Tranport systems in the human body Flashcards
How do the transport systems of some invertebrae work
Their surface-volume
ratio is such that transport takes place via diffusion eg. Arthropods
Their open blood system does not play a role in the transport of gases, only in
transporting nutrients and phagocytic cells.
What kind of blood system do vertebraes have
Vertebrates have a closed blood system; the blood circulates in blood vessels, never leaves the blood vessels, and is
circulated by a pump (heart)
They have a double blood circulation or the pulmonary circulation (lung) and the systemic circulation (body)
What is the disadvantage of a closed blood circulatory system
not all cells can be directly in contact with the blood, but this
problem is solved by substances diffusing from the fine branched capillary
blood vessels
How does an open blood circulatory system work
Blood vessels transport all
fluids into a cavity. When the animal moves, the blood inside the cavity moves freely around the body in all directions and is in direct contact with the organs
Blood flows very slow due to the absence of smooth muscles, which are
responsible for contraction of blood vessels.
How does a closed blood circulatory system work
Blood never leaves the blood
vessels, it is transferred from one blood vessel to another continuously without entering a cavity.
Blood is transported in a single direction, delivering oxygen and nutrients to cells and removing waste
products.
What categories can closed blood circulatory systems be divided into
single circulatory systems and double circulatory system
Describe single circulatory pathways
Consist of a double chambered heart with an atrium and ventricle eg. fish
The heart pumps deoxygenated blood to the gills where it gets oxygenated and is then supplied to the entire fish
body, with deoxygenated blood returned to the heart
Describe double circulatory systems
Four-chambered heart; The right atrium receives deoxygenated from the body and the right ventricle sends it to the lungs to be oxygenated; The left atrium receives oxygenated blood from the lungs and the left ventricle sends it to the rest of the
body eg. in birds and mammals
Why are double circulatory systems called that
because they are made up of two circuits,
referred to as the pulmonary and
systemic circulatory systems.
What about our circulatory systems makes it possible to maintain a high level of activity
The high rate of oxygen rich blood flowing through the body
How many chambers does the heart have
The heart consists of four chambers which function as two separate pumps.
Where is the heart situated
The heart is situated in the thoracic cavity, above the diaphragm and between
the lungs.
What is the space between the lungs where the heart is found called
the mediastinum
What keeps the heart in position
the large blood vessels that enter and leave it
What is the tough connective tissue with a double walled membrane that encloses the heart called
the pericardium
What does the pericardium do
it protects the heart
How is the heart attached in the body
ligaments attach the heart by means
of the pericardium to the breastbone, the vertebral column and other
areas in the thoracic cavity
What is the moist membrane that surrounds the pericardium
the epicardium
What does the watery fluid between the pericardium and the epicardium do
prevents friction
between the heart and surrounding organs when the heart contracts and
relaxes
What blood vessels are visible on the outside surface of the heart and what do they do
coronary blood vessels
These vessels transport blood to and from the cardiac muscle
What is the septum of the heart
the strong muscular wall that divides the heart into a left and right half
What kind of blood do the right and left side of the heart contain
The left side contains
oxygenated blood, while the
right side contains
deoxygenated blood.
Why can the heart be seen as a double pump system
The blood in the left side never
mixes with the blood in the right
side
What is the difference between atria and ventricles
The two upper chambers of the heart are known as atria (receiving chambers) and are smaller, with thinner muscular walls than the lower two chambers, which are
known as the ventricles (pumping chambers)
What is the inside of the heart lined with
a thin membrane of squamous epithelium, the endocardium
Why are the walls of the right atria thinner
because blood only needs to be pumped from the right atria to the right ventricle
What does the inferior vena cava transport
deoxygenated blood from the lower limbs and abdomen to the heart
What does the superior vena cava transport
deoxygenated blood from the head and arms to the heart.
How does transportation of blood work in the right ventricle
The blood flows from the right atrium to the right ventricle through an opening, the atrio-ventricular opening. Deoxygenated blood is then pumped to the lungs
via the pulmonary arteries
How many pulmonary veins open into the left atrium
4
Why is the left ventricle the thickest chamber with the thickest muscular wall
the left ventricle must
pump oxygenated blood throughout the whole body
How does blood flow through the left ventricle
The blood flows from the left atrium to the left ventricle through the atrio-ventricular opening. The oxygenated blood is then pumped to the rest
of the body via the largest artery in the body, the aorta
Where is the tricuspid valve situated
between the right atrium and the right ventricle
What are the inelastic tendons that attach the flaps of the tricuspid valve to the inner walls of the right ventricle called
chordae tendinae
What are chordae tendinae in the heart attached to
small protrusions, the papillary muscles, on the inside wall
of the right ventricle
Explain how the tricuspid valve works
- When the right atrium contracts, the flaps of the valves are pushed open and the blood flows through the atrio-ventricular opening to the right ventricle.
- When the right ventricle contracts, the blood pushes the valve flaps up and closes the atrio-ventricular opening.
- The papillary muscles contract and this pulls the chordae tendineae tight and prevents the flaps from being pushed too far back into the right atrium.
4, The valve is now closed and blood cannot flow back
from the right ventricle to the right atrium.
Where is the bicuspid/mitral valve situated
in the opening between the left atrium and the left ventricle.
Describe the structure of the bicuspid valve
This valve consists of two flaps, which are
attached to the papillary muscles in the inner wall of the left ventricle by the chordae tendineae
What is the function of the bicuspid valve
it prevents backflow of blood
into the left atrium when the left ventricle
contracts
Where are semilunar valves situated
Semilunar valves occur at the base of the aorta and pulmonary artery, where these blood vessels leave the ventricles; they occur on the inside of the blood vessels and look like half-moon shaped membrane sacks, with their free ends pointing away from the ventricles.
How do semilunar ventricles work
When the ventricles contract, the blood pushes the flaps flat against the artery walls and the valves are open. When the ventricles relax, the blood flows back
and fills the sacks, which then push against each other and close the valves.
This prevents the blood flowing back into the ventricles.
True or false
Arteries transport blood to the heart
False
They transport blood away from the heart
What are the 3 layers that the walls of arteries consist of
- an outer fibrous layer of connective tissue
- a middle layer of smooth muscle tissue and elastic fibres
- an inner endothelial layer of squamous epithelium
What does the middle layer of artery walls do
The middle layer allows the artery to stretch when blood under high pressure is pumped from the heart into the artery.
What do the outer fibrous layer of connective tissue and the elastic fibres in an artery do
The thick muscular layer and elastic fibres help the artery wall to resist the high pressure and to avoid distortion
True or False
The lumen of an artery is larger and irregularly shaped compared to that of a vein
False
It is smaller and regularly shaped
What are arterioles
smaller thinner branches of arteries as a result of the two outer layers of arteries also getting thinner
Do valves occur in arteries and why/why not
Because of the high pressure, no valves occur in the arteries except for the aorta and pulmonary artery, which each have semilunar valves at their bases
What happens after the arterioles branch
they become microscopically small tubes, the capillaries, which form a branched network between cells in the tissue
What do the walls of capillaries consist of
only one layer of endothelium
Where does the exchange of substances (gases, nutrients and waste products) occur
Between the blood of the capillaries and the cells
How small is the lumen of the capillaries
The lumen of a capillary is so small that red blood corpuscles can only move through in single file.
How does the size of the lumen of capillaries affect the blood flow
This slows the blood flow so that the exchange of gases into and out of cells can take place more effectively
From what do veins form
Capillary vessels reunite and form larger blood vessels, the venules, which
combine to form the veins
To where do veins transport blood
Towards the heart
How do walls of veins differ from artery walls
The walls of veins consist of the same three layers as artery walls, but the outer two layers are thinner.
Describe the lumen of a vein
Because of the thinner walls, the lumen of a vein is larger than that of an artery and it appears more irregularly shaped in cross-section
Does blood in veins flow under high or low pressure
Blood in veins flows under very low pressure.
What helps blood in veins to move in the direction of the heart
The contraction of skeletal muscles close to the veins and semilunar valves in the veins (they also prevent backflow)
True or false
Pulmonary veins are the only veins in the body that transport deoxygenated blood. All the other veins transport oxygenated blood.
False
pulmonary arteries are the only arteries in the body that transport
deoxygenated blood. All the other arteries transport oxygenated blood.
True or false
The pulmonary arteries are the only arteries in the body that transport oxygenated blood. All the other arteries transport deoxygenated blood
False
The pulmonary veins are the only veins in the body that transport
oxygenated blood. All the other veins transport deoxygenated blood
How many times does the average human heart beat per minute
72
What is systole and diastole
contraction and relaxation of the heart muscles
What happens during each heartbeat
During this time the ventricles will contract for about 40% of the time, and
the atria for about 10%. The rest of the time the heart is in diastole
What is the cardiac cycle
All the changes that occur in the heart during one heartbeat
What are the 3 phases of the cardiac cycle
- Atrial systole
- Ventricular systole
- General diastole
What happens during general diastole
- 0.4s
- ventricles and atria relax.
- decrease in pressure would draws the blood in the pulmonary artery and aorta back to the ventricles, but the semilunar valves close, preventing this backflow.
- both atria are now filled with blood.
- deoxygenated blood flows from the two venae cavae into the RA.
- oxygenated blood flows from the four pulmonary veins into the LA.
- tricuspid and bicuspid valves are open and the blood in the atria flows through to the ventricles
What happens during atrial systole
- 0.1s
- Both atria are now filled with blood and contract simultaneously.
- ventricles are now in diastole.
- openings of the vena cavae and the pulmonary veins are squeezed closed due to the contraction of the atria.
- tricuspid and bicuspid valves are forced open and the blood is pumped through the atrio-ventricular openings to the ventricles
What happens during ventricular systole
- 0.3s
- As the Ventricles fill with blood, the pressure on the ventricle walls cause systole to start.
- The ventricles contract simultaneously.
- The contraction and high pressure in the ventricles closes the tricuspid and bicuspid valves so that no blood can flow back into the atria.
- deoxygenated blood is pumped out of the RV into the pulmonary artery and oxygenated blood is pumped from
the LV into the aorta. - The semilunar valves in the pulmonary artery and aorta are open.
What happens during ventricular diastole
The ventricles take a short rest while the atria fills with blood
What happens during atrial diastole
When the atrio-ventricular valves close, atrial diastole begins.
Atrial systole lasts long enough to ensure that blood flows to the ventricles
Describe what occurs in the pulmonary circulatory system
Blood flows from the heart, to the
lungs and back. Deoxygenated blood leaves the right ventricle through the pulmonary artery and flows to the lungs.
The blood absorbs oxygen from the
lungs, via diffusion, and releases
carbon dioxide. Oxygenated blood flows back to the left atrium via the pulmonary vein
Describe what happens in the systematic circulatory system
- Blood flows from the heart to the rest of the body and back. Oxygenated blood leaves the left ventricle through the aorta (largest artery in the body) and branches throughout the body into smaller arteries,
arterioles, and eventually into microscopically small capillaries, which branch between all tissue cells. - The exchange of substances (O2, CO2, nutrients and wastes) occurs
between the blood in the capillaries and the tissue cells. - The capillaries join to form venules and veins.
- Deoxygenated blood flows through the superior and inferior venae cavae
to the right atrium.
What is one of the first branches of the aorta
the coronary artery that splits into the left and right coronary arteries and provides the heart muscle itself with blood
What is another branch of the aorta
the bronchial artery that also splits to provide the lungs with oxygen and nutrients
What do the carotid arteries do and give examples
They take blood to the head and in the abdominal cavity arteries branch form the aorta to all the organs eg. the coeliac artery with its branches to the stomach, intestine and liver and the renal arteries to the kidneys
What does the pulmonary artery do
It leaves the heart from the right ventricle and splits into the right and left pulmonary arteries that take the deoxygenated blood to the lungs in order for gaseous exchange to take place
What takes the deoxygenated blood collected from different parts of the body to the heart
two large vena cavas
Where does blood from the head and shoulders drain to
the vena cava superior
Where does the blood from the lower half of the body go through to the heart
the vena cava inferior
Into which veins does blood from all over the body drain
the renal veins, jugular veins etc. to join the blood in the venae cavae
Through what does oxygenated blood flow from the lungs to the heart
4 pulmonary veins
What takes the blood from the digestive tract to the liver
the hepatic portal vein
What is a portal vein
a vein with a capillary network at both ends eg. the hepatic portal vein
What does it mean when we say that the cardiac muscle has the property of automatism
it can contract and relax without any external stimuli.
Where do the heart contractions begin
within the muscle cells
What causes the lub sound in a heartbeat
the closing of the bicuspid and tricuspid valves and is louder than the dup sound.
What causes the dup sound in a heartbeat
the closing of the semilunar valves in the
aorta and pulmonary artery
What is the group of muscle cells found in the wall of the right atria and what does it do
sino-atrial node;
it initiates the impulses for contraction and is known as the pacemaker of the heart
What is the group of muscle cells that occurs at the lower end of the septum between the right atria and left atria
atrio-ventricular node
How does the heart beat
- the bundle of His extends throughout the
septum between the two ventricles and conducts impulses from the atria to
the ventricles. - At the apex of the heart the bundle of
His branches into Purkinje fibres which branch throughout the walls of the ventricles to conduct impulses faster and move effectively. - During the cardiac cycle, the contraction
begins at the SA node and spreads
across the two atria to the AV node. - The two atria contract simultaneously.
- From the AV node the impulse passes along the bundle of His, between the
two ventricles, to the Purkinje fibres, causes the ventricles to contract simultaneously from their lower ends. - The transfer of an impulse along the SA node towards the AV node is occurs at a speed of 0.6m/s.
- It then slows down towards the bundle of His, then picks up speed and
rushes through the fibres of Purkinje at almost 2m/s. This speed ensures the co-ordinated contraction of the ventricles.
What controls the heartbeat
the nervous system and hormones
What controls the rate at which the heart beats
- cardio-vascular centre in the Medulla Oblongata
- Automonic Nervous System
Involves conducting impulses along the sympathetic and parasympathetic
nerves from the brain to the SA node. - The nerve impulses that are conducted along the sympathetic nerve fibres accelerate the heartbeat, while the nerve impulses from the parasympathetic nerve fibres slow the heartbeat down to normal
How does the cardio-vascular control centre react to adrenaline
- Adrenaline: Secreted by the adrenal glands in crisis situations/ times of stress. Causes the heart to beat faster and blood is pumped faster to the brain and muscles faster distribution of oxygen.
- 6.
How does the cardio-vascular control centre react to Thyroxine
Thyroxine, which are transported in the blood, also accelerate the
heartbeat.
How does the cardio-vascular control centre react to low ph
Low pH: There is too much CO2 in the blood. Heart must beat faster to get blood to the lungs for faster gas exchange.
How does the cardio-vascular control centre react to too little oxygen
Too little Oxygen: Heart beats faster to get the blood to the lungs for faster gas exchange.
How does the cardio-vascular control centre react to increased bp
Increased blood pressure: Pressure receptors in the carotid artery and
aorta detect an increased blood pressure in the arteries.Heart rate will drop.
How does the cardio-vascular control centre react to decreased bp
Decreased blood pressure: Pressure receptors in the vena cava and atrium
detect a drop in blood pressure in veins. The heart rate will increase. Called Bainbridge reflex.
How do parts of the brain play a role in increase of heart rate when
emotions are involved
The cerebral hemispheres send impulses during periods of sexual excitement.
Hypothalamus send impulses when emotions such as fear and anger are
experienced.
What is the effect of exercise on heartbeats
more respiration occurs in the muscles to release more energy for muscle contraction. More CO2 is released into the blood. Receptors in the carotid arteries (neck arteries) detect the increase in CO2
concentration in the blood and send nerve impulses to the brain. Sympathetic nerve fibres transmit nerve impulses to the SA node, which accelerates the heartbeat.
Blood is pumped faster so that more deoxygenated blood can be pumped to
the lungs to release excess CO2. Oxygenated (O2-rich) blood also reaches the muscles faster
Explain electral activity in the heart
can be measured from the
surface of the body as an electrocardiogram (ECG).
A normal heart has a very regular rhythm.
e.
What is Arrhythmia
a condition where the heart has an abnormal rhythm
What is Tachycardia
when the resting heart rate is too fast (more than 100 beats per minute)
What is Bradycardia
when the heart rate is too slow (less than 60 beats per minute)
What is P wave
The depolarization of the atria
Blood now begins to flow from the atria into the ventricles
What is the PR segment
Represents the time delay to allow the ventricles to fill
What is the QRS complex
The main contraction of the heart where the ventricles depolarize
What is the ST segment
The time delay between depolarization and repolarization of the
ventricles
What is a T wave
Repolarization of the ventricles.
What can be used to observe abnormalities in the functions
The P wave, PR segment, QRS complex, ST segment and T wave
What is the stroke volume
the amount of blood pumped through the heart during each cardiac cycle
What is a reason that the heart would increase its stroke volume and stroke rate
During exercise when muscles need more oxygen and glucose in order to produce energy in the form of ATP. This is a temporary change to maintain homeostasis, and after exercise the heart rate and stroke volume return to normal
What happens when a person exercises regularly
It goes through long term adaptations, gets stronger and expels more blood with each contraction. There is a greater stroke volume with each heartbeat. The heart has to beat less often in order to maintain the same volume of blood flow. Therefore, fit people often have lower resting heart rates
What are cardiovascular diseases
Heart and blood vessels
What are hereditary cardiovascular diseases called
congenital diseases
What is hypertention and hypotention
hypertension: high bp
hypotension: low bp
What is blood pressure
the force that is exerted by the circulating blood on the blood vessel walls.
What is systolic pressure
The maximum pressure reached in the arteries with each heartbeat when
the ventricles contract
What is diastolic pressure
The minimum pressure is reached when the cardiac muscle is relaxed and
the elastic walls of the arteries return to normal
What is blood pressure measured with
the sphygmomanometer
How is blood pressure measured (unit)
mmHg (millimetre mercury)
What is the normal resting bp
120 mmHg systolic and 80 mmHg diastolic
What are the symptoms of low bp
Weakness and dizziness
What are the effects and treatment of high bp
damaged blood vessels, a stroke or a heart attack. It cannot be treated but be managed with medication, as well as
by maintaining a healthy lifestyle, i.e. a healthy diet and regular exercise.
What is stroke
A stroke is the loss of brain function due to a disturbance in the blood supply
to the brain. A shortage of oxygen supply to the brain can be caused by a blood clot that blocks a blood vessel or bursts a blood vessel. This leads to bleeding in the
brain tissue
What is are the effects of a stroke
The result is that the brain cannot function correctly, and this can lead to: paralysis of one or more limbs, usually on one side of the body; the inability to understand or to form speech; or the inability to see the one side of the field of vision. It can lead to permanent neurological damage, complications and death. Risk factors include: advanced age,high blood pressure, diabetes, high cholesterol, smoking
What happens during a heart attack
The supply of blood to the cardiac muscle is interrupted, which leads to the death of a part of the cardiac muscle tissue.
Fat deposits (usually cholesterol) on the inside of the blood vessels narrow
the arteries and this is known as atherosclerosis. Blood cells accumulate in these narrowings and form blood clots (thrombi), which block the coronary arteries. This blood clot formation in a coronary artery is known as a coronary
thrombosis. When a thrombus forms in one part of the body, it breaks off and is
transported to a coronary artery where it causes a blockage, it is known as a
coronary embolism. In both cases the oxygen supply to the cardiac muscle is interrupted and the cardiac muscle tissue dies
What does medication do for treatment of cardiovascular diseases
dissolves the blood clot which thins the blood and prevents formation of new clots which controls high blood pressure
What does angioplasty do for treatment of cardiovascular diseases
a procedure that is carried out to stretch a narrowed artery and to remove the blockage
What does a bypass operation do for treatment of cardiovascular diseases
a surgical procedure where arteries or veins are cut from other parts
of the body and used to restore the blood flow to the cardiac muscle
by providing an alternative route for blood around the blocked part of
the artery
What does a heart surgery do for treatment of cardiovascular diseases
an operation where an unhealthy heart is removed from a person’s
body and replaced with a healthy heart from a dead or brain dead donor
