Unit 11 – Physiology of Human Body Systems
D2 – explain how digestive, respiratory, and cardiovascular systems are in interrelated
The three systems all work together to help the body run as efficiently as possible.
The digestive system breaks down large molecules into smaller ones which are transported to the
body’s cells via the cardiovascular system which also removes waste products.
The respiratory system takes in oxygen and removes carbon dioxide, a process known as gas
exchange, with the help of the cardiovascular system which transports it around the body through
the blood.
The cardiovascular system transports oxygen to the cells of the body and carbon dioxide to the lungs
where it is removed via the respiratory system.
A key process where all three systems work together to keep the body functioning is cellular
respiration. Cellular respiration is where the body converts energy eaten into energy that can be
used by the body’s cells. The way the cells get energy from food is by ATP being extracted from
glucose, which the cells can then use the ATP as their own form of energy. In cellular respiration the
digestive system works to get glucose from food by breaking down starch. The respiratory and
cardiovascular system work to provide the cells with oxygen that they need.
The way cellular respiration occurs is by three phases; glycolysis, the Krebs cycle and
oxidative phosphorylation.
In the first phase, glycolysis is brought about by the glucose being broken down in the cytoplasm of
the cell. The process of glycolysis will then produce chemicals needed in each of the other two
stages for cellular respiration to be brought about.
In the second phase, pyruvate that was created from the glycolysis process makes its way into the
mitochondria. Pyruvate is a three-carbon molecule but before entering the Krebs cycle it strips itself
down to a two-carbon molecule and CO2 is given off. There are many different chemical reactions
taking place and at the end one ATP molecule is released. But because for every glucose molecule,
there are two pyruvate molecules, therefore two ATP molecules are released overall. The molecules
left over from the chemical reactions occurring in the Krebs cycle are two ATP molecules, ten ADH
molecules and two FADH2 molecules.
In the third and final phase of cellular respiration, an electron transport chain and chemiosmosis
both occur to deliver ATP. In the electron transport chain multiple electrons go from one molecule to
another where energy is released multiple times. This release of energy forms a gradient which helps
with ATP synthesis which is known as chemiosmosis.
D2 – explain how digestive, respiratory, and cardiovascular systems are in interrelated
The three systems all work together to help the body run as efficiently as possible.
The digestive system breaks down large molecules into smaller ones which are transported to the
body’s cells via the cardiovascular system which also removes waste products.
The respiratory system takes in oxygen and removes carbon dioxide, a process known as gas
exchange, with the help of the cardiovascular system which transports it around the body through
the blood.
The cardiovascular system transports oxygen to the cells of the body and carbon dioxide to the lungs
where it is removed via the respiratory system.
A key process where all three systems work together to keep the body functioning is cellular
respiration. Cellular respiration is where the body converts energy eaten into energy that can be
used by the body’s cells. The way the cells get energy from food is by ATP being extracted from
glucose, which the cells can then use the ATP as their own form of energy. In cellular respiration the
digestive system works to get glucose from food by breaking down starch. The respiratory and
cardiovascular system work to provide the cells with oxygen that they need.
The way cellular respiration occurs is by three phases; glycolysis, the Krebs cycle and
oxidative phosphorylation.
In the first phase, glycolysis is brought about by the glucose being broken down in the cytoplasm of
the cell. The process of glycolysis will then produce chemicals needed in each of the other two
stages for cellular respiration to be brought about.
In the second phase, pyruvate that was created from the glycolysis process makes its way into the
mitochondria. Pyruvate is a three-carbon molecule but before entering the Krebs cycle it strips itself
down to a two-carbon molecule and CO2 is given off. There are many different chemical reactions
taking place and at the end one ATP molecule is released. But because for every glucose molecule,
there are two pyruvate molecules, therefore two ATP molecules are released overall. The molecules
left over from the chemical reactions occurring in the Krebs cycle are two ATP molecules, ten ADH
molecules and two FADH2 molecules.
In the third and final phase of cellular respiration, an electron transport chain and chemiosmosis
both occur to deliver ATP. In the electron transport chain multiple electrons go from one molecule to
another where energy is released multiple times. This release of energy forms a gradient which helps
with ATP synthesis which is known as chemiosmosis.
