Chapter 8 - Transport in Animals Flashcards
Why are specalised transport systems important multicellular organisms?
High metabolic demands
Small SA:V so substances can’t just diffuse in and out and get to all of the organism
Hormones and enzymes can be one place but needed in another place
Food is digested in one organ but the products are needed in ever cell across the body
Waste products from metabolism need to be removed from cells, then removed in certain organs
What is a circulatory system?
A system which carries gases, nutrients, waste products and hormones around the body
What do most circulatory systems have in common?
A transport medium that circulates around the system (e.g. blood)
Vessels to carry the transport medium
A pumping mechanism to move the transport medium around the system?
What is a mass transport system?
When substances are transported in a mass of fluid with a mechanism for moving the fluid around the body
What is an open circulatory system?
Very few vessels to contain transport medium
Pumped from heart to body cavity of animal
Usually found in invertebrate animals
Open body cavity called haemocoel
Transport medium called haemolymph
Why are open circulatory systems less efficient?
Due to the transport medium being free flow throughout most of the body cavity, it is difficult to maintain a steep concentration gradient for efficient diffusion
What is a closed circulatory system?
Blood is enclosed in blood vessels and doesn’t come into direct contact with body cells
High pressure
Blood returns back to the heart
Most contain a blood pigment essential for carrying respiratory gases
What is a single closed circulatory system?
Blood leaves the heart, goes around the body and comes back to the heart
Blood only needs to enter the heart once to complete a full circulation
Blood pressure is very low so exchange processes are slow and inefficient
What is a double closed circulatory system?
Blood is pumped from heart to lungs to heart
Then blood is pumped from heart to body to heart
The blood has to travel through the heart twice to complete a full circuit
High blood pressure and fast blood flow can be maintained to improve efficiency of exchange
What are elastic fibres in blood vessels?
Composed of elastin
Can stretch and recoil
Provide blood vessel walls with elasticity
What is smooth muscle in blood vessels?
Can contract or relax to change the size of the lumen
What is collagen in blood vessels?
Provides structural support
Maintains shape and volume of blood vessel
What is the order of blood vessels from aorta to vena cava?
Artery
Arteriole
Capillary
Venule
Vein
What is an artery?
Carries oxygenated blood from heart to organs (except for pulmonary artery and umbilical artery)
Blood under high pressure
Can vasoconstrict and vasodilate
Tough collagen outer layer
Thick muscle layer
Thick elastic layer
Smooth endothelium layer to prevent friction between erythrocytes
What is an arteriole?
Link arteries to capillaries
Less elastic in walls
More smooth muscle
Lower blood pressure
Muscle contracts and relaxes to control blood flow
What is a capillary?
Tiny vessels to carry out gas exchange
Can be oxygenated or deoxygenated
Endothelium lining layer only one cell thick
What is a venule?
Connect capillaries with veins
Very thin walls with small amounts of muscle
What is a vein?
Caries deoxygenated blood (except pulmonary vein and umbilical vein)
Have valves to prevent back blood of blood
Very low blood pressure compared to arteries
Tough collagen outer layer
Thin muscle layer
Thin elastic layer
Thin endothelium - smooth to prevent friction
Large lumen
What are the functions of the blood?
Transporting many types of molecules such as gases for/from respiration, digested food, hormones, cells, antibodies and platelets
Maintaining a constant body temperature
Minimise pH changes by acting as a buffer
What are the components of the blood?
Red blood cells (erythrocytes)
White blood cells (leukocytes)
Platelets
Plasma
What are the functions red blood cells?
Transport oxygen and play a role in transporting carbon dioxide (haemoglobin)
What are the functions of white blood cells?
Different types of white blood cells play different roles on the organisms immune system
What are the functions of platelets?
Cell fragments which play a part in the clotting process
What are the functions of plasma?
Liquid medium which carries dissolved substances
What is tissue fluid?
Similar to blood plasma
Doesn’t contain plasma proteins or most of the cells
Formed by plasma leaking from capillaries
Surrounds cells in the tissue and supplies them with oxygen and required nutrients
Waste products from metabolism can be returned to capillaries
Low hydrostatic pressure
Higher oncotic pressure
Very few white blood cells
Contains water and dissolved solutes
What is lymph fluid?
The 10% of fluid that isn’t returned to capillaries is returned as lymph via the lymphatic system
Similar to tissue fluid, but contains more white blood cells
White blood cells collect in large quantities in the lymph nodes to fight infection
Low hydrostatic pressure
Higher oncotic pressure
Contains water and dissolved solutes
What is hydrostatic pressure?
Pressure of fluid on the capillary walls, usually forcing plasma out of the circulatory system
What is oncotic pressure?
Osmotic pressure from proteins in the blood plasma that draws water into the circulatory system
How does pressure affect the movement of blood?
Tissue fluid, own hydrostatic pressure and oncotic pressure + solutes have an influence
Hydrostatic pressure of blood pushes fluid out of capillaries into tissues
Oncotic pressure of blood pulls water back into blood
How does pressure affect the movement of tissue fluid?
Hydrostatic pressure of tissue fluid pushes fluid back into capillaries
Oncotic pressure of tissue fluid pulls water from blood to tissue fluid
Why is haemoglobin needed?
Carries oxygen as it isn’t soluble in water
Otherwise there wouldn’t be enough oxygen to meet the body’s demand
Absorbs oxygen to transport it around the body
What is the structure of haemoglobin?
Quaternary globular protein
2 alpha, 2 beta chains
Each chain contains a haem group (contains iron)
Iron has a high affinity for oxygen
Each oxygen can carry 4 oxygen molecules
What is affinity?
Attraction (to oxygen)
How is oxygen transported?
Joins with haemoglobin to form oxyhaemoglobin (reversible reaction)
Oxygen joining = association
Oxygen leaving = dissociation
Hb + 4O2 <-> HbO8
How does oxygen affinity change around the body?
Depends on external conditions
Partial pressure of oxygen changes (pO2)
Increases oxygen concentration = higher pO2 = high oxygen affinity (e.g. in the lungs)
Decreased oxygen concentration = lower pO2 = low oxygen affinity (e.g. in the body cells)
How does oxygen affinity affect associating and dissociating?
High oxygen affinity = Oxygen associates into the red blood cells
Low oxygen affinity = Oxygen dissociates out of the red blood cells
How is haemoglobin relevant to carbon dioxide transport?
Carbon dioxide needs to be excreted
5% gets dissolved into blood plasma
10% binds to Hb and forms carbaminohaemoglobin
75% from HCO3- which is formed in the RBC then gets transported in the blood plasma
How does carbon dioxide change to be carried as hydrogen carbonate?
- Carbon dioxide diffuses in RBC
- Carbon dioxide converts to carbonic acid by enzyme carbonic anhydrase
- Carbonic acid dissociates into a H+ ion and hydrogen carbonate ion
- Hydrogen carbonate diffuses out of RBC down the concentration gradient and combines with sodium ions in the plasma
- Chloride ion enters RBC (chloride shift) to maintain the electrochemical neutrality
- H+ combines with HB to form haemoglobinic acid (HHb) which prevents the H+ ion from decreasing RBC pH
What is the Bohr effect?
Partial pressure of carbon dioxide rises
Hb gives up oxygen easier
What is the heart?
Made up of cardiac muscle
Has coronary arteries covering it to supply it with oxygen (if blocked causes angina or a heart attack/myocardial infarction)
Why does the valves have tendinous cords?
Prevents the valves from turning inside out during ventricular wall contractions
What is the order of the cardiac cycle starting at the right atrium?
Right atrium
Tricuspid valve
Right ventricle
Semilunar valve
Pulmonary artery
Lungs
Pulmonary vein
Left atrium
Bicuspid valve
Left ventricle
Semilunar valve
Aorta
Body
Vena cava
What is the cardiac cycle?
Sequence of events in one full beat of the heart
Averagely 0.8s in humans
What is systole?
Period of contraction
What is diastole?
Period of relaxation
How is blood pumped in the heart?
Pressure is exerted by blood causes pressure changes which moves the valves
Heart muscles contract and relax to force blood into different chambers/vessels in the heart
What are the 3 parts of the cardiac cycle (contractions)?
Diastole
Atrial systole
Ventricular systole
What is the function of the valves?
Ensures blood flows in the correct direction
Increased pressure behind the valves forces them open
Decrease pressure through the valves forces them shut
