Biology 1A - circulation Flashcards
how does exchange of substances occur in different types of organisms
cellular level = across plasma membrane
unicellular organisms = directly with environment via diffusion
multicellular organisms = require a circulatory system
what is Fricks law
rate of diffusion α surface area x concentration difference/thickness of membrane
what is the purpose of the circulation system
supplies cells in multicellular organisms with nutrients (eg oxygen if it uses aerobic respiration)
and rids cells of waste products such as carbon dioxide (in animals) and nitrogenous compounds
what are the 3 components of circulatory systems
circulatory fluid
interconnecting vessels
muscular pump
what are the two types of circularity systems
open circulatory system
closed circulatory system
what is an open circulatory system
- circulatory fluid = hemolymph (this is also the interstitial fluid that bathes body cells and organs)
- in arthropods and molluscs
- heart contracts pumping hemolymph through circulatory vessels into interconnected sinuses (spaces surrounding organs)
- in this space exchange of substances occurs
- heart relaxes, draws hemolymph back through pores
what is a closed circulatory system
- circulatory fluid = blood, confined to vessels and distinct from interstitial fluid
- in annelids, cephalopods, and all vertebrates
- one (or more) heart pumps blood into large vessels that branch into smaller ones that infiltrate tissues and organs
- exchange occurs between body cells and interstitial fluid, and between interstitial fluid and blood
what is the cardiovascular system
type of closed circulatory system that all vertebrates and humans have
what are the three types of blood vessels in the vertebrate closed circulatory system (cardiovascular system)
arteries, veins, capillaries
what are arterioles (vertebrate closed circulatory system, cardiovascular system)
arteries branch into arterioles and they carry blood away from the heart to capillaries
what are capillary beds (vertebrate closed circulatory system, cardiovascular system)
networks of capillaries
sites of chemical exchange between blood and interstitial fluid
what are venules (vertebrate closed circulatory system, cardiovascular system)
converge into veins and return blood from capillaries to the heart
what are arteries and veins NOT distinguished by (vertebrate closed circulatory system, cardiovascular system)
O2 content
describe the order of flow through blood vessels (vertebrate closed circulatory system, cardiovascular system)
heart => arteries => arterioles => capillaries => venules => veins => heart
what are the different types of vertebrate closed circulatory systems (cardiovascular systems)
single circulation:
- fish, rays and sharks
- one atrium and one ventricle
- maintains lower blood pressure
double circulation:
- amphibians, reptiles, birds, mammals
- O2 poor and O2 rich pumped separately from left and right side of heart
- maintains higher blood pressure
describe single circulation in fish (vertebrate closed circulatory system, cardiovascular system)
- two chambered heart (one ventricle and atrium)
- blood leaving heart passes through two capillary beds (gill and systemic/body capillaries) before returning to heart
- blood reaches tissues after first passing through gills
- therefore, blood in systemic part of system is low pressure ( okay because fish have low metabolic rate)
fish are ectothermic, what does this mean
cold blooded
rely on environmental heat sources as have very small/no internal heat sources to control body temp
describe the double circulatory system in amphibians (vertebrate closed circulatory system, cardiovascular system)
- three chambered heart (two atria and one ventricle)
- two capillary beds (pulmocutaneous and systemic)
- O2 poor blood flows through pulmocutaneous circuit to pick up oxygen -through skin and lungs
- O2 rich flows through systemic circuit
- ridge in ventricle diverts O2 rich and poor blood to different circuits, some mixing occurs
what happens to their circulatory system when amphibians are underwater
blood flow to lungs is nearly shut off and respiration occurs through skin
describe the double circulatory system in reptiles (vertebrate closed circulatory system, cardiovascular system)
- three chambered heart (two atria and one ventricle that is partially divided by incomplete septum)
- some mixing occurs (O2 rich and poor)
- have lung capillaries and systemic capillaries
describe the double circulatory system in mammals and birds (vertebrate closed circulatory system, cardiovascular system)
- 4 chambered heart ( two atria and two ventricles)
- left side receives and pumps only O2 rich blood
- right side receives and pumps only O2 poor blood
- system meets bodies continuous demand for O2 as they are endotherms
- two loops of blood vessels (pulmonary circulation and systemic circulation)
describe the atria and ventricles in the human heart (cardiovascular systems)
- two atria with relatively thin walls, serve as collection chambers for returning blood to the heart
- ventricles have thicker walls and contract more forcefully
what is the cardiac cycle
rhythmic cycle by which heart contacts and relaxes
what are the two stages of the cardiac cycle
- systole (contraction) and diastole (relaxation)
describe the right atrium (human heart)
receives O2 poor from the body (systemic circulation)
pumps blood to right ventricle
describe the right ventricle (human heart)
receives O2 poor blood from right atrium
pumps O2 poor blood to lungs via pulmonary arteries (pulmonary circulation)
describe the left atrium (human heart)
- receives O2 rich blood from lungs via pulmonary veins (pulmonary circulation)
- pumps blood to left ventricle
describe the left ventricle (human heart)
receives O2 rich blood from left atrium
- pumps O2 rich blood to body via aorta (systemic circulation)
what is the purpose of valves in the human heart
ensures blood flows in the correct direction
prevents backflow
what causes the lub-dub sound in the heart
the closure of heart valves
(detected by stethoscope)
what can cause heart murmurs
backflow of blood through a defective valve
describe atrioventricular valves (human heart)
attach to tendinous cords
tricuspid = between right atrium and ventricle
mitral = between left atrium and ventricle
describe semilunar valves
aortic = between left ventricle and aorta
pulmonary = between right ventricle and pulmonary trunk
some cardiac muscle cells are autorythmic. what does this mean (heart conduction system)
contract and relax repeatedly without any signal from the nervous system
what coordinates contractions in the heart (heart conduction system)
group of autorythmic cells call the sinoatrial (SA) node
what does the SA node produce (heart conduction system)
electrical impulses (similar to those from nerve cells)
these impulses spread rapidly through heart tissue
what measures impulses generated by SA node (heart conduction system)
electrocardiogram (ECG)
what is the atrioventricular (AV) node (heart conduction system)
- group of autorythmic cells, located in wall between left and right atria
- relay point where electrical impulses delayed for about 0.1 secs before spreading to heart apex
- delay allows atria to empty completely before ventricles contract
describe the heat conduction system and what each stage looks like on a ECG
1) signals from SA node spread through atria (first small bump)
2) signals delayed at AV node (flat line)
3) bundle branches pass signals to heart apex (dip before spike)
4) signals spread throughout ventricles (large spike)
what can alter heart rate
physiological control:
nerve impulses
hormones (eg. epinephrine from adrenal glands speeds up SA node)
body temp
what is largely responsible to the regulation of heart rate (heart conduction system)
autonomic nervous system
booth sympathetic and parasympathetic
how to the sympathetic nervous system (autonomic) affects heart rate (heart conduction system)
- nerves originate from T1-T4 levels of spinal chord
- release norepinephrine
- increases heart rate and force of contraction
how does the parasympathetic nervous system (autonomic) affect heart rate
- nerves originate from vagus nerves
- release acetylcholine which acts on SA node
- decreases heart rate and force of contraction
describe the cardiac cycle
1) atrial and ventricular diastole - semilunar valves close (dub sound)
2) atrial systole and ventricular diastole
3) ventricular systole and atrial diastole -atrioventricular valves close (lub sound)
what is cardiac output (cardiac cycle)
volume of blood pumped into the systemic circulation per minute
depends on heart rate and stroke volume
what is heart rate (cardiac cycle)
beats of the heart per minute
what is stoke volume (cardiac cycle)
amount of blood pumped in a single contraction
what is blood pressure (cardiac cycle)
determined by cardiac output and peripheral resistance met by blood as it passes from the arteries into the capillaries
what do all blood vessels contain
a central lumen lined with an epithelial layer (endothelium) that lines blood vessels
endothelium is smooth and minimises resistance
describe structure of arteries
thick elastic walls to accommodate high blood pressure
describe structure of capillaries
smallest diameter blood vessel
allows for diffusion of nutrients, waste in and out of tissues
describe structure of veins
contains valves to maintain unidirectional blood flow
describe functions of arteries
- transport blood from the heart to capillaries
- acts as pressure reservoir for forcing blood into small diameter capillaries as thick arterial walls withstand pressure
- dampen oscillations in pressure and flow generated by heart, producing more even flow to capillaries
describe the functions of veins
- transport blood from capillaries back to the heart
- act as a storage reservoir for blood
- blood pressure is low in veins, one way valves prevent backflow of blood
- return of blood is also enhanced by skeletal muscle contraction
what are conditions/ diseases related to blood vessels
Atherosclerosis = deposition of plaques, composed of fatty substances in arterial walls, can cause myocardial infraction (heart attack) and stroke
Deep Vein Thrombosis (DVT) = pooling of blood in deep veins leading to clot formation, can be caused by prolonged inactivity after surgery or long journeys
describe blood flow velocity in capillaries
velocity of blood flow is slowest in capillary beds as a result of high resistance and large total cross sectional area
necessarily slow for exchange of materials
what is pulse pressure
systolic - diastolic
what is systolic and diastolic blood pressure
systolic = the pressure in arteries during ventricular systole, highest pressure in the arteries
diastolic = pressure in arteries during diastole, lower than systolic pressure
what is healthy blood pressure for a 20 year old human at rest
120/70 mmHg
what controls blood pressure
homeostatic mechanisms by altering diameter of arteries
vasoconstriction
vasodilation
describe vasoconstriction
contraction of smooth muscle in arterial walls, increases blood pressure
describe vasodilation
relaxation of smooth muscles in arterial walls, causes blood pressure to fall
what ways does movement occur in and out of capillaries
passively = through thin capillary endothelial cell wall, lipid soluble substances & dissolved gasses
actively = bulk flow through intercellular spaces between endothelial cells
what is the blood brain barrier (active transport in capillaries)
in brain capillaries there are tight junctions
what pulls blood proteins back into capillaries (fluid exchange)
Blood proteins, creating osmotic pressure, tends to pull fluid back into capillaries
on average is there a net gain or loss, of fluid from capillaries
net loss (because blood pressure wins)
describe blood and osmotic pressure along a capillary (fluid exchange)
arterial end => venous end, blood pressure decreases
arterial end => venous end, osmotic pressure stays constant
describe flow of blood in and out of a capillary (fluid exchange)
arterial end = blood pressure is much greater than osmotic pressure (counterbalance mechanism), has a net pressure of 10mmHg that drives fluid out
venous end = blood pressure has dropped, osmotic stays the same so osmotic pressure is greater and fluid is drawn back in, although less than the amount that is driven out
therefore net loss of fluid
what is the lymphatic system (fluid exchange)
system that returns fluid that leaks out from capillary beds into interstitial space
it drains into veins in the neck
what is the fluid lost by capillaries called (lymphatic system)
lymph
what is oedema (lymphatic system)
swelling in lymph nodes caused by disruptions in the flow of lymph
happens when body is fighting infection
what are lymph nodes (lymphatic system)
organs that filter lymph and play important role in bodies defence
describe the mammalian respiratory system
- air is inhaled through nostrils, filtered, warmed, humidified and sampled for outdoors
- system of branching ducts conveys air to the lungs
- cilia and mucus line air ducts and move particles up towards the pharynx cleaning the respiratory system
describe the flow of air through the respiratory system
nasal cavity => pharynx => larynx => trachea => splits into two primary bronchi (left and right) => bronchi split into bronchioles => branch into terminal bronchioles => alveoli complex covered by capillary beds
how can you see alveoli (respiratory system)
SEM imaging
describe the structure of the lung membrane
pleural membrane: has parietal and visceral layers/ pleura
pleural space: potential space between these layers containing pleural fluid
pleural fluid: prevents friction, causes layers of pleural membrane to adhere to one another
describe alveoli (respiratory system)
- form honeycombs (large surface area)
- surrounded by dense capillary networks
- made of simple squamous epithelium (thin)
- gas exchange occurs by diffusion across alveolar and capillary walls
what does diffusion rate at alveoli depend on (respiratory system)
surface area (large)
distance (short)
concentration difference (high to low; driving force)
therefore high diffusion rate
what allows alveolar expansion when breathing in
fluid with surfactant lining the alveolus that reduces surface tension
describe the layers of the respiratory membrane
- alveolar epithelium (simple squamous epithelial cells)
-fluid and surfactant layer - interstitial space
- capillary endothelium (simple squamous epithelial cells)
what is the diffusion distance across the respiratory membrane?
0.2-0.6 micro meters
describe inhalation (respiratory system)
- diaphragm contacts (moves down) and rib cage expands as rib muscles contract
- lungs expand too fill the enlarged thoracic cavity
- air drawn into lungs
- called negative pressure breathing
describe exhalation (respiratory system)
- diaphragm relaxes and moves up, rib cage gets smaller as rib muscles relax
– the elasticity of lungs drives air out of them
how is breathing controlled (respiratory system)
my monitoring pH of the blood
pH will go down when more CO2 in tissues (may happen when exercising)
describe the process of increasing breathing rate (respiratory system)
1) blood pH falls due to rising levels of CO2 in tissues
2) medulla and detects decrease in CSF, sensors in major blood vessels (carotid arteries and aorta) detect decrease in blood pH
3) medulla receives signals from major blood vessels
4) medulla sends signals to ribs and diaphragm to increase rate and depth of ventilation
5) blood CO2 level falls and pH rises
what is haemoglobin
- transports oxygen in the blood
- in all vertebrate animals and is contained within red blood cells
- protein containing four subunits each consisting of a polypeptide chain and haem group
- each haem group contains an iron atom to which an oxygen molecule can bind
when is haemoglobin 100% saturated (respiratory system)
when the iron atom in each each haem group is bound with oxygen
what happens when gasses are exchanged from red blood cells to tissue cells
- oxygen molecules are unloaded from haemoglobin
- protein diffuses into blood plasma, through capillary wall, into interstitial fluid, and into cells where its used for cellular respiration
describe partial pressure of oxygen in the respiratory system
air = 160 mmHg
lungs = 100 mmHg
tissue = 40 mmHg
(decreases throughout system)
what is the haemoglobin dissociation curve
a graph that depicts the relationship between the amount of oxygen bound to haemoglobin and the partial pressure of oxygen in the blood
describe the haemoglobin association curve
- sigmoid curve - relatively flat and then drops off
- shows how partial pressure of oxygen drops as you move from lungs to tissues at rest to - - - tissues during exercise (when haemoglobin has given up most of its O2 to tissues)
- doesn’t decrease at a steady rate as there is cooperativity between haem subunits
what does it mean for haem sub units to have co-operativity (haemoglobin dissociation curve)
when one subunit unloads O2 the others then more readily unload because changes in their shape decrease their affinity
(slope of dissociation curve becomes steeper)
how is CO2 transported in the blood (3 ways)
1) 5% as dissolved carbon dioxide
2) 5% attached to haemoglobin and other blood proteins (it forms carbamino compounds by attaching to terminal NH2 group)
3) 90% as bicarbonate ions in plasma
describe exchange of co2 between tissue cell and the blood
- diffuses into interstitial fluid, through capillary wall and into blood plasma
- some remains here, most enters red blood cells
- some binds with haemoglobin, most reacts with water forming carbonic acid
- breaks into hydrogen ion (stays in haemoglobin) and bicarbonate ion (diffuses back into blood plasma)
describe exchange of co2 between blood and the lungs
- o2 poor blood containing co2 leaves tissue capillaries and moves to heart
- pumped to alveolar capillaries in lungs
- haemoglobin gives up co2 and hydrogen ions
- bicarbonate combines with hydrogen ions to form carbonic acid which is converted to co2 and water
- co2 diffuses out of red blood cell, out of blood plasma, into alveolus in lung
- expelled with exhaled air
- triggered by less co2 in alveolus space than in blood
