Transport in humans Flashcards
What do unicellular organisms rely on for movement of substances in and out of the cell?
Diffusion
Unicellular organisms are small enough that diffusion distances are short, allowing for quick substance movement.
Why can’t multicellular organisms rely solely on diffusion?
Distances are too big, risking cell death before materials can diffuse in and out
Multicellular organisms require transport systems to efficiently move substances.
What type of circulatory system do humans have?
Double circulatory system
In a double circulatory system, blood passes through the heart twice in a full cycle.
What is the flow of oxygenated blood in the human heart?
From the lungs to the left atrium, then to the left ventricle and out through the aorta
Oxygenated blood is delivered to the body from the left side of the heart.
What is the flow of deoxygenated blood in the human heart?
From the body to the right atrium, then to the right ventricle and out through the pulmonary artery
Deoxygenated blood returns from the body to the right side of the heart for reoxygenation.
What happens to blood when it enters the atria?
The walls of the atria contract, increasing pressure and forcing blood through the valves into the ventricles
This process initiates the cycle of blood flow through the heart.
What occurs when the ventricles are full?
They contract, increasing the pressure of the blood in the ventricles
This contraction is crucial for ejecting blood into the aorta and pulmonary artery.
What closes the valves after the ventricles empty?
Higher pressure in the aorta and pulmonary artery
This pressure prevents backflow of blood into the ventricles.
Fill in the blank: The blood enters the _______ before being pumped into the ventricles.
atria
Atria are the upper chambers of the heart that receive blood.
True or False: The cycle of blood flow through the heart is continuous.
True
The heart continuously pumps blood in a cycle to maintain circulation.
What does the right atrium receive?
Deoxygenated blood from the vena cava
The vena cava is a large vein that carries deoxygenated blood to the heart.
Where does blood go after the right ventricle?
To the lungs through the pulmonary artery
The pulmonary artery is responsible for carrying deoxygenated blood from the heart to the lungs for oxygenation.
What type of blood does the left atrium receive?
Oxygenated blood from the lungs via the pulmonary vein
The pulmonary vein is the vessel that carries oxygenated blood back to the heart.
What happens to oxygenated blood in the left ventricle?
It gets pumped to the rest of the body through the aorta
The aorta is the largest artery in the body, distributing oxygenated blood to all parts.
What is the function of the heart valves?
Prevent the back flow of blood
Valves ensure unidirectional blood flow through the heart chambers.
Why is the muscle thicker on the left side of the heart?
It needs to pump blood around the whole body
The left side of the heart works harder than the right side due to the higher pressure required to circulate blood throughout the body.
What is the function of bicuspid and tricuspid valves?
Prevent back flow of blood from ventricles to aorta when relaxed
Bicuspid (mitral) valve is on the left side, and tricuspid valve is on the right side of the heart.
What do semi-lunar valves prevent?
Back flow of blood into the ventricles when relaxed
Semi-lunar valves are located at the exit of the ventricles leading to the aorta and pulmonary artery.
What is the primary function of arteries?
Carry blood away from the heart
Arteries are responsible for transporting oxygenated blood (except for the pulmonary arteries) to various body tissues.
Describe the structure of arteries.
Thick walls of muscle and elastic fibres, narrow lumen
These adaptations help arteries withstand and maintain high blood pressure.
What is the primary function of veins?
Carry blood towards the heart
Veins generally carry deoxygenated blood (except for the pulmonary veins).
How do the walls of veins compare to arteries?
Veins have thinner walls and wider lumen
This structure accommodates lower blood pressure in veins.
What assists blood flow in veins back to the heart?
Gravity or contracting skeletal muscles
Skeletal muscle contractions help propel blood through the veins, especially in the limbs.
What is the function of valves in the circulatory system?
Prevent blood flow in the wrong direction
What happens to blood after a contraction in the veins?
It gets pushed through the next valve
What are capillaries primarily responsible for?
Exchange of materials
Describe the walls of capillaries.
Thin, permeable, only one cell thick
What substances can diffuse through capillary walls?
Oxygen, carbon dioxide, other products, waste products
What is the blood pressure and flow rate like in capillaries?
Low blood pressure and slow flow rate
What are the main components of blood?
Platelets, plasma, red blood cells, white blood cells (phagocytes, lymphocytes)
What is plasma?
The liquid part of the blood, mainly water with dissolved minerals
What does plasma transport?
Carbon dioxide, glucose, urea, hormones, amino acids, antibodies, heat energy
What is the role of the pulmonary artery?
Carries deoxygenated blood from the heart to the lungs
What is the function of the vena cava?
Returns deoxygenated blood to the heart