3. Circulation Flashcards
What is Fick’s Law
rate of diffusion is proportional to (SA * conc. difference) / thickness of membrane
Diffusion is important where distances are short - how short.
<100um
What is a circulatory system?
Specialised transport system that connects the fluid that surrounds cells with organs for:
∙gas exchange
∙nutrient absorption
∙disposal of waste products
Why do multicellular organisms need circulatory systems?
rate of diffusion too low to meet metabolic needs of organism
What are the three main structures of all circulatory systems?
∙Circulatory fluid ∙Interconnecting vessels
∙muscular pump
What is an open circulatory system?
Circulatory system where the circulatory fluid (blood) is mixed with the interstitial fluid that comes into direct contact with the organs and tissues.
What is a closed circulatory system?
Circulatory fluid (blood) is distinct from the interstitial fluid and remains in vessels. Chemical exchange occurs between blood and interstitial fluid and then between the interstitial fluid and body cells.
Describe the process of circulation in open circulatory systems
The heart contracts to pump the hemolymph through the circulatory vessels into the interconnecting sinuses where gas exchange occurs. When the heart relaxes, the hemolymph is drawn back through pores into the heart. Valves on pores close when the heart contracts.
Body movements (e.g. muscle contraction) squeeze sinuses to aid circulation.
Describe the process of circulation in closed circulatory systems
Heart(s) pumps blood through blood vessels. Smaller blood vessels infiltrate tissues and organs where chemical exchange then occurs (blood to interstitial fluid to body cells). Then, the blood returns to the heart.
What is hemolymph comprised of?
Interstitial fluid and blood / circulatory fluid
Give examples of organisms with open circulatory systems
Anthropods (e.g. grasshoppers) + molluscs (e.g. clams)
Larger crustaceans have a more extensive system of vessels and an accessory pump
Give examples of organisms with closed circulatory systems
Annelids (e.g. earthworms), cephalopods (e.g. octopus) and all vertebrates
What is the specific name of the circulatory system that humans and vertebrates have?
cardiovascular system = closed circulatory system with blood, interconnecting vessels (arteries, capillaries and veins), and a heart
Describe the path of blood through interconnecting vessels in the cardiovascular system (starting from the heart)
Heart → Arteries → Arterioles → Capillaries → Venules → Veins → Heart
What are capillary beds?
The sites of chemical exchange between blood and interstitial fluid
What is a single circulatory system and why is it suitable for some organisms
Blood passes through the heart once per circuit. Heart consists of one atrium and one ventricle.
e.g. bony fish, sharks and rays
Why is a single circulatory system not sufficient for some animals but is for others?
Maintains lower pressure than double circulation. Therefore there is a lower rate of chemical exchange. But the organisms metabolic demands are low as they are ectothermic (body temperature is regulated by environmental hear sources)
What is a double circulatory system?
Blood passes through the heart twice per circuit.
Heart consists of two atria and two ventricles.
Maintains higher pressure than single circulation.
e.g. amphibians, reptiles, birds + mammals
Describe the structure of the Amphibian double circulatory system
Describe the structure of the Reptilian double circulatory system
Describe the structure of the double circulatory system of mammals and birds
Describe the movement of blood through the heart
Describe the movement of blood through the heart
Explain why ventricles have thicker walls than atria
Explain why the left ventricle has a thicker wall than the right
What are the functions of the atrioventricular valves, semilunar valves and the septum?
Atrioventricular valves prevent back-flow from the ventricles into the atria.
Semilunar valves prevent back-flow from the arteries into the ventricles.
Septum separates the left and right sides of the heart so that oxygen-rich and oxygen-poor blood do not mix.
CIRCULATION LECTURE 3
CIRCULATION LECTURE 3
Describe the passive movement of fluid in and out of capillaries
What molecules move in / out of the capillaries passively?
Describe the active movement of fluid in and out of capillaries by active transport
What are the two ways in which fluid is actively transported in and out of capillaries
Describe the active movement of fluid in and out of capillaries by bulk flow
What molecules move in / out of the capillaries passively?
Brain
What is osmotic pressure and how is it created?
What is blood pressure / hydrostatic pressure?
Explain (in reference to pressure) the net loss of fluid from capillaries
Explain (in reference to pressure) the net gain of fluid from capillaries
Explain how the lymphatic system interacts with the circulatory system to aid transport of fluid
Describe the role of the lymphatic system in the body’s defence against disease
What is oedema?
Describe the pathway of air inhaled into the lungs
Nose, pharynx, larynx, trachea, bronchi, bronchioles, alveoli
Where are the lungs?
Thoracic cave (chest)
Why is the right lung bigger than the left lung?
To make space for the heart
Describe the structure of human lungs
What is the purpose of pleural fluid?
Gas exchange occurs along the respiratory membrane - where is this?
Gas exchange by diffusion occurs across the alveolar and capillary walls
Describe the features of alveoli that make diffusion efficient
Large surface area = forms honeycomb structure
Short diffusion distance (0.2-0.6um) = simple squamous epithelium + surrounded by capillaries
Maintained conc. difference = surrounded by dense capillary networks
Describe the role of the fluid containing surfactant, which lines the alveolus
Explain the process of inhalation
Describe the process of exhalation
How is breathing rate regulated?
- Chemoreceptors in major blood vessels detect decrease in blood pH (more acidic = more CO2) and sends signals to medulla
or
Medulla detects decrease in pH (<7.4) of cerebrospinal fluid - Medulla send signals to rib muscles and diaphragm
- Increase rate and depth of ventilation
- Blood CO2 level falls + pH rises
Stuff about haemoglobin
Explain how partial pressure of oxygen changes as oxygen is transported
Air = 160mmHg
Lungs = 100mmHg
Arterial blood = 95mmHg
Venous blood = 40mmHg
Venous blood during exercise = <20mmHg
dissociation curve
Describe the co-operativity between the haem subunits
What are the three ways in which CO2 is transported in the blood? **** CHECK THIS
- 5% as dissolved CO2 in blood plasma
- 5% forms carbaminohaemoglobin by attaching to haemoglobin and blood proteins
HbNH2 + CO2= Hb.NH.CO2- + H+
(attached to terminal NH2 groups) - 90% as bicarbonate ions
CO2 + H2O = H2CO3 (carbonic acid)
^ catalysed by carbonic anhydrase within red blood cells
H2CO3 = H+ + HCO3- (bicarbonate)
Describe how CO2 is released from blood
