organisation in animals 1 Flashcards
the human digestive system, levels of organisation, bile, heart, blood vessels, blood
why is the heart considered to be an organ
organ - group of tissues that work together to perform a specific function
the function of the heart is to pump blood throughout your body
the heart is mainly made up of a type of muscle tissue called cardiac muscle
what tissues make up the stomach and what is the function of each tissue type
stomach - made of mucosa - inner lining on stomach and is made of glands that make mucus, hydrochloric acid and enzymes
mucosa has ridges - rugae - when the stomach is empty (flattens as stomach fills)
surrounding mucosa - submucosa - connective tissue that contains larger blood and lymph vessels, nerve ends & fibres
covering submucosa - muscularis propria that’s the main stomach muscle and is made of 2 fatty layers
covering outside of stomach - serosa that is called the visceral peritoneum
the human digestive system (10)
mouth - teeth break down food and mix it with enzymes in saliva
oesophagus - thin tube that connects mouth to stomach
stomach - muscular bag which mixes food and drink with acid
small intestine - carbohydrates, proteins and lipids digest and nutrients are absorbed into blood
large intestine - non broken down foods pass here and water is absorbed into blood
rectum - undigested food passes here where it’s spread as faeces
anus - opening at the end of the digestive system where faeces leaves the body
liver - releases a chemical called bile into intestines which breaks down lipids
pancreas - releases enzymes into the intestines which breaks down carbohydrates, proteins and lipids in food
gallbladder - stores bile and releases it into the small intestine
levels of organisation (8)
cells - smallest unit of life that shows all 7 characteristics of living things
tissues - groups of similar cells linked together doing the same job
organs - groups of tissues working together to perform a function
organ system - organs working together
organism - groups of systems working together to make one independent living thing
population - groups of individual organisms of the same species
community - different species and the relationships between them
biosphere - relationship between all living and non-living parts of the planet
point of digestion
large food molecules (carbohydrates, proteins, fats) are too big to be absorbed.
physical and chemical digestion break down these large molecules into smaller ones
what is bile
produced in liver and stored in gallbladder
2 main roles:
- neutralises stomach acid as it enters the small intestine to provide correct pH for the small intestine enzymes
- emulsifies (breaks up) fat into smaller fat droplets to provide a larger surface area for lipase enzymes to work on
4 chambers of the heart
two atria at the top and two ventricles at the bottom
upper right and left atria receive incoming blood
the lower, more muscular right and left chambers squeeze and pump blood out of the heart
right side of the heart
pulmonary circulation
- deoxygenated blood from body
- enters heart through vena cava
- drains into right atrium
- flows through tricuspid valve to right ventricle
- blood leaves through pulmonary valve into pulmonary artery
- goes to lungs
left side of heart
systemic circulation
- pulmonary vein carries oxygenated blood from lungs
- blood goes to the left atrium
- through mitral valve blood flows from left atrium to left ventricle
- through the aortic valve into the aorta the blood then leaves
- flows to rest of body
blood flow in terms of veins and arteries
blood is pumped TOWARDS the heart in veins and AWAY from the heart in Arteries
why is the left ventricle wall more thick than the right ventricle wall
the left ventricle has to pump blood all around the body at a high pressure
the right ventricle pumps blood at a lower pressure to the lungs (closer to the heart)
what is self-regulating
when something doesn’t require messages from anywhere to keep it going – heart
pacemaker cells
the heart has pacemaker cells in the right atrium which create electricity
these signals cause the muscular walls of the ventricles to contract (to beat)
if someone’s heart doesn’t beat as it should, they can be fitted with an artificial pacemaker
describe and explain an artery
- circular shape
- two layers
- small lumen (inner hole)
- thickk layer of muscles and elastic fibres
- outer thick-ish wall
–>needs thick, muscular, elastic walls to carry blood under high pressure
–> small lumen expands when blood forces through
describe and explain a vein
- triangular shape
- two layers
- large lumen (inner hole)
- thin layer of muscle and elastic fibres
- fairly thin outer wall
–> needs thinner, less muscular walls than arteries as they carry low pressure blood
–> they have a bigger lumen than arteries
–> they have valves to protect backflow of blood
