Unit 3: Digestion, Circulation, and Gas Exchange Flashcards
How many functions are there in the digestive system?
4
What are the 4 functions of the digestive system?
- ingestion
- digestion
- absorption
- assimilation
Ingestion (2)
- the act of taking food into the body
- done through mouth
Digestion (4)
- begins in the mouth
- breaking down of large food molecules into smaller ones by enzymes in saliva glands
- tongue forms food into an oval shape
- food goes down the esophagus
Esophagus
made of muscles that allow for food to go down to stomach
Why is digestion necessary?
nutrient molecules need to be made small enough so absorption can take place and the organism can get energy and build its tissues
Absorption
nutrients are broken into molecules that go into the blood stream
Assimilation
nutrients become a part of the tissue
What are the structures of the digestive system? (8)
- mouth
- esophagus
- stomach
- small intestine
- large intestine
- liver
- pancreas
- gallbladder
How many main digestive enzymes are there?
3
What are the main digestive enzymes? (3)
- amylase
- pepsin
- lipase
Where is amylase located?
salivary glands
Where is pepsin located?
stomach wall
Where is lipase located?
pancreas
What is the substrate to amylase?
starch
What is the substrate to pepsin?
proteins
What is the substrate to lipase?
triglycerides
What is the product of amylase?
small maltose
What is the product of pepsin?
peptides
What is the product of lipase? (2)
- fatty acids
- glycerol
What is the optimum pH for amylase?
7
What is the optimum pH for pepsin?
1.5
What is the optimum pH for lipase?
7
Stomach (2)
- responsible for storing food and digesting proteins
- acidity is very low, so it also destroys many food born pathogens
What is after the stomach?
the small intestine
What is at the beginning of the small intestine?
the duodenum
Duodenum
connected to the liver, gall bladder, and pancreas where the liver and pancreas release bile salts and the pancreas releases enzymes
What pancreatic enzymes are released? (3)
- pancreatic lipase
- pancreatic amylase
- trypsin
What does the occurrences of the duodenum allow for?
food to be further broken down into chyme
Large Intestine (colon)
responsible for reclaiming water and removing solid waste
What can lead to colon cancer? (3)
- not eating enough fiber
- less activity
- little liquid
Small Intestine (3)
- responsible for more digestion, and absorption of nutrients
- 25 ft
- food becomes chyme here, any food that move past the small intestine becomes waste
Why does it take longer for lipids to be digested in the small intestine?
lipids and fats stick together in clumps
Emulsification (3)
- breaking of fat clumps into tiny droplets
- allows for increased surface area for catalysis by lipase
- nutrients are then absorbed by small intestine
What allows for the emulsification of fats?
bile salts from the liver and gall bladder
What structure is directly linked to the absorptive function of the small intestine?
the villi
Villi (2)
- small, fingerlike projections increase the surface area available for absorption
- the villi are further folded into microvilli, further increasing surface area
What is right under the villi?(2)
- blood vessels
- allows for food to be absorbed actively through a membrane
Why is a single layer of epithelial cells over the villi helpful?
nutrients are able to easily pass through the membrane
Why are many mitochondria in the single epithelial layer of the villi?
they are needed for active transport of amino acids and large carbohydrates
Where do fats and cholesterol go?
into the lymph system
Goblet Cells (2)
- secrete mucous that capture food and lubricate the intestinal wall
- located on villi
Peristalsis (2)
- involuntary smooth muscle contraction all through digestive system, happens with circular and longitudinal muscles
- prevents backflow
How many functions the liver perform?
5
What are the functions of the liver? (5)
- storage of nutrients - glycogen
- break down of red blood cells
- secretion of bile for fat emulsification
- production of cholesterol
- breakdown of toxic substances
How do we store glucose?
in glycogen
How does lipase aid in breaking down fat clumps?
it breaks down the outer part of the fat clumps
What are examples of the assimilation of nutrients into tissue? (3)
- glucose is assimilated in the body then stored as glycogen in the liver and skeletal muscles
- proteins are assimilated into the body and the amino acids contribute to muscles
- triglycerides are broken down into fatty acids then, stored in fat tissue
What is the circulatory system made up of? (2)
- heart
- blood vessels
What does the heart do as it pumps blood?
contract and relax
What is the direction of blood flow? (15)
- vena cava
- right atrium
- AV valve
- pulmonary artery
- lungs
- pulmonary vein
- left atrium
- AV values
- left ventricle
- semilunar valve
- aorta
- arteries
- tissue
- veins
- vena cava
How does blood move through the heart?
the blood with less oxygen goes to the lungs, then the heart pumps the oxygen rich blood to the rest of the body
Coronary Arteries
supply the heart itself with oxygen and nutrients that allow for waste to be expelled
Why does the heart need coronary arteries?
- oxygen is needed by the heart muscle cells because they need a lot to be able to pump as much as it does
- oxygen is needed for cellular respiration
How do heart attacks happen?
coronary arteries are clogged with plaque
What are ways to fix the effects of a heart attack? (3)
- altering diet
- taking medicine
- bypass surgery
What is the structural difference between the left and right side of the heart?
the walls of the left side are thicker than the right
Why is the left side of the heart thicker than the right?
the left side must pump blood to the rest of the body
Why are valves one way?
it allows for blood to pump in one direction
Atria
collect blood
Ventricles
pump blood
Arteries
carries blood away from the heart
Veins
bring blood back to the heart
Capillaries
exchange gasses between tissues and blood
Valves
one way gates regulating volume of blood flow
What is the function of blood?
to carry oxygen and CO2, as well as nutrients, to tissues
What is the composition of blood? (4)
- red blood cells
- glucose
- hormones
- oxygen
How many types of blood vessels are there? (3)
- arteries
- veins
- capillaries
Arteries
carries blood away from the heart
What provides the force to move blood through the arteries?
the left ventricle
What are some characteristics of arteries? (5)
- high pressure
- thick walls
- made of elastic and fibrous tissue
- small lumen
- the ability to expand and contract
Why is blood pressure higher in the arteries?
the arteries compress the blood
How is high pressure developed in the arteries? (2)
- thick layer leave little space for the blood, which creates pressure
- high volume & low space = pressure
Why is blood able to move forward in arteries?
there is more blood behind it
What happens to blood in the arteries as you go further from the heart?
The volume of blood gets smaller
Veins
move blood towards the heart
What are some characteristics of veins? (4)
- thin walls
- low pressure
- have valves
- no elastic or fibrous tissue
Where are veins typically located?
between skeletal muscles
How is blood moved through the veins?
when the skeletal muscles contract, blood is pushed through
Why is pressure low in veins? (2)
- walls are thin
- lumen is large
Capillaries (2)
- small and numerous, branch from arteries and veins
- capillaries penetrate tissues in order to exchange oxygen and CO2
What are some characteristics of capillaries? (4)
- have a single layer of cells
- branch out
- regulate blood pressure
- regulate body temp
Why is it helpful that capillaries have a single layer of cells?
single layer of cells which allow the gasses to easily diffuse through the surrounding fluid
Why is branching helpful in capillaries? (3)
- provide greater surface area
- small size creates pressure gradient
- easy to clot if damaged
Myogenic
the heart is able to beat involuntarily where it beats independently and causes its won contraction
What is unique about the heart? (2)
- it has its own bundle of nerves
- it is myogenic
Sinoatrial (SA) node
- located in the right atrium of the heart and serves as a pacemaker
- it sends out an electrical signal which causes contraction first in the atria then in the ventricles
How does the brain control the heart?
through releasing hormones such as epinephrine which speeds up the heart rate
Blood Pressure
measures the pressure exerted on arterial walls
Systolic
the high blood pressure, when ventricles contract and blood is forced through the arteries
Diastolic
the lowest pressure, when the ventricles are refilling with blood
Hypertension
high blood pressure
What are some causes of high blood pressure?
less space in the blood vessels
What can cause for there to be less space in blood vessels?(3)
- high cholesterol
- salts
- saturated fats
Hypertension (2)
- low blood pressure
- blood cannot deliver oxygen as fast
- individuals with it have poorer circulation
Atherosclerosis
the hardening of the arteries due to plaque buildup, and blockage of the flow of blood
What can be the result of atherosclerosis? (2)
- chest pain
- heart attack
What are common causes of heart issues? (3)
- smoking
- high cholesterol diet
- high blood pressure
What are some respiratory diseases? (3)
- cystic fibrosis
- pneumonia
- lung caner
What are components of the ventilation system? (6)
- trachea
- bronchi
- bronchioles
- lungs
- alveoli
- diaphragm
Process of Ventilation
- Nose
- Mouth
- Trachea
- Bronchi
- Bronchioles
- Alveoli
What happens at the alveoli?
oxygen is exchanged with CO2
How does breathing occur? (2)
- negative pressure
- pulled down the trachea into the lungs
Inhalation
ribcage is lifted by external intercostal muscles, while the diaphragm contracts, abdominal muscles open
What happens to pressure and and volume during inhalation? (2)
- volume of lungs increase, so pressure drops
- air is brought into the body from outside where pressure is higher
Exhalation
ribcage drops as internal intercostal muscles contract, and the diaphragm relaxes, abdominal walls collapse inward
What happens to pressure and volume during exhalation? (2)
- lung volume decreases, so pressure rises
- air flows out the body to area of low pressure
Gas Exchange
- the process which takes place in the alveoli, oxygen is exchanged for CO2 in the blood
- CO2 is generated by cellular respiration, oxygen is needed in order to generate adequate amounts of ATP
Ventilation (2)
- simply breathing
- getting rid of CO2 filled air and bring in oxygen rich air
Why is the respiratory system necessary?
so cells have adequate amounts of oxygen for cellular respiration
What is breathing rate mainly controlled by? (3)
- CO2 levels
- High CO2 levels will decrease pH
- the brain will send a signal to regulate this
What are characteristics of the alveoli? (4)
- spherical
- single celled walls
- thin coating of liquid
- surrounded by capillary beds
Why is the structure of the alveoli helpful?
it increases surface area for gas exhchange
Why is a single celled alveoli layer helpful?
so gasses can easily diffuse through
Why is the alveoli being covered in a thin coating of liquid helpful?
it enhances the dissolving and diffusing of gasses
Why is being surrounded by capillary beds helpful to surrounding alveoli?
it ensures easy passage of gasses
Type 1 Pneumocyte
cells that are thin, and adapted for gas exchange
Type 2 Pneumocytes
cells that secrete surfactant, which helps keep the alveoli from collapsing
What to alveoli do as they fill with air?
expand and contract
What resides in the alveoli?
immune cells
