Circulatory System Flashcards
What does blood transport?
Oxygen
Carbon dioxide
Nutrients
Urea
(Heat, Hormones, Antibodies)
“Circulatory system” of unicellular organisms?
None
Diffusion across a surface membrane due to the large surface area to volume ratio
Deoxygenated blood leaves the heart to the lungs in…
Pulmonary artery
Oxygenated blood enters the heart from the lungs in…
Pulmonary vein
Why is a double circulatory system more efficient?
It pumps the blood twice and helps maintain a higher pressure so the blood can quickly reach all parts of the body.
In a single circulatory system, blood loses pressure as it passes through the gills
The job of the arteries and veins is?
Arteries carry oxygenated blood away from the heart
Veins carry deoxygenated blood towards the heart
Vein between the digestive system and the liver?
Hepatic portal vein
Explain the cardiac muscle cells
Cardiac muscle cells make up the wall of the heart
Made up of branching cells called muscle fibres that form a strong, mesh-like framework
The cells are striated and there are several nuclei per cell
This framework allows waves of contraction to spread through the heart in a coordinated way
The special properties of cardiac muscle cells?
It never gets fatigued (unlike skeletal muscle)
It contracts on its own without nerve stimulation.
Nerves are present only to adjust the rate of contraction
Systole?
Phase during the cardiac cycle when the heart is contracting
Diastole?
Phase during the cardiac cycle when the heart is relaxing
How are the left and right sides of the heart separated?
By a muscular wall called the septum
The function of valves?
Valves flow in only one direction through the heart and there’s no backflow of blood
Adaptation of the atria?
They have thin walls so they can be stretched while receiving blood but also contract with enough force to push blood through the valves into the ventricles
Blood supply of the cardiac muscle?
Coronary circulation: coronary arteries (to the heart)
capillaries
coronary veins (to right atrium)
What is the output of the heart?
The stroke volume and the heart rate determine the cardiac output
How can the cardiac output be changed?
Actions of the nerves
By hormone: adrenaline from the adrenal glands
Describe the reflex action that causes changes in cardiac output
An increase in CO2 is detected by receptors at the aorta and carotid artery
Nerve impulses via sensory nerve sent to the cardiac centre in the medulla
Medulla responds by sending nerve impulses along the accelerator nerve which increases heart rate and causes the heart to beat with more force and increases blood pressure
When CO2 levels return to normal, impulses are sent down the decelerator nerve and the opposite happens
How is a pulse created?
The blood leaves the aorta in short bursts of pressure causing the aorta’s wall to stretch.
As the ventricle relaxes, the stretched portion of the aorta recoils increasing the pressure inside it
A wave of stretching and constriction passing along the aorta and the arteries caused by a surged of blood at each heartbeat is known as the pulse
Structure of the arteries
They have a thick layer of elastic tissue allowing them to stretch and recoil
Thick smooth muscular walls that help control the flow of blood by constricting and dilating (same for arterioles but due to nerve ending)
Narrow lumen
No valves
Size of capillaries?
Wall: one cell thick
Tiny lumen that the RBCs can just fit through
How does the tissue fluid come about?
The squamous epithelial cells of the capillary wall are leaky…
The function of tissue fluid?
Forms pathway for the diffusion of substances
Signs of increased physical fitness
The resting heart rate is lower
Stroke volume increases
Length of recovery time (Heart returns to normal more quickly after exercise)
How is CO2 carried in the plasma?
As HCO3- (hydrogen carbonate) ions
Where are RBCs destroyed?
Spleen
Features of RBCs?
Biconcave
Thin walls
Flexible
No nucleus
Hemoglobin (iron-containing protein)
Two main actions taken up by WBCs?
Phagocytosis
Production of antibodies
What are antibodies and how do they work?
Antibodies are soluble proteins
They recognize antigens on the surface of pathogens, stick to the surface antigens and destroy them
How do antigens destroy pathogens?
- Causing bacterial cells to stick together…
- Acting as a ‘label’ on the pathogen…
- Causing bacterial cells to burst open
- Neutralising toxins produced by pathogens
What is vaccination?
Artificially supplying an agent that carries the antigen of a specific pathogen to stimulate an immune response and creation of memory lymphocytes
Some agents used as a vaccine:
- Weakened strain
- Dead microorganism
- Modified toxins of the bacteria
- Just the antigens themselves
- Harmless bacteria, engineered to carry the antigens of a pathogen
Process of blood clotting:
exposure to air ⋙ chemical release ⋙ fibrinogen ⋙ fibrin ⋙ network across the wound ⋙ trapped RBCs ⋙ clot ⋙ scab ⋙ new cells
Antigens are determined by ______
Genes
People who cannot have a heart transplant are:
Those with:
- an advanced lung
- liver or kidney disease
- cancer
- diabetes
How to deal with organ rejection?
Tissue typing
Immunosuppressive drugs
Benefits of aerobic exercise
Maintain the glucose level of blood
Strengthen intercostal muscles and increase vital capacity
Stimulates the immune system
Reduces risk of certain cancer
Reduces the level of lipids
Define atherosclerosis
Hardening of the coronary arteries due to the build of fatty substances like cholestrol (plaque)
How do statins work?
Statins lower blood cholesterol by inhibiting an enzyme involved in the synthesis of cholesterol and also affect lipid metabolism
Where is most of the cholesterol synthesized?
Liver
What are plant stanol esters?
Naturally occurring molecules found in plants that have a similar structure to cholesterol and lower blood cholesterol
Found in vegetable oils and dairy products
What do beta blockers do?
Beta-blockers are drugs that manage unusual heart rhythms and prevent a second heart attack
Effective treatment for angina
How do beta-blockers work?
They act on the nervous system by blocking the action of adrenaline at its receptor sites in various parts of the body, including the heart.
Therefore, reducing cardiac output so the heart has to work less hard and needs less O2.
What is used to treat angina?
Beta-blockers
Unit of blood pressure
millimeters of mercury
mmHg
Blood pressure is expressed as two measurements:
Systolic pressure (higher)
Diastolic pressure
Risk factors for hypertension:
- High salt content
- Diseases such as kidney disease
- Alcohol
- Pregnancy
- Genetic factors
- Stress
- Lack of exercise
- Overweight
- Smoking
ACE stands for:
Angiotensin-Converting Enzyme
Explain the renin-angiotensin system (the system that controls blood pressure)
(At low blood pressure) Kidneys ⋙ Renin (enzyme) ⋙ angiotensinogen (plasma protein) ⋙ angiotensin 1 (a peptide of 10 amino acids) ⋙ (ACE) ⋙ angiotensin 2 (a peptide of 8 amino acids) ⋙ constricts blood vessels
How are monoclonal antibodies produced?
They are produced from a single clone of hybridoma cells
A special feature of monoclonal antibodies?
Monoclonal antibodies are specific to one binding site on one protein antigen
So, they can target a specific chemical or specific cells in the body
Uses of monoclonal antibodies:
- Pregnancy testing
- Measuring levels of hormones
- Detecting diseases
- Treating diseases such as cancer
Example of a monoclonal antibody:
Herceptin used to treat breast cancer. It binds to the HER2 receptors and blocks their action or marks them for destruction by the immune system.
Advantages of monoclonal antibodies:
- Cause no damage to healthy cells
- Used to treat a wide range of conditions
How do monoclonal antibodies work against cancer?
They bind to particular antigens on the infected or cancerous cells and act in various ways: killing the cell or interfering with the signaling pathways in the cells.
What’s HER2 (human epidermal growth factor receptor 2)?
A receptor protein on the cell membrane. It responds to chemicals in the blood that switch on mitosis. Some cells have too many HER2 receptors, resulting in uncontrolled cell division that leads to cancer
