Component 3: animal transport (new) Flashcards
When does an organism require a transport system?
A multi-cellular organism, has an anatomy that is more than 2 cells thick so diffusion is too slow to provide everything they need to survive
What does the plasma transport?
O2, CO2, nutrients, waste, hormones, ions, antibodies, plasma proteins, platelets and clotting factors
What is blood plasma important for?
heat distribution in the body
What are erythrocytes?
- red blood cells
- contain haemoglobin protein
- biconcave shape increases SA:V
- no nucleus
- flexible
What is another name for RBC?
erythrocytes
What is another name for WBC?
leucocytes
What are leucocytes?
- white blood cells
- prevent and fight infection
- nucleus present
- several types
What attributes should a transport system in animals have?
- a suitable medium to carry materials in
- a pump for moving medium/blood
- valves to maintain flow in one direction
What are some attributes present in some transport systems?
- respiratory pigment
- system of vessels to transport medium to all parts of the body
What is the type of circulation in earthworms?
closed and single circulation system
How does blood move in earthworms?
- blood moves under pressure by five ‘pseudohearts’ with thickened, muscular blood vessels (pump the blood)
- respiratory gases are transported in the blood
- organs are not in direct contact with blood
- blood is pumped from the dorsal vessel into the ventral vessel and back
What type of circulation is in insects?
open circulation system
How is blood pumped in insects?
- have a dorsal-shaped heart
- this pumps haemolymph into a fluid filled cavity, haemocoel
- tissues bathe in the blood directly and materials are exchanged
- lack of respiratory gases in blood (no pigment), O2 diffuses directly to tissue from tracheae
What type of circulation do fish have?
closed and single circulatory system
How is blood pumped in fish?
- heart has one atria and one ventricle
- hearts pump deoxygenated blood to the gills
- oxygenated blood carried to the tissues
- deoxygenated blood returns to the heart
- blood goes through the heart once for each circuit around the body
heart, gills, body, heart
What is an open circulatory system?
blood does not move around the body in blood vessels, instead bathes in tissues directly
What is a closed circulatory system?
blood moves in blood vessels, there are 2 types: single and double circulation
- tissues are not in direct contact with the blood
- blood pumped by a muscular heart at high pressure
- contains respiratory pigments
What is the circulation type in mammals?
double and closed
How is blood pumped around in mammals?
- blood passes through the heart twice in its circuit around the body
- 2 atria, 2 ventricles
- blood pumped by muscular heart at high pressure at rapid flow
- organs bathed in tissue fluid
- blood pressure reduced in lungs
- blood leaves lungs fully oxygenated
Why is the pressure of blood reduced in the lungs?
high pressure of blood would damage delicate tissue
What happens when an organism has a greater metabolic rate?
the greater the metabolic rate, the greater need for rapid delivery of oxygen and glucose and removal of waste such as CO2
Why does the mammal have the most efficient circulation?
double circulation of mammal is most efficient as blood is pumped at a high pressure
What is the pulmonary circulation?
circulation that serves the lungs
- the right side of the heart pumps deoxygenated blood to the lungs
- oxygenated blood returns from lungs to the left side of the heart
What is the systemic circulation?
circulation that serves the body tissues
- left side of the heart pumps oxygenated blood to the tissues
What are the major blood vessels of the heart?
vena cava, pulmonary artery, aorta, pulmonary vein and coronary arteries (the heart’s own blood supply)
What are the different layers of the structure of large vessels?
tunica externa
tunica media
tunica interna
lumen
Describe the tunica externa layer
- made up of collagen
- tough layer
- helps withstand pressure and resist overstretching
Describe the tunica media layer
contains smooth muscle and elastic tissue (sustains pressure)
- elastic tissue: elastic recoil to maintain blood pressure and stretch to accommodate changes in blood pressure
- smooth muscle: contraction regulates blood flow and maintains blood pressure
Describe the tunica interna layer
single layer of endothelial cells
these are smooth and flat to reduce friction of flowing blood
Describe the lumen
cavity through which the blood flows
What is tissue fluid and what is the role?
Plasma without plasma proteins or red blood cells and formed by leakage from capillaries
- bathes all cells
- transports O2 and nutrients from blood to cells and CO2 and waste products from cells to blood
What other molecules are present in tissue fluid and lymph?
WBC, water, ions, glucose, antibodies and lipid
What is lymph?
90-99% of tissue fluid is forced out and returns to venous end of capillary bed, the remaining tissue fluid removed by drainage into the lymphatic system becomes lymph
- same composition but contains more lipids and CO2 and less O2 and nutrients
What are lymph vessels?
Lymph vessels are blind-ended and only allow fluid to enter, they form a drainage network and return lymph to the bloodstream via the subclavian vein
What are lymph nodes?
Lymph nodes are situated in the armpit, groin, neck and groin
- these hold many lymphocytes (a type of WBC) which intercept bacteria and viruses and help prevent spread of microbial infection in the body
What are problems associated with lymph?
- low blood proteins can affect capillary filtration which may result in fluid retention in tissues (oedema) e.g. Kwashiorkor
- If lymph vessels become blocked, swelling can occur in the affected limbs due to accumulation of tissue fluid
What is the exchange in capillary bed at the arteriole end?
- Hydrostatic pressure is high due to contraction of the left ventricle (the water potential of the blood is lower that the tissue fluid so water will want to enter the blood by osmosis)
- However the hydrostatic pressure is higher than the osmotic pressure and therefore there is net movement of fluid out of the capillary and into the tissue space
- The tissue fluid will now be high in glucose, oxygen, ions and amino acids
- However the blood will still contain the RBC, WBC and the large plasma proteins
Describe the exchange in the capillary bed?
- The cells will take in oxygen and glucose by diffusion and use it for aerobic respiration
- The amino acids will be used in the cell to make new proteins
- This ensures a concentration gradient is maintained
- Carbon Dioxide and any other waste products will diffuse into the tissue fluid
Describe the capillary bed exchange at the venous end?
- Hydrostatic pressure is lower due to loss of fluid from the capillary
- The water potential of the blood is lower than the tissue fluid due to the retention of the large plasma proteins in the blood
- So water will want to enter the blood by osmosis
- Now the osmotic pressure is greater than the hydrostatic pressure therefore there is net movement of fluid into the capillary by osmosis
- The fluid returning into the capillary is high in waste products including carbon dioxide
- This will be returned to the heart via the vena cava and then to the lungs via the pulmonary artery
Describe the lymphatic system in terms of capillary bed exchange?
- Normally 90-99% of the tissue is returned to the capillary at the venous end
- The excess drains into the lymphatic system
- This fluid travels in the thoracic duct to the subclavian vein where it’s returned to the blood
Arteries vs veins structure
arteries vs veins
small diameter lumen v large diameter lumen
thick walls v thinner walls
muscular walls vs less muscular walls
lots of elastic tissue in wall v little elastic tissue
no valves v valves
blood pumped out at high pressure v low pressure
What is the structure of arteries and arterioles?
- thick walls made of collagen (thick tunica externa)
- lots of elastic tissue in tunica media
- smooth muscle in arteriole wall
Why do arteries have thick walls made of collagen?
- provides resistance against high pressured blood
Why do arteries have lots of elastic tissue?
vessels can stretch to accomodate a surge of blood from ventricles and elastic recoil maintains pressure
Why do arteries have smooth muscle in wall?
allows vasoconstriction to reduce the diameter of the lumen and so reduce blood supply to organs
What is the structure of veins?
- thinner walls than arteries - blood is travelling at a low pressure and therefore there is less need for these structures
- large diameter of the lumen - aids in returning low pressure blood to the heart
- semi-lunar valves - ensures blood travels in one direction (no back flow)
What is the structure of capillaries?
- small diameter of lumen - causes friction with walls to slow the blood flow, enhancing ability to exchange new materials with surrounding tissue by diffusion
- single cell thick wall - short diffusion distance pathway
Why is there a large number of capillaries in the body?
provides a large total cross-sectional area
What adds up to enhance ability to exchange materials in tissue fluid?
small diameter (friction) + large cross sectional area = low velocity of blood + thin walls = enhances ability to exchange materials with surrounding tissue fluid
How is blood able to return to the heart?
- blood in the veins are not influenced by contractions of the heart
- under low pressure
- gravity helps blood return from organs above the heart
