Circulatory System Flashcards
Purpose of the Circulatory System
Achieve mass movement of molecules around the body
Source
a place in the body where molecules enter the bloodstream
Sink
a place in the body where molecules leave the bloodstream
Oxygen Source
Alveoli
Oxygen Sink
All living cells
Carbon Dioxide Source
All living cells
Carbon Dioxide Sink
Alveoli
Glucose Source
Small Intestines
Glucose Sink
All living cells
Urea Source
All living cells
Urea Sink
Kidneys
Why do large organisms need a circulatory system?
Molecules have a further distance to travel. Large organisms need large amounts of oxygen, glucose, water etc to survive. Requires mass movement
Pulmonary Artery
Blood flows into lungs from heart (deoxygenated) high pressure
Pulmonary Vein
Blood flows to the heart from the lungs (oxygenated) low pressure
Vena Cava
Blood flows to heart from body (deoxygenated) low pressure
Aorta
Blood flows to body from heart (oxygenated) highest pressure
Bit separating the two sides of the heart
Septum
Chamber with highest pressure
Left Ventricle (therefore has thicker walls to generate and cope with pressure)
Chamber with lowest pressure
Right Atrium (thinner walls as doesn’t need to cope with high pressure)
Structure of Arteries
Thick elastic walls to cope with high blood pressure. Small lumen
Structure of Veins
Thin, less stretchy walls as they don’t need to cope with high pressure. Large lumen
How do some veins allow blood flow against gravity?
Muscle tissue lining to contract and push blood and valves to stop blood flow in wrong direction
Heart Strings
Keep valves from opening the wrong way and letting blood flow in wrong direction
Valves between atria and ventricles
Atrio-ventricular Valves
Valves between ventricles and arteries
Semi-lunar Valves
Cardiac Cycle
Sequence of events during one heartbeat
Cardiac Cycle steps
Atrial Systole → Ventricular Systole → Diastole
Atrial Systole
Atrium walls contract to push blood through atrio-ventricular valves. Blood flows into ventricles. swoosh
Ventricular Systole
Ventricle walls contract to push blood through semi-lunar valves. Blood flows into arteries. BOOM
Diastole
Both atria and ventricles relax to lower blood pressure inside the heart to draw new blood in from veins. boom
Structure of Capillaries
Single-cell walls. Very small lumen
Structure of Arterioles
Smooth muscle rings to contract and slow down blood for diffusion. Redirect blood to prioritised organs during exercise.
Composition of Blood
- 54% plasma
- 1 % buffy coat (wbc + platelettes)
- 45% red blood cells
Red Blood Cells
Carry oxygen around body using haemaglobin
White Blood Cells
Responsible for defense against disease
Platelettes
Tiny cell fragments responsible for clotting blood
Plasma
Transports cells in blood
- urea, water, salt, rbc, wbc, platelettes, hormones, fats, amino acids, glucose, anitbodies, plasma proteins
How are red blood cells adapted to their function?
- packed with haemoglobin
- no internal organelles (more room for haemoglobin)
- biconcave disc shape (high SA:vol ratio + short diffusion distance for oxygen)
- small (travel in billions)
Types of WBC
- phagocytes | lobed nucleus | engulf + digest pathogens
- lymphocytes | large central nucleus | produce antibodies to enhance immune response
