Biology20 IB - Unit 3a

Question 1

Definition of “enzyme”

Answer 1

An enzyme is produced by a living organism and acts as a catalyst to bring upon a biochemical reaction. Its function is to lower the activation energy of the reactions.

Question 2

What is “Digestion”

Answer 2

It is an enzyme-facilitated chemical process. The events associated with this are; ingestion, digestion, absorption, and transportation.

Question 3

What are “Villi”? What is their role?

Answer 3

Villi (plural) make up the mucosa. There are many small folds and projections which are the villi. Each villus is composed of many cells whose job is to selectively absorb molecules which are found in the lumen of the small intestine. The absorption happens one the epithelial layer. Villi increase the surface area for absorption.

Question 4

What are “Microvilli”? What is their role?

Answer 4

The epithelial cells have tiny membrane projections called microvilli that extend into the lumen of the intestine.

Question 5

What is the epithelial layer?

Answer 5

The epithelial layer is any layer that can come into contact with the outside.

Question 6

Explain the passive mechanisms used by epithelial cells to absorb nutrients.

Answer 6

Simple Diffusion: the direct movement through the cell membrane following a conc. gradient.
Facilitated Diffusion: the movement through a cell membrane following a conc. gradient, but the molecule must travel through a “protein channel” because of its size and polarity.
Neither use ATP (energy)

Question 7

Explain the active mechanisms used by epithelial cells in order to absorb nutrients.

Answer 7

Membrane Pumps: molecules that are moved against their conc. gradient by certain proteins using ATP to ‘pump’ the molecules across the membrane.
Endocytosis: molecules are trapped in an invagination of the membrane and pass through to the other side of the membrane as a vesicle.

Question 8

What is physical digestion?

Answer 8

This type of digestion is purely physical. It is the brutal breaking down of larger pieces (i.e. teeth, tongue, churning of the stomach uses hydrochloric acid).

Question 9

What is chemical digestion?

Answer 9

This type of digestion uses the broken down pieces from the physical digestion and chemically breaks them down further into molecules. Enzymes in the digestive trach (tubes from the mouth to the intestine) help in chemical digestion.

Question 10

What is the role of endopeotidase?

Answer 10

It is an enzyme that hydrolyses proteins into polypeptides.

Question 11

Name some important enzymes.

Answer 11

Amylase: Come from the Salivary glands. They break down the carbs/starches. It then creates maltose.
Lipase: Comes from the pancreas. Break down lipids/fats. It then turns them into fatty acids or glycerol.
Endopeptidase: Come from the pancreas. Breaks down proteins and create polypeptides.

Question 12

What are “Smooth Muscles”?

Answer 12

It is a type of intestinal muscle. They are controlled by the ANS (autonomic nervous system). It basically keeps the food moving. The tube of the alimentary canal has 2 layers of smooth muscle.

Question 13

What is the thoracic cavity and your abdominal cavity?

Answer 13

Thoracic cavity: They are your lungs, heart

Abdominal cavity: They are all of your digestive structures (besides your mouth and oesophagus).

Question 14

What is the alimentary canal?

Answer 14

It is a muscular tube that is fundamentally the human digestive system. The 2 accessory organs to tho the canal is the pancreas and the liver. They are connected by the ducts in the canal. (Mouth to anus)

Question 15

What is the relationship between circular and longitudinal muscles?

Answer 15

The contraction of circular and longitudinal muscle of the small intestine mixes the food with enzymes and moves it along the gut. This motion and food movement is called peristalsis.

Question 16

What is the role of peristalsis?

Answer 16

Peristalsis is used in the stomach to mix food with digestive secretions including a protein-digesting enzyme. This movement is called churning. Peristalsis is used along your alimentary canal. Peristalsis causes a contraction just behind the food mass and thus keep it moving through the canal. This is how food is moved, not because of gravity.

Question 17

What is the role of the pancreas?

Answer 17

It is a multipurpose organ It produces hormones such as insulin and glucagon which is a main part in glucose metabolism. The pancreas also produces amylase, lipase, and endopeptidase.

Question 18

What is pancreatic juice made up of?

Answer 18

Amylase, lipase, and endopeptidase. It is released into the first portion of the small intestine through a duct.

Question 19

What is the role of the small intestine?

Answer 19

Pancreatic juice is secreted into the first section of the small intestine (duodenum). Amylase molecules begin to catalyse the hydrolysis of starch into maltose. These hydrolytic reactions continue. Within the small intestine, there is another enzyme that completes the digestion of the starch, maltase is produced by the cells of the inner lining of the two molecules of glucose.

Question 20

What make up the mucosa? What is it?

Answer 20

The cells in the inner lining of the small intestine make up the mucosa. The mucosa has many small folds or projections called villi.

Question 21

What are arteries? What are pulmonary arteries?

Answer 21

They are blood vessels that take blood away from the heart that has not yet reached the capillary. Arteries are a thick, smooth, muscle layer that is used by the ANS to change the lumen sizes. They also have elastic fibres that help maintain the high blood pressure from the contractions of the ventricle. Pulmonary arteries are on their way to be re-oxygenated/move away from the heart. Arteries are also directly connected to the heart.

Question 22

What are veins? What are pulmonary veins?

Answer 22

They are blood vessels that collect blood from the capillaries and return it to the heart. The pulmonary veins bring oxygenated blood back towards the heart.

Question 23

What is the difference between a capillary bed and a capillary?

Answer 23

A capillary bed is a network of capillaries that typically all drain into 1 venule.

Question 24

How can coronary thrombosis be caused?

Answer 24

When a main coronary artery or one of the main branches are blocked. This can be caused by buildup in the lumen by typically, lipids. The vessels become less flexible and harder.

Question 25

What vessel supplies the heart directly with blood?

Answer 25

The coronary arteries.

Question 26

What is the role of the SA node in the cardiac cycle? How does the AV node relate to this?

Answer 26

In the right atrium, there is a mass of specialized tissue that has both muscle and nervous system cells within it’s walls; this tissue is called the Sinoatrial Node. It acts as a pacemaker for the heart by sending out an electrical signal to initiate the contraction of both atria.
There is also another mass of specialized tissue called the atrioventricular node. The AV node recerives the signal from the SA node, delays for .1 second and then sends out another signal . This signal goes to the thick muscular ventricles and results in their contraction. This is why both atria contract and then later both ventricles contract in synchrony.

Question 27

How does the heart beat faster?

Answer 27

A part of your brain called the Medulla sends a signal through a cranial nerve called the cardiac nerve, which will reach the SA node. This will change the speed of the heartbeat, aka the timing of the two nodes.

Question 28

What does systole and diastole mean?

Answer 28

Systole: contraction
Diastole: ‘at rest’

Question 29

What happens when the atria is in diastole and the ventricle is in systole?

Answer 29

the pressure will increase in the ventricle opening up the semilunar valve so that the blood can be pushed through.

Question 30

How does gas exchange in the capillaries work?

Answer 30

It is the opposite of gas exchange in the alveoli. The oxygenated blood flows through body and, for example, stops at a muscle and diffuses 02 into the muscle and picks up the C02. Then it heads back to the lungs to refuel.

Question 31

How does gas exchange in the alveoli work?

Answer 31

Blood from the pulmonary artery passes by an alveoli and will diffuse C02 into the alveoli as well as pick up 02. The blood will then leave in the pulmonary vein and travel to the heart.

Question 32

What is the pathway of breath?

Answer 32

Mouth>trachea>lungs>split into either bronchi>into bronchioles>into alveoli>towards the heart and around the body and then back.

Question 33

What kind of relationship does pressure and volume have?

Answer 33

An inverse relationship

Question 34

What happens during inspiration?

Answer 34

Is the process of inhaling:
>Diaphragm contracts (moves down=more volume)
>Rib cage widens (increase in volume of thoracic cavity)
>Less pressure on cavity = pressure on lung tissue
>Lung tissue increase in volume b/c less pressure on it
>Decrease in pressure in the lungs»which makes it a partial vacuum.
>Air enters to counter the partial vacuum and fill the alveoli.

Question 35

What does the left side of the heart do?

Answer 35

> The left side sends blood on a systemic circulation.
The Aorta is the beginning of the route.
Blood picks up C02 and releases 02 along the way
Pulmonary veins get oxygenated blood then it moves down past the left atrioventricular valve, then gets pushed out past the semilunar valve and then out the aorta.

Question 36

What does the right side of the heart do?

Answer 36

> The right side sends blood along route called the pulmonary circulation
It picks up 02 and leaves behind CO2
Superior/Inferior vena cavas receive deoxygenated blood, then into the right atria and then past the atrioventricular valve and into the right ventricle. Then it will be pushed up past the semilunar valve and out the pulmonary artery.

Question 37

What us myogenic muscle contraction?

Answer 37

Cardiac muscles spontaneously contracts and relax without any control by the nervous system. However, this myogenic activity needs yo be controlled. This is where the SA and AV nodes come into play.