Transcript Humans as Organisms

Humans as Organisms
Contents
Nutrition
 Digestive System
 Circulatory System
 Breathing
 Respiratory System
 Aerobic Respiration
 Anaerobic Respiration
 Nervous System
 Hormones
 Homeostasis
 Disease
 Drugs
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Nutrition
The main food types are:
Carbohydrates (sometimes referred to as Starch) are required by our bodies
as a source of energy. Example of food which carbohydrates can be found in are
pasta, potatoes and rice.
Fats are needed to insulate our bodies and to make cell membranes. They also
contain fat-soluble vitamins. Example of food which fats can be found in are
cheese, butter, oils and margarine.
Protein are required for growth and repair. Examples of food which contain
protein are meat, fish, eggs and cheese.
Fibre is important because it allows the muscles in our intestines to move the
material along (called peristalsis). Fibre is not digested in our diet. Examples
of food which contain fibre are wholemeal products e.g. bread, fruit and
vegetables.
Digestive System
The food we eat needs to be broken down into small pieces which we chew up
into even smaller ones before swallowing them. Once the food gets to the
stomach the food is broken down further by the stomach's muscular walls. This is
known as physical digestion.
Substances which our body needs cannot be absorbed into our blood until they
have been broken down further and converted into small soluble chemicals.
Enzymes are responsible for this process. This process is called chemical
digestion.
Peristalsis is the movement of food through the digestive system by the
contractions of two sets of muscles in the walls of the gut. The two sets of
muscles produce wave-like contractions enabling food to move down the gut.
Carbohydrate is turned into glucose, which our bodies need to make energy.
Protein is turned into amino acids, required for cell growth and repair.
omach produces
se, HCl and pummels
th muscular walls
Digestive System1. Chemical
Digestion starts in
the mouth through
enzymes and saliva.
The food is then
moved to the
stomach
The Pancreas
produces enzymes:
2. The Small Intestine
receives the food next
and produces protease
and lipase, food is
absorbed into blood,
large surface area by
villi
3. Large
Intestine (Colon)
is where
indigestible food is
passed to. Any
Villi
Villi are small projections covering the inside
walls of the small instestine. Food products pass
into the blood stream through the villi.
Villi are located in the small intestine, and absorb
very small molecules into the blood stream
All other molecules (indigestible) are passed into the large intestine
Circulatory System
The heart is a four-chambered muscular pump which pumps blood round the
circulatory system. The right side of the heart pumps de-oxygenated blood to the
lungs to pick up oxygen. The left side of the heart pumps the oxygenated blood from
the lungs around the rest of the body.
1. Deoxygenated blood enters through the vena cava into
the right atrium
2. It’s then pumped through a valve into the right
ventricle chamber
3. And then up through the pulmonary valve into the
pulmonary artery towards the lungs
4. Oxygenated blood enters through the pulmonary
veins into the left atrium
5. It’s then pumped through a valve into the left
ventricle
6. And then through the aortic valve and out of the
aorta to the rest of the body
How the Blood is Transported
Arteries (thick walled muscular
tubes) carry blood away from
the heart at high pressure in
thick walled lumen
Capillaries (very narrow
tubes) have thin walls to
allow glucose and oxygen to
diffuse through
Veins (thin walled tubes) carry low pressure blood
back to the heart. Veins have thinner walls and
valves to prevent backflow of blood
Breathing
When we breathe in and out we suck air into them then expel it again. Oxygen is
absorbed from the lungs into the blood, and carbon dioxide is removed from the
blood and breathed out from the lungs. This exchange is vital
Alveoli
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Alveoli are the final
branchings of the respiratory
tree and act as the primary
gas exchange units of the
lung
Used for exchanging gases:
Deoxygenated enters lungs
from body, oxygenated enters
capillaries from lungs
Advantages of alveoli:
Moist
Large surface area
Good blood supply
Respiratory System
Respiration is the release of energy from
glucose or other organic substances.
Energy is required for growth, repair,
movement and other metabolic activities.
There are two main types of respiration,
aerobic and anaerobic.
Aerobic Respiration
Aerobic respiration takes place in the presence of oxygen. Glucose molecules react
with oxygen molecules to form carbon dioxide and water molecules, with energy
being released by the breaking of bonds in the glucose molecules.
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Our bodies require energy for the seven life processes
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This energy is obtained from respiration
glucose + oxygen  water + carbon dioxide + energy
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Glucose comes from our food, oxygen from breathing
Water and carbon dioxide are exhaled
Anaerobic Respiration
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Anaerobic respiration occurs when oxygen is not
available. Glucose is only partially broken down, and lactic
acid is produced - together with a much smaller amount of
energy.
Energy can still be produced without oxygen
Only a little bit of energy is obtained from respiration
glucose  lactic acid + energy
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Anaerobic respiration occurs in humans when oxygen is not
obtained quick enough (e.g. running fast)
Only 1/20th energy amount is produced compared to aerobic
Lactic acid builds up, which causes muscle fatigue due to
oxygen debt
Nervous System
The nervous system is a means of gathering information about, and responding to,
changes in the environment either inside or outside the body.
The nervous system is made up of receptors which respond to stimuli and pass on
information about them. The central nervous system co-ordinates the information
and responds by sending signals to the effectors, which bring about a response.
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e.g. you walk into a bright room
Stimulus  receptor  CNS  effector  response
So…
Light intensity  eye  brain  eye muscles receive
information  eye muscles make pupil smaller
Electrical signals are carried around the body along neurones
Neurones
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There are 3 neurones:
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Sensory – carry signals from sense organs to brain
Relay – carry messages from one part of CNS to another
Motor – carry signals from CNS to muscles
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Reflex Arc
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The subconscious movement from a stimulus that can
cause harm e.g. a bee sting
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The reflex arc does not require a conscious action, which
might be too slow
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So… the brain is bypassed…
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Stimulus  receptor  effector  response
Hormones
The endocrine system
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Hormones help to
regulate metabolic
processes in the body
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Hormones are secreted
into the blood through
endocrine glands
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They travel in the blood
to organs where they
take effect
Hormone
Gland
Action
Anti-diuretic hormone (ADH)
Pituitary gland
Controls blood water level by
triggering uptake of water in
kidneys
Follicle stimulating hormone
(FSH)
Pituitary gland
Triggers egg ripening and
oestrogen production in ovaries
Luteinising hormone (LH)
Pituitary gland
Triggers egg release and
progesterone production in
ovaries
Thyroxine
Thyroid gland
Controls metabolic rate
Adrenaline
Adrenal gland
Prepares body for action (fight
or flight)
Insulin
Pancreas
Controls blood sugar levels by
increasing uptake of glucose
Glucagon
Pancreas
Controls blood sugar levels by
decreasing uptake of glucose
Oestrogen
Ovaries
Controls puberty and the
menstrual cycle in females;
stimulates production of LH
and suppresses production of
FSH in pituitary
Progesterone
Ovaries
Maintains womb-lining;
suppresses FSH production in
pituitary
Testosterone
Testes
Controls puberty in males
The Menstrual Cycle
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Four hormones are involved: The Key stages are
1. The egg ripens in the ovaries - stimulated FSH
Oestrogen
2. Womb lining build-ups - stimulated by Oestrogen
3. Egg is releases - stimulated by the LH (about day 14)
Progesterone
4. Maintenance of uterus lining - stimulated by
progesterone
FSH (Follicle stimulating hormone )
5. Uterus lining breaks down - caused by low levels of
oestrogen and progesterone
LH (Luteinising hormone )
6. Blood and tissue loss (menstruation)
Homeostasis
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Homeostasis is the body’s method of controlling the
internal conditions
Controlling Temperature
– Too hot?
 1. Our hairs lie flat so we let more body heat out
 2. We sweat and the evaporation of this cools us down
 3. Increased blood flow occurs through the skin to radiate out heat
– Too cold?
 1.Our hairs stand up trapping a layer of air which acts like an
insulator
 2. We stop sweating stopping the heat loss by evaporation
 3. Decreased blood flow occurs through the skin
Homeostasis
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Controlling Blood Sugar Level
– Blood Glucose level too high?
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Insulin injected by pancreas
Glucose absorbed by tissues
Glucose absorbed by liver
Blood glucose reduced
– Blood Glucose level too low?
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Insulin not injected by pancreas
Less glucose absorbed by tissues
Less glucose absorbed by liver
Blood glucose increased
Diabetes – This is a condition where people who suffer from this do
not make insulin so it needs to be injected
Homeostasis
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Controlling Body Water
– Too much water?
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Hypothalamus (part of brain) detects too much water in blood
Pituitary gland releases less ADH
Kidneys absorb more water from blood
More water reaches bladder and is lost through urine
Blood water level returns to normal
– Too little water?
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Hypothalamus (part of brain) detects too little water in blood
Pituitary gland releases more ADH
Kidneys absorb less water from blood
Less water reaches bladder and is lost through urine
Blood water level returns to normal
Fighting Infection
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Microbes (an organism too small to be seen by the naked
eye) can enter the body through the mouth, nose and cuts
or bites in the skin
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Microbes (bacteria and viruses) can cause diseases
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Two types of white blood cell:
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Lymphocytes – engulf pathogens
Phagocytes – contain antibodies
White blood cells do 3 things:
Engulf the microbe
Produce antibodies to neutralise the microbe
Produce antitoxins to neutralise the toxins released by the
microbe
Tobacco & Smoking
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Cigarettes are harmful in three ways:
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Nicotine – addictive drug that leads to heart disease.
Nicotine raises blood pressure and narrows arteries
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Tar – coats the lining of the lungs  less O2 is absorbed.
Tar contains carcinogens which cause cancers
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Carbon monoxide – poisonous gas which joins onto red
blood cells making them incapable of transporting
oxygen around the body
Drugs
Drug type
Example
Effect
Stimulants
Caffeine, nicotine
Increased alertness
Sedatives
Alcohol,
tranquilisers
CNS slowed
Painkillers
Aspirin, morphine
Suppress pain receptors &
neurones in CNS
Hallucinogens
LSD, cannabis
Feeling of enormous energy,
hallucinations
Alcohol
Alcoholic drinks
Lowers inhibitions, slowed
CNS and reaction times
Solvents
Glue, paint, fuel
Distorted perception,
hallucinations
Summary
Food is digested  v small molecules are absorbed into blood
 The heart pumps oxygenated blood to the body, and
deoxygenated blood to the lungs
 Organisms inhale oxygen and exhale CO2
 Organisms respire to produce energy required to survive
Glucose + oxygen  water + carbon dioxide + energy
 Anaerobic respiration produces energy without oxygen
Glucose  lactic acid + small amounts of energy
 Stimulus  receptor  CNS  effector  response
 Hormones help regulate the body’s metabolic rate
 The body controls: water, temperature, glucose content by
homeostasis
 The body’s white blood cells fight disease
 The body is affected in different ways by many types of drug
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