How do things get around the body? Flashcards
What is the Cardiovascular System?
- Transports fluids, nutrients, waste products, gases, and hormones throughout the body.
- Exchange materials between blood, cells and extracellular fluid.
What is the role and what does the cardiovascular system consist of?
- Plays a role in the immune response, blood pressure and the regulation of body temperature.
- Consists of the heart, blood vessels, capillary beds and blood.
What are the functions of the heart?
- Generating blood pressure – moves blood through vessels.
- Routing blood: separates pulmonary and systemic circulations.
- Ensuring one-way blood flow.
- Regulating blood supply.
- Changes to match need.
Describe the location of the heart
-Size of a closed fist
-Shape
o Apex: Blunt rounded point of cone
o Base: Flat part at opposite of end of cone
-Located in thoracic cavity in mediastinum
What is the Fibrous & Serous Pericardium?
- Fibrous pericardium: tough fibrous outer layer, prevents over distention; acts as anchor.
- Serous pericardium: thin, transparent, inner layer, simple squamous epithelium.
Describe the Parietal & Visceral Pericardium
- Parietal pericardium: lines the fibrous outer layer.
- Visceral pericardium: covers heart surface.
- The two are continuous and have a pericardial cavity between them filled with pericardial fluid.
Describe the three layers of tissue in the heart
- Epicardium: Serous membrane; smooth outer surface of heart.
- Myocardium: Middle layer composed of cardiac muscle cells – contractility.
- Endocardium: Smooth inner surface of heart chambers.
What is the Pectinate muscles & Trabeculae Carnae?
- Pectinate muscles: muscular ridges in auricles and right atrial wall.
- Trabeculae carnae: muscular ridges and columns on inside walls of ventricles.
What are the chambers of the heart?
- Atrium (L & R)
2. Ventricle (L, I & R)
What is the left and right atrium?
- Right atrium: three major openings to receive blood returning from the body.
- Left atrium: four openings that receive blood from pulmonary veins.
What is the left, right, atrioventricular and inter-ventricular ventricles?
- Atrioventricular canals: openings between atria and respective ventricles.
- Right ventricle: opens to pulmonary trunk.
- Left ventricle: opens to aorta – very muscular wall.
- Interventricular septum: between the two ventricles.
What are the great vessels going into the heart and out of the heart?
-Blood into the heart:
o Into Right Atrium – superior and inferior vena cava
o Into Left Atrium – left and right pulmonary veins
-Blood out of the heart:
o Out of right ventricle – pulmonary trunk
o Out of left ventricle - aorta
What is the Atrioventricular Valves?
- Each valve has leaf-like cusps that are attached to cone shaped papillary muscles by tendons (chordae tendineae).
- Right has three cusps (tricuspid).
- Left has two cusps (bicuspid, mitral).
- When valve is open, blood flows from A → V.
- When it is closed, blood exits ventricle.
What is the Semilunar Valves?
- Each cusp is shaped like a cup.
- When cusps are filled, valve is closed – stop backflow.
- When cusps are empty, valve is open – blood exits heart.
Describe the Arteries
- Elastic, Muscular, Arterioles
- Take blood away from the heart
- Contain blood under pressure
Describe the Veins
- Large, medium, small, venules
- Take blood to the heart
- Thinner walls than arteries, contain less elastic tissue less smooth muscle
- Valves to prevent backflow
What is the function of the Capillaries and describe them
Functions: The site of exchange with tissues (interstitial fluid)
- Capillary beds – extensive networks for exchange.
- Wall consists of endothelial cells (simple squamous epithelium), basement membrane and a delicate layer of C.T.
- Substances move through capillaries by diffusion
What is the Tunica Intima, Externa & Media in the arteries and veins?
- Tunica intima: Endothelium
- Tunica media: smooth muscle cells arranged circularly around the blood vessel.
- Tunica externa (adventitia): connective tissue
What is Vasoconstriction & Vasodilation?
- Vasoconstriction: smooth muscles contract, decrease in blood flow.
- Vasodilation: smooth muscles relax, increase in blood flow.
What is the function of blood?
- Transport: gases, nutrients, waste products, processed molecules, hormones, enzymes
- Regulation of pH and osmosis (normal pH 7.4)
- Maintenance of body temperature
- Protection against foreign substances
- Clot formation
Describe red blood cells
- No nucleus & bi-concave shape to increase SA and thus oxygen carrying capacity.
- Oxygen from lungs to body cells: 98.5% attached to haemoglobin protein 1.5% dissolved in plasma.
Why do we need a cardiovascular system in terms of transport?
- Humans are multicellular
- Cells around the body all need a constant supply of oxygen and nutrients, and constant removal of waste products.
- We need a circulating fluid for transportation.
- Exchange materials between blood, cells and extracellular fluid (interstitial fluid).
- Blood and blood vessels.
- Capillaries - exchange
Why do we need a cardiovascular system in terms of a pump?
- Generating blood pressure – moves blood through vessels.
- Routing blood: separates pulmonary and systemic circulations.
Describe the process of gas exchange in the pulmonary circulation
- Deoxygenated blood enters right atrium and flows into right ventricle.
- Exits heart through Pulmonary trunk.
- Pulmonary trunk divides into left and right pulmonary arteries.
- Blood travels to right and left lung – gas exchange.
- Oxygenated blood travels in left or right pulmonary veins and enter the left atrium.
Describe the process of gas exchange in the systemic circulation
- Capillary exchange in the body/cells.
- Oxygenated blood enters left atrium. Blood flows into left ventricle.
- Left ventricle contracts and pushes blood out of heart through aorta.
- Aorta branches into Ascending aorta, Aortic arch, Descending aorta.
- Blood is delivered to all cells and tissues in the body for gas/nutrient/fluid exchange.
- Blood travels back to heart and re-enters right atrium through vena cava.
What does the contraction of the heart do?
-Contraction of heart produces the pressure
o Blood moves through circulatory system from areas of higher to lower pressure
o Cardiac cycle – Repetitive contraction (systole) and relaxation (diastole) of heart chambers – moves blood through the heart and body.
What is blood proportional to?
-Blood flow is proportional to metabolic needs of tissues.
o Brain, kidneys, liver, exercising skeletal muscle – very high.
o Can change: Cardiac output = Heart rate x Stroke Volume.
In terms of the Nervous System what does the heart do?
- Maintains blood pressure and thus blood flow. Re-routing blood flow. E.G. Increase BP with exercise.
- Re-route blood flow away from skin and viscera towards brain and cardiac muscle in response to blood loss / injury.
In terms of hormonal control what happens to the heart?
-Epinephrine (adrenaline) from adrenal gland – increase HR and SV, vasoconstriction in response to stress.
What is an action potential?
-A rapid change in membrane potential. Acts as an electrical signal / impulse.
What does the heart generate on its own?
-The heart can generate its own action potentials.
In the conducting zone what happens?
- Auto-rhythmicity – repetitive contractions.
- Sinoatrial node (SA) – pacemaker.
- Atrioventricular node (AV).
- Action potentials spread through the conducting system of the heart to all cardiac muscle cells – as a result the cardiac muscle cells contract. Blood is ‘pumped’.
What is lipid and water soluble?
- Lipid soluble - diffuse through plasma membrane of endothelial cells (O2, CO2, steroid hormones, fatty acids).
- Water soluble - diffuse through intercellular spaces or through fenestrations of capillaries. Glucose, amino acids.
What is capillary exchange?
-Capillary exchange: the movement of substances into and out of capillaries. How cells receive what they need to survive and eliminate waste products.
What have large & small spaces between cells
- Large spaces between endothelial cells – proteins and whole cells can pass e.g. liver or spleen.
- Very small spaces between cells – very few molecules can pass – e.g. blood brain barrier.
What affects the movement of fluid from the capillaries?
-Capillary permeability, Blood pressure, and osmotic pressure affect movement of fluid from capillaries.
What is the most important means of exchange?
-Most important means of exchange: diffusion. Oxygen, hormones, nutrients diffuse from a high concentration in the capillary to low concentration in the interstitial fluid.
What does transport in and out of cells require?
A pressure gradient
In terms of the lymphatic system what happens to the fluid?
- Fluid moves out of capillaries into interstitial (intercellular) space and most returns to capillaries.
- The fluid which remains in tissues is picked up by the lymphatic system then eventually returned to venous circulation.
What is the Edema?
-Edema (oedema): swelling caused by excess fluid accumulation in body tissues (interstitial space).
What are the causes of Edema?
-Problems with capillaries, Heart failure, Kidney disease, Liver problems, Pregnancy, Problems with lymphatic system, Standing or walking a lot in hot weather, Eating too much salt.
What happens if capillaries become leaky?
-If capillaries become ‘leaky’ blood proteins can leak into the interstitial fluid. This increases the osmotic pressure (osmolarity) outside the capillary. More fluid moves from the capillaries into the interstitial fluid.
