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Biology
Chapter 2
Mr.Ayman Elsangary
Chapter 2
Transport in living organisms
The concept of transport and the need for it:
1- All plants need CO2 , water and mineral salts to perform photosynthesis
2- In primitive plants such as algae these materials move from one cell to
another by osmosis or active transport, so they are in no need for a
specialized transport system
3- In higher plants gases move by diffusion but water
and mineral salts are moving by a specialized
transport system (vascular tissue)
4- In small animals like hydra and protozoan gases
and food substances move by diffusion.
5- Higher animals have a specialized transport system
Transport in higher plants:
1- Water passes from the soil to the xylem of the root
then xylem of stem then xylem of the leaves ,
Leaves carry out photosynthesis and produce food
(Carbohydrates, Fats, and proteins ) which are
transported to the places of storage and
consumption.
2- Food passes through sieve tubes in the phloem of
leaves, stems, and roots.
Structure of young stem of dicot plant:
1- Epidermis:
One row of adjacent barrel shaped parenchyma cells (the outer cells are covered
with cuticles)
2- Cortex:
1- Several rows of collenchyma cells
2- The corners of the cells are thickened
by deposition of cellulose (which help
as a mechanical support for the stem)
3- The presence of some chlorophyll in
the collenchyma cells make them
participate in photosynthesis.
4- They are followed internally by
several rows of parenchyma cells
(with plenty of intercellular spaces)
5- The innermost row of cells in the
cortex is the starch sheath (for storage
of the starch)
3- Vascular cylinder:
1- occupies much of the stem
Biology
Chapter 2
Mr.Ayman Elsangary
2- consists of
a. pericycle: parenchyma cells alternate with fibers (to make the stem strong and elastic)
b. Vascular bundles: They are arranged in a cylinder , Each bundle is a triangular shape its base
directed outwards and consists of:
i. Phloem:
1. The outer tissue of the bundle.
2. Consists of Sieve tubes, Companion cells and phloem parenchyma.
3. Transports organic food
substances.
ii. Cambium:
1. one or more rows of
meristimetic cells
2. lies between phloem and xylem
3. When they divide they give rise
to secondary phloem externally
and secondary xylem
internally.
iii. Xylem:
a. The internal part of the bundle
b. Transports water and solutes
c. Act a s a support for the stem
d. Consists of:
1. Vessels:
a- Tubes formed from elongated cylindrical cells joined end to end
b- Transverse walls dissolved making one tube
c- The cellulose wall becomes thickened by lignin (impermeable to water and solutes)
d- The protoplasmic content dies leaving hollow vessels
e- Numerous pits are scattered over the wall (Where the primary wall is left without being thickened)
f- Pits permit water to pass outside the vessels
g- Lignin is laid down the inner wall on different forms such as annular or spiral (they support the vessel
and prevent it from collapse)
2. tracheids:
a- Mostly similar to vessels but they appear pentagonal or hexagonal in T.S
b- They are pitted
c- Their ends are pointed and closed
3. Xylem parenchyma
a- One row of cells between xylem vessels
b- A network of vessels spread all over the plant (connect xylem of root, stem and leaves also phloem of
them together)
4. pith
a- Occupies the center of stem
b- Contains parenchyma (for storage).
5. Medullary rays
a- extend between vascular bundle in the form of parenchyma cells
b- They join to the cortex with the pith
Factors responsible for ascent of sap:
1- Root pressure theory:
2- If a plant stem is cut very near to the soil level, you can see exudation of water from the stump. This
phenomenon is known as exudation,
Biology
Chapter 2
Mr.Ayman Elsangary
3- Due to the root pressure continuing to force water up the plant. An osmotic pressure mechanism in the root
tissues leading to continuous and direct root absorption from the soil.
4- Water is forced vertically upward through xylem vessels for a short distance to a certain level.
5- At this level, the water stops because the opposing pressure of the water column in xylem vessels has
become equal to the root pressure.
6- The maximum root pressure does not exceed 2 atmospheres.
7- Pinus and other conifers have no root pressure.
8- The force of root pressure is affected quickly by external factors.
9- So we can say that root pressure is not enough to explain the ascent of sap.
2- Imbibition theory:
1- The colloidal nature of cellulose and lignin has helped the walls of xylem vessels imbibe water.
2- Imbibition has a very limited effect on the ascent of sap,
3- Experiments have proved that the sap ascends through the cavities of the xylem vessels and not along
their walls.
4- The importance of this phenomenon is restricted to the transport of water along the cell walls until it
reaches the walls of vessels and tracheids the root, and from these vessels and tracheids to the neighbor
cells in the leaves.
3- Capillarity theory:
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Water rises through tiny tubes by capillarity.
Xylem vessels are considered as capillary tubes with diameters ranging from 0.02 mm to 0.5 mm.
Water will rise in these by the phenomenon of capillarity.
The finest capillary tube does not allow the rise of water more than a height of 150 cm.
Capillarity is a weak secondary force for the ascent of sap.
4-Transpiration pull – Cohesion - Adhesion theory:
1- (By H. H. Dixon and J. Joly in 1895).
2- Plant physiology proved that these are the principal forces which pull the water upward to very high
levels, approximately 100 meters.
3- This theory states in brief, that the water column ascends through the xylem vessels depending upon the
following forces:
a. Cohesive force: due to the existence of strong mutual attraction between the molecules of water
inside the xylem vessels and tracheids. This explains the existence of a continuous column of
water.
b. Adhesive force: between water molecules and those of the walls of xylem vessels. It helps the
water column to be held against the effects of gravity.
c. Transpiration pull: this attracts the water column upwards due to the continuous process of
transpiration in the leaves.
Water has been shown to have a high pulling force in tubes under the following conditions:
1- It must be a capillary tube.
2- The walls of the tube must possess an adhesive force to attract water.
3- The tubes must be free of any gas or air bubbles to avoid any breaking and therefore
descent of the water column.
The path of the sap during its ascent from the root to the leaves:
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Transpiration lessens the water concentration in the air chamber above the stoma in the leaf.
Evaporation will therefore, increase from the cells of the mesophyll surrounding the stomata chamber.
This will lessen the water content of these cells and increase their concentration.
This state will create a diffusion pressure gradient for the water called "pulling force" which attracts water
from the surrounding cells.
Biology
Chapter 2
Mr.Ayman Elsangary
5- This will continue as far as the xylem elements in the venules and veins, finally form the midrib of the leaf.
6- Being subjected to a great force, the water will ascend through the xylem vessels and tracheids of both the
stem and the root as they are connected to one another.
7- Transpiration pull of the leaf will not only pull water that has reached the vascular cylinder of the root up,
but it will also help in the lateral pull of water from the root hairs.
Transport of manufactured food from the leaf to other parts of the plant
1- Food manufactured by the leaf must :
a. Move upwards in order to feed the stem
b. Move downwards to feed the root system.
2- The phloem consists of sieve-tubes that appear in a longitudinal section as elongated cells, arranged end
to end.
3- They contain cytoplasm without a nucleus,
4- Each sieve-tube has a nucleated companion cell.
5- Vital functions the sieve tube are organized by the ribosome and mitochondria present in companion
cell.
6- The sieve-tubes are separated from each other by perforated (has tiny pores) cross-walls
7- Cytoplasm strands extend from one tube to another.
Some experiments to prove the role of the sieve-tubes is the transport of ready-made
food substances to various parts of the plant.
1- Rapeden and Bohr in 1945
a. They supplied a green bean leaf with CO2 (containing radioactive carbon 14C)
b. The plant carried out photosynthesis and to produce radioactive carbohydrates.
c. These carbohydrates, being radioactive, could be traced during their path in the plant.
d. It was discovered that they are transported upwards as well as downwards in the stem.
2- The scientist Mittler
a. He used the aphid insect, to describe the content of the sieve-tubes
b. Aphid penetrates the tissues of the plant until it reaches the sieve tubes, by its piercing moth parts.
c. During the process of feeding, the scientist separated the whole body of the insect from its
mouthparts, he collected a sample of the sieve tube's contents.
d. By analyzing this sample it was shown to consist of the organic substances manufactured in the
leaves (sucrose and amino acids).
e. To make sure that this was the phloem content, he sectioned the region of the plant where the
proboscis of the insect was inserted. It appeared to be inserted in a sieve-tube by its piercing
mouthparts.
3-Thain and canny 1961:
a- They could see long cytoplasmic threads which contain organic substances inside the sieve tubes,
and these lines extend through tiny pores from one tube to another.
b- And so they explained the transportation of the organic substances in the phloem on the basis of
cytoplasmic streaming, i.e. the cytoplasmic circular movement inside the sieve tubes and companion
cells during that,
c- The organic substances translocate from one end to other end then they pass to the neighboring sieve
tubes through the cytoplasmic threads which pass from one tube to another.
d- They explained that this activity needs more of ATP molecules which exist in the companion cell.
e- And this is proved later by experiments which show that the transportation process is delayed with
the decrease of temperature or oxygen in cells, thus delaying the movement of cytoplasm tubes
(sieve tubes)
Biology
Chapter 2
Mr.Ayman Elsangary
Questions on Chapter 2
Complete the following:
6- All plants need ……… , ……… and mineral salts to perform photosynthesis
7- In ……… plants such as algae materials move from one cell to another by …………… or active
transport, so they are in no need for a specialized ………… system
8- In higher plants gases move by …………. but water and mineral salts are moving by a specialized
transport system (………….. tissue)
9- In small animals like hydra and protozoan gases and food substances move by ……………..
10- Water passes from the soil to the xylem of the root then xylem of …… then xylem of the ………..
11- Leaves carry out ……………….. and produce food
12- Carbohydrates, Fats, and proteins are transported to the places of ……… and ………………..
13- Food passes through sieve tubes in the …………. of leaves, stems, and roots.
14- …………. is one row of adjacent barrel shaped parenchyma cells (the outer cells are covered with
…………………..)
15- ……………… are several rows of collenchyma cells,
16- The corners of the cortex cells are thickened by deposition of ……………….
17- Cellulose help as a mechanical ………….. for the stem
18- The presences of some ………….. in the collenchyma cells make them participate in photosynthesis.
19- Cortex are followed internally by several rows of ……….. cells (with plenty of intercellular spaces)
20- The innermost row of cells in the cortex is the ……… ………… (for storage of the starch)
21- …………. cylinder occupies much of the stem
22- ………………. in parenchyma cells alternate with fibers (to make the stem strong and elastic)
23- Vascular bundles are arranged in a cylinder, each bundle is a ………... shape its base directed ………
24- Vascular bundle consist of ………., …………… and ……….,
25- The outer tissue of the bundle is ……………
26- …………….. consists of Sieve tubes, Companion cells and parenchyma.
27- ……………. transports organic food substances.
28- ………………. is one or more rows of meristimetic cell that lies between phloem and xylem
29- When cambium divides they give rise to secondary phloem ……….. and secondary xylem ………...
30- …………… is the internal part of the bundle which transports water and solutes
31- Xylem act a s a mechanical ……………. for the stem
32- ………… Consists of vessels, tracheids, parenchyma, pith and Medullary rays
33- …………… are tubes formed from elongated cylindrical cells joined end to end
34- Transverse walls of vessels dissolved making one ………….
35- The cellulose wall of vessels becomes thickened by ……….. (impermeable to water and solutes)
36- The protoplasmic content of the vessels …………… leaving hollow vessels
37- Numerous ………… are scattered over the wall of the vessels
38- …………….. permit water to pass outside the vessels
39- ………….. is laid down the inner wall of vessel on different forms such as annular or spiral (they
support the vessel and prevent it from collapse)
40- Tracheids are Mostly similar to vessels but they appear ………….. or ……………. in T.S
41- ……………… are pitted
42- Tracheids ends are ………. and closed
43- Xylem ……………. is one row of cells between xylem vessels
44- ……………. occupies the center of stem and contains parenchyma (for storage).
45- Medullary ………. extend between vascular bundle in the form of parenchyma cells and
46- …………….. rays join to the cortex with the pith
47- If a plant stem is cut very near to the soil level, you can see ……… of water from the stump. This
phenomenon is known as …………….,
48-
Biology
Chapter 2
Mr.Ayman Elsangary
Correct the underlined words:
1- All animals need CO2 , water and mineral salts to perform photosynthesis
2- In higher plants such as algae these materials move from one cell to another by osmosis or active
transport, so they are in no need for a specialized transport system
3- In primitive plants gases move by diffusion but water and mineral salts are moving by a specialized
transport system (vascular tissue)
4- In large animals like hydra and protozoan gases and food substances move by diffusion.
5- Water passes from the soil to the phloem of the root then xylem of stem then xylem of the leaves.
6- Leaves carry out respiration and produce food
7- Respiration, Fats, and proteins are transported to the places of storage and consumption.
8- Food passes through xylem tubes in the phloem of leaves, stems, and roots.
9- Endodermis is one row of adjacent barrel shaped parenchyma cells (the outer cells are covered with
proteins)
10- Epidermis are several rows of collenchyma cells,
11- The middle of the cells are thickened by deposition of cellulose
Put T in front of the true statement and F in front of the false one:
1- Cellulose help as a mechanical support for the stem
2- The presences of some fats in the collenchyma cells make them participate in photosynthesis.
3- Cortex are followed internally by several rows of parenchyma cells (with little intercellular spaces)
4- The outer row of cells in the cortex is the starch sheath (for storage of the starch)
5- Vascular cylinder occupies much of the stem
6- Pericycle in parenchyma cells alternate with fibers (to make the stem strong and elastic)
7- Vascular bundles are arranged in a cylinder , Each bundle is a triangular shape its base directed
outwards
8- Vascular bundle consist of phloem, cambium and xylem,
9- The inner tissue of the bundle is phloem
10- Phloem Consists of Sieve tubes, Companion cells and parenchyma.
11- Phloem transports organic food substances.
12- Cambium is one or more rows of meristimetic cell that lies between phloem and xylem
13- When cambium divide they give rise to secondary phloem internally and secondary xylem internally.
14- Xylem is the internal part of the bundle which transports water and solutes
15- Xylem act a s a support for the stem
16- Phloem Consists of vessels, tracheids, parenchyma, pith and Medullary rays
Join:1- Vessels are tubes formed from
2- Transverse walls of vessels dissolved making
3- The cellulose wall of vessels becomes thickened
by
4- The protoplasmic content of the vessels
5- Numerous pits are scattered
6- Pits permit water to
7- Lignin is laid down the inner wall of vessel on
different forms such as
a. annular or spiral
b. pass outside the vessels
c. over the wall of the vessels
d.
e.
f.
g.
dies leaving hollow vessels
lignin
one tube
elongated cylindrical cells joined end
to end
Give reasons for:
1- Primitive plants such as algae are in no need for a specialized transport system
2- Cellulose help the plant
3- Some stems can perform photosynthesis.
Biology
Chapter 2
Mr.Ayman Elsangary
4- The innermost row of cells in the cortex ( the starch sheath ) is important to the plant.
5- Pericycle in parenchyma cells alternate with fibers
6- Cambium act as double layers
7- Transverse walls of vessels dissolved
8- The cellulose wall of vessels becomes thickened by lignin
9- The protoplasmic content of the vessels dies
10- Numerous pits are scattered over the wall of the vessels
11- Lignin is laid down the inner wall of vessel
12- Tracheids are Mostly similar to vessels but still there are differences
13- Pith occupies the center of stem and contains parenchyma
14- Root pressure is not enough to explain the ascent of sap
15- Imbibition is not enough to explain the ascent of sap
16- Capillarity is not enough to explain the ascent of sap
17- Dixon and joly explained the ascent of sap
18- Some seedlings, when transplanted from a nursery to open soil, fail to grow if they remain exposed to
the sun for a long time before they are transplanted in the new soil?
Best wishes and always remember to do your best to get the best Mr.Ayman Elsangary.
Biology
Chapter 2
Mr.Ayman Elsangary
Transport in animals
Transport in humans:
1- Blood vascular system (circulatory system)
2- Lymphatic system.
Circulatory system:
Closed circulatory system consists of heart and blood vessels
1- Heart:
2- It is a hollow muscular organ.
3- Lies nearly in the middle of the chest
4- Enclosed in the pericardium (protects it and facilitates its action)
5- Consists of 4 chambers
Upper chambers (atria)
Lower chambers (ventricles)
Relatively thin walled
Have thick muscular wall
Receive blood from the veins
Pump blood to arteries
Each one is connected to its ventricle with an
Each valve consists of thin flaps, whose free edges
opening guarded by a valve
attached to the ventricle wall by tendons.(to
prevent the flaps from turning inside out)
Blood is allowed to pass in one direction from atrium to ventricle and not vice versa.
6- Heart is divided longitudinally into 2 sides by a muscular wall
7- The right valve (tricuspid valve) is made up of 3 flaps.
8- The left valve (bicuspid valve or mitral valve) is made up of 2 flaps.
9- Semi lunar valves are found between heart and both aorta and pulmonary artery
10- The heart beats regularly through whole life time
2- The blood vessels:
Arteries
Fairly wide vessels
Cary blood from the heart to the
body organs
Wall consists of 3 layers of
tissue:
1- Outer coat of connective t.
2- Middle thick layer of
involuntary muscles
(contract and relax under the
control of nerve fibers) .
3- Inner endothelium consists
of one row of tiny epithelial
cells followed by elastic
fibers)
Usually buried among the body
muscles
Carry oxygenated blood except
pulmonary artery.
They pulsate
Veins
Less thick.
Carry blood from body organs to
the heart
Same 3 layers but with less
elastic fibers and the middle
layer is less thick.
Accordingly the wall is thinner
They have a system of valves to
prevent the backflow of blood.
(discovered by William Harvey
along with the blood circulation)
Capillaries
Tiny microscopic vessels
Connect arteries to venules (7-10
micron in diameter)
Discovered by Malpighi
Walls are thin , consist of one
row of thin epithelial cells with
pores between them.
The wall is .001 micron to allow
the exchange of substances.
If all capillaries are put together
they will reach about 80,000 Km
Can be seen in the arm if it is
tied tightly with a bandage
(tourniquet).
Carry de- oxygenated blood
except pulmonary vein.
They do not pulsate
Spread in the spaces between
cells all over the body.
Both
Both
Biology
Chapter 2
Mr.Ayman Elsangary
3- Blood
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Red viscous liquid tissue
Contains RBCs, WBCs and platelets.
Part of the tissue fluid is called plasma
The principal medium of transport
Humans have 5-6 liters
Weakly alkaline (pH=7.4)
Components of the blood
1- Plasma:
1- 54% of the blood
2- Contains 90% water, 1% inorganic salts (Calcium, Sodium and
carbonates), 7% proteins (Albumin, globulin, fibrinogen) 2% absorbed
food, enzymes, hormones and waste (Urea).
2- Red blood cells
(Erythrocytes)
4- 5 millions/mm3 in males and 4-4.5
millions/mm3 in females
Destroyed after 120 days (172000
circulation)
Produced in bone marrow of
backbones.
Round, biconcave and enucleated.
3- White blood cells
(Leucocytes)
4- Blood
platelets
7000/mm3 (increases during
diseases).
Live for 13-20 days
250000/mm3
Formed in bone marrow, spleen
and lymphatic system.
Colorless and nucleated.
Formed from
bone marrow
enucleated
Its main function is to protect
the body against diseases by
attacking strange bodies ,
destroy and engulf them
Some RBCs produce antibodies
Play an important
role in blood
clotting
Live for 10 days
Contain hemoglobin (protein + iron)
which give the blood its red color
Hemoglobin combines with Oxygen
forming bale oxy-hemoglobin which
transports Oxygen to body parts, it
can also combine with carbon
dioxide to form dark red
carboxyhemoglobin and this is why
venous blood is darker than arterial
blood.
RBCs are destroyed in liver, spleen
and bone marrow
Proteins such as hemoglobin are
used to form bile
Functions of the blood
1- Transportation of: Food, Oxygen, Carbon dioxide, waste nitrogenous compounds, hormones and
enzymes.
2- Controlling the process of metabolism
3- Keeping body temperature 37C0
4- Regulating homeostasis of internal environment such as osmotic potential
5- Protection against diseases and pathogenic organisms through immunity involving lymphatic system .
6- Protection of the blood from bleeding by clotting
Biology
Chapter 2
Mr.Ayman Elsangary
Heart beats
1- The rhythmic heart beats are spontaneous as they originate from the cardiac tissue itself.
2- Heart continues beating regularly even after it has been disconnected from the body and cardiac nerves.
3- There is a specialized bundle of thin cardiac muscular fibers buried the right arterial wall near the
connection between the right auricle and the large veins.
4- This bundle called the sino-atrial node which is considered as the pace maker of the heart.
5- The sino-atrial node sends impulses over the two atria which are stimulated to contract.
6- When the electrical impulse reaches the atrio-ventricular node (at the junction between atria and
ventricles) the impulse will spread rapidly through special fibers from the inter-ventricular septum to the
wall of both ventricles, where it stimulates their muscles to contract.
7- The sino-atrial node, i.e. the pace-maker, beats at a regular rate of 70 beats/minute. It is connected to
two nerves, one lowers its rate and the other increases it, so that the number of cardiac beats changes
according to the physical and psychological state of the body. For example, the number of heart beats is
lowered during sleep and gradually increases after waking up. It is also lowered in states of grief and
increases in states of joy. It also increases with severe physical effort.
8- We can distinguish two sounds in the heart beat, one is long and low pitched (lubb) and is due closure
of the two valves between the atria and ventricles during ventricular contractions, and the other is
shorter and high pitched (dupp) and is due to the closure of aortic and pulmonary valves during
ventricular relaxation.
Blood pressure:
1- Pressure is needed for blood to pass into blood capillaries.
2- The largest Bp is measured in the arteries near the heart
3- The maximum blood pressure is measured when the ventricle contract and minimum as the ventricle
relax
4- Bp is measured by mercuric instruments sphygmomanometers (Normal is 120/80)
5- The 2 digits represent the blood pressure as the ventricle contracts and relax.
6- Bp in the venules is very low (10 mm Hg).
7- The very low Bp in the veins is not enough to move blood back to the heart
8- When the skeletal muscles near the veins contract, they put pressure on the collapsible walls
9- Valves prevent backward flow, Now pressure is enough to return blood to the heart
10- Blood pressure increases with aging so medical care is required to control it
11- The values of Bp are determined by listening to the heart beats or by digital instruments.
Biology
Chapter 2
Mr.Ayman Elsangary
Questions on Chapter 2-2
Compare between:
a. atria and ventricles
b. Arteries veins and capillaries
c. RBCs, WBCs and platelets
Give reasons for:
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Valves consist of thin flaps, whose free edges attached to the ventricle wall by tendons
Blood is allowed to pass in one direction from atrium to ventricle and not vice versa.
Medical control is important with aging
Pulmonary artery and veins are up normal
Put T in front of the true statement and F in front of the false one, and then correct it:
1- Respiration in humans is represented by Blood vascular system (circulatory system) and lymphatic
system.
2- Human circulatory system is an open circulatory system consists of heart and blood vessels
3- Heart is a hollow muscular organ.
4- Heart Lies nearly in the middle of the chest
5- Aorta is enclosed in the pericardium (protects it and facilitates its action)
6- Heart consists of 6 chambers
7- Heart is divided longitudinally into 4 sides by a muscular wall
8- The left valve (tricuspid valve) is made up of 3 flaps.
9- The right valve (bicuspid valve or mitral valve) is made up of 2 flaps.
10- Semi lunar valves are found between heart and both aorta and pulmonary artery
11- The heart beats regularly through whole life time
12- Blood is red viscous liquid tissue
13- Blood Contains RBCs, WBCs only
Complete the following statements.
1- Part of the ……..… tissue fluid is called plasma
2- ……..… is the principal medium of transport
3- Humans have ……..… to ……..… liters of blood
4- Blood is weakly alkaline (pH=……..…)
5- Plasma forms about ……..… % of the blood
6- Plasma Contains ……..% water, ……..… % inorganic salts (Calcium, Sodium and carbonates), ……..%
proteins (Albumin, globulin, fibrinogen) 2% absorbed food, enzymes, hormones and waste (Urea).
7- Blood Transports ……..… , ……..… , Carbon dioxide, waste nitrogenous compounds, hormones and
……..… .
8- ……..… is Controlling the process of metabolism
9- Blood is Keeping body temperature ……..… C0
10- Blood is Regulating ……..… of internal environment such as osmotic potential
11- ……..… is protecting body against diseases and pathogenic organisms through immunity involving
lymphatic system.
12- Blood Protects itself from bleeding by ……..…
13- The rhythmic heart beats are ……..… as they originate from the cardiac tissue itself.
14- Heart continues beating regularly even after it has been disconnected from the body and cardiac ……...
15- There is a specialized bundle of thin cardiac muscular fibers buried the right arterial wall near the
connection between the right auricle and the large veins called ……..….
16- Sino-atrial node is considered as the ……..… maker of the heart.
17- The sino-atrial node sends impulses over the two ……..… which are stimulated to contract.
Biology
Chapter 2
Mr.Ayman Elsangary
18- When the electrical impulse reaches the ……..… node (at the junction between atria and ventricles) the
impulse will spread rapidly through special fibers from the inter-ventricular septum to the wall of both
ventricles, where it stimulates their muscles to contract.
19- The sino-atrial node, i.e. the pace-maker, beats at a regular rate of ……..… beats/minute. It is connected
to two nerves, one lowers its rate and the other increases it, so that the number of cardiac beats changes
according to the physical and psychological state of the body. For example, the number of heart beats is
……..… during sleep and gradually increases after waking up. It is also lowered in states of grief and
increases in states of joy. It also increases with severe physical effort.
20- We can distinguish ……..…sounds in the heart beat, one is long and low pitched (……..…) and is due
closure of the two valves between the atria and ventricles during ventricular contractions, and the other is
shorter and high pitched (……..…) and is due to the closure of aortic and pulmonary valves during
ventricular relaxation.
21- ……..…is needed for blood to pass into blood capillaries.
22- The largest Bp is measured in the ……..…near the heart
23- The maximum blood pressure is measured when the ……..…contract and minimum as the ventricle
relax
24- Bp is measured by mercuric instruments ……..… (Normal is ……..…/……..…)
25- The 2 digits of Bp represent the blood pressure as the ventricle ……..…and ……..….
26- Bp in the venules is very low (……..… mm Hg).
27- When the skeletal muscles near the veins ……..…, they put pressure on the collapsible walls
28- ……..…prevent backward flow, Now pressure is enough to return blood to the heart
29- Blood pressure increases with ……..…so medical care is required to control it
30- The values of ……..… are determined by listening to the heart beats or by digital instruments.
Biology
Chapter 2
Mr.Ayman Elsangary
Blood circulation
1. Pulmonary circulation:
Right ventricle contracts  tricuspid
valve closes the opening 
deoxygenated blood rush through
pulmonary artery  Semi lunar valve
closes  Lungs through 2 branches 
franchise into capillaries spread
around the alveoli  exchange of
gases occurs  blood becomes
oxygenated  4 pulmonary veins (2 from each lung)  open in the left atrium. 
Bicuspid valve  left ventricle 
2. Systematic circulation:
Left ventricle contracts  mitral (bicuspid valve closes)  blood rushes to Aorta (under great pressure.)
semi lunar valve  franchise to arterioles  blood capillaries  gases exchange in body parts, blood is
loaded with products of catabolism  blood change its color from light to dark red  Now it is deoxygenated
blood  venules  veins  superior and inferior vena cava  right atrium  right ventricle. 
3. The hepatic portal circulation:
Glucose and amino acids (after being absorbed by villi) blood capillaries of the
same villi  venules  hepatic portal vein  (also receives veins from pancreas,
spleen and stomach) branches inside the liver into blood capillaries 
excess food substances filtered by liver blood capillaries unite back to
form hepatic vein  upper part of inferior vena cava  right atrium 
Blood Clot
1. Blood vessel cut
2. Blood exposed to air or friction with a rough surface (damaged
vessel )
3. Blood platelets and destroyed cells form protein called thromboplastin
𝑇ℎ𝑟𝑜𝑚𝑏𝑜𝑝𝑙𝑎𝑠𝑡𝑖𝑛 𝑎𝑛𝑑 𝐶𝑙𝑜𝑡𝑖𝑛𝑔 𝑓𝑎𝑐𝑡𝑜𝑟𝑠 𝑎𝑛𝑑 𝐶𝑎++
4. 𝑝𝑟𝑜𝑡ℎ𝑟𝑜𝑚𝑏𝑖𝑛 →
𝑡ℎ𝑟𝑜𝑚𝑏𝑖𝑛
Contractions of
both left and
right sides occur
at the same
time.
Biology
Chapter 2
Mr.Ayman Elsangary
5. Prothrombin is formed in the liver by the help of vitamin K and pass directly to blood
6.
7.
8.
9.
𝑡ℎ𝑟𝑜𝑚𝑏𝑖𝑛
𝑓𝑖𝑏𝑟𝑖𝑜𝑔𝑒𝑛 (𝑠𝑜𝑙𝑢𝑏𝑙𝑒 𝑖𝑛 𝑝𝑙𝑎𝑠𝑚𝑎 ) →
𝑓𝑖𝑏𝑟𝑖𝑛(𝐼𝑛𝑠𝑜𝑙𝑢𝑏𝑙𝑒 𝑖𝑛 𝑝𝑙𝑎𝑠𝑚𝑎)
Fibrin precipitates as a network of microscopic interlacing fibers.
Blood cells aggregates forming a clot to block the whole in blood vessel and stop bleeding.
Liver secrets heparin to prevent blood clotting in the blood vessels. (absence of clotting factors also
prevent blood from clotting inside)
Lymphatic system:
1. It is the immune system of the body
2. Able to defense and produce antibodies
3. Consists of large number of lymphatic
capillaries
4. Lymphatic capillaries take blood fluid
from blood capillaries (this is the
lymph)
5. It contains most of the plasma
components and leucocytes
6. Lymphatic capillaries empty the lymph
into circulatory system along the
superior vena cava
7. The lymph passes across the lymph
nodes
8. Lymphocytes are packed into the space
of lymph nodes which traps microbes by
WBCs (Which they produce)
9. Spleen is considered one of the most
important lymphatic organs.
Happy Eid..Your homework is :
1- Write each one of the 3 circulations 10 times
2- School book questions p77, 78, 79
3- Studying every tiny whiny ultimate disgusting detail from the
previous lessons ,BECAUSE we are going to have a test after Eid
Elfetr.
4- Again
have a
happy Eid