Animal Lesson 4 Flashcards
Why do animals eat?
All physiological functions require energy and/or matter.
Animals are heterotrophic.
Bioenergetics
the overall flow and transformation of energy within an organism.
Chemical energy
Carbs, fats, other.
Where is chemical energy?
Stored in the bonds of Carbs, fats, other. The bonds need to get broken to get the energy.
Chemical waste
CO2 and water (some is exhaled).
Overview of Bioenergetics of an Animal
Organic molecules in food then go into the mouth. Then in the animal body there is digestion and absorption, where heat is lost and energy is lost in faces.
Then nutrient molecules in body cells where energy lost in nitrogenous waste (urine).
Then cellular respiration, where heat is lost. Then ATP which goes into cellular work and biosynthesis (Both lose heat).
Then cellular respiration also goes into carbon skeletons which goes into biosynthesis.
Then the biosynthesis goes back to nutrient molecules in body cells.
Carbon Skeletons
Building blocks to make new things
Biosynthesis
need to do this in order to make new things. E.g., body growth/repair, fat storage, gametes production.
Is all food being kept in the body?
Not 100% of it.
How much energy does an animal need?
Enough to maintain basic metabolic functions. ie. maintain cellular activity, blood flow, respiration, temp.
The more active an animal is, the more energy is needed. ie. moving, eating, mating, etc.
Metabolic rate
amount of energy used per unit time
Basal metabolic rate (BMR)
the metabolic rate of a non-growing endotherm that is at rest, has an empty digestive tract, and is not
experiencing stress. i.e., the min amount of energy to maintain basic functions.
What could you measure to determine an animal’s energy use?
Heat production. Oxygen consumption. Carbon dioxide production. Food consumption/waste production.
What does metabolic rate also depend on?
Activity. ie. Measuring energy cost of flight in a bird. Measuring energy cost of swimming in a shark. Measuring resting metabolic rate of a juvenile sea lion (not Basel because it’s still growing).
Metabolic rate depends on size
BMR=Mass^(3/4). It’s a straight y=x line. Elephants have a higher absolute BMR. i.e., need more food
overall.
Metabolic rate depends on unit/body mass (e.g., per kg)
Backwards exponential line. Elephants have a
lower BMR for each kg (than mouse). i.e., use energy more efficiently.
Does the elephant or mouse eat more?
The mouse eats more per unit body mass (eats ~12-13% of body weight).
The elephant eats more in absolute terms (eats ~4-6% of body weight).
An animal’s diet must supply what?
energy, organic molecules, and essential nutrients
Chemical energy in food is used in what?
cellular respiration to produce ATP or is stored
Organic molecules are needed for what?
biosynthesis of new body parts.
– E.g., Nucleic acids, carbohydrates, proteins, and lipids.
Essential nutrients
Things we can’t produce on our own.
– E.g., Essential amino acids, essential fatty acids,
vitamins, and minerals.
The 4 functions of the digestive system?
Ingestion, Digestion, Absorption, Elimination
Ingestion
Food handling
Food Handling
how you bring the food to your mouth.
Digestion
Break down of food into absorbable components. Ie. mechanical and chemical.
Absorption
Nutrients molecules enter body cells.
Elimination
Removal of undigested material.
What’s the most diverse part of digestive system?
Ingestion, because it depends on the animal. ie. sponges don’t have a mouth and corals don’t have an anus.
Why is ingestion so diverse?
Huge variety in sources of food. It’s also reflected in mammalian teeth. ie. animals have evolved structures that allowed them to exploit these various food sources.
Carnivore teeth
Big and pointy incisors and canines to grip and shred the animals they prey on. ie. lion.
Herbivore teeth
Big premolars and molars to break down and grind cellulose. ie. cows.
Omnivore teeth
A mix of herbivore and carnivore teeth. ie. humans.
Four main feeding mechanisms
Suspension Feeders and Filter Feeders, Substrate
Feeders, Fluid Feeders, Bulk Feeders.
Suspension Feeders and Filter Feeders
They use baleen to take big gulps of food with all the krill inside and squish the water out, so all that’s kept behind is the krill and then they can swallow it. ie. whale.
Substrate Feeders
They live on the food they eat. ie. caterpillars
Fluid Feeders
They have specific appendages in their mouth to pierce the host to drink their blood. ie. mosquitoes.
Bulk Feeders
Feed in large amounts at a time. ie. the majority of animals.
Two parts of the digestive system
Alimentary canal and accessory organs.
Alimentary canal
Tube from month to anus.
Oral cavity
pharynx
esophagus
stomach
Duodenum of small intestine
small intestine
Large intestine
Rectum
Anus
Accessory organs
Help to digest the food.
Salivary glands
liver
gall-bladder
pancrease
Why does the digestive organs look different at different stages?
Specialized for sequential stages of food processing.
peristalsis
How food is pushed along. Squeezing, retracting, and contracting of muscles throughout the tube in alternating waves (squeeze then relax)/
Sphincters
They are between compartments. They close off a section. Anus is technically one.
first site of mechanical and chemical digestion?
Oral cavity
Oral cavity
Tongue, salivary glands, pharynx.
Salivary glands produce what?
Saliva
Saliva contains what?
– Mucus (protects lining of mouth and lubricates food).
– Buffers (help prevent tooth decay by neutralizing acid).
– Antimicrobial agents that protect you from any kind of bacteria that you are consuming (e.g., lysozyme).
– Salivary amylase (enzymatic breakdown of carbohydrates).
From mouth to stomach?
swallowing reflex & esophageal peristalsis (in the esophageal region).
Tongue
Manipulate food into a bolus and push it down towards the pharynx area.
Pharynx
Opens to two parts: the trachea to the lungs and the esophagus to the stomach.
Epiglottis down
Blocks the airway that leads to trachea and lungs.
How does the food get to the esophagus?
The esophageal sphincter relaxes.
Mechanical and chemical digestion continue what?
In the stomach
Stomach
- Epithelium secretes gastric juice.
- Food mechanically mixed with gastric juice to become chyme.
Where is the gastric juice produced?
Gastric glands.
Where is the gastric glands?
In the pits of the stomach.
Gastric glands three specialized types of cells?
Mucous cell, Chief cell, and parietal cell.
Parietal cell
Once you get trigger from endocrine system it triggers the gastric glands (lining of stomach) to release two kinds of ions. H+ and Cl- to from HCI.
HCI
Produced in lumen of stomach (where food is). Kills bacteria and start breakdown of the cellular material that connects the cells of plant material. It also triggers the pepsinogen to turn into pepsin.
Pepsinogen
Inactive form that when will turn into pepsin.
Pepsin
Responsible for breaking down and digesting protein. Can reinforce more production of pepsinogen into pepsin.
Chief cell
Hormones trigger them to release Pepsinogen.
Mucous cell
Protects lining of stomach from HCI and pepsin.
The conversion of pepsinogen to pepsin is
an example of what?
Positive feedback loop.
The location of carb digestion
Oral Cavity Pharynx Esophagus
Small Intestine: Pancreatic Enzymes
Small Intestine: Epithelial Enzymes
The location of protein digestion
Stomach
Small Intestine: Pancreatic Enzymes
Small Intestine: Epithelial Enzymes
The location of nucleic acid digestion
Small Intestine: Pancreatic Enzymes
Small Intestine: Epithelial Enzymes
The location of lipid digestion
Small Intestine: Pancreatic Enzymes
Pancreatic Enzymes
Responsible for breaking down everything we consume.
What happens when you consume big globs of fat?
The pancreatic enzymes can’t really digest it. They need to be emulsified into smaller globules before they can be digested by them.
How to they make smaller globules of fat?
Liver produces bile then Gall bladder stores bile.
Bile then released into small intestine to emulsifies fats.
How do we not digest ourselves?
- Mucus provides protection for cells lining
alimentary canal - HCl and digestive enzymes maintained in
inactive forms until released to alimentary
canal lumen (until we need them). - We do digest some of our own cells but Rapid turnover of cells lining alimentary canal (new cells get reproduced all the time).
An organ responsible for absorbing food molecules should have what?
have a large surface area and be well connected with the blood supply (how nutrients travel).
The structure of the small intestine is well suited for what?
digestion and absorption by having a large surface area to volume ratio.
Villi
Even more projections that increase ratio. In them are blood capillaries and lymph vessels.
Large circular folds
Increases ratio
Liver
regulates distribution of nutrients to rest of body. So all nutrients (but lipids) need to get to the liver. Determines what you keep or get rid of. Acts like a “guard post” between what you ingest and the rest
of your body.
Microvilli at apical surface
Allows the passage of even more nutrients directly through the cells. Small convoluted eggs that face the lumen. They are on the epithelial cells, nutrients are absorbed through them.
Lymph vessels
Carry lipids to the lymphatic system.
Parts of small intestine
– Long narrow tube
– Large circular folds
– Villi
– Microvilli
The many blood vessels connecting with the small
intestine carry material to where?
The liver.
The large intestine is composed of what?
colon, cecum, and rectum
cecum
functions in fermenting ingested plant material. Because it has symbiotic bacteria in them to help with the further digestion of plants.
Appendix
Plays role in immune system.
Differences between carnivore and herbivore Alimentary canal?
Carnivore: Cecum and canal shorter.
Herbivore: Cecum and canal longer.
Why is herbivore canal longer?
Because it takes more time to process hard to digest foods.
Colon functions
water reabsorption and formation and elimination of the feces.
Majority of water is reabsorbed in the small
intestine, but colon also reabsorbs water
Feces
consist of undigested material and bacteria
Hormones regulate
digestion and energy storage and appetite
Secretion of digestive hormones is triggered
by what?
the presence of food. Digestive hormones then trigger the secretion of gastric juices and digestive
enzymes.
Hormones insulin and glucagon regulate what?
Energy storage
Insulin
causes excess energy to be stored 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.
satiety center
in the brain that generates the nerve impulses that make us feel hungry or full.
Leptin
produced by adipose and regulates long-term appetite. Makes us feel full.
Insulin and Peptide YY
are secreted in response to a meal. Makes you feel full.
ghrelin
secreted when the stomach is empty. Makes you feel hungry.
Obesity and Evolution
E.g., Grey seals have evolved a period of obesity critical to early survival. Pups spend ~ 3 weeks nursing on very high fat milk and store it in their body. Remain on land for several weeks. Continue to live off
blubber as they learn to swim and hunt.
Metabolic rate depends on what?
on activity, age, sex, size, temperature (endotherm/ectotherm), and nutrition.
Digestive system structures reflect what?
diet and function
