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The functioning of body
systems in relation to
energy metabolism.UNIT 5 -TOPIC 2
Learning Outcome:
By the end of this topic you will:Understand the functioning of body systems in association with energy metabolism.
This includes:
1. Energy Laws
2. Forms of Energy
3. Energy Metabolism
4. The Cardiovascular System
5. The Respiratory System
6. The Digestive System
7. The Role of Enzymes in Digestion
8. Major Products of Digestion
9. Absorption of Food
Topic 2
There is a glossary at
the back of your
booklet for keywords
and their meanings, fill
it in as we go along,
adding any more that
are new to you.
Assessment Objectives:
By the end of this topic you will be able to:
Explain the physiology of two named body systems
in relation to energy metabolism in the body. (P4)
Discuss the role of energy in the body. (M1)
Analyse how two body systems interrelate to
perform a named function. (D1)
Topic 2
What is energy?
Energy Laws
Energy is defined as ‘the ability to do work’.
It takes a variety of different forms, for example, light, heat, sound, electrical, chemical and atomic energy.
It can be changed from one form to another.
It cannot be created or destroyed.
It is measured in joules (J)
What forms of energy are there?
Forms of energy
Energy can exist in several forms:
The most common is chemical energy.
This joins atoms or molecules to one another.
Energy is needed to join these bonds.
When the bonds are broken, energy is released.
Energy Metabolism
Anabolism and Catabolism
Catabolic reactions – reactions that
involve breaking down molecules and
releasing energy. (Respiration)
Anabolic Reactions – Building complex
molecules from simple substances and
using energy. Eg. Enzymes and hormones.
Metabolism= Anabolism+catabolism
Why do organisms need energy?
Why do organisms need energy?
What is energy needed in the body for?
Energy in the
body
What is energy needed for in the body?
Muscle activity
Circulate blood, lymph, tissue fluid.
Breathing
Growth and repair
To transmit nerve impulses
To build complex molecules such as enzymes
and hormones.
Why do organisms need energy?
Metabolism
All the reactions that take place in living organisms involve energy
Movement
Both within and organism(e.g. the circulation of blood) and of the organism itself (e.g. locomotion)
Active transport
Of ions and molecules against a concentration gradient across plasma membranes.
Maintenance, repair and division
Of cells and of organelles within the cells.
Production of substances
Used within organisms, for example, enzymes and hormones.
Maintenance of body temperature
In birds and mammals. These organisms are endothermic and need energy to replace that lost as heat to the environment.
Activities involved in supplying energy to the cells.
What systems are involved in supplying
energy to cells?
The activities involved in energy
supply include the roles of the
cardiovascular, respiratory and
digestive systems.
Role of the digestive system in energy
supply to the body.
Responsible for taking in food and water.
Uses enzymes to break up complex molecules into
simpler, soluble materials.
These simpler molecules are then able to pass into
capillaries to be transported around the body.
Eg. Carbohydrates are broken down to smaller glucose
units than can be absorbed in to the capillaries to be
transported and delivered around the body.
Role of the cardiovascular system in
supplying energy to the body.
Once the simpler food substances
have been absorbed into the
capillaries of the digestive system,
these simpler materials are taken to
the liver and body cells via the
bloodstream.
This is driven by the pumping action
of the heart
Role of the respiratory system in supplying
energy to body cells.
The lungs constantly refresh lung oxygen and dispose of waste products such as carbon dioxide and water.
Dissolved oxygen passes through the thin alveolar walls into the bloodstream and is transported to cells.
How does the body release energy?
Body cells have a constant delivery of raw materials from these
systems.
Raw materials such as oxygen, glucose and other nutrients are
continually delivered by the bodily systems to the bodily cells.
This allows the breakdown (catabolic) process of glucose
oxidation which releases energy to do work.
This takes place in the cytoplasm and mitochondria of the cell.
This process is called RESPIRATION
Respiration
C6H12O6 + 6O2 → 6H2O + 6CO2 + Energy
The cardiovascular
system
Your heart is a muscle about the size of your fist.
It is constantly beating, on average about 1 beat every second.
Open and close your
fist, once every
second. Do you get
tired quickly?
What is the appearance of the heart and its associated vessels?
Right Pulmonary Artery
Right Atrium
Right Ventricle
Left Pulmonary Artery
Pulmonary VeinsLeft AtriumSemi-Lunar ValvesLeft Atrioventricular
ValveSeptumLeft Ventricle
Thick Muscle of Wall of Left Ventricle
Superior (Anterior) Vena Cava
Aorta
Inferior (Posterior) Vena Cava
Right Atrioventricular Valve
AortaPulmonary Artery
Pulmonary VeinVena Cava
Right Atrium
Left Atrium
Right Atrioventricular Valve
Left Atrioventricular Valve
Right Ventricle
Left Ventricle
Semi-Lunar Valves
Septum
Why is the heart made up of two adjacent pumps?
How blood flows through our heart. Both sides of the heart work together
One complete contraction and relaxation is called a heartbeat.
After contraction and the compartment has been emptied of blood, it relaxes, to
be filled with blood once more.
The ventricles contain more muscle than the atria and so generate more pressure
to force the blood a greater distance.
The LV has a thicker muscular wall – why do you think this is?
How does blood flow through the heart?
Why are their differences in the thickness of the walls of the chambers?
The muscle of each chamber contracts to create increased pressure in the blood.
The higher the pressure created in the heart, the further it will push the blood.
Explain the thickness of the following chambers,
Atria: The muscle of the atria is very thin.
Right ventricle: The walls of the right ventricle are thicker than the walls of the atria.
Left ventricle: The walls of the left ventricle can be two or three times thicker than those of the right ventricle.
Why are their differences in the thickness of the walls of the chambers?
Atria:
The muscle of the atria is very thin. This is because these chambers do not need to create much pressure. Their function is to push the blood to the ventricles.
Why are their differences in the thickness of the walls of the chambers?
Right ventricle:
The walls of the right ventricle are thicker than the walls of the atria. This enables the right ventricle to pump blood out of the heart. But the walls of the right ventricle are much thinner than those of the left ventricle. The right ventricle pumps deoxygenated blood to the lungs. The lungs are in the chest cavity beside the heart, so the blood does not need to travel very far. Also, the lungs contain a lot of very fine capillaries that are in close contact with the walls of the alveoli. The alveoli walls are very thin and there is very little or no tissue fluid. So the capillaries are not supported and could easily burst. The pressure of the blood must be kept down to prevent the capillaries in the lungs bursting.
Why are their differences in the thickness of the walls of the chambers?
Left ventricle:
the walls of the left ventricle can be two or three times thicker than those of the right ventricle. The blood from the left ventricle is pumped out through the aorta and needs sufficient pressure to overcome the resistance of the systemic circulation.
What is the cardiac cycle?
The sequence of events that make up one heart beat.
There are two phases to the beating of the heart: contraction (systole) and relaxation (diastole).
Contraction occurs separately in the ventricles and the atria and is therefore described in two stages.
For some of the time relaxation takes place simultaneously in all chambers of the heart and is therefore treated as a single phase.
What are the stages of the cardiac cycle?
Relaxation of the heart (diastole)
Contraction of the atria (atrial systole)
Contraction of the ventricles (ventricular systole)
Name of Stage of the Cardiac Cycle
Description about what happens during stage
Atrial Systole
Atrial muscle contracts
Volume of atria decreases
Pressure on blood increases
Blood forced down into ventricles
AV valves pushed open
Name of Stage of the Cardiac Cycle
Description about what happens during stage
Ventricular Systole
Ventricle muscle contracts bottom up
Volume of ventricle decreases
Pressure on blood increases
Blood forced upwards
AV valves pushed shut and semi-lunar valves pushed open so blood enters arteries
Blood also entering atria through veins as higher pressure there
Name of Stage of the Cardiac Cycle
Description about what happens during stage
Diastole
Cardiac muscle relaxes
Semi-lunar valves close as higher pressure in arteries
Volumes of atria and ventricles increase
Pressure decreases inside heart
Blood at higher pressure outside heart so enters atria through veins
Some blood trickles through AV valves into ventricles.
Valves
How do valves control the flow of blood through the heart?
Valves prevent the backflow of blood.
Examples of such valves include Atrioventricular valves
Semi-lunar valves
Pocket valves
How do valves control the flow of blood through the heart?
What causes a valve to open and what causes it close?
What causes a valve to open and what causes it close?
A valve will open when there is a higher pressure behindthe valve than in front of it.
For example, when there is a higher pressure in the atrium (where the blood has come from) compared with the ventricle (where the blood is passing into) then the atrioventricular valve (between thje atrium and ventricle) will open.
What causes a valve to open and what causes it close?
A valve will close when there is a higher pressure in front of the valve than behind it.
For example, when there is a higher pressure in the ventricle (where the blood has passed into) compared with the atrium (where the blood has come from) then the antrioventricularvalve (between the atrium and ventricle) will close.
What makes the heart sound?
The familiar lub-dup sound made by the heart is actually made by the valves closing.
The first sound, lub, is made by the atrioventricular valves closing as the ventricles start to contract.
The second sound, dup, is made by the semilunar valves closing as the ventricles start to relax.
The atrioventricular valves snap shut, so this noise is louder than the closing of the semilunar valves, which shut because blood is accumulating in their pockets.
What causes the heart to beat?
What is myogenic stimulation of the heart?
Cardiac muscle is myogenic, i.e. its contraction is initiated from within the muscle itself, rather than nervous impulses from outside (neurogenic), as is the case with other muscles.
How does the autonomic nervous system control heart rate?
Changes to the heart rate are controlled by a region of the brain called the medulla oblongata.
How does the autonomic nervous system control heart rate?
The medulla oblongata has two centres:
1. A centre that increases heart rate, which is linked to the heart’s sinoatrial node by the sympatheticnervous system.
2. A centre that decreases heart rate, which is linked to the heart’s sinoatrial node by the parasympathetic nervous system.
What is meant by cardiac output and how is it calculated?
Cardiac output is the volume of blood pumped by one ventricle of the heart in one minute. It is usually measured in dm3min-1 and depends upon two factors:
The heart rate (the rate at which the heart beats)
The stroke volume (volume of blood pumped out at each beat).
What is meant by cardiac output and how is it calculated?
To summarise:
Cardiac Output = Heart Rate x Stroke Volume
dm3min-1 min-1 dm3
Activity
1. Sohail has a heart rate of 70. What does this mean?
2. At this heart rate, how long is one cardiac cycle?
3. What is meant by the terms stroke volume and cardiac output?
4. Cheryl has a stroke volume of 100cm3 and a heart rate of 62bpm. Calculate her cardiac output.
There are 3 types of blood vessel within the cardiovascular system.
These are Arteries, veins and capillaries
Each can be identified by their different properties and appearance.
Blood Vessels
What are the structures of arteries and veins?
Arteries carry blood away from the heart
Pressure is high and when it is cut it spurts out
Artery walls are thick and very elastic.
The blood they carry is bright red with high oxygen content.
Arteries
Veins take blood back to the
heart
Veins have low blood pressure
and when cut only oozes out.
Vein walls are thin and not very
elastic
The blood they carry is dark red
due to low oxygen content
Contains a valve to prevent
back flow
Veins
Within the Capillaries blood travels from the arteries to the veins between the cells
The blood pressure in the Capillaries is medium.
Capillary walls are thin, allowing oxygen and nutrients to pass out into cells
Cell waste products pass into the capillary
http://www.bbc.co.uk/schools/gcsebitesize/science/21c/disease/heartdiseaserev2.shtml
Capillaries
Arteries
Blood Vessels
Lumen
Muscle + elastic fibres
Non-elastic fibres
Non-elastic fibres
Muscle + elastic fibres
Arteries carry
blood away from the heart
and have a
thick, elastic,
muscular wall.
They stretch as blood is
pumped in
and the
muscle wall
contracts to
force blood along.
Veins
Blood Vessels
Lumen
Muscle + elastic fibres
Non-elastic fibres
Non-elastic fibres
Muscle + elastic fibres
Veins have
a relatively
thinner and
less
muscular
wall than
arteries.
The blood is
under a
lower
pressure
than in the
arteries.
They carry
blood back
to the heart.
Capillaries
Blood Vessels
Capillary
walls are
one cell
thick.
Exchange
of nutrients
and
respiratory
gases
occurs
across
their
surface.
This is
called
diffusion.
Arteries, veins or capillaries?
1. Which vessel(s) carries blood at the:
a) Highest rate
b) Lowest rate?
2. Which blood vessel(s) carries blood at the:
a) Highest pressure
b) Lowest pressure?
3. Which blood vessel has the largest total cross-sectional area?
4. What happens to the pressure of the blood in the arteries and why do you think this happens?
Components of blood:
Blood contains a mixture of cells and plasma,
Red blood cells, white blood cells and platelets.
Plasma: This is a thick fluid which
contains dissolved proteins, sugar,
fats, salts and minerals.
Red blood cells: Red blood cells (RBC) contain
no nucleus, they make up 40-50% of blood volume and they are produced in the bone marrow from stem cells.
Red blood cells contain an iron rich protein called
haemoglobin which picks up oxygen as blood passes through the lungs. Red blood cells are biconcave
in shape to increase surface area for oxygen transport.
Components of blood
White blood cells:White blood cells (leukocytes) are found in blood but they are also found in other tissues in the body. There are several different types of white blood cells. Most are produced in bone marrow and can be found in the spleen, liver and lymph glands. They play a major role In defending the body from disease producing bacteria, viruses and fungi, hence they are a major part of the immune system.
Components of blood
Platelets:
Platelets are disc shaped cells that help prevent
abnormal or excessive bleeding by forming a clot
Blood Pressure
The digestive system
What is digestion?
In humans, as with many organisms, digestion takes place in two stages:
1. Physical breakdown
2. Chemical digestion
Mouth
Oesophagus
Liver
Gall-BladderIleumColon
RectumAnus
Salivary Gland
Pharynx (Throat)
Stomach
PancreasDuodenum
What is the structure of the digestive system?
How does the digestive system break down food physically?
If the food is large, it is broken down into smaller pieces by means of structures such as the teeth.
Food is churned by the muscles in the stomach wall and this also physically breaks it up.
This not only makes it possible to ingest the food but also provides a large surface area for chemical digestion.
How does the digestive system break down food chemically?
Chemical digestion breaks down large, insoluble molecules into smaller, soluble ones. It is carried out by enzymes.
All digestive enzymes function by hydrolysis.
The general term for such enzymes is hydrolases.
What is the role of enzymes in digestion?
There are different types of digestive enzymes, three of which are particularly important:
1. Carbohydras's – break down carbohydrates, ultimately to monosaccharides.
2. Lipases – break down lipids (fats and oils) into glycerol and fatty acids.
3. Proteases- break down proteins, ultimately into amino acids.
What happens to the simple molecules produced at the end of digestion?
Once the large food molecules have been hydrolysed into monosaccharides, glycerol, fatty acids and amino acids, they are absorbed by various means from the small intestine into the blood.
They are carried to different parts of the body and can either be: Respired by the cells of the body
Or, built up again into large molecules, although these are not necessarily of the same type as the molecules from which they were derived.
http://highered.mcgraw-
hill.com/sites/0072495855/student_
view0/chapter26/animation__orga
ns_of_digestion.html
Part of the Digestive System
Description about what happens here
1.
2.
3.
4.
5.
6.
Amylase
The mouth performs two functions:
1. Mechanical digestion
involves chewing – teeth chop and grind food into small pieces.
2. Mixing food with saliva
saliva starts the break down of carbohydrates (starch) using an enzymecalled amylase.
The Mouth
What happens in the mouth?
Three pairs of salivary glands pour their secretions known as saliva into the mouth.
Saliva, a digestive juice, contains an enzyme known as salivary amylase, which begins the digestion of carbohydrates as well as lubricating the mouth and helping bolus formation.
The Oesophagus
After being swallowed the food travels down the oesophagus.
What happens in the oesophagus?
The oesophagus transports the food bolus from the back of the mouth (the pharynx) to the stomach in the abdomen.
The swallowed bolus is in the oesophagus for a few seconds only and no enzymes are secreted here, although salivary amylase will continue to act during this brief journey.
The oesophagus is mainly a transit for food boluses which it moves by muscular contractions known as peristalsis.
The Stomach The stomach continues to mix the food with digestive enzymes. Amylasecontinues to digest carbohydrates
Proteins are digested in the stomach and small intestine. Protease enzymes break down proteins into amino acids. Digestion of proteins in the stomach is helped by stomach acid, which is strong hydrochloric acid. This also kills harmful micro-organisms that may be in the food.
What happens in the stomach?
Gastric glands produce gastric juice that contains gastric protease and hydrochloric acid. The gastric juice works on proteins.
In babies, another enzyme, rennin, solidifies and digests milk protein.
The pH of the stomach is 1-2; this is strongly acidic.
The epithelial lining on the stomach contains goblet cells, which produce thick mucus to protect the lining from acid erosion.
The stomach empties the chyme in spurts into the duodenum through the pyloric sphincter, a thick ring of muscle that alternately contracts and relaxes.
Small Intestine Lipase enzymes break down fat into fatty acids and glycerol. Digestion of fat in the small intestine is helped by bile, made in the liver. Bile breaks the fat into small droplets that are easier for the lipase enzymes to work on.
Lipase
What happens in the duodenum?
The duodenum is the first C shaped part of the small intestine.
The liver and the pancreas pour their secretions or juices into the duodenum.
The duodenal wall also contains glands which secrete enzyme rich juices (called succus entericus) that continue the digestive process on proteins, carbohydrates and lipids (fats).
These enzymes work either on the surface or inside the epithelial lining cells.
What happens in the ileum?
The remainder of the small intestine, known as the ileum, is mainly concerned with the absorption of the now fully digested food.
It is specially adapted for this by its: Long length Folded interior Lining covered in many thousands of tiny projections called villi Epithelial cells of villi covered in microvilli, projections so small that
they can only be detected using a microscope.
These adaptations enormously increase the surface area for absorption of nutrients from digested food.
What is the structure of the small intestine?
The walls of the small intestine are folded.
Lumen(in effect
outside of body)
The Small Intestine- Microvilli
The inside of the intestine is folded and covered in microvilli. The microvilli increase the surface area of the intestine to increase the absorption of carbohydrates, amino acids and fats
What are villi?
The folded walls of the small intestine are further folded, forming finger-like projections, about 1mm long, called villi.
The villi considerably increase the surface area of the small intestine and therefore accelerate the rate of absorption.
What are villi?
Each villus has a thin wall, lined with epithelial cells.
On the inside of each villus there is a rich network of blood capillaries.
The appendix is used to help some animals digest cellulose in plants. In humans the appendix has a very limited role as humans do not need to digest cellulose for carbohydrates.
Large Intestine
By the time food reaches the large intestine all useful nutrients have been absorbed into the blood. All that remains are waste products of digestion and water.
The water is very valuable so is absorbed into the blood stream
Waste products pass through the large intestine to be stored in the rectum before passing out of the anus as faeces.
What happens in the colon?
In the right-hand lower corner of the abdomen, the small intestine meets the large intestine.
The large intestine consists of the caecum and appendix (which have no function in the human digestive system), colon and rectum, ending in the sphincter (the anus) for the elimination of faeces.
The colon has a puckered appearance because the outer longitudinal muscle coat splits into three bands and the circular muscle bulges out between the bands.
What happens in the colon?
The function of the colon is to reabsorb water from the food waste. This results in semi-solid faeces.
Faeces contain: Cellulose (fibre or roughage) from plant cell walls from fruit and
vegetables. Dead bacteria, including the usually harmless bacteria living in the
large intestine that have died a natural death, and other bacteria, which are often killed by the hydrochloric acid in the stomach.
Scraped off cells from the gut lining.
The brown colour of faeces is due to bile pigments.
What are the functions of the liver and pancreas in digestion?
Liver and Pancreas
The liver and the pancreas play important part in digestion. The liver produces bile, which helps the digestion of fat.
The pancreas produces chemicals called digestive enzymes such as:
Protease - proteins
Carbohydrase (amylase) -carbohydrates
Lipase - fats
Major Products of Digestion
Anabolism or catabolism?
What happens to the major products of digestion?
Peptides and amino acids are nitrogenous compounds; they travel via the bloodstream to areas of need in body cells.
They are important in making enzymes, some hormones, plasma proteins, new cells (growth) and in repair processes.
What happens to the major products of digestion?
Surplus amino acids are broken down in the liver, as they cannot be stored.
Some parts of the molecules are used for energy but the nitrogen-containing part is converted into urea in the liver, by a process called deamination, and excreted by the kidneys in the urine.
What happens to the major products of digestion?
Sugars, chiefly glucose, are transported to cells to be broken down in respiration to release energy in the form of ATP.
What happens to the major products of digestion?
Fatty acids travel from the lacteals, through the lymphatic system into the main veins of the neck; this circuitous route enables smaller quantities of potential harmful lipids to enter the circulation gradually.
Glycerol and fatty acids are is used in respiration to release energy in the form of ATP.
Glycerol and fatty acids may also be reconverted into a form of fat that can be stored under the skin and around organs.
This can be used in respiration after glycogen stores have been depleted.
ASSESSMENT:
You should complete this assessment by yourself and are not allowed to ask for help. You can use your workbook and any other research you can find. Please remember to reference any books or websites that you have used.
Explain the physiology of two named body systems in relation to energy metabolism in the body. (P4)
Discuss the role of energy in the body. (M1)
Analyse how two body systems interrelate to perform a named function. (D1)
You should present your work in the form of a essay, include pictures and diagrams to illustrate the points you are making.
TASK 2
