Studied by 13 peopleWhat 6 nutrients do we need as humans?
Carbohydrates, proteins, lipids, minerals, vitamins, and water
What is the difference between endothermic and ectothermic animals?
Endothermic - regulate their own body temperature (warm-blooded), requires more energy but can live in any kind of environment
Ectothermic - depend on outside conditions to regulate body temperature (cold-blooded), don’t need to eat as often
What are some factors that affect energy requirements? How?
Being endothermic: requires energy
Age: decreases with age
Body size: takes more energy to move
Sex: males tend to require more energy due to larger bodies
Activity level: muscles require more energy than fat
Hereditary factors
What is your metabolic rate? What is metabolism?
Metabolic rate: the rate at which an individual converts stored energy into working energy
Metabolism: the set of chemical reactions that occur in living organisms necessary to maintain life
What is the Basal Metabolic Rate? What is one flaw?
Your individual basic energy requirements to maintain a body at rest. It does not account for muscle vs fat percentage.
What are some of the basic functions of carbs, proteins, and lipids?
Carbs:
main source of energy
glucose is needed in cellular respiration
Protein:
building block of cells
muscle repair and movement
important in metabolic activities
may serve as hormones
Lipids:
building block of cell membranes
thermal insulation for body
concentrate source of energy
help absorb fat soluble vitamins (A,D,E, and K)
may serve as hormones
What are the three kinds of carbohydrates? How are they different?
Monosaccharides (one sugar), disaccharides (two sugars), polysaccharides (multiple sugars)
What are some important kinds of polysaccharides?
Starch (amylose), cellulose (provides fiber), and glycogen (can be broken down into glucose)
What are proteins made of?
Long chains of amino acids
Describe the two sources of protein.
Animal sources: animal proteins contain all essential amino acids, sources are meat, fish, eggs, cheese
Plant sources: most plant proteins lack at least one essntial amino acids, must eat in greater amounts and variety than animal sources, sources are beans, lentils, nuts, seeds
Why must proteins be broken down into individual amino acids during digestion?
To be rearranged and use as building blocks for human proteins
What are the building blocks of lipids? Explain saturated vs unsaturated lipids
Triglycerides are building blocks of lipids.
Chains of triglycerides can be either saturated or unsaturated.
Saturated lipids: chains are single bonded and straight, so that they have a dense structure that creates plaque build up in your arteries, contain LDL cholesterol
Unsaturated lipids: double bonded chains, can be broken down, contain HDL cholesterol
What are steroids? Mention two kinds of steroids
Steroids are a special group of lipids. Sex hormones (estrogen/testosterone) and cholesterol are kinds of steroids
What is the difference between HDL and LDL cholesterol?
HDL: high density, absorbs LDL cholesterol, in unsaturated fats
LDL: low density, plaque build up in arteries, leading to heart disease, in saturated fats
Why is water important in our bodies?
Bodies are 55-60% water
Water is needed for:
chemical reactions
digesting food
eliminate waste products
regulate body temp
keep skin moist
What are vitamins? What are their functions? How do we store and eliminate them?
Vitamins are organic molecules required in small amounts by the body.
Function: regulate cell functions, growth, and development
Vitamins may be either fat soluble or water soluble
Fat soluble: can be stored in the body’s fatty tissue, so will not be eliminated easily
Water soluble: cannot be stored, will be excreted in urine if in excess
What vitamins are fat soluble? Which are water soluble?
Fat A,D,E, & K
Water B & C
What vitamins can be produced by the body?
Vitamin A (body converts from food)
Vitamin D (body converts from sunlight)
Vitamin K (synthesized by bacteria in the stomach)
What are minerals? What is their function? Mention most important ones + function
Minerals are elements needed in small amount by the body
Function: role in cell processes and repair
Most important ones:
Calcium and phosphate: formation and maintenance of bones
Sodium and potassium: nerve transmission and muscle contraction
Iron: key component of hemoglobin (oxygen transmitter)
What is the body mass index? What are some flaws?
Ratio of height vs mass
What are the four steps of digestion? Explain
Ingestion: taking in of nutrients
Digestion: chemical and physical breakdown of complex food molecules into smaller molecules
Absorption: the transfer of digested nutrients from the digestive system into the bloodstream
Egestion: the removal of waste from body
What are the two parts of metabolism?
Anabolism (metabolic reactions to produce larger molecules from smaller molecules for repair and growth) and catabolism (break down of larger molecules into smaller ones)
What are the two types of digestive systems? Which ones do humans have? Explain each
Incomplete digestive system:
one sac-like cavity, where food is placed
cells in lining absorb nutrients
nutrients diffuse through body
less effective in nourishing body
Complete digestive system:
two openings, tube-like digestive cavity
Food enters through mouth, travels thru the esophagus, broken down in stomach, absorbed in intestine, any undigested waste is eliminated thru the anus
How is the digestive system related to other systems?
Muscoskeletal: bones and muscles allow individuals to catch, ingest, and digest food
Circulatory system: nutrients are transferred into capillaries and arteries to be delivered throughout the body
Nervous and Endocrine: regulate the actions of the digestive system
Explain the digestion in the mouth
Salivary glands produce saliva at the sight, smell, or taste of food
Saliva contains amylase, which begins to break down carbs (continues in small intest)
As food is chewed and broken down by saliva, it turns into bolus
Types of teeth:
flat: grind and crush food (often plant matter)
sharp: cut food (often animal matter
Explain mechanisms that prevent choking
Soft palate rises to seal nasal passages
Tongue pressure prevents backwards movement of food during swallowing
Larynx seals trachea with epiglottis
What mechanism moves bolus down the esophagus? Define it
The rhythmic wave-like contractions of smooth muscle, called peristalsis
What are sphincters? What are the two stomach sphincters called + functions?
Sphincters are round muscles that contract or relax to control the movement of matter
The cardiac sphincter controls the passage of food from the esophagus into the stomach and prevents gastric juices from flowing into the esophagus
The pyloric sphincter controls the amount of food that passes into the duodenum, to not overwhelm the small intestine
What is chyme?
The name given to food in a semisolid state once it is mixed with gastric juices in the stomach
What are the four layers of the stomach + functions?
Mucosa: ridged tissue lining the stomach; secretes gastric juices AND mucus (protect the lining of the stomach from gastric juices)
Submucosa: contains capillaries and nerves
Muscularis: three layers of muscle in the stomach, to churn chyme
Serosa: smooth outside lining of the stomach, secrete lubricating fluid to prevent friction with other organs
Describe how gastric juices are released + the relationship with protein digestion
Nerves in the stomach detect presence of food, cause hormone gastrin to signal the mucosa to release gastric juices (pH of 2).
Gastric juices disable amylase, but activate pepsin
Pepsin breaks down proteins in acidic conditions, breaking them down into amino acids
Explain the safety mechanism behind pepsinogen vs pepsin
Pepsinogen is the inactive enzyme form of pepsin, which is only activated into pepsin under acidic conditions. This is an important safety mechanism because it ensures that pepsin, the protein digesting enzyme, is only at work in the presence of foods, when there are gastric juices. If pepsin was active all the time, it would digest proteins in the stomach itself.
What are stomach ulcers? What causes them? How are they treated?
Stomach ulcers are open sores in the stomach lining. They are caused by the bacteria H. Pylori, which can survive gastric juices by producing a neutralizing agent. This bacteria inhibits mucus-producing cells, causing a sore in the linign due to burning acid
What are the three sections of the small intestine?
Duodenum: most enzymes and hormones are added to chyme, digestion begins
Jejunum: most digestion occurs, some absorption
Ileum: most absorption occurs here
Explain how the surface area of the small intestine is maximized
The small intestine has ridges covered in small finger-like projections called villi, which are then also covered in similar, smaller projections called microvilli. This increases the SA by 500x
What are lacteals? What are capillaries? Explain relationship to absorption
Lacteals and capillaries are small blood vessels within villi that absorb nutrients. Capillaries absorb most nutrients, lacteals are part of the lymphatic system and absorb digested fats
What are accessory organs?
Organs key to the digestive system by secreting fluids, but that do not come into direct contact with bolus or chyme. Are the pancreas, liver, and gallbladder
Describe the structure and placement of the pancreas
Spongy and elongated, looks like cottage cheese
Sits behind the stomach
Connected to the duodenum by the pancreatic duct
What are the two functions of the pancreas?
Secretes pancreatic juice to aid digestion; mixture of water, digestive enzymes, bicarbonate, and hormones
Regulates blood sugar by secreting insulin and glucagon
What two hormones control the pancreas and liver? Explain
CCK hormone:
is released in response to fat
signals the pancreas to release substances including enzymes needed for digestion
signals the stomach to slow down movement of chyme into duodenum so fats can be properly digested
stimulates the gallbladder to contract, releasing bile into the duodenum
Secretin:
released in response to acidic chyme
stimulates pancreas to release bicarbonate into duodenum to neutralize chyme
this protects small intestine from acidic gastric juices
stimulates flow of bile from liver to gallbladder
How are proteins digested in the small intestine?
Because pepsin is only active in acidic conditions, it is neutralized by bicarbonate ions in the SI. At this point, trypsin (enzyme) is also released into the duodenum by the pancreas, to continue to digest proteins
How are lipids digested in the small intestine?
Bile is released into the duodenum from the gallbladder, and it emulsifies fats. This breaks them down into smaller droplets, giving the enzyme lipase more surface area to digest them.
What are the functions of the liver?
Produces bile to help digest lipids
Filters out toxins
Produces glycogen and fat-soluble vitamins
Describe the movement of bile
Produced in the liver
Moves through hepatic ducts
Moves through common hepatic duct
Moves through cystic duct
Enter gallbladder
Bile is squeezed out of gallbladder by CCK
Moves through cystic duct
Moves through common bile duct
Enter duodenum
What are the two kinds of transport mechanisms?
Passive transport: movement of small particles with their concentration gradient through diffusion or facilitated diffusion (using channels); requires NO ENERGY
Active transport: movement of large particles against their concentration gradient; requires ENERGY
How can the names of the small and large intestine be misleading?
Because the small intestine is longer, but the large intestine has 2-3 the diameter of the small intestine
What are the different parts of the large intestine?
Ileocecal sphincter, cecum, appendix, ascending colon, transverse colon, descending colon, sigmoid colon, rectum, and anus
What is a gut biome?
The collection of bacteria present in the intestines, which facilitate digestion, as well as produce important substances, like vitamins A & K, as well as serotonin. This is a symbiotic relationship, as the bacteria are given a suitable environment and plentiful food supply.
What is the function of the large intestine?
By the time chyme reaches the large intestine, most nutrients and water have been absorbed
Any remaining water is absorbed by the large intestine, turning chyme into fecal matter
Vitamins B and K, minerals sodium and chloride are also absorbed
How are indigestible foods important?
They provide bulk and provide full feeling
Retain water in large intestine to help egestion
If not enough fiber → not enough water → constipation
If too much fiber → too much water retained → diarrhea
How is defecation controlled?
Nerves in rectum detect movement of feces, and signal to the brain
Internal sphincter in anus is smooth and involuntary
External sphincter in anus is skeletal and voluntary
What is an endoscopy?
A procedure that uses an endoscope to look inside the body, by entering through the mouth, anus, or incision
What are some of the hormones and enzymes involved in digestion?
Name + type | Location (action) | Response to + function |
Amylase (enzyme) | Added in mouth, stops in stomachs, starts again in SI | Breaks down carbs |
Pepsin (enzyme) | Becomes active in stomach under acidic conditions | In response to acidic conditions; breaks down proteins in stomach |
Trypsin (enzyme) | Small intestine | Breaks down proteins into amino acids after pepsin is no longer active |
Lipase (enzyme) | Small intestine | Breaks down lipids |
CCK hormone | Small intestine | Response to lipids in duodenum; signals pancreas to release digestive enzymes into duodenum, signals stomach to slow down flow of chyme, and makes gallbladder release bile |
Secretin (hormone) | Small intestine | Response to acidic chyme; signals pancreas to release bicarbonate to neutralize acid in duodenum and stimulates bile from liver to gallbladder |
What is aerobic cellular respiration? What is produced?
series of chemical reactions that occur in the mitochondria of cells that require oxygen to produce ATP energy.
What is phosphorylation?
the formation of ATP energy when the breakdown of glucose is used to attach a phosphate group onto a molecule called ADP (adenosine diphosphate)
What does ATP energy stand for?
Adenosine triphosphate
For each molecule of glucose that undergoes respiration, how many molecules of ATP are formed?
36 molecules
How does oxygen get to body cells in simple organisms vs complex organisms?
Simple organism: oxygen moves from environment into cells through diffusion
Complex organism: have special organ systems that supply oxygen to all parts of the body. ALSO REQUIRES DIFFUSION
What is ventilation?
a process moving oxygen rich air into the lungs and carbon dioxide away from the lungs
What is gas exchange?
a process moving oxygen into the blood/cells and moving carbon dioxide out of the blood/cells
How do gas exchange and ventilation work together for aerobic cellular respiration? How are they different?
Ventilation: moves oxygen into lungs and carbon dioxide out of lungs
Gas exchange: brings oxygen to the blood stream and into the cells, and takes out CO2 from the cells and into the blood stream
Ventilation enables gas exchange by providing oxygen and moving CO2 out of lungs
They work together to provide oxygen to the cells so that mitochondria can perform phosphorylation, and take out the byproduct of CO2
Label
Nasal passage
Oral cavity
Larynx
Pleural membranes
Right bronchi
Diaphragm
Pharynx
Trachea
Left bronchi
Bronchioles
Alveoli
What are four important structural features of the mammalian respiratory system?
Thin permeable respiratory membrane through which diffusion can take place
Large surface area for gas exchange
A good supply of blood (capillaries)
Breathing system for bringing oxygen rich air into the respiratory membrane
Describe the adaptations of the nasal passage
has turbinate bones for more surface area
warms the air to body temperature
adds moisture to make it easier for oxygen to dissolve
hair and mucus filter out bacteria and airborne particles
What are some of the important adaptations of the human respiratory system?
Nasal passage, epiglottis, larynx, trachea, bronchi, bronchioles, alveoli, capillaries
What is the epiglottis? What function does it serve?
small flap that the trachea presses against when food is in the trachea; prevents choking by stopping food from entering the trachea
Describe the larynx
the voice box; allows for production of sound (communication of ideas, concepts, emotions)
Describe the function of the trachea
connects nasal and oral cavities to lungs; lined w rings of cartilage to prevent collapse; lined w mucus and cilia to trap airborne particles
What is the function of cilia? Where are they located?
small hair-like structures, located in trachea, bronchi, bronchioles; wave-like motion helps to trap and sweep out airborne particles
Describe the bronchi and the bronchioles
Bronchi:
one in each lung
branch off the trachea into each lung
reinforced by cartilage
lined with cilia and mucus
Bronchioles:
smaller tubes branching off bronchus
reinforced by cartilage
lined with cilia and mucus
Describe the alveoli
microscopic air sacs
surrounded by capillaries
lots of surface area to maximize absorption
gas exchange occurs thru one-cell thick walls of alveoli
NO CARTILAGE
Describe the pulmonary capillaries
microscopic blood vessels wrapped around alveoli
contain plasma and red blood cells
red blood cells contain hemoglobin to carry oxygen and pick up CO2 from cells
Describe the function of the external and internal intercostal muscles
external intercostal muscle: contract to move rib cage up and out to increase size of the chest during inhalation (more volume = less pressure inside lungs = air flows in due to pressure difference); relax to move rib cage down during exhalation (less volume = more pressure inside lungs = air moves out)
internal intercostal muscles: during strenuous exercise, will pull ribcage down to decrease size of the chest, causing you to forcibly exhale and reach into expiratory reserve volume
What is the diaphragm? Explain its role
Muscle at the bottom of your rib cage; separates thoracic cavity from when it contracts, flattens out to make rib cage expand; when it contracts, forms an upside down U
What prevents friction between the lungs and ribs during ventilation? Describe how
The pleural membranes prevent this from happening, as they line the lungs and the thoracic cavity; the space between the membranes is called the pleural cavity, filled with fluid to allow the membranes to slide against each other without friction
What occurs if air gets into the pleural cavity? (name)
If air gets into the pleural cavity, the pleural membranes lining the lungs and the thoracic cavity separate, causing the lung to collapse. This is called a pneumothorax
Why is it important that moisture be added to air in the nasal/oral cavities and the pharynx?
Because oxygen must be dissolved in a liquid in order to move through a membrane in diffusion; air being moist facilitates gas exchange at the alveoli
Describe what physical feature of alveoli make them critical for gas exchange
Alveoli have one-cell thick walls, allowing for efficient diffusion of oxygen through it. Also, they have a large surface area, maximizing the number of cells there are for absorption. They’re also covered in capillaries, which are also one-cell thick.
What is the primary function of the respiratory system?
To obtain and deliver oxygen to body cells and get rid of CO2 produced during aerobic cellular respiration
Explain the process of inhalation and exhalation
Inhalation:
external intercostal muscles and diaphragm contract to make ribcage move up and out, making the ribcage expand
more volume = less pressure = negative pressure
air moves from high pressure to low pressure, so moves from outside environment into lungs
Exhalation:
external intercostal muscles and diaphragm relax, bringing ribcage down and inward
less volume = more pressure
higher volume in lungs than environment = negative pressure = air is forced out of lungs
What is tidal volume? What is vital capacity?
Tidal volume: the normal volume of air inhale and exhaled in an unconscious, normal breath
Vital capacity: refers to the maximum volume of air that can be inhaled or exhaled, excluding residual volume; maximum volume inhaled after a forced exhalation
What does total lung capacity refer to?
The total volume of air that can be contained by your lungs after maximum inspiration
What is inspiratory/expiratory reserve volume?
the volume of air that can be forcibly inhaled or exhaled (higher/lower volume than tidal volume)
What is residual volume? Why is it important?
The air left in your lungs after a forced inhalation; it is important that some air stay in your lungs, because otherwise the pressure difference between your lungs and the environment would be too great and your lungs would collapse
Label
Inspiratory reserve volume
Tidal volume
Expiratory reserve volume
Residual volume
Vital capacity
Total lung capacity
What is VO2? What is VO2 max? What do they tell us?
VO2 is a measure of the rate at which oxygen is used in the body
VO2 max is the maximum amount of oxygen an individual uses during sustained strenuous exercise
A person’s VO2 max shows how efficient the respiratory system is at delivering oxygen to the body. More efficient = larger vital capacity = higher VO2 max
Why do we have trouble breathing at higher altitudes?
At higher altitudes, there is less air pressure. This interferes with ventilation because it decreases the difference in pressure between the lungs and the environment. Usually, the negative pressure in the lungs causes the air in the environment (high pressure) to move into the lungs (low pressure). But since the pressure is lower at high altitudes, it will not move with the concentration as easily. This makes the diaphragm and external intercostal muscles have to work harder to make the ribcage expand more, creating more volume to create a stronger negative pressure
How does the human body respond to high altitudes?
breathing gets faster and deeper to try to inhale more air / bring in more oxygen
EPO (erythropoietin), stimulating the production of more blood cells so amount of oxygen carried is greater
Why do athletes train at high altitudes? How is this dangerous?
makes respiratory system release EPO, creating more red blood cells
good for athletes bc there are more red blood cells to carry oxygen during exercise, so athletes perform better bc they get less tired
dangerous bc more red blood cells = higher blood volume = more strain on your heart bc it has to pump a greater volume of blood
therefore can lead to heart disease and heart failure over time
Why do we have hemoglobin in our blood?
it increases the concentration of oxygen in our blood from 0.3mL/100mL to 20mL/100mL; this is because the oxygen can bond to the hemoglobin in erythrocytes, to be carried throughout the body; otherwise oxygen would just be dissolved into plasma
How does oxygen move from the lungs into erythrocytes, and how does it move from erythrocytes into tissue cells?
Blood going into the lungs through the pulmonary artery is deoxygenated; as a result, the alveoli will have a higher partial pressure of oxygen than the capillaries, so oxygen will diffuse into the capillaries and bond with hemoglobin in the blood.
When the oxygenated blood reaches the tissue cells, the tissue cells will have a lower concentration, so the oxygen dissolved in plasma will diffuse into the tissue cells. The pressure in plasma will then be lower than in erythrocytes, causing oxygen to separate from hemoglobin, diffuse into plasma, then into tissue fluids, and finally tissue cells.
Why can we hold our breath for relatively long periods of time and not die?
Because after blood diffuses into tissue cells, there is still some oxygen bonded to hemoglobin due to the pressure in veins. As blood moves from the tissues to the heart and lungs, it still has some oxygen
Why do people with low-iron feel tired all the time, despite getting enough sleep?
Low iron → not enough hemoglobin produced in the blood → less oxygen is bonded so there is a lower concentration of oxygen in blood → less oxygen to be delivered in body cells → body cells cannot perform aerobic cellular respiration
How does CO2 diffuse from tissue cells to blood vessels and then to alveoli?
Pressure gradient
How is CO2 transported throughout the body in the blood?
dissolved in plasma (7%)
bonds to hemoglobin (20%)
73%: reacts with water in the bloodstream to form carbonic acid, which decomposes into H+ ions and bicarbonate ions. The H+ ions bond with hemoglobin. Hemoglobin and bicarbonate ions are carried to the lungs.
at the lungs, H+ ions separate from hemoglobin and recombine with bicarbonate ions to form carbon dioxide and water. This creates a high concentration of CO2 in the capillaries, so that it diffuses into the alveoli and the negative pressure forces it out of the lungs
What happens if too many hydrogen ions build in the blood? Why would this happen?
The increase of H+ ions in the blood increases the acidity of blood, which can be life threatening. This might happen if there is not enough hemoglobin to bond with the ions.
How is breathing controlled?
normal controlled rhythmic efforts are controlled by the brain stem, the medulla oblongata
Brain sends out signals causing the external intercostal muscles to contract, causing inhalation
Receptors in the lungs indicate to the brain that the lungs have expanded
The brain stops telling the diaphragm and external intercostal muscles to relax, bringing exhalation
What determines the rate of breathing? What is the most important factor?
the demand for oxygen but more importantly the need to eliminate carbon dioxide
How are carbon dioxide levels monitored?
As more CO2 is produced during aerobic cellular respiration, it will cause an increase in H+ ions in the blood as CO2 and water react to form carbonic acid that decomposes into H+ ions and bicarbonate ions. The increase in H+ ions decreases the pH of blood, which triggers chemical receptors in the neck and in arteries leaving the heart. These signal the medulla oblongata, which in turn signals the diaphragm/external intercostal muscles to contract more rapidly and forcefully, to increase the rate of breathing and the volume of inhalation. Heart rate also increases so that more oxygen is delivered while CO2 is removed.
Which is more significant: the monitoring of oxygen or of CO2?
the monitoring of CO2 levels is more significant, as receptors of the level of oxygen will not signal the medulla oblongata to trigger an increase in breathing rate until the oxygen level falls significantly below normal; the change in blood pH will trigger a response first
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