unit2- human body Flashcards
specialised cell
a cell with a particular function
tissue
made of groups of specialised cells working together
organ
made of different tissues working together to do a special job
organ system
made of many organs working together to do a special job
red blood cells
small round and biconcave shape
to absorbs and transfers oxygen
nerve cells
(neurons) long length for transmitting nerve impulses over long distances
sperm cell
tail which allows cell to swim to egg to fertilise it
stem cells
unspecialised cells that can replicate itself or differentiate into many cell types
embryonic stem cells
come from embryos produced during IVF treatment. can become the widest range of specialised cells
adult stem cells
stem cells found in specific tissues which can only give rise to a small variety of specialised cells
the nervous system is made up of
brain
spinal chord
nerves
function of the nervous system
send and receive messages by the specialised cell- neurons
sensory nerves carry the information from -
the sensory organs to the CNS
CNS
central nervous system. sorts information and stores some of it
order of flow of information in the brain
sense organs sensory nerves central nervous system motor nerves muscles + glands
axon
long thin section of a neuron that the information travels along
dendrites
where the nerve cell connects to another. long bits on end
messages that move along the neuron
electrical impulses
electrical impulses get converted into
chemical signals (neurotransmitters)
chemical signals diffuse across the
synapse
space between one neuron and the next
process of a reaction
stimulus to sense organ to sensory neuron to inter neuron to motor neuron to response
reflex arc
tracks the flow of messages to the different nerves from the stimulus through the CNS and to the body’s response
reflex action
transmission of electrical and chemical signals through a reflex arch
rapid, automatic and involuntary
what do reflexes do
protect the body from harm
maintain body’s position
examples of reflex actions
knee jerk impulse
contraction of pupil in bright light
blinking
sneezing
medulla
controls the rate of breathing and heart rate
cerebellum
controls balance and muscle coordination
cerebrum
controls learning, memory, personality, reasoning, control of conscious movement and reactions
touch receptors
detect whenever something touches us
more touch receptors in some parts of the body than others
what does a homunculus do
the size of the different parts of the body are in proportion to the number of sensory neurons that body part has (how sensitive they are)
the endocrine system is
a collection of glands that secrete hormones directly into the circulatory system.
how are hormones specific
target cells (tissues/organs) have receptors (proteins) on their surface which are specific to a particular hormone
endocrine glands release hormones into
the blood stream usually
hormones are
chemical messengers that can be transported around the body in the blood and affect other organs
how do hormones work
secreting cells found in endocrine glands release the hormone into the bloodstream. only cells with specific receptors on their surface will receive the signal
we need hormones because
they maintain stable internal conditions to maintain enzyme activity and metabolism
examples of changes that take place outside of the body
temperature, carbon dioxide/oxygen levels
examples of changes that take place inside the body
blood sugar levels, growth
glucose levels in the blood increase by
eating carbohydrates
glucose levels in the blood decrease by
not eating or exercising
two hormones that control the blood glucose levels
insulin and glucagon
insulin
produced in pancreas
changes glucose into glycogen
reduces blood glucose levels
(glycogen stored in liver)
glucagon
causes stored glycogen changed into glucose and transported in the blood
increases blood glucose levels
the alveoli are surrounded by
a sense network of blood capillaries to increase surface area within the lungs
rings of cartilage are for
strength and allowing the trachea to open whilst also being flexible
mucus - where it’s produced and it’s function
produced in mucus secreting cells that line the trachea and bronchi
small particles that are breathed in are stuck in the mucus
keeps surface of lungs moist
cilia
tiny hairs that cover cells in the trachea and bronchi
move in a wave like motion and cause mucus to flow up from the lungs to the top of the trachea
has exchange
oxygen diffuses through the alveoli into the blood stream. carbon dioxide diffuses from the blood stream into the alveoli
why the lungs are so efficient for gas exchange
large surface area
alveoli and capillary walls are thin so gas diffuses quicker
dense network of blood capillaries that are close to the alveoli ensuring that gases have to travel a small distance so gas exchange is more rapid
intercostal muscle
muscle between the ribs which contract to move rib cage up and out to increase chest volume and pull air into lungs
diaphragm
large muscle below rib cage which contracts to increase chest volume and pull air into lungs
what is the link between the heart and the lungs
the lungs collect the gases to exchange and deliver them to the blood which the heart must circulate
why must the blood be continuously circulated
to allow the exchange of materials between the internal and the external environment
blood vessels
capillaries
veins
arteries
four chambers
right atrium
right ventricle
left atrium
left ventricle
veins =
towards the heart
arteries =
away from the heart
blood is transported to the heart by… (left and right)
left- pulmonary vein
right- vena cava
blood is transported away from the heart by… (left and right)
left- aorta
right- pulmonary artery
order of blood flow
vena cava right atrium right ventricle pulmonary artery lungs pulmonary vein left atrium left ventricle aorta body tissues
what are valves for
valves prevent the backflow of blood into the heart from the arteries and ensures blood only flows in one direction through the heart
why is the muscle on the left side thicker
it needs to contract to pump blood at high pressure around the body. whereas the right ventricle only pumps blood to the lungs so less force is required
the heart requires its own blood supply to ensure
that it obtains all the required nutrients and oxygen for muscular contraction. the heart is supplied w blood through the coronary artery
arteries
transport blood away from heart thick muscular walls blood pumped at high pressure narrow lumen carries oxygenated blood has a pulse
veins
transports blood towards the heart from the other organs thinner muscular walls and a wide lumen contain valves lower pressure carries deoxygenated blood
capillaries
transports blood close to every living cells
walls are one cell thick
exchange vessels because all exchange of materials take place through their thin walls
very narrow lumen
gas exchange takes place
plasma
liquid part of blood
transports soluble food molecules, waste products, hormones, antibodies
white blood cells
part of the immune system
defence
large than RBCs but far fewer of them
phagocytes and lymphocytes
platelets
help the blood clot when there is a wound
phagocytes
non specific
engulf pathogens
lymphocytes
produce antibodies
antibodies
specific to markers on the surface of pathogens
only effective against other pathogens with these markers
pathogens
diseases, viruses
haemoglobin
contains iron and gives red blood cells their colour
can associate with four molecules of oxygen
oxygen transporting molecule within RBCs
when does haemoglobin associate w oxygen
when there is a high conc of oxygen eg in the lungs
when does haemoglobin dissociate w oxygen
when there is a low conc of oxygen eg in body tissues
humans need to eat a balanced diet to
provide energy
allow growth and repair
maintain health
5 main food groups
protein carbohydrates fat vitamins minerals
protein is for
growth and repair
carbs are for
energy and fibre
far is for
storing energy and insulation
vitamins are for
promoting biochemical reactions
glucose builds up to be
starch
amino acids build up to be
protein
fat breaks down into
3 fatty acids and glycerol
digestion is
the breakdown of large complex insoluble molecules into small simple soluble molecules so that they can be absorbed into the blood stream
mechanical digestion takes place in
mouth (teeth)
stomach (contracts to churn food)
chemical digestion takes place in
mouth (salivary amylase and mucus)
stomach (gastric juices)
oesophagus
long thin muscular tube which food travels along
peristalsis
good moves through the digestive system by contractions of two sets of muscles in the walls of the gut.
contract to squeeze food down the oesophagus and intestines
do muscles in stock crush food
no
gastric juices
made by glands in pits within stomach walls
contains pepsinogen which is activated by hydrochloride acid forming pepsin
pepsin
enzyme the catalysed the breakdown of protein into peptides and amino acids
optimum ph= 2
hydrochloride avid
activated pepsinogen to form pepsin. kills bacteria in food. establishes optimum pH for pepsin
mucus (in stomach)
lines stomach protecting it from hydrochloride acid that could break it down
sphincters
rings of muscle in the digestive system. open to allow food to enter and exit
small intestine
where breakdown of food is completed and small soluble food molecules are absorbed into the blood stream
vikki
have a dense network of blood capillaries and a lacteal in each
blood capillaries for glucose and amino acids
lacteal for fatty acids and glycerol
large intestine
absorbs water and salt
liver
produces bile which is stored in the gall bladder
bile
helps in digestion of fats
breaks down fat into smaller globules in a process called emulsification
amylase for
starch into maltose
lipase for
fat into fatty acids and glycerol
pepsin for
protein into amino acids
