body systems (science)

booodyyy auuuoooouuaouoauoaououaoouuuuuuaaooooouauoauo

what are the basic requirements for life?

1. water

2. a suitable temperature range (interal + external)

3. nutrients

4. oxygen/other gas for metabolism

5. waste removal

6. space

in multicellular organisms, the following requirements are achieved through the coordinated functions called body systems.

body systems

humans are complex multicellular organisms made up of about 37 trillion cells. these cells are organized into progressively more complicated structures and systems called body systems. survival is only possible if these structures communicate and coordinate their activities.

in multicellular animals, the nervous system and endocrine system allow such communication to occur.

cells to systems definitions

cells: the building blocks of life. multiple cells of a certain type make up tissues.

tissues: a group of the same cells, working together to make organs.

organs: a group of tissues that have been adapted to perform a specific function

organ systems: a group of organs that work together as a system to perform one or more functions.

cells to systems example

cardiac muscle cells —> cardiac muscle tissue —> heart —> circulatory system

photosynthesis

carbon dioxide + water —> oxygen + glucose

- needs sunlight, chlorophyll, and water to happen
- occurs in the chloroplast
- creates glucose for energy from sunlight in plants

cellular respiration

oxygen + glucose —> carbon dioxide + water + ATP (adenosine triphosphate)

- occurs in the mitochondria
- extracts energy (ATP) from glucose

roots (root + root hair cells) in plants

absorbs water and nutrients

stomata (singular: stoma) in plants

in leaves and stems
are sites of gas exchange (oxygen + carbon dioxide)

what is energy used for?

MRNGREWW
(movement, reproduction, nutrition, growth, respond to stimuli, exchange gases, waste, water)

diffusion in plants

plants lack a respiratory system (which animals need to actively transport gases), so oxygen and carbon dioxide move through diffusion instead.

diffusion: the movement of a substance from an area of high concentration to an area of low concentration. it is a passive transport, meaning it doesn’t require an input of energy. happens in both air and liquid.

• inside leaves, CO₂ is high, so this gas exits

• outside leaves, O₂ is high, so this gas enters

occurs in plant roots, leaves, and individual cells. plants use diffusion to move gases in and out of their leaves. water moves from the soil into the roots of the plant via diffusion

waste removal in plants

plants prevent the build up of wastes by removing them via stoma (plural, stomata)

stomata on leaves and stems are pores formed by two ‘guard cells’. They are holes through which water and gases can pass.

● oxygen exits (byproduct from photosynthesis)

● carbon dioxide waste exits (from cellular respiration, regulate amount)

● water exits (transpiration)

the plant vascular system

the internal transport network of tissues that moves water, minerals, and sugars throughout the plant. it delivers water, minerals, and food to all parts of the plant, allowing it to grow, make food, and stay alive.

primarily composed of two specialized tissues, xylem and phloem.

substances are transported within sap.

the xylem

transports water and dissolved minerals through sap upward from the roots to the leaves (one way flow).
composed of dead, hollow tubular cells.
thick cell wall made of lignin.
on the inside of the bundle.

the phloem

transports sugars and nutrients through sap around the plant (two way flow).
thin cell wall made of cellulose.
on the outside of the bundle.

rules for drawing cells

1. use a sharp pencil.   

2. draw only the lines that you see (no shading or colouring).

3. diagrams should take up about a third to half of a page each.

4. record the magnification next to each diagram. (size of eyepiece lens x objective lens)

5. name the specimen (title) and date of observation

6. draw only two or three representative cells for each observation.

7. label only what you can see.

what is transpiration?

when water leaves the plant via the leaves (stomata) and evaporates into the air

why are more stomata found on the underside of the leaf?

to conserve water. stomata on the upside are directly exposed to the sun, meaning the rate of transpiration (water evaporating out of the stomata) is faster. stomata on the underside are in cooler regions, significantly slowing down the rate of transpiration.

the role of the circulatory system

the circulatory system moves blood, nutrients, oxygen, carbon dioxide, and hormones around the body.

it consists of the heart, blood, and blood vessels (arteries, veins, capillaries).

the heart pumps blood, containing things required by cells (nutrients, oxygen, hormones, wastes) around the body.
blood vessels transport this blood around the body.

what are the three blood vessel types?

artilleries, veins, and capillaries

artilleries

carry blood AWAY from the heart under HIGH pressure.

walls are thick, tough, and elastic to allow expansion and contraction. they need to withstand the high pressure of blood being pumped from the heart and to help maintain blood pressure and flow. 

this expansion and contraction is your pulse.

arteries are buried deep in your body and will bleed profusely + squirt if damaged.

veins

carry blood BACK TO the heart.

the pressure of the heartbeat is lost as the blood flows through the capillaries. therefore, walls of veins don’t need to be as thick as artery walls.

blood is pushed back to the heart (against gravity) by the contraction of muscles.

valves in the veins ensure blood flow is in one direction (prevents back flow).

capillaries

arteries branch into smaller blood vessels known as capillaries and eventually connect to the veins. 

capillaries reach almost every cell in the body.

capillary walls are only one cell thick which allows for the transfer of materials:

• materials needed by the cell pass out of the capillary

• waste materials from the cell are passed into the capillary

the capillaries have very thin walls, and deliver nutrients and oxygen to the cells through the walls. waste products are brought into the capillaries (for removal from the body).

what is the composition of blood?

red blood cells,
white blood cells,
plasma,
platelets

red blood cells

made in the bone marrow.
carries O₂ around the body.
contains hemoglobin (a molecule specially designed to hold oxygen and carry it to cells that need it) and iron. the hemoglobin gives it the signature red color.
the cell is a bi-concave disc that is round and flat without a nucleus, which can change shape to an amazing extent, without breaking, as it squeezes single file through the capillaries.

white blood cells

are part of the immune system.
protect body from infectious disease and foreign cells.
created from stem cells in bone marrow
has different types, responsible for fighting different pathogens.

plasma

makes up 55% of blood content
appears as clear yellowish liquid as it is made up of 90% water and 10% nutrients/waste.

transports glucose, nutrients, hormones to cells.
contains red and white blood cells, and platelets.
digested food, wastes, vitamins, and minerals are also found within plasma.

platelets

broken up bits of cells produced in the bone marrow.
help to clot and coagulate (thicken) blood by producing fibrin – to heal wounds.

when you don't have enough platelets in your blood, your body cannot form clots. a low platelet count may also be called thrombocytopenia. this condition can range from mild to severe, depending on its underlying cause. for some, the symptoms can include severe bleeding and are possibly fatal if they're not treated.

vascular system vs circulatory system

main transport tissues: xylem + phloem vs blood vessels
transports: water + minerals + sugars vs oxygen + wastes + nutrients + carbon dioxide + hormones
main pump: N/A vs heart
found in: plants vs animals

blood vessel features

-

the human heart

is a muscle that continuously pumps blood around the body.
has two partitions divided by the septum (deoxygenated and oxygenated).
has four chambers (left atrium and ventricle and right atrium and ventricle) working as two pumps.
electrical signals in the heart force it to contract and pump blood.
sits between the left and right lung in the chest cavity protected by the rib cage.
valves separate the chambers and open/close like doors to allow blood to flow into the next chamber at appropriate times.

the double circulatory system

the human circulatory system is a double circulatory system in that there are two separate pathways for oxygenated and deoxygenated blood.

the septum in the heart prevents oxygenated and deoxygenated blood from mixing.

mixing oxygenated and deoxygenated blood would dilute the overall oxygen concentration in the blood and force the heart to work harder to circulate the required amount of oxygen.

blood flow (oxygenated/deoxygenated)

the left side of the heart (right side on diagrams) collects oxygenated blood from the lungs and pumps it to the body. the red colour indicates blood that is rich in oxygen (O₂).

the right side of the heart (left side on diagrams) collects deoxygenated blood from the body and pumps it back to lungs. the blue colour indicates blood with carbon dioxide (CO₂)

the heart is made of cardiac muscle, which does not tire.

the labelled chambers, valves, and vessels of the heart.

note that the left and right sides are flipped in ALL diagrams because it is from the heart owner’s perspective (a person standing in front and facing you’s perspective), so for you, it’s flipped.

the phases of a heartbeat

1. the two atria contract, pushing blood down into the ventricles.
   

2. the ventricles contract, forcing blood out of the heart to the body and lungs.
   

3. the heart muscle relaxes, and the atria fill with blood.

observing the pathway of blood through the heart

body —> inferior/superior vena cavas —> right atrium —> tricuspid valve —> right ventricle —> pulmonary valve —> pulmonary artery —> lungs —> pulmonary vein —> left atrium —> bicuspid (mitral) valve —> left ventricle —> aortic valve —> aorta —> body

the respiratory system

a set of organs that allows a person to breathe and exchange oxygen and carbon dioxide throughout the body.

works alongside the circulatory system which transports oxygen and carbon dioxide.

parts of the respiratory system

• nose/mouth

• pharynx and larynx

• trachea (windpipe

• bronchi

• lungs

• bronchioles

• alveoli

• diaphragm

air enters the body…

the nose is lined with cilia (hair). The nose filters and moistens the air entering.

the two openings of the airway (the nasal cavity and the mouth) meet at the pharynx, or throat.

the bottom of the pharynx divides in two; one path for food and the other for air.

the epiglottis, a small flap of tissue, covers the air passage when we swallow, keeping food and liquid from going into the lungs.

the trachea (windpipe) is a tube that separates into the left bronchi and the right bronchi.

the lungs: alveoli

alveoli are tiny air sacs inside the lungs. they are covered in capillaries.

oxygen passes through the walls of the alveoli into the red blood cells of the capillaries. (diffusion)

carbon dioxide passes from the red blood cells through the walls of the alveoli into the lungs. (diffusion)

how does the respiratory system work w/ the circulatory system?

the respiratory system transfers oxygen from the air into the lungs (alveoli). the circulatory system then transports this oxygen via diffusion into the capillaries around the alveoli back to the heart , which pumps it around the body to cells for cellular respiration. at the same time, carbon dioxide from the blood is carried back to the lungs, where it is exhaled.

what is digestion?

food molecules contain chemical potential energy.

digestion is the process where the body releases the chemical energy stored in food.

it breaks down food into smaller, absorbable nutrients like amino acids, simple sugars, and fatty acids.

the body then absorbs these nutrients into the bloodstream to fuel energy, growth, and cellular repair.

what is SA:V?

the surface area to volume ratio is a comparison between the surface area of an object and its volume, expressed as a ratio (SA:V). it shows how much surface area is available relative to the space inside the object. 

• small objects: have a large surface area relative to their volume, meaning they have a higher SA:V ratio —> easier for things to diffuse

• large objects: have a smaller surface area relative to their volume, resulting in a lower SA:V ratio —> harder for things to diffuse

why is a large SA:V ratio important in digestion?

a smaller cell =  higher SA:V ratio. it allows for more efficient exchange of substances into and out of the cell. 

specialized structures (eg intestinal villi) can increase the surface area available for exchange.

the digestive tract

the digestive tract is the pathway that food takes through a series of organs:

• mouth

• oesophagus

• stomach

• duodenum

• small intestine

• large intestine

• rectum

• anus

associated organs/structures to the side of the digestive tract

there are a range of organs and parts of the body to the side of the digestive tract that produce chemicals for digestion.

• liver (produces bile)

• pancreas (produces enzymes)

• gall bladder (stores + concentrates bile)

• salivary glands (produces saliva in mouth)

the teeth are involved in initially chewing food into smaller pieces (mechanical digestion).

mechanical digestion

the physical process of breaking down food into smaller pieces without chemically altering it. 

the process begins in the mouth with chewing (using teeth breaks down food into smaller pieces). 

it continues in the stomach with churning. (the stomach wall's muscles churn and mix the food with digestive juices, further breaking down the food bolus).

the purpose of mechanical digestion is to increase the surface area of food, making it easier for chemical digestion (where enzymes break down food molecules) to occur efficiently. 

chemical digestion

the process of breaking down large, complex food molecules into smaller, simpler molecules using enzymes and other chemical agents. 

this process occurs throughout the digestive tract, primarily in the stomach and small intestine.

enzymes, (which are biological catalysts), speed up the chemical reactions involved in breaking down food.  They do not get used up in the reaction.

how do mechanical and chemical digestion work together?

both mechanical and chemical digestion are needed because they work together to break food down completely. mechanical digestion physically breaks food into smaller pieces, which increases the surface area. this makes it easier and faster for chemical digestion to work. chemical digestion then uses enzymes and acids to break food down into small nutrients that the body can absorb and use for energy, growth, and repair.

enzymes (biological catalysts)

carbohydrates are broken down by the enzyme amylase into simple sugars (glucose) which is used by the cells for energy.

(amylase)
                     carbohydrates —> simple sugars

proteins are broken down by protease into amino acids (the building blocks of cells) which are used to repair old cells and build new cells (skin, blood, muscle, bone and nerve).
(protease)
                proteins —> amino acids

fats are stored for future use. they contain vitamins.
(lipase)
                    fats (lipids) —> fatty acids and glycerol

peristalsis

a series of muscular contractions that push food along the digestive tract, including the oesophagus, stomach, and intestines.

the mouth

digestion begins in the mouth

chewing:  teeth break food into smaller pieces (mechanical digestion)

saliva (containing the enzyme amylase) is mixed with food  - this starts the breakdown of carbohydrates (chemical digestion)

the oesophagus

peristalsis pushes the food down towards the stomach.

the stomach

the stomach breaks down food by mixing it with gastric juices and churning it into a liquid or paste called chyme. (mechanical digestion)

gastric juice contains acid (which kills bacteria) and gastric enzymes.

protein digestion occurs due to the enzyme protease, which breaks down proteins into amino acids

the small intestine

a 6-7m long tube containing small projections called villi. 

the site of most of the chemical digestion occurs: proteins, fats, and carbohydrates are digested here.

the pancreas, gall bladder and liver release enzymes and bile to help with digestion.

villi increase the SA:V ratio for nutrient absorption (through to the circulatory system); they are only one cell thick and contain capillaries.

the large intestine

the remaining waste (mostly undigested material and water) moves into the large intestine. 

water is absorbed into the blood.
waste is compacted into feces.

the rectum and anus

this is where all the undigested food (waste) is stored before it passes out of the body. this waste is called feces. the rectum stores the feces, while the anus is the opening that passes it out.

how does the digestive system work w/ the circulatory system?

the digestive system uses physical and chemical processes to turn meals into simple molecules. once in the small intestine, tiny finger-like projections called villi absorb these nutrients through their walls, passing through to the capillaries and getting absorbed into the bloodstream. once the nutrients are in the blood, the circulatory system takes over. the heart pumps this nutrient-rich blood through arteries, which branch into other capillaries that drop off nutrients and oxygen to cells. the cells then use the various molecules to produce energy (ATP), repair damaged structures, and store energy.

digestive system + respiratory system + circulatory system

the digestive system breaks down food into small molecules such as glucose. these nutrients are absorbed in the small intestine. the respiratory system brings oxygen into the body through the lungs. the circulatory system transports both oxygen and glucose in the blood to all body cells. inside the cells, oxygen and glucose are used to release energy through cellular respiration. a waste product called carbon dioxide is produced and carried back to the lungs to be breathed out.

artificial organs

advancements in medical technology have lead to the development of artificial organs or components.

such development vastly improve health outcomes and life expectancies, especially for those waiting on lengthy organ transplant lists.

valves in the heart

valves regulate bloodflow and prevent blood from flowing backwards.

if any of the valves in the heart become faulty, blood could flow backwards making the heart work harder.

consequences of faulty heart valves

faulty heart valves cause the heart to work harder to pump blood. this extra strain reduces the body's oxygen supply and can lead to heart damage (severe issues like heart failure, blood clots, strokes, and abnormal heart rhythms if left unmanaged).

physical symptoms of faulty valves:

• shortness of breath: during physical activity or even while resting or lying down.

• fatigue and weakness: the body doesn't receive the required oxygen and glucose for daily energy needs.

• chest pain: a feeling of tightness caused by the heart muscle working harder than normal.

• dizziness or fainting: caused by disrupted or inadequate blood flow to the brain.

• swelling: fluid retention frequently occurs in the ankles, feet, and abdomen.

artificial heart valves

artificial heart valves mimic natural valve function through a combination of hydraulic pressure and physical design, opening to allow blood to flow forward and snapping shut to prevent backward leakage.

how can an artificial heart mimic the function of a real one?

it uses a mechanical pump system to push blood through the circulatory system, just like the natural heart contracts and relaxes. the device creates rhythmic pressure changes that move blood through arteries and veins, supplying the body with oxygen and nutrients and removing carbon dioxide and waste products. some artificial hearts are powered by batteries or external pumps, which help control the rate and strength of each beat so it matches the body’s needs.

normal vs abnormal electrocardiogram

a normal ECG shows a regular, repeating pattern of electrical activity. one heartbeat has a P, followed by QRS, and then T. the waves are evenly spaced, indicating a normal, steady heart rhythm. at P, the muscle cells of the atria are contracted. after the QRS wave, the ventricles are contracted.

the normal ECG has evenly spaced P, QRS, and T waves that occur in a regular pattern, showing the heart is beating with a normal rhythm. in contrast, the abnormal ECG has an irregular pattern, with uneven spacing between heartbeats and abnormal wave shapes. this suggests that the electrical signals controlling the heartbeat are not functioning normally, which may indicate arrhythmia or another heart condition.