8 - Transport in animals Flashcards
Why do animals need metabolic transport systems?
High metabolic demand
long distance diffusion not enough
SA:V gets smaller as animals get larger
results increase in diffusion distance and lower relative SA for diffusion to occur
Molecules synthesised in one location, need to be transported to another (hormones, enzymes)
Food digested in one organ system
must be transported to every cell
Metabolic waste products need to be removed and transported to excretory organ.
Define mass transport system.
Where substances are transported in a fluid mechanism around the body.
What are the features of an insect’s open circulatory system?
A
Haemocoel: An insect’s open body cavity
Haemolymph: Insect blood
No separate tissue fluid, so haemolymph is in in contact with organs and cells
Few vessels so blood pumped straight from heart to haemocoel
Haemolymph holds no O2 or CO2 - gas exchange performed in tracheal system
It transports: nitrogenous waste, disease defence cells
Oxygenated & deoxygenated blood freely mix
Body movements affect circulation
Pressure cannot be changed to support circulation
Give features of a closed circulatory system in fish
Blood in vessels - no direct contact to cells
Substances leave by diffusion
Pressure can be maintained and is higher than an open system
Flow can be directed to different tissues and organs
Give features of a single closed circulatory system.
Blood flows through the heart once per circulation
Blood flows through 2 sets of capillaries before the heart
1st one for gas exchange - e.g. gills
2nd for substance exchange in organs
LIMITATIONS:
Blood passes through narrow capillaries, lowering blood pressure
Blood returns to heart slowly minimising efficiency
As opposed to other organisms with single closed circulatory systems, why are fish efficient?
Countercurrent flow maximising gas exchange
Body weight supported by water
Doesn’t maintain own body temperature
What are features of a double circulatory system?
Blood flows through heart twice for every circuit of circulation
2 circuits
1st is the pulmonary circulation - used to carry blood to lungs and oxygenate
2nd is to carry O2 and other nutrients around the body
Per circuit, the blood only passes one capillary network, so pressure is maintained
State and describe the 3 components of blood vessels.
Elastic fibres: composed of elastin, can stretch and recoil, providing vessel walls with flexibility Smooth muscle: contracts or relaxes, changing the lumen size Collagen: structural support for vessels (maintains shape
Describe the functions of arteries.
- Carries bloody away from heart to body tissues - Usually carries oxygenated tissue (except pulmonary artery) AWAY from the heart umbilical artery carries fetus’s deoxygenated blood to placenta for gas exchange with mothers blood - Pressure in arteries > veins
Describe the structure and related functions of arteries.
Has elastic fibers, smooth muscle, collagen - Elastic fibers enable arteries to withstand force of blood pumped from heart & stretch to take large volumes of blood - Between heart contractions - elastic fibers recoil - helps even out blood surges giving a continuous flow - Artery lined with endothelium, smooth and doesn’t interrupt blood flow
Describe the function and structure of arterioles.
Arterioles have more smooth muscle and less elastin than arteries - due to less pulse surge from heart - Arterioles constrict or dilate to control blood flow to organs
Define vasoconstriction and vasodilation.
Vasoconstriction - when arteriole smooth muscle constricts, blood vessels constrict, stopping blood flow to capillary bed (stops heat loss)
Vasodilation - when smooth muscle in arterioles relax, blood flows into the capillary bed (increasing heat loss)
What are the adaptations of blood capillaries?
Large SA for diffusion of substances into and out of the blood - Total cross-sectional area of capillaries is greater than arterioles, blood flow rate falls - Slower blood movement allows more time for diffusion - Walls are single endothelial cell thick - this shortens diffusion distance.
Give vein adaptations for blood flow back to heart.
When veins go back to the heart, blood pressure is too low and it is against gravity 1. Veins have 1 way valves 2. Larger veins run between big, active muscles in body When muscles contract, they give blood extra push in vein 3. Breathing movements in the chest act as pump Pressure in chest changes, squeezing actions move blood into veins of chest of abdomen towards heart
What is blood plasma?
Main component of blood, yellow, carries dissolved substances such as blood cells
What is the % composition of components of blood?
55% plasma (most of which is water)
45% RBCs, wbc, platelets