3.2 Transport in Animals Flashcards
why do multicellular animals need transport system?
. small surface area to volume ration
. short diffusion distance
. high metabolic rate
. size of larger animals
what are the different types of circulatory systems?
. open- blood is not enclosed within vessels
. closed- blood is enclose within vessels
. single- blood passes the heart once
. double- blood passes the heart twice.
what is the structure and function of the arteries?
. carry blood away from the heart to the rest of the body at high pressure
. thick wallsans small lumen to withstand high blood pressure
. elastic tissue which allows them to stretch and recoil which smooths blood flow
. smooth muscle enables them to vary blood flow
. smooth endothelium to reduce friction and ease flow of blood
what is the structure and function of the arterioles?
. branch off arteries
. have thinner and less muscular walls . . their role is to feed blood into capillaries
what is the structure and function of the capillaries?
.smallest blood vessels
. site of metabolic exchange
. only one cell thick for fast exchange of substances as it reduces diffusion distance
. walls are leaky to let fluid proteins to leak out
what is the structure and function of the venules?
larger than capillaries but smaller than veins
what is the structure and function of the veins?
. carry blood from the body to the heart at low pressure
. contain a wide lumen to maximise volume of blood carried to the heart . . thin walled as blood is under low pressure
. valves to prevent backflow of blood, . no pulse of blood meaning there’s little elastic tissue or smooth muscle as there is no need for stretching and recoiling
what is tissue fluid?
- contains dissolved oxygen and nutrients which it
supplies the tissues withexchange for waste products such as carbon dioxide. - enables exchange of substances between blood and cells.
how does tissue fluid form from plasma?
- at arterial end hydrostatic is greater than, oncotic and fluid / plasma moves, out capillary
- at venous end hydrostatic is lower than, oncotic so tissue fluid moves into capillary
remaining tissue fluid goes to the lymphatic system, what is this?
drains waste products from tissue fluid
what is the difference in composition in the blood, tissue fluid and lymph?
blood : contains erythrocytes, neutrophills, platelets, proteins, water and dissolved solutes
tissue fluid: contains few neutrophills, few proteins, water, and dissolved solutes
lymph: contains neutrophills, water and dissolved solutes
what is the external structure of the heart?
- superior vena cava
- inferior vena cava
- aorta
-pulmonary veins
- coronary arteries
- pulmonary arteries
what is the internal structure of the heart?
- superior and inferior vena cava
- left and right atrium
- left and right ventricle
- aorta
- pulmonary veins
- pulmonary arteries
- AV valves
- Semilunar valves
describe atrial systole
- ventricles are relaxed
- atria contract, decreases volume and increases the pressure
- blood is pushed into the ventricles through the AV valves
- there is a slight increase in ventricular pressure and volume as blood is ejected into the ventricles
describe ventricular systole
- atria relax
- ventricles contract, increases pressure in the ventricles than the aorta so the AV valves close, to prevent back flow of blood
- this high pressure in the ventricles cause the Semi-lunar valves to open and blood is forced out into the pulmonary artery and aorta
describe diastole
- ventricles and atria relax
- the high pressure in the pulmonary and aorta cause the Semi-lunar valve to close, to prevent back flow of blood
- atria fills with blood, increasing their pressure
- ventricles continue to relax
describe how heart action is initiated by the SAN
- generaties a wave of excitation that spreads to the atrial walls to contract
describe how heart action is initiated by the AVN
- Depolarisation passed into conducting fibres, known as Bundle of His.
- Purkinje fibres carry the wave upwards to the ventricles
- This delay enable the ventricles to fill with a sufficient amount of blood before contracting.
how to calculate cardiac output
heart rate x stroke volume
What do the different waves mean in ECG’s
- QRS complex : activation of ventricles
- P wave : activation of atria
- T wave : recovery wave
what are some examples of ECG’s ?
- fast heartbeat : tachycardia
- slow heartbeat : bradycardia
- irregular heartbeat : fibrillation
- extra heartbeat : ectopic heartbeat
Define oxygen association
in the lungs, at high pO2 Hb affinity increases and binds easily with O2
Define oxygen dissociation
in the blood, pO2 decreases and Hb affinity decreases so O2 is released to respiring cells and tissues
Define affinity and its relation with oxygen
- Affinity is how well substances combine (liking for another substance)
- Hb has a high affinity for O2 in lungs because the high O2 lvls whereas Hb releases O2 in blood because O2 lvls decrease
describe the oxygen dissociation curve
-shows the rate at which oxygen associates, and also dissociates, with haemoglobin at different partial pressures of oxygen (pO2)
- when pO2 lvls are high Hb has a higher affinity for O2 and so will associate
- when pO2 lvls are low Hb releases O2 and dissociates
why does respiration do to the availability of oxygen?
- Decreases partial pressure, in turn decreasing affinity of oxygen for haemoglobin.
- As a result, oxygen gets released to respiring tissues where needed.
how is carbon dioxide transported?
- CO2 reacts with water to form carbonic acid, catalaysed by carbonic anhydrase
- carbonic acid dissociates into hydrogen and hydrogencarbonate ions
- the increase of hydrogen ions means that oxyhaemoglobin unloads its O2 so haemoglobin takes hydrogen ions
- this forms haemoglobonic acid - this process stops the cell’s acidity from increasing
- the hydrogen carbonate ions diffuse out of the red blood cells and transported to the blood plasma (chloride shift)
- when blood reaches the lung the low pCO2, the process is reversed
- H2CO3 -> H20 + CO2
- CO2 diffuses into alveoli and is breathed out
what is the chloride shift?
HCO3- ions move out of red blood cells into the blood plasma
RBC are more +ve
Cl- ions move into RBC to prevent an electrical imbalance
what is the Bohr effect?
more CO2 produced so more O2 released
what effect does tachycardia have on blood flow
- ventricles dont have enough time to refill
- less blood leaves ventricles to rest of body/lungs
what is the difference between fetal and adult haemoglobin
fetal Hb has a higher affinity for oxygen
must be able to bind to oxygen at lower pO2 in placenta
why does tissue fluid not contain erythrocytes
too big to pass through gaps in endothelial cells
describe and explain how substances that are dissolved in the blood plasma e.g Oxygen and glucose enter tissue fluid from the capillaries
capillary walls are leaky
diffuse down a concentration gradient
high hydrostatic pressure pushes plasma out of the capillaries into the surrounding tissue fluid
why is the cartilage essential in the trachea
strength and support to prevent it from collapsing
flexible to keep airway open
what are two advantages for keeping the blood enclosed within vessels
maintain high blood pressure
increase rate of blood flow to and from heart
why is the left ventricle wall thicker than left atrium wall
needs to create a higher pressure
to push blood against greater friction
pumps blood to all parts of body
