Week 4 - Unit 4: Cardiovascular System Part 1 Flashcards
Explain why a vein may be described as an organ.
Made of different tissues / more than one tissue
Layer in wall Thickness / µm Artery Vein Endothelium 20 20 Smooth muscle 490 240 Elastic tissue 370 240 Connective tissue 120 120
Use information from the table to suggest the thickness of a capillary wall.
Give the reason for your answer.
20µm as it conists of endothelium only / does not contain muscle, connective tissue and elastic tissue
Layer in wall Thickness / µm Artery Vein Endothelium 20 20 Smooth muscle 490 240 Elastic tissue 370 240 Connective tissue 120 120
The diameter of the artery was 4 mm. Calculate the diameter of the lumen of this artery.
Show your working.
Wall is 20 + 490 + 370 + 120 = 1000µm thick = 1mm
Diameter of lumen = Diameter of artery (4mm) – 2X wall thickness (2mm)
Answer 2mm / 2000 µm
Explain how the elastic tissue in the wall helps to even out the pressure of blood flowing through the artery.
- Stretches as a result of high pressure / surge of blood
* Then recoils
Describe the advantage of having elastic tissue in the wall of an artery.
Allow recoil
For smooth blood flow / maintains blood pressure /avoids pressure surges
Calculate the cross-sectional area of the lumen of the artery shown in the diagram. Show your working.
The area of a circle is given by πr2, where r is the radius of a circle (π = 3.14).
• Radius measured from diagram (half of diameter) = 12 mm
image magnified X10
• Divide by 10 (because image is x10 magnification) = 1.2 mm
• 3.14 X 1.2 X 1.2 = 4.5 mm2
(ALLOW radius = 12.5 mm and subsequent correct calculations)
Name two substances which are at a higher concentration in the blood in an artery compared to a vein
ANY TWO: oxygen; glucose; amino acids; fatty acids; glycerol; minerals
Explain what causes the rate of blood flow to be slower in capillaries than in other vessels.
- Small diameter / lumen / increase in total cross-sectional area
- More surface in contact with blood
- Greater friction /resistance
- (Causes) loss of pressure
Which type of blood vessel has most elastic tissue in its wall?
• Artery
How does this elastic tissue help to smooth out the flow of blood in the blood vessel?
- Stretches when ventricles contract / stretches to accommodate increase in blood volume / increase in blood pressure
- Recoils when ventricles relax / when blood volume decreases / when blood pressure decreases
Describe why living organisms need a supply of Carbohydrates
For energy
Describe why living organisms need a supply of Proteins
For growth and repair
Describe why living organisms need a supply of fats
For energy and to make cell membranes
Describe why living organisms need a supply of vitamins
In small amounts for cells to work properly
Describe why living organisms need a supply of minerals
In small amounts to make body chemicals
Describe why living organisms need a supply of Oxygen
Needed for cellular aerobic respiration to release energy from organic fuels
Describe why living organisms need a supply of water
For chemical reactions to occur and for transport
How is carbon dioxide produced in the body
Produced as a by-product of cellular aerobic respiration, when oxygen is used to release energy from fuels
How is urea produced in the body?
A nitrogenous waste product produced by cellular metabolism and protein turnover
How is lactate produced in the body?
Produced as a result of anaerobic respiration where cells respire without oxygen
Why do humans need a transport system?
Organisms need special exchange surfaces in order to absorb substances that they require and to allow removal of waste substances.
Small (single-celled) organisms have a large SA:V ratio.
Nutrients and Waste can move in and out by simple diffusion alone.
No specialized exchange system(s) are needed.
Large (Multicellular) organisms have a small SA:V ratio.
Nutrients and Waste cannot move in and out by simple diffusion alone.
Specialized exchange systems are needed.
Summarise the structure & function of the blood, including its components and cells.
Blood is a tissue; made of cells, a fluid matrix known as plasma which contains proteins, as well as serum which contains nutrients.
Cells include:
Blood is always transported in blood vessels:
Along with the heart, and blood vessels; blood contributes to the circulatory system.
Identify what substances the blood transports around the body.
Nutrients and substrates (Glucose and Oxygen)
Waste and products (Urea and Carbon dioxide)
Chemical messengers (Hormones and cytokines)
Immunological components (White blood cells and antibodies)
Heat
What does blood regulate? (keep in homeostasis)
pH Body temperature Water potential Blood volume Immune responses, inflammation and blood clotting (haemostasis) Blood production (haematopoiesis)
Describe the structure of a red blood cell under a microscope
Red blood cells (Erythrocytes) are among the simplest of cells (approximately 7-8µm in diameter and 2-3µm thick). (Most other body cells are 10-30µm).
They lack a nucleus,
They have a biconcave shape
Their cytoplasm contains an iron-containing protein called haemoglobin.
What colour are the erythrocytes and why?
Red, because they contain hemoglobin which contains Iron – reflects red when oxidised.
Why do erythrocytes have no nucleus and a biconcave shape?
Increase volume in cytoplasm to contain more hemoglobin for more oxygen transport.
Most other animal body cells are 10-30µm in diameter. What limits the size of erythrocytes?
The lumen diameter of capillary vessels.
What might limit the lifespan of an Erythrocyte to approximately 120 days?
Wear and tear (oxidative stress accumulation) of hemoglobin and the cell membrane of the red blood cell.
How are erythrocytes formed?
Erythropoiesis – in bone marrow from special cytokine treatment of Hematopoietic stem cells.
What 5 things does the blood transport?
Nutrients, Waste, Chemical messengers, immunological components and heat.
Summarise the function of the human circulatory system
Functions:
- transport of respiratory gases (oxygen and carbon dioxide)
- transport of metabolites e.g. glucose, amino acids
- transport of metabolic wastes (e.g. urea)
- transport of hormones (from glands to target sites)
Identify and name the major blood vessels associated with the heart, lungs and kidney
Heart
Left and right coronary artery
lungs
pulmonary artery and vein
Kidney
renal artery and vein
Summarise the structure of the human circulatory system
- Heart acts as a pump
- Blood vessels (Arteries, arterioles, capillaries, venules, veins)
- The human circulatory system is a CLOSED SYSTEM because blood is confined to blood vessels
The advantage of this is: High blood pressure is maintained
The human circulatory system is a DOUBLE SYSTEM because:
Blood is pumped through the heart twice in one circulation
the advantages of this is High blood pressure maintained (therefore high flow rate)
and Oxygenated & deoxygenated blood kept separate (maintaining high diffusion gradients in lungs & tissues)
Name the one major artery that carries deoxygenated blood
Pulmonary artery
Name the one major vein that carries oxygenated blood.
Pulmonary vein
List the vessels of the heart in order from highest to lowest pressure.
Aorta
Pulmonary artery
Pulmonary vein
Vena cava
Blockage of coronary artery leads to heart attack. Why?
Prevents delivery of oxygen & glucose to cardiac (heart) muscle
So muscle can’t respire & dies (heart stops)
Why would High blood pressure in pulmonary artery cause a problem
Would force tissue fluid out of lung capillaries into alveoli
(so you’d drown!)
Explain why you might find blood clots in a heart during a dissection
A blood clot will form, if the heart valves are closed and blood is trapped inside the chambers.
Compare the structures of arteries, arterioles, veins and capillaries
capillaries - Wall made up of a single layer of endothelium
Compare the structures of arteries, arterioles, veins and capillaries
Describe the varying blood pressures in capillaries
Total cross-sectional area increases further, cause even more friction/resistance and loss of pressure.
Low blood pressure is important here because:
There is more time for diffusion of substances in/out of capillaries for exchange with surrounding tissues
Describe the varying blood pressures in capillaries
Total cross-sectional area increases further, cause even more friction/resistance and loss of pressure.
Low blood pressure is important here because:
There is more time for diffusion of substances in/out of capillaries for exchange with surrounding tissues
Describe the varying blood pressures in veins
Blood pressure is so low that valves are needed.
Valves: Prevent backflow of blood
What are the 3 blood vessels called?
Arteries, Veins and Capillaries
What are the 2 types of heart chamber called?
Atria and Ventricles
How do heart valves work?
Pressure sensitive. Open when pressure behind the valve is greater than the pressure in front to ensure unidirectional blood flow.
What are the two circuits called?
Pulmonary
Systemic
What is the difference between the left side and right side of the heart, in terms of the blood transported?
Left side has oxygenated blood.Right side has deoxygenated blood.
Which side of the heart is the thickest? Why?
Left side. Must pump blood at a higher pressure to enable perfusion of the whole body. Contrast to the right side which pumps blood a shorter distance to the lungs.
Describe The Cardiac Cycle: 1 heart beat
- Atrial DiastoleThe heart beat begins when the heart muscles relax and blood flows into the atria.
- Atrial SystoleThe atria then contract and the valves open to force blood into the ventricles.
- Ventricle SystoleThe Ventricles contract forcing the blood to leave the heart. At the same time, the atria are relaxing and once again filling with blood.
what stops back Flow of blood in the heart?
AV & SL valves in the heart are forced open or shut by pressure differences
However they can only open one way.This helps to prevent backflow of blood.The tendinous cords help heart values to stay in place.
The cardiac cycle describes the events which occur during one heartbeat.
One whole cardiac cycle (1 heart beat) takes 0.8 seconds.
How many cycles take place in 1 minute? Show you working.
60 seconds / 0.8 for 1 cardiac cycle= 75 beats per minute.
This measurement is known as Heart rate.
How is cardiac output calculated?
Cardiac output = stroke volume X heart rate
You need to be able to re-arrange this equation!
Define cardiac output
Volume of blood pumped
by the heart per minute
(units: cm3min-1)
Define stroke volume
Volume of blood pumped
during each heart beat
(units: cm3)
Define heart rate
Number of heart beats per minute
units: min-1
What is the stroke volume if your heart rate is 80 beats per minute and your cardiac output is 5440 cm3min-1?
68 cm3
How does the heart beat automatically? what controls this?
The heart beats automatically:
Control centre: Medulla Oblongata in the brain
ANS: Sympathetic nervous system and accelerator nerve Parasympathetic nervous system and vagus nerve
Heart pacemakers:S.A.Node A.V.Node
Bundle of Hiss Purkije fibres
The wave of electrical activity which coordinates the heart beat is delayed slightly at AV node. It then passes along part to the base of the ventricles.
Explain the importance of
(i) the slight delay at the AV node
To allow the atria to finish systole and finish emptying before the ventricles contract / systole.
Explain the importance of:
(ii) the electrical activity being passed to the base of the ventricles.
The ventricles contract / systole from the apex / bottom upwards.
This generates an upward contraction force to pump the blood out of the heart and into the arteries effectively.
Explain the importance of:
The electrical activity being passed to the base of the ventricles.
The ventricles contract / systole from the apex / bottom upwards.
This generates an upward contraction force to pump the blood out of the heart and into the arteries effectively.
The maximum pressure in the ventricle is much higher than that in the atrium.
Explain what causes this.
The muscle wall is thicker in the ventricle, compared to the atria.
Contraction produces a greater force .
The blood is therefore pumped at higher pressure.
The heart controls and coordinates the regular contraction of the atria and ventricles.
Describe how.
Control = via pacemaker cells in the SA.Node and A.V.Node, and purkinjie fibres. Coordination = nerve action potential conduction.
Starting in S.A.Node atria contract A.V.Node slight delay bundle of Hiss purkinjie fibres ventricles contract…
What is the stroke volume if your heart rate is 80 beats per minute and your cardiac output is 5440 cm3min-1?
CO = HR X SV SV = CO / HR SV = 5440cm3min-1 / 80min-1 = SV = 68cm3
What determines the opening the closing of the Atrioventricular (AV) and Semilunar (SL) valves?
What does this help to ensure?
Pressure differences between the Atria, Ventricles and Arteries.
Prevents backflow of blood / ensures blood flow is unidirectional.
What is a normal Heart rate (beats per minute) =
70bpm
What is a normal Stroke volume (volume of blood per beat) =
70ml
What is a normal Cardiac output (HR X SV) =
4.9litres per minute
What is a normal Diastolic pressure (blood pressure when heart is relaxed) =
80mmHg
What is a normal Systolic pressure (blood pressure when heart is contracted) =
120mmHg
Describe the survival response
Stimulus = change in an organism’s internal or external environment.
Organisms respond to stimuli increases changes of survival.
e. g. response to external temp. (too hot; too cold) to maintain optimum temp. for enzymes
e. g. response to internal environment to maintain optimum pH for enzymes.
Animals respond by sending messages to different parts of the body (communication). Messages can be of two types:
(1) Hormonal communication
(2) Nervous communication
Both involve:
A receptor to detect stimulus
A coordinator to formulate a response
An effector to produce a response
What are Hormones?
Hormones = chemical messengers secreted by glands & transported in blood
Mostly proteins (e.g. insulin) or steroids (e.g. oestrogen)
Bind to specific receptors (proteins) on cell surface membranes of target cells.
What is the receptor, hormone, effector and response to rise in blood sugar levels (stimulus)?
β-cells in
pancreas, insulin, liver or muscle cell, glycogenesis
Nervous system consists of…
(1) CNS & PNS
(2) 3 types of neurone (transmit electrical impulses)
(3) Synapses (using chemical neurotransmitters )
Describe the central nervous system.
Central Nervous System (CNS) Brain & spinal cord Contains relay neurones Processes sensory information Decides what to do with it Initiates a response
Describe the Peripheral Nervous System (PNS)
Peripheral Nervous System (PNS)
All other nerves
Made up of sensory & motor neurones
Sensory neurones bring information from receptors to the CNS.
Motor neurones carry information from CNS to effectors (muscles & glands).
Describe conscious and unconscious Nervous Communication
Conscious Nervous Coordination (£5 Drop)
- voluntary - involves thinking - uses the brain
Unconscious Nervous Coordination (Simple reflex arc)
- involuntary - no thinking - uses spinal cord only
Nervous v. Hormonal Response (Differences)
Nervous System Electrical impulse carried by neurones to specific sites Fast response Localised effect short lived
Hormonal response
Hormones carried in the blood all around the body
slow response
(It takes time for hormones to travel in blood (whereas nerve impulse travel quickly).
widespread effect
(Hormones travel to all parts of the body and target cells are dispersed (whereas neurones link directly to specific effectors).
long lasting effect
(Hormones are broken down slowly (whereas neurotransmitters are broken down quickly).
What is meant by myogenic control?
MYOGENIC CONTROL
The heart initiates its own contractions: electrical impulses start in the SAN (pacemaker) at a set frequency of ~ 70 per minute
What is the function of the sinoatrial node?
Sends impulses which spread through atria so they contract together to pump blood into ventricles
What is the function of the Bundle of His & Purkyne fibres?
Conducts impulses through ventricles so they contract together from base upwards, pumping blood into aorta & pulmonary artery
What is the function of the Atrioventricular
node (AVN)
Relays impulses to ventricles with a slight delay (so ventricles contract after atria), ensuring one-way flow of blood through the heart
What is the function of chemoreceptors?
Detect changes in
blood CO2, pH & O2
What is the function of Sympathetic neurone
Impulses along this nerve cause release of noradrenaline
binds to receptors on SAN increased heart rate
What is the function of parasympathetic neurone
Impulses along this nerve cause release of acetylcholine
binds to receptors on SAN decreased heart rate
where are baroreceptor and chemoreceptors located?
Aorta & carotid artery
What is the function of baroreceptors?
Detect changes in
blood pressure
what happens when chemoreceptors detect
High blood CO2
Low blood pH
Low blood O2
Impulses along Sympathetic neurone cause release of noradrenaline binds to receptors on SAN increased heart rate
What happens when baroreceptors detect High blood
pressure?
Impulses along Sympathetic neurone cause More acetylcholine released decreased heart rate
What are the 7 parts to a homeostatic control mechanism?
- stimulus
- sensor or receptor
- afferent path
- integrating centre
- efferent path
- effector
- response
True or false. Chemoreceptors are sensitive to changes in blood chemistry.
True
True or false. Peripheral chemoreceptors are located in the aorta and carotid arteries.
True
True or false. The central chemoreceptor in the medulla oblongata is less powerful than the peripheral chemoreceptors.
False
True or false. Stretching of alveoli, bronchi and muscles stretch receptor Vagus nerve Medulla Oblongata
True
True or false. Phrenic nerve Diaphragm, and Intercostal nerve Intercostal muscles
True
True or false. The dive reflex prevents the lungs from overstretching during inhalation.
False
True or false. Myogenic = muscle cells with pacemaker, intrinsic electrical activity and contraction.
True
True or false. The Sympathetic nervous system decreases heart rate.
False
True or false. The Parasympathetic nerve system uses an accelerator nerve and acetylcholine to slow down heart rate.
False
True or false. Baroreceptors are sensitive to pressure and decrease heart rate when stimulate.
True
Define Sympathetic system
Fight or flight domain of the ANS
What is the function of Adrenaline ?
Efferent hormone of the SPNS, which increases heart rate and force of contraction
Define parasympathetic system.
Rest and digest domain of the ANS
What is the function of acetylcholine?
Efferent hormone of the PSPNS, which decreases heart rate
What is the role of the vagus nerve?
Efferent nerve of the PSPNS
What is the Cardiovascular control centre ?
Control centre in the brain which controls heart rate and force of contraction - medulla oblongata
In which part of the brain is the cardiovascular centre located?
medulla
Describe how an impulse reaches the base of the ventricles of the heart from the sinoatrial node.
spreads through the atria / right atrium / through cardiac muscle;
to the atrioventricular node;
then through bundle of His / Purkyne fibres;
Explain how a rise in blood pressure results in a decrease in the rate of heartbeat.
baroreceptors in aorta / carotid arteries;
send impulses to cardiovascular centre / medulla;
which sends impulses along parasympathetic nerves;
to SAN;
(more) acetylcholine released / acetylcholine binds to receptors on SAN to slow it down;
so fewer impulses sent to AVN;
Some drugs inhibit the transmission of nerve impulses to the heart. Explain how these drugs reduce high blood pressure
Inhibit impulses in sympathetic nerves;
Heart rate lowers because SAN not stimulated
/ because noradrenaline not released;
