Merge branch 'patch-8' into 'master'

Respiratory system, circulatory system

See merge request magicalsoup/Highschool!24

Grade 10/Science/SNC2DZ/Unit 2: Biology.md

@@ -364,7 +364,7 @@ A person contains roughly 100 trillion cells
         - Villi contain capillaries and absorbing and goblet cells
         - Absorbing cells caintain microvilli, which absorb nutrients via diffusion
 
-### Respiratory system
+## Respiratory system
  - Exchanges oxygen gas and carbon dioxide gas between red blood cells and the surrounding air, which is required for cellular respiration
  - Diaphragm contracts to lower itself, causing the rib cage to rise, which increases lung volume, which subsequently causes pressure to decrease and air to rush in to the lungs
  - Diaphragm relaxes to return everything to its normal position
@@ -377,4 +377,93 @@ A person contains roughly 100 trillion cells
     - Nose hairs and mucous trap debris which is swept out by cilia
  - Alveoli (singular "alveolus") epithelial tissue is one cell thick
     - Surrounded with capillaries which exchange gases via diffusion
- - Trachea -> 2 bronchi -> bronchioles -> alveoli
+ - Trachea -> 2 bronchi -> bronchioles -> alveoli
+ - Gas exchange
+    - Swapping of carbon dioxide and oxygen gas between the bloodstream and the environment (e.g., red blood cells and alveoli)
+    - A large surface area, thin membrane, and moisture are all required for optimal gas exchange
+    - Alternate gas exchange systems include
+        - Fish using a constant water flow forcing dissolved oxygen through their gills
+        - Gills stick together out of water, resulting in suffocation
+        - Frogs use lungs on land, but can also perform gas exchange underwater using their skin
+
+## Circulatory system
+
+<img src="https://i.pinimg.com/originals/06/0d/48/060d48aa995e2da30405e7cef07679f8.png" width="400">
+
+ - Interacts with literally every other system
+ - Carries oxygen and nutrients to cells, carries carbon dioxide and waste away
+
+### Components
+ - Composed of heart, arteries, veins, and capillaries
+ - `Arteries` flow **away** from the heart
+    - Made of **thick** muscle layers and elastic connective tissue
+    - Muscle layers must withstand and **maintain** higher blood pressure throughout body due to proximity to heart
+    - May `vasoconstrict` or `vasodilate` to increase or restrict blood flow, for example, to blush or to pale, respectively
+ - `Veins` flow **to** the heart
+    - Made of **thin** muscle layers and elastic connective tissue
+    - Carries low pressure blood with valves to ensure one-way flow
+    - Blood moves by movement of skeletal muscles pushing blood
+ - `Capillaries` are one cell thick
+    - They transition between arteries and veins
+    - Blood cells are forced to go in single file
+    - Present, amongst other places, in alveoli and villi
+ - The `heart` pumps blood throughout the body
+    - Has one-way valves
+    - Has four chambers, two `atria` (sing. `atrium`) and two `ventricles`
+        - Blood is returned to atria which push them to ventricles which push them out of the heart
+    - **Right** side of heart receives and sends **deoxygenated** blood **to** lungs
+    - **Left** side of heart receives and sends **oxygenated** blood **from** lungs
+ - Invertebrate circulatory systems are either **open** or **closed** (douse everything with blood then collect or use vessels like we do, respectively)
+ - Most invertebrates have an open circulatory system
+
+### Mycardial infarction
+ - Also known as **heart attack**
+ - When `atherosclerosis` occurs in `coronary arteries` (when fatty plaque deposits build up in arteries feeding the heart)
+ - If clots break open a larger clot forms over it
+ - This repeats until the artery is completely blocked, leading to death of cardiac muscle cells
+ - Caused by lifestyle choices, although predisposition can be increased due to genes
+
+### Blood
+ - Composed of red blood cells, white blood cells, platelets, and plasma
+ - `Red blood cells`: Biconcave discs carrying oxygen and carbon dioxide to and from cells, respectively, using `hemoglobin`
+    - Denucleated, instead packing as much hemoglobin as possible inside
+    - Hemoglobin and oxygen give them their colour
+ - `White blood cells`: Part of the immune system, they neutralise and remove foreign threats
+    - Can make antibodies
+    - Can engulf and kill pathogens
+    - 700:1 ratio of red blood cells to white blood cells
+ - `Plasma`: Clear fluid made of 90% water filled with proteins and dissolved nutrients
+ - `Platelets`: Irregular colourless "bodies" that form **fibrous** clots
+
+## Immune system
+ - `Pathogens`: any**thing** that cause disease
+    - Pathogen waste can be toxic which cause symptoms of disease
+ - Passive defense
+    - Skin - physical barrier
+    - Sweat/tears - `lysozymes` kill bacteria
+    - Stomach acid - it's acid dangit acid kills things
+    - Beneficial bacteria overpopulate surfaces to prevent harmful bacteria from settling
+ - Adaptive defense
+    - `White blood cells`: For the sake of G10, divided into two subtypes:
+        - Cells that engulf and consume bodies (`phagocytes`, e.g., macrophages)
+        - Cells that produce antibodies (`plasma B cells`, i.e., plasma B cells)
+    - `Antibodies`: Secreted proteins that stick to a specific molecule found on pathogens
+        - Clumps pathogens together for simple cleanup and prevents them from spreading
+        - Covers and prevents toxins from reacting
+        - Acts as a flag for phagocytes to destroy marked pathogen or toxin
+ - Acquired immunity
+    - After initial immune response, antibodies are still produced for that type of pathogen
+    - Once pathogen is detected again, "memory cells" reactivate and kill things faster
+    - Much faster than initial response, typically resulting in no symptoms
+    - This is why you generally can never be sick from the same pathogen twice
+    - Pathogens mutate (e.g., influenza) so that they are no longer recognisable by antibodies
+ - `Vaccination`: Injecting a small amount of a **dead/weakened** version of pathogen giving acquired immunity without actually getting disease
+    - There may be mild side effects
+    - `Boosters` are required for some vaccines as "memory" fades over time (e.g., tetanus)
+    - `Herd immunity`: When enough of the population (90% in general) is immune to a disease, drastically reducing rate of disease even amongst those not immune
+        - Those who cannot be vaccinated for whatever reason are protected due to a far lower chance of encountering the disease itself
+    - Prevention (vaccine) > cure (treatment)
+    - Chance of disease from the vaccine are far lower than chance of death or serious infection from a pathogen
+    - Vaccines do not cause autism or seizures, but may act as a trigger for the latter due to genetics
+
+## Musculoskeletal system