Animal: Lecture 4 Flashcards
Why do animals eat?
- Maintain metabolic rate for cellular activites
- Get minerals and vitamins that they otherwise wouldn’t get (can’t make by themselves)
- Carbohydrates (building blocks for new things)
- All physiological functions require energy (chemical ~> ATP) and/or matter (carbon skeletons)
- All animals are heterotrophic and have to obtain energy from other things.
What is bioenergetics?
Bioenergetics is the overall flow and transformation of energy within an organism.
Where is chemical energy stored?
It is stored in the bonds of fat molecules, protein molecules, carbohydrate molecules.
- They must be broken to be absorbed
Ways energy comes in?
Energy comes in as food, is converted to chemical energy (ATP) which is used for metabolism.
What ways is energy lost?
- Chemical waste (CO2 and H2O)
- Heat from ATP conversion
- Heat from metabolism
What processes lose energy?
- Heat lost from digestion and absorption
- Energy lost in faces from digestion and absorption
- Energy lost in nitrogenous waste (urea) from nutrient molecules in body cells.
- Heat lost from cellular respiration
- Heat lost from cellular work
- Heat lost from biosynthesis
Process of moving energy?
- Organic molecules in food
- Digestion and absorption
- Nutrient molecules in body cells
- Cellular respiration
- ATP
- Cellular work
- Biosynthesis
What is biosynthesis?
Carbon skeletons and cellular work allow biosynthesis to occur. Biosynthesis is used for body growth, repair, fat storage, gamete production.
How much energy does an animal need
- Enough to maintain their basic metabolic functions (maintain cellular activity, blood flow, respiration, temperature of body)
- The more active an animal is, the more energy is needed (moving, eating, growing, mating, etc.)
- Depends on the size of the organism and how effective they are at using their energy.
What is metabolic rate?
Amount of energy used per unit time.
What is Basal Metabolic Rate (BMR)?
The metabolic rate of a non-growing endothermic that is at rest, has an empty digestive tract, and is not experiencing stress.
- The minimum amount of energy to maintain basic functions
What could you use to measure an animal’s energy use?
- Heat production
- Oxygen consumption
- Carbon dioxide production
- Food consumption
- Waste production
Why couldn’t we measure the BMR of a juvenile sea lion?
It is still growing (juvenile).
What are things we could measure in different animals?
- Measuring energy cost flight in a bird
- Measuring resting metabolic rate of a juvenile sea lion.
- Measuring energy cost of swimming in a shark.
Which animal eats more?
Mouse or Elephant?
Depends on what we measure:
- Absolute/total amount
- Amount per unit body weight
Metabolic rate depends on size?
BMR = Mass ^ 0.75
Elephants vs. mice absolute BMR?
Elephants have a higher absolute BMR and need more food overall.
Metabolic rate depends on unit/body mass (ex. per kg)?
Elephants have a BMR for each kg, and therefore use energy more efficiently.
Therefore, which animal eats more?
- The mouse eats more per unit body mass (~12-13% of body weight)
- The elephant eats more in absolute terms (~4-6% of body weight)
An animal’s diet must supply what?
Energy, organic molecules, and essential nutrients.
Chemical energy is used..?
Chemical energy in food is used in cellular respiration to produce ATP or is stored.
Organic molecules are needed for?
Organic molecules are needed for biosynthesis.
- Nucleic acids, carbohydrates, proteins and lipids.
What are essential nutrients?
Essential amino acids, essential fatty acids, vitamins, and minerals.
What functions are carried out by digestive systems?
Ingestion (food handling)
Digestion (break down of food into absorbable components)
Absorption (nutrient molecules enter body cells)
Elimination (removal of undigested material - faces, urea)
The four stages of food processing ?
- Ingestion (mechanical digestion)
- Digestion (chemical digestion with enzymatic hydrolysis)
- Absorption (nutrient molecules enter body cells)
- Elimination (of undigested material)
Why are digestive structures involving ingestion the most diverse of the digestive system?
There is a huge variety in food sources from one organism to another:
- Animals have evolved structures that allow them time to exploit these various food sources (size and type)
Mammalian teeth reflect diet?
Herbivore - mostly molars and pre-molars which are good for grinding
Carnivore - mostly incisors and canines which are good for tearing/shredding
Omnivore - Have all of them equally prominent which is good for mixed diets.
Four main food mechanisms?
- Suspension feeders and filter feeders (baleen whale)
- Substrate feeders (caterpillars live where they eat)
- Fluid feeders (mosquitos need to pierce their food)
- Bulk feeders (feed in large amount)
Alimentary canal?
The actual pathway of the food
What are the structures in the alimentary canal?
- Oral cavity
- Pharynx
- Esophagus
- Stomach
- Duodenum (of sm. intestine)
- Small intestine
- Large intestine
- Rectum
- Anus
Accessory organs?
Organs that help digest.
What are the different accessory organs?
- Salivary glands
- Liver
- Gallbladder
- Pancreas
What are sphincters?
Sphincters are between the compartments of the stomach.
What is the tongue specialized for?
The tongue is specialized for sequential stages in food processing
- sequential stages are those that have to happen in a specific order.
How is food pushed along?
Food is pushed along by peristalsis:
- squeezing and retracting/contracting of muscles throughout the alimentary canal. Occurs in a wave-like motion and pushes food down.
The oral cavity is..?
The first site of mechanical and chemical digestion.
Salivary glands…?
Produce saliva
What does saliva contain?
Saliva contains:
- Mucus (protects lining of mouth and lubricates food)
- Buffers (help prevent tooth decay by neutralizing acid)
- Antimicrobial agents (lysozyme)
- Salivary amylase (enzymatic breakdown of carbohydrates)
From mouth to stomach?
The bolus of food (ball of chewed food) is pushed down by the tongue into the pharynx.
- This is done by the swallowing reflex and esophageal peristalsis.
Next step?
The epiglottis is pushed down and the esophageal sphincter relaxes, allowing the bolus of food to travel down the esophagus.
Next step..?
Peristalsis occurs as the bolus travels down the esophagus. The food then travels through the relaxed sphincter into the stomach. Then, mechanical and chemical digestion continue in the stomach.
Stomach?
Epithelium secretes gastric juice. Food mechanically mixes with gastric juice to form chyme.
Parietal cell?
Once you get the trigger from the endocrine system that food is arriving , this triggers the lining of the stomach (parietal cells) to release two kinds of ions.
- These ions are H and Cl, which effectively forms HCl in the lumen of the stomach.
What does HCl do?
It kills bacteria
- starts the breakdown of cellular material connecting cells of plant material.
What do chief cells do?
Hormones trigger the chief cells to release pepsinogen (inactive form)
Pepsinogen ~> Pepsin?
Once you produce HCl, some can be used to trigger run of pepsinogen to pepsin.
Pepsin?
Breaks down and digests proteins.
Positive feedback pepsin and pepsinogen?
The presence of pepsin turns pepsinogen into pepsin.
Mucuous cell?
Protects the lining of the stomach from the acidic HCl.
True or false? The conversion of pepsinogen to pepsin is an example of negative feedback?
FALSE. It is an example of positive feedback!
What varies between nutrients?
the location of chemical digestion varies between nutrients.
Chemical digestion - Carbohydrates?
- Oral cavity, pharynx, esophagus
- Small intestine (pancreatic enzymes)
- Small intestine (epithelial enzymes)
Chemical digestion - proteins?
- Stomach (PEPSIN)
- Small intestine (pancreatic enzyme)
- Small intestine (epithelial enzymes)
Chemical digestion - nucleic acids?
- Small intestine (pancreatic enzymes)
- Small intestine (epithelial enzymes)
Chemical digestion - lipids?
- Small intestine (pancreatic enzymes)
Lipids must be emulsified before the pancreatic enzymes can actually digest them.
- Liver produces bile
- Gall bladder stores bile
- Bile is released into small intestine which emulsifies the fats.
Animals are composed of the same biological molecules that their digestive enzymes beak down… how do we not digest ourselves?
- Mucus provides protection for cells lining the alimentary canal
- HCl and digestive enzymes maintained in inactive forms until released to alimentary canal lumen
- Rapid turnover of cells lining alimentary canal (create new cells quickly when they die).
An organ responsible for absorbing food molecules should….?
A. Have a large lumen (internal space/volume)
B. Have several layers of thick muscle
C. Have a large surface area
D. Be very hard
E. Be well connected with the blood supply.
ANSWERS: C and E
Why is the structure of the small intestine is well-suited for digestion and absorption?
There is a large surface area to volume ratio just by having the long tubes, which is optimal for digestion and absorption.
What does the liver do?
The liver regulats the distribution of nutrients to the rest of the body (other than lipids)
Large circular folds?
Increases the surface area to volume ratio
Villi?
Also increase surface area to volume ratio.
Where are nutrients absorbed?
In the villi, which are on the large circular folds.
Microvilli at the apical surface?
Even smaller villi that are on the surface of villi - increase surface area to volume ratio.
- they are on the epithelial cells of the lumen
What does the liver regulate?
The liver regulates distribution of nutrients to the rest of the body.
What do lymph vessels do?
They carry lipids!
What do blood capillaries do? q
They carry the blood with the nutrients in it! Nutrients are from nucleic acids, proteins and carbohydrates.
Why does the small intestine have a large surface area?
- Long narrow tube
- Large circular folds
- Villi
- Microvilli
Connection to the liver?
There are many blood vessels that connect with there small intestine to carry materials to the liver.
What does the liver regulate?
The liver regulates the distribution of nutrients to the rest of the body, and functions in detoxification (things that aren’t good are redirected to kidneys or anus)
- Acts like a guard post between what you ingest and the rest of your body.
What are the components of the large intestine?
The cecum, colon and rectum.
Cecum?
Functions ion fermenting ingested plant materials with the help of bacteria.
Carnivore vs. herbivore cecum?
herbivore cecum is bigger because they have to digest more plant material. Herbivores also have a longer tract in general because it is harder to break down the plant material.
Cecum do what?
Plant material is fermented by the cecum using symbiotic bacteria.
What does the colon do?
The colon functions in water reabsorption and formation and elimination of the feces.
Water reabsorption?
Majority of water is reabsorbed in the small intestine, but the colon also reabsorbs water.
Feces?
Feces consists of undigested material and bacteria.
hormones and digestion?
Hormones regulate digestion and energy storage.
When is the secretion of digestive hormones?
Secretion of digestive hormones is triggered by the presence of food.
- Digestive hormones then trigger the secretion of gastric juices and digestive enzymes.
Hormones regulate?
Hormones regulate digestion and energy storage.
- Hormones insulin and glucagon regulate energy storage.
- Insulin causes excess energy to be stores as glycogen in liver and muscle, then as fat in adipose cells.
- Glucagon, secreted during energy deficit, causes breakdown of liver glycogen, then muscle glycogen and fat.
How do hormones regulate appetite?
A satiety centre in the brain generates the nerve impulses that make us feel hungry or full.
- Leptin is reduced by adipose and regulates long term appetite.
- Insulin and peptide YY are secreted in response to a meal (not hungry) and ghrelin is secreted when the stomach is empty (hungry)
Obesity and Evolution?
Grey seas have evolved a period of obesity critical to early survival.
- Pups spend ~3 weeks nursing on very high fat milk.
- Remain on land for several weeks
- Continue to live off blubber as they learn to swim and hunt.
Obesity plays a role non the evolutionary success of seals.
All animals eat to..?
Obtain energy and nutrients.
Amount of energy animals need?
The amount of energy an animal needs depends on its metabolic rate
Metabolic rate?
Depends on activity, age, sex, size, temperature (endothermic/ectotherm), and nutrition.
Digestive system?
Structures reflect diet and function
Hormones and digestion?
Hormones regulate digestion, energy storage, and appetite.
