2.3.1 Transport in Animals Flashcards
(27 cards)
What is a single circulatory system?
A heart with two chambers where blood passes through once per circulation
What is a double circulatory system?
A heart with four chambers where blood passes through twice per circulation
How is hydrostatic pressure created?
When blood flows from arteries to arterioles to capillaries
What is the function of red blood cells?
Red blood cells transport oxygen. Their biconcave shape increases surface area, and they contain haemoglobin for oxygen binding. They lack nuclei to maximize haemoglobin content
What are the roles of white blood cells?
White blood cells are involved in immune responses. Lymphocytes produce antibodies, while phagocytes engulf and digest pathogens.
What is the role of platelets in blood?
Platelets are cell fragments that initiate blood clotting upon injury, preventing excessive blood loss and protecting against infection.
How are arteries adapted to their function?
Arteries have thick, muscular walls to withstand and maintain high blood pressure as they carry oxygenated blood from the heart.
How are veins adapted to their function?
Veins have thinner walls and valves to prevent backflow, facilitating the return of deoxygenated blood to the heart under low pressure.
What is the structure and function of capillaries?
Capillaries are one cell thick, providing a short diffusion pathway for efficient exchange of gases, nutrients, and waste products between blood and tissues.
What is the role of the heart in circulation?
The heart pumps blood through two circuits: the pulmonary circuit to the lungs and the systemic circuit to the rest of the body, maintaining unidirectional blood flow.
What are the components of tissue fluid?
Tissue fluid is composed of dissolved oxygen and nutrients. It surrounds body cells, facilitating the exchange of gases, nutrients, and waste products.
What is the function of the lymphatic system?
The lymphatic system returns excess tissue fluid to the bloodstream and is involved in immune responses, filtering pathogens and debris.
What is the cardiac cycle?
The cardiac cycle is the sequence of events in one heartbeat, consisting of atrial systole, ventricular systole, and diastole. It ensures coordinated contraction and relaxation of the heart chambers for efficient blood flow.
What happens during atrial systole?
The atria contract, increasing pressure inside the atria. This forces blood through the open atrioventricular (AV) valves into the ventricles. The ventricles are relaxed at this stage.
What happens during ventricular systole?
The ventricles contract, increasing pressure and closing the AV valves to prevent backflow. This forces blood through the semilunar valves into the aorta and pulmonary artery.
What happens during diastole?
The heart muscle relaxes. Pressure in the atria and ventricles falls. Semilunar valves close to prevent backflow. Blood flows into the atria from the vena cava and pulmonary veins, beginning the cycle again.
What causes the “lub-dub” sound of the heartbeat?
“Lub” = closing of AV valves at the start of ventricular systole.
“Dub” = closing of semilunar valves at the start of diastole.
What type of protein is haemoglobin?
Haemoglobin is a water-soluble globular protein made up of four polypeptide chains (two alpha and two beta) and four haem (Fe²⁺) groups.
What is the function of the haem (Fe²⁺) group in haemoglobin?
The haem group binds oxygen, allowing haemoglobin to carry up to four oxygen molecules per molecule.
What is meant by “affinity” in the context of haemoglobin and oxygen?
Affinity refers to how tightly haemoglobin binds to oxygen. This varies depending on the partial pressure of oxygen (pO₂).
What happens to haemoglobin affinity in the lungs?
In the lungs, the partial pressure of oxygen is high, so haemoglobin has a high affinity for oxygen — this is where loading occurs.
What happens to haemoglobin affinity in respiring tissues?
In respiring tissues, the partial pressure of oxygen is low, and haemoglobin’s affinity for oxygen decreases, causing it to release oxygen — this is unloading.
What does a haemoglobin dissociation curve show?
It shows the relationship between haemoglobin saturation and partial pressure of oxygen. It has a sigmoidal (S-shaped) curve due to cooperative binding.
What is cooperative binding in haemoglobin?
After the first oxygen binds, haemoglobin changes shape, increasing its affinity for the next oxygen molecules, making it easier for them to bind.
