached by the action potential of the sinotrial’s electrical signals.
- At the AV node, this signal is delayed by 1sec during which the atria contracts its blood into the ventricles.
- The AV node then fires electrical signals throughout both ventricles along fibres of nerves that tell the muscle of both ventricles to contract, pushing the blood out of the ventricles out of the heart.
The Cardiac Cycle
Systole?
- Movement of blood as a result of heart muscle contraction.
- This movement occurs when the heart muscle around a chamber contracts, and increases the pressure on the blood in the chamber, causing it to leave through available openings.
1. Atrial systole –> atria contracting, ventricle is relaxed. Blood flows from atrium to ventricle. AV valve open, aortic valve closed (semilunar valve).
2. Ventricular systole –> ventricles contracting, atrium is relaxed. Blood flows from ventricle to aorta. AV valve are closed, aortic valve opens. (semilunar valve)
The Cardiac Cycle
Diastole?
When the muslce of the heart chambers is not contracting but instead relaxed.
* During this time chambers open and blood is able to flow into them.
* When measured by a blood pressure monitor –> measures the force still on the arteries in between pumps –> measuring extent of relaxation of the heart.
The Cardiac Cycle
Electrocardiogram?
A graph that is plotted in real time of the electrical activity from the Sinoatrial and Atrioventricular nodes.
* The ECG shows pattern that represents one cardiac cycle –> a way on ensuring heart is firing properly.
Water Transport in Plants
What does Cohesion Tension Theory Say?
- The upwards movement of water through xylem by capillary action –> possible beacuase:
1. As water leaves stomata by transpiratoin, creating a pressure at the upper part of the xylem tube –> tension pulls water up to form adhesive bonds
2. Due to cohesion, pulls entire column of water upwards.
Water Transport in Plants
Capillary Action?
- Refers to the tendency for water to move upwards against gravity when in a thin tube.
Due to.
1. Cohesion of water molecules to allow one to pull another.
2. Adhesion between the water movluelces and the polar side surfaces of the tube.
Allows water to move upward in xylem tubes.
Water Transport in Plants
Lignin?
- A special polymer inside thick cell walls that make up a thick vessel wall.
Xylem vessel are surrounded by dead xylem cells, with remaining dead cell walls creating thick vessel wall. - Lignifited walls allow for strenth & enables xylem to withstand tension caused when transpiration pull is pulling water up out of xylem.
Water Transport in Plants
Vascular Bundle?
- Clusters of vessels, containing bessels of both xylem and phloem.
- In dicots vascular bundles are clustered in rings in stems and centrally in roots.
Water Transport in Plants
Cambium?
- Cells that produce more xylem and phloem cells as needed for scondary growth/ plants growing wider.
Water Transport in Plants
Cortex?
- A thick layer of unspecialized tissue that is between the epidermis & vascular bundles.
1. Used for storage of water and plant materials.
2. Provides structural sypport.
3. Found in root tissues
4. Is a thicker layer, as vascular tissuse is in the centre of the tissue.
Water Transport in Plants
Epidermis?
- Outerlayer of cells that add to waterproofing of the tissues, and provide protection by creating a barrier from microorganisms.
Water Transport in Plants
Dicotyledon
- Flower plants that have two seed leaves in the seed embryo.
- Usually have flower parts in multiples of 4-5 & taproots instead of fiborous roots.
- Vascular bundles in dicots are arragned in a ring.
Water Transport in Plants
Adaptations of Xylem
- Made of vertically stacked dead cells that therefore lack cytoplasm & nuclei –> creates an empty pathway .
- Thick cell walls made of later of dead cells (lignin) allowing them not to collapse with pressure changes from transpiration.
- Small pits in walls of xylem to allow water in and out.
Translocation in Phloem
Root Pressure?
- A positive pressure potential caused by the movement of water into root cells.
- The build up of water in the vacuoles of roots cells exters pressure - this positive presure potential raises water potential of roots.
- Active transport of minerals (K) into the xylem lowers its water potential to further move water.
- This pressure helps water movement in absence of transpiration.
Water Transport in Plants
Translocation (See process in booklet)
Defined: **The bidirectional movement of surcorse from source to sink in Phloeom Sieve Tube. **
* Movement of sugars made in photosynthesis to other parts of the plant for use and storage.
* Involves (briefly) pulling water due to high sugar levels at leaves, which then exerts a hydrostatic pressure that pushes the solution of water & solutes to a new location.
Water Transport in Plants
Sieve Tubes and Plates?
- Sieve Tubes: One of Two of the main components of the Phloem tube –> Columns of ‘cells’ that are connected by incomplete cell walls that have large holes in them.
- Sieve Plates: Holed connective walles in the sieve tubes.
Note: Content of cells have mostly be broken, allowing sap to easily flow through.
Water Transport in Plants
Companion Cells?
- Normal cells next to the sieve tube cells, with nucleus, cytoplasm and mitochondira.
- The transfer of sugars into the phloem needs energy for active transport, the companion cells make ATP, which transfers INTO the sieve tube cells via the plasmodesmata openeing.
Water Transport in Plants
Plasmodesmata?
- Thin, cytoplasmic connections/ gaps in the cell membranes and walls that connect the cytoplasms of 2 cells to allow for transport between them.
- Largest in diameter between companion cells & sieve tube elements so ATP made in companion cells can be transferred to sieve tubes.
Translocation in Phloem
Sap?
- The fluid that is transported in phloem –> an aqueous solution with high conc. of sugars.
- Glucose made in photosynth. often converted to sucrose (more stable, easier to transport than glucose)
- Small amounts of minerals, hormones & amino acids in sap
- Sucrose can be used for cell resp.
(broken into fructose to store in fruits or converted to store in roots)
Translocation in Phloem
Movement without Transp. Pull
- Plants upwatke water into the roots creating high water potential in roots (due to positive pressure potential)
- This causes water to move upwards from the roots towards rest of plant.
- This transpiration freel pull of wate upwards –> ROOT PRESSURE
Translocation in Phloem
Root Pressure from Membrane Transport
- Dry roil has little available water –> may not naturally move from soil into hydrated plant.
- To overcome fact that root cells have naturally higher water potential, energy is used to actively transport minerals & ions into root cells –> increasing solute conc, giving root lower water potential/hypertonic.
- Then water can passively move by osmosis from soil to solute rich root cells.
Translocation in Phloem
Adaptations of Phloem Sieve Tubes
- Reduced cytoplasm & no nucles to create open space for transport of sap.
- Holes in sieve tube plate allow for easy transport between vertical cells.
- Plasmodesmata connection sieve tube cells to compaion cells faciliates transport of ATP and glucose.
Translocation in Phloem
Movement from Source to Sink
Movement of sap moves from source (leaf cells) to sink (fruit or root), moving from where they’re made to where they can be stored.
* This movemen of sap in phloem is bidrectional, as there’s sinks above the leaves (fruits) and below the leaves (roots).
Translocation in Phloem
Interaction between Sieve Tubes and Companion Cells
- Sieve tube cells have no organelles –> can’t create energy needed to faciliate active transport of sucrose into cells.
- Comapnion cells are beside them, have nuclei & mitochondira, and recieve carbs from leaf cells & produce ATP to transport sugards.
- Plasmodesmata between companion cells & sieve tube cells allow for transfer between them.
Translocation in Phloem
What do Osmosis and Pressure do in Sap Translocation?
- Surcose is actively loaded into phloem at source, meaning the high sugar conc. causes water to move from the nearby xylem vessel into the phloem.
- This build up of fluid at source creates hydrostatic pressure that pushes surcrose water solution away from source.
- When it reaches the sink, sucrose is moved in, and by doing so, drops the water potential of the phloem, so water moves by osmosis back to xylem.
