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.