Shadowing Practice: Understanding the Immune System in One Video - Learn English Speaking with Video
Choose a practice mode
Each mode opens a full-screen practice room.
157 sentences
If sentences are too short or too long, click Edit to adjust them.
1
Hi, this is Tom from zerodefinals .com.
2
This video was designed to give an overview of immunology, so that you understand all the basic features of the immune system.
3
It will also help you to return to this video once you've already learned the details,
4
so that you can again fit those details back into the bigger picture about how the immune system works.
5
The immune system can be categorized into the innate immune system and the specific immune system.
6
The innate immune system consists of the components that are already at the location of the infection
7
and respond immediately with a generalized response.
8
The specific immune system involves specialized T and B cells
9
that are waiting in places away from the site of infection
10
and then when they're activated they launch a specialized system
11
that fights the specific invading pathogen the specific immune system takes a little
12
while longer to recognize the infection particularly
13
when a pathogen is invading the body for the first time
14
so in this video we're going to cover both of these systems
15
and also talk about a system called the complement system
16
that works alongside the innate and specific immune systems let's look at what happens
17
when a pathogen invades the body initially there are physical barriers that need to be broken before an infection can take place.
18
The skin is an example of one of these barriers.
19
Most invaders will get stuck at this barrier, however occasionally an invading pathogen will get through, such as when there's a cut in the skin.
20
As well as the skin, there's other physical barriers, such as the mucosa of the respiratory system, the gastrointestinal tract, and the urinary tract.
21
There are also chemical barriers that help destroy harmful pathogens before they can cause any infection, such as the hydrochloric acid in the stomach,
22
lysozyme in sweat and tears, and lactic acid in the vagina.
23
Let's look at the initial responses of the immune system once an invading pathogen has broken through the physical
24
and chemical barriers to infection.
25
Three things happen.
26
Number one, macrophages recognize the pathogen and activate the innate immune system.
27
Number two, dendritic cells pick up antigens from the pathogen
28
and then head off in the blood
29
and lymphatic systems to track down the relevant T and B cells of the specific immune system and activate them.
30
And number three, the invading pathogen activates the complement system directly via the lectin pathway and the alternative pathway
31
And we'll talk a bit more on those later
32
First let's look at how the innate immune system provides an immediate response to infection
33
The first to respond are the macrophages
34
They recognise pathogens by specific characteristics that occur on pathogens but don't occur on cells of the body
35
These characteristics are called pathogen -associated molecular patterns, or PAMPs.
36
They recognise PAMPs using various receptor types, including toll -like receptors.
37
At this point, I need to talk briefly about a process called phagocytosis.
38
Now, phagocytosis is the process that macrophages and other phagocytes like neutrophils use in order to destroy pathogens.
39
So what happens is once they've recognized the pathogen they start to wrap their cell membrane around
40
that pathogen and absorb them to with inside their cell.
41
The pathogen is then left inside something called a phagosome
42
and this phagosome fuses with surrounding lysosomes that provide digestive enzymes
43
that then break down that pathogen destroying it and also processing all of the components into harmless waste products.
44
If the invading pathogens are harmless enough
45
that the macrophages can deal with them alone then they're cleared and it goes no further.
46
If the attacking army is too great the macrophages need help
47
so they release cytokines which are signaling proteins sort of like local hormones
48
that sound the alarm of an infection in the local area.
49
This leads to a process called inflammation.
50
One of the most important actions of these cytokines is to recruit and activate more cells of the immune system, such as macrophages, monocytes and neutrophils.
51
Monocytes are precursors to macrophages that float around in the blood.
52
Once they enter tissues, they differentiate into macrophages and can then carry out all the processes that macrophages normally carry out.
53
Neutrophils are another type of phagocyte that circulate in the blood and can enter the tissues and help by destroying invading pathogens.
54
The inflammatory response also involves a number of other processes that help to contain and fight the infection.
55
These are vasodilation, increased vascular permeability, mast cell activation and degranulation,
56
releasing more cytokines that further stimulate the inflammatory response, activation of the clotting system, and activation of the kinin system.
57
Inflammation itself actually stimulates macrophages and neutrophils to secrete more cytokines, notably chemicals called interleukins.
58
This is known as the acute phase response, and it leads to a more systemic inflammatory response.
59
this involves sending cytokines specifically interleukin 1 to the brain to tell it to produce a fever
60
that leads to high temperatures that are poorly tolerated by many pathogens
61
and cause reduced appetite and lethargy so that the person conserves more energy
62
that can be used to fight the infection
63
it also involves sending interleukin 6 to the liver to produce acute phase protein
64
that act as something called opsonins and remember this word
65
because we'll talk about opsonins in a minute additionally interleukin 8 is released
66
that recruits and activates more neutrophils interleukin 2
67
and 12 activate natural killer cells and tumor necrosis factor alpha is released
68
that does all of these effects by itself as i just mentioned
69
i want to take a quick look at opsonins as these are very important in the immune system.
70
Opsonins are complex molecules that attach themselves to pathogens
71
and make it easier for macrophages and neutrophils to recognize and phagocytose that pathogen.
72
I think of them a bit like a fork
73
that spears the pathogen so that macrophage can attach to the other end of the fork
74
and then use it to eat the pathogen.
75
An example of an opsonin that you may have heard of is C -reactive protein or CRP.
76
CRP is produced by the liver in response to interleukin -6
77
and we actually measure the level of CRP in our patients to assess how much inflammation
78
there is in the body
79
and it can be a really good indicator of the severity of the infection
80
that our patient is suffering with so
81
that summarizes the innate immune system a generalized system that recognizes
82
and responds to an invading pathogen by causing an inflammatory response
83
and recruiting cells
84
that destroy the pathogens by phagocytosis next let's look briefly at
85
the complement system the complement system works alongside the innate and the specific immune system to help them destroy pathogens
86
This involves a series of complement proteins labelled C1 to C9.
87
Once the complement system is triggered, the proteins start to activate each other in something called the complement cascade.
88
Various products of the complement cascade have important functions such as acting as opsonins,
89
triggering further inflammation and directly attacking and destroying the pathogens.
90
The complement system is triggered in one of three ways
91
The lectin and the alternative pathway are activated directly by pathogens
92
and the classical pathway is activated by antibody -antigen complexes that arise from the specific immune system
93
And that brings us nicely onto looking at the function of the specific immune system
94
The specific immune system involves two characters the T and the B cells and these are both types of lymphocyte.
95
They are free to float around the lymphatic system and the blood
96
but they spend most of their time in the lymph node and the mucosa -associated lymphoid tissue.
97
Think of these lymphoid tissues as army barracks that are full of soldiers
98
that are all sat around waiting to get word of an enemy that they've specifically been trained to fight.
99
Each pathogen has molecules that are unique to them.
100
They're known as antigens.
101
Each T cell has T cell receptors that are specific to a single type of antigen.
102
B cells have antibodies on their cell membrane that, just like T cell receptors, are specific to a single type of antigen.
103
The result is there's millions of different T and B cells that are all specific to a single type of antigen.
104
When a new pathogen arrives and causes an infection, The T and B cells that are specific to that pathogen need to be alerted.
105
The trouble is they're sat in lymphatic tissue such as lymph nodes while the infection is happening somewhere completely different.
106
This is where the dendritic cell comes in.
107
These cells are like messengers and they pick up the antigens at the site of the invasion,
108
display them on their cell surface and then bring them through the blood and lymphatic system into the lymphatic tissue.
109
When they're there all the T and B cells have a look at the antigen and see whether they recognize it.
110
When the T and B cells are found that specific to that antigen, those cells become activated.
111
So the specific immune response starts with the dendritic cell presenting
112
the antigens on the HLA class II molecules to the CD4 cells.
113
These CD4 cells, which are a type of T cell, then proliferate and become T helper cells.
114
The T helper cells present antigens on their HLA class 1 molecule that can be recognized by CD8 cells, another type of T cell.
115
They also secrete cytokines that are responsible for making the CD8 cells proliferate and differentiate into cytotoxic T cells.
116
These T helper cells also release cytokines that stimulate B cells to proliferate
117
and differentiate into plasma cells that can release large quantities of antibodies
118
and memory B cells
119
that hang around as part of the immune memory to respond quickly in future inflections with that specific pathogen.
120
The T helper cells also travel to areas of infection and
121
secrete cytokines that help to recruit monocytes and macrophages to the infected tissue
122
and activate the macrophages to cause inflammation and start the process of phagocytosis.
123
Cytotoxic T cells are responsible for killing cells that have been infected by pathogens, such as virally infected cells.
124
To do this, they need to attach themselves to the infected cell via the T cell receptor
125
and the HLA class 1 molecule expressing the relevant antigen protein on the infected cell.
126
once they're attached to the virally infected cell they have two killing mechanisms
127
that they can choose from the first is called granule exocytosis where they basically spray the infected cell with enzymes
128
that destroy the membrane and lead to cell lysis and cell death
129
the second is they can activate the fast molecule the fast molecule is like a self -destruct switch
130
that once it's activated it causes the cell to undergo apoptosis.
131
Plasma cells and antibodies are an essential part of the specific immune system.
132
Plasma cells are B cells that have differentiated and become antibody producing cells
133
and their job is to produce tons of antibodies that are specific to the invading pathogen.
134
These antibodies are proteins
135
that are shaped like a Y one end is variable in
136
shape to match different antigens whereas the other end is fixed in shape
137
and can be recognized by many cells of the immune system these proteins float around the blood
138
and attach themselves to antigens that match their specific variable region
139
and these antibodies help the immune system fight pathogens in a number of different ways firstly
140
they can attach themselves to enemy toxins which themselves are antigens and neutralize their toxic effect.
141
Secondly antibodies can attach themselves to the receptors of viruses and bacteria and prevent them from carrying out their function.
142
For example it can stop viruses from being able to recognize cells
143
that it may want to invade and therefore prevent the viral invasion of that cell.
144
Thirdly antibodies can attach themselves to pathogens then clump together to slow the spread of that pathogen down this is called agglutination.
145
Finally it can be very difficult for the simplistic receptors of macrophages and neutrophils to recognize certain pathogens.
146
Antibodies can act as opsonins that are highly specific to the invading pathogen
147
and by attaching themselves to that pathogen acting as upsonins they can help the macrophages
148
and neutrophils to recognize and destroy that pathogen.
149
That summarizes an overview of the immune system.
150
I hope you found this video helpful.
151
It was created as part of a set of videos
152
that covers everything you need to know about the immune system for medical school
153
and practicing as a doctor so go ahead and check out the rest of those videos.
154
If you like this one then please like, comment
155
and subscribe for more videos to you achieve success in your medical career
156
you can also check out the zero to finals website where you'll find notes illustrations practice questions
157
and a blog and i hope it's all useful for you and i'll see you in the next video
Download App
Everything you need to speak fluently
AI PronunciationScore every sentence
IPA PracticeMaster every sound
VocabularyBuild your word bank
Vocab GameLearn while playing
Same Channel
FOR YOU
Recommend Video
C11
163 sentences
Session #1: Life Sciences in the 21st Century – A Pathway to Scientific Discovery - Rotem Sorek
Daily ConversationUniversity Students
C1117 sentences
Anatomy & Physiology: The Ultimate Beginner's Guide | Dr. Bee's Tutorials
Daily ConversationUniversity Students
C11
67 sentences
Viruses: Components & Shapes - Microbiology Acellular Pre-Nursing, Pre-Med | @LevelUpRN
Daily ConversationUniversity Students
B22
8 sentences
Every Cybersecurity Beginner Should Watch This First (Networking Fundamentals)
Daily ConversationUniversity StudentsWorking Adults
C15
189 sentences
Say Goodbye to Candida - How To Get Rid Of Candida For Good | Dr. Taz
Daily ConversationUniversity StudentsWorking Adults
C11
166 sentences
Introduction to Optoelectronics and Photonics
Daily ConversationUniversity Students
C12
28 sentences
Explanation of Vaccine Adjuvants
Daily ConversationUniversity Students
C15
91 sentences
The Powers of Horror Exploring Julia Kristeva’s Theory of Abjection
Daily ConversationUniversity Students
C11
43 sentences
Understanding COPD
Daily ConversationUniversity StudentsWorking Adults
C12
39 sentences
Immunology of the rheumatoid joint
Daily ConversationUniversity Students
C1170 sentences
Glycolysis
American AccentDaily ConversationUniversity Students
C11
48 sentences
Pharmaceutical Industry Overview | Pharma and Biotech: Distinctions | Understanding Pharmaceuticals
Daily ConversationUniversity StudentsWorking Adults
Vocabulary and speaking notes for this lesson
This speaking lesson is built on the video “Understanding the Immune System in One Video”. The speaker keeps coming back to these words: cell, pathogen, immune, specific, macrophage. This video has 157 sentences and 2165 words to shadow. The speech runs for 15:11. The speaker talks at a steady 143 words per minute, a comfortable pace for shadowing. Only 73% of the words are among the 3,000 most common in English, so the vocabulary is demanding.
Key vocabulary in this video
15 words from the video worth learning, with pronunciation and meaning:
| Word | Pronunciation | Meaning |
|---|---|---|
| immune adjective | /ɪˈmjuːn/ | Exempt; not subject to. |
| infection noun | /ɪnˈfɛkʃən/ | The act or process of infecting. |
| activate verb | /ˈæktɪˌveɪt/ | To encourage development or induce increased activity; to stimulate. |
| invade verb | /ɪnˈveɪd/ | To move into. |
| complement noun | /ˈkɑmpləmənt/ | The totality, the full amount or number which completes something. |
| attach verb | /əˈtæt͡ʃ/ | To fasten, to join to (literally and figuratively). |
| tissue noun | /ˈtɪʃ.(j)u/ | Thin, woven, gauzelike fabric. |
| receptor noun | /ɹɪˈsɛp.tə/ | A protein on a cell wall that binds with specific molecules so that they can be absorbed into the cell in order to control certain functions. |
| molecule noun | /ˈmɑ.lɪ.kjul/ | The smallest particle of a specific element or compound that retains the chemical properties of that element or compound; two or more atoms held together by… |
| involve verb | /ɪnˈvɑlv/ | To have (something) as a component or a related part; to comprise, to include. |
| barrier noun | /ˈbæɹi.ə/ | A structure that bars passage. |
| inflammation noun | /ɪnfləˈmeɪ̯ʃən/ | The state of being inflamed. |
| recruit verb | /ɹɪˈkɹut/ | To enroll or enlist new members or potential employees on behalf of an employer, organization, sports team, the military, etc. |
| pathway noun | /ˈpæθˌweɪ/ | A footpath or other path or track. |
| inflammatory adjective | /ɪnˈflæmət(ə)ɹi/ | Tending to inflame or provoke somebody. |
Phrasal verbs you will hear
| Word | Pronunciation | Meaning |
|---|---|---|
| carry out verb | /ˈkæ.ɹi aʊt/ | To hold while moving it out. |
| check out verb | To record the departure or withdrawal of someone or something (such as guests, employees, books, etc.). | |
| pick up verb | To lift; to grasp and raise. | |
| break down verb | To stop functioning. | |
| break through verb | To gain popularity. | |
| get through verb | /ɡɛt ˈθɹu/ | To overcome; to endure. |
| go ahead verb | /ˌɡoʊ əˈhɛd/ | To proceed with; to begin. |
| hang around verb | To stay, linger, or loiter. |
Grammar in this video
The structures the speaker uses most, with the exact words from the video:
| Structure | In the video |
|---|---|
| Passive voice be + past participle — the focus is on what happens, not who does it | was designed · can be categorized · be broken |
| Present perfect have/has + past participle — a past action that still matters now | you've already learned · has broken · they've recognized |
| Relative clauses who / which + clause — extra information about a person or thing | cytokines which are · cells, which are |
Pronunciation to watch
The speaker uses 15 contractions and reduced forms, such as they're, they've, we'll. Say them the short way, as you hear them.
- The “th” sounds: pathway /ˈpæθˌweɪ/, pathogen /ˈpæθəd͡ʒn̩/, lethargy /ˈlɛθ ər dʒi/, thirdly /ˈθɚdli/
- The “sh” and “zh” sounds: infection /ɪnˈfɛkʃən/, tissue /ˈtɪʃ.(j)u/, inflammation /ɪnfləˈmeɪ̯ʃən/, differentiate /dɪf.əˈɹɛn.ʃi.eɪt/, activation /ˌæktəˈveɪʃən/
- Long words — get the stress right: inflammation /ɪnfləˈmeɪ̯ʃən/, inflammatory /ɪnˈflæmət(ə)ɹi/, differentiate /dɪf.əˈɹɛn.ʃi.eɪt/, activation /ˌæktəˈveɪʃən/, characteristic /ˌkæɹ(ə)ktəˈɹɪstɪk/
How to practise with this video
- Listen to the whole video once without speaking and note the words you do not know.
- Shadow it sentence by sentence at normal speed, repeating each one until your rhythm matches the speaker.
- Record yourself and compare with the original, paying attention to words like immune, infection, activate.
What is the Shadowing Technique?
Shadowing is a science-backed language learning technique originally developed for professional interpreter training and popularized by polyglot Dr. Alexander Arguelles. The method is simple but powerful: you listen to native English audio and immediately repeat it out loud — like a shadow following the speaker with just a 1–2 second delay. Unlike passive listening or grammar drills, shadowing forces your brain and mouth muscles to simultaneously process and reproduce real speech patterns. Research shows it significantly improves pronunciation accuracy, intonation, rhythm, connected speech, listening comprehension, and speaking fluency — making it one of the most effective methods for IELTS Speaking preparation and real-world English communication.