Animal form, function, & nutrition
Animal form & function:
Animal Nutrition:
Animal form and function are correlated at all levels of organization
Exchange with the environment:
animals must exchange nutrients, waste products, and gases w/ their environment
exchange occurs as substances dissolved in an aqueous solution move across the plasma membrane of each cell
a single celled organism has a sufficient membrane surface area in contact with its environment to carry our all necessary exchange
a multicellular organization therefore only works if every cell has access to a suitable aqueous environment, either inside or outside the animal's body
many animals w/ a simple internal organization have body plans that enable direct exchange between almost all their cells & the external environment
ex: pond dwelling hydra, their gastrovascular cavity opens to the external environment
increasing the number of cells decreases the ratio of outer surface area to total volume
ex: the ratio of outer surface area to volume for a whale is hundreds of thousands of times smaller than a water flea
every cell in the whale must be bathed in fluid and have access to oxygen, nutrients, and other resources
the respiratory, circulatory, digestive, and excretory system help with the internal exchange in complex animals
interstitial fluid: the spaces between cells are filled w/ this fluid
Hierarchical organization and body plans:
tissues: groups of cells w/ a similar appearance and a common function
organs: different types of tissues is further organized into functional units (organs)
Organ System:
Digestive: for food processing (ingestion, digestion, absorption, elimination)
main organs: mouth, pharynx, esophagus, stomach, intestines, liver, pancreas, anus
Circulatory: internal distribution of material
main organs: heart, blood vessels, blood
Respiratory: Gas exchange (uptake of oxygen; disposal of carbon dioxide)
main organs: lungs, trachea, other breathing tubes
Immune and lymphatic: body defense (fighting infections and virally induced cancers)
main organs: bone marrow, lymph nodes, thymus, spleen, lymph vessels
Excretory: disposal of metabolic wastes, regulation of osmotic balance of blood
main organs: kidneys, ureters, urinary bladder, urethra
Endocrine: coordination of body activities (such as digestion and metabolism)
main organs: pituitary, thyroid, pancreas, adrenal, and other hormone- secreting glands
Reproductive: gamete production; promotion of fertilization; support of developing embryo
main organs: ovaries or testes and associated organs
Nervous: coordination of body activities; detection of stimuli and formulation of responses to them
main organs: brain, spinal cord, nerves, sensory organs
Integumentary: protection against mechanical injury, infection, dehydration; thermoregulation
main organs: skin and its derivatives
skeletal: body support, protection, of internal organs, movement
main organs: skeleton (bones, tendons, ligaments, cartilage)
Muscular: locomotion and other movement
main organs: skeletal muscles
Animal tissue type:
Epithelial tissue: cover the outside of the body and line organs and cavities w/in the body
stratified squamous epithelium: new cells formed by division near the basal surface push outward, replacing cells that are sloughed off
located on the outer skin and the linings of the mouth, anus, and vagina
Pseudostratified columnar epithelium: forms a mucous membrane that lines portions of the respiratory tract
simple squamous epithelium: the exchange of material by diffusion; lines blood vessels and the air sacs of the lungs
simple columnar epithelium: found where secretion or active absorption is important
cuboidal epithelium: specialized for secretion, makes up the epithelium of kidney tubules, and many glands, including the thyroid gland & salivary glands
Connective tissue: consisting of a sparse population of cells scattered through an extracellular matrix, holds many tissues and organs together in place
Fibroblast: numerous cells w/in the matrix, which secrete fiber proteins and macrophages
loose connective tissue: binds epithelia to underlying tissues and holds organs in place
furious connective tissue: dance w/ collagenous fiber found in tendons
bone: a mineralized connective tissue
blood: has a liquid extracellular matrix called plasma which consist of red blood cells or white blood cells
cartilage: strong flexible support material. Located in the disks that act as cushions between vertebrae
Adipose tissue: a specialized loose connective tissue that stores fat in adipose cells distributed throughout its matrix; insulates the body and stores fuel as fat molecules
Muscle tissue: tissue responsible for nearly all types of body movement
skeletal muscle: responsible for voluntary movements; attached to bones by tendons; contains muscle fiber
smooth muscle: found in the walls of the digestive tract, urinary bladder, arteries, and other internal organs
cardiac muscle: forms the contractile wall of the heart
Nervous tissue: functions in the receipt, processing, and transmission of information
neurons: receives nerve impulses from other neurons via its cell body dendrites
glia: help nourish, insulate, and replenish neurons
Coordination and control
animals have 2 major systems for coordinating and controlling responses
Endocrine system: signaling molecules released into the bloodstream by endocrine cells are carried to all locations in the body
nervous system: neutrons transmit signals along dedicated routes connecting specific locations in the body
Hormones: the signaling molecules that are broadcasted throughout the body
different hormones cause distinct effects, and only cells that have receptors for a particular hormone respond
nerve impulses travel to specific target cells along communication lines consisting mainly of axons
well adapted for coordinating gradual changes that affect the entire body, such as growth, development, reproduction
well suited for directing immediate and rapid responses to the environment such as reflexes
Feedback control maintains the internal environment in many animals
Regulator: an animal is a regulator for an environmental variable if it uses internal mechanisms to control internal change in the face of external fluctuation
conformer: an animal is a conformer if it allows its internal condition to change in accordance with external changes in the particular variable
Homeostasis: the maintenance of internal balance
requires a control system
maintaining a variable, such as a set point
ex: body temp is a set point
a fluctuation in the variable above or below the set point serves as the stimulus detected by a sensor
a control center generates the output that triggers the response
negative feedback: a control mechanism that "damps" its stimulus
ex: when you exercise, you start to sweat to cool your body and return to regular body temp
Positive feedback: a control mechanism that amplifies the stimulus
ex: labor, the contractions result in greater pressure against the opening of the uterus, until the baby is born
homeostasis is sometimes altered by acclimatization (an animal's physiological adjustment to changes in its external environment
Homeostatic processes for thermoregulation involve form, function, and behavior
Thermoregulation: the process by which animals maintain their body temperature w/in a normal range
endothermic: warmed mostly by heat generated by metabolism
ex: some fishes and insect species
ectothermic: they gain most of their heat from external sources
Ex: a bird will warm itself when the sun is out
in hot environments, they have mechanisms for cooling their bodies
generates enough heat to keep its body warmer than its surroundings
adjust their body temperature by behavioral means, like seeking out shade
Balancing heat loss and gain:
controlling the exchange of heat w/ its environment consist of 4 processes
radiation: such as when a lizard absorbs heat radiating from the distant sun
evaporation: like evaporation of water from a lizards moist surfaces that are exposed to the environment has a strong cooling effect
convection: a breeze passing the lizard's dry skin
conduction: the direct transfer of heat between molecules of objects in contact w/ each other
integumentary system: the outer covering of the body, consisting of the skin, hair, and nails
Insulation: reduces the flow of heat between an animal's body and it's environment
found at the body surface, such as hair and feathers, and beneath layers of fat formed by adipose tissue
often animals can adjust their insulating layers to further regulate body temperature
most mammals react to cold by raising their fur, which traps a thicker layer of air, thereby increasing insulation
can vary heat production to match changing rates of heat loss
Hypothalamus: the brain region that also controls the circadian clock; activates mechanisms that promote heat loss or gain
Energy requirements are related to animal size, activity, and enviornment
most animals obtain their chemical energy from food, which contains organic molecules synthesized by other organisms
Metabolic rate: the sum of all the energy an animal uses in a given time interval
energy is measured in joules or calories, and kilocalories
Nutritional Differences:
Herbivores: eat mainly on plants or algae
Ex: cattle, sea slugs, caterpillars
Carnivores: mostly eat other animals
ex: sea otters, hawks, and spiders
Omnivores: eat both animals and plants or algae
ex: humans, crows
most animals are opportunistic feeders, eating foods outside their standard diet when their usual foods aren't available
An animal's diet must supply chemical energy, organic building blocks, and essential nutrients
an adequate diet must satisfy 3 nutritional needs:
chemical energy for cellular processes
organic building blocks for macromolecules
essential nutrients: it's the substances that an animal requires but can't assemble from simple organic molecules
essential amino acids: all organisms require a standards set of 20 amino acids to make a complete set of proteins
the proteins in animal products, such as meat, eggs, and cheese are complete
essential fatty acids: animals typically obtain it from seeds, grains and veggies
vitamins: are organic molecules that are required in the diet in very small amount
there are 13 vitamins required by humans
ex: Biotin, ascorbic acid, thiamine, retinol
Minerals: inorganic nutrients that are usually required in small amounts
ex: calcium, potassium, chlorine, iron
Malnutrition: failure to obtain adequate nutrition
found in salt, dairy products, dark green veggies, meats, tea, and many more
can be found in pork, dairy products, green veggies, egg yolk, nuts, tea, and many more
Food processing involves ingestion, digestion, absorption, and elimination
Ingestion: the act of eating or feeding
filter feeders: strain small organisms or food particles from surrounding medium
substrate feeding: animals that live in or on their food source
fluid feeding: fluid feeders suck nutrient- rich fluid from a living host
bulk feeding: when eating large pieces of food
ex: humans are bulk feeders
digestion: food is broken down into molecules small enough for the body to absorb
Mechanical digestion, such as chewing or grinding, breaks food into smaller pieces
chemical digestion cleaves large molecules into smaller components
Absorption: the animal's cells take up small molecules
ex: amino acids and simple sugars
Elimination: undigested material passes out of the digestive system, completes the process!
food vacuoles, cellular organelles in which hydrolytic enzymes break down food
intracellular digestion: the hydrolysis of food inside vacuoles
extracellular digestion: the breakdown of food in compartments that are continuous w/ the outside of the animal's body
gastrovascular cavity: functions in digestion as well as in the distribution of nutrients throughout the body
Human digestive tract:
Oral cavity/ mouth: where food processing begins
teeth with specialized cut, mash and grind, breaking the food into smaller pieces
Salivary glands: releases saliva; the food in the oral cavity triggers it
Mucus: lubricates food for easier swallowing, protects the gums against Branson, and facilitates taste and smell
Anylase: an enzyme that breaks down starch
the tongue aids digestive processes by evaluating ingested material, distinguishing which food should be processed further
pharynx: throat region which leads to the esophagus and trachea
esophagus: a muscular tube that connects to the stomach
trachea: a windpipe that leads to the lungs
within the esophagus food is pushed along by peristalsis, alternating waves of smooth muscle contraction and relaxation
sphincter: a ringlike valve of muscle acting like a drawstring, regulating passage of the ingested food into the next compartment, the stomach
Stomach: functions as storage and to process food into liquid suspension
gastric juice: mixes it w/ the food through a churning action
protease: protein digested enzyme
small intestine: most enzymatic hydrolysis of macromolecules from food occurs in the small intestine
duodenum: the first 25 cm in the small intestine
pancreas: secretes bicarbonate, which neutralizes the acidity of chyme and acts as a buffer for chemical digestion in the small intestine
liver: where bile is made and needed to make fats soluble (in order to be digested)
gallbladder: where the bile is concentrated
Heptic portal vein: a blood vessel that leads directly to the liver, from the liver blood travels to the heart and then to other tissues and organs
Chylomicrons: the fat globs
Nutrient digestion
Digestive Hormones:
Carbohydrates:
Oral cavity, pharynx, esophagus: polsaccarides (starch) gets broken down to smaller polysaccharides with the help of salivary amylase
then in the small intestine, pancreatic amylases breaks it down to disaccharides
after that, its broken down to monosaccharides
Protein:
In the stomach, pepsin breaks proteins down to small polypeptides
in small intestine, proteases breaks it down to even smaller polypeptides. pancreatic carboxypeptidase breaks it down to small peptides
then broken down to amino acids
Nucleic acid:
IN small intestine, DNA and RNA are broken down to nucleotides by pancreatic nucleases
the enzymes from intestinal epithelium, nucleotidases, breaks it down to nucleosides
nucleosides and phosphates break nucleosides into nitrogenous bases, sugars, and phosphates
Fat:
In small intestine, fat is broken down to glycerol, fatty acids, by pancreatic lipase
Gastrin: circulates via the bloodstream back to the stomach, where it stimulates production of gastric juices
as food arrives at the stomach, it stretches the stomach walls triggering release of gastrin
Hormones Cholecystokinin and secretin
chyme passes from the stomach to the duodenum, which responds by releasing cholecystokinin and secretin
cholecystokinin stimulates the release of digestive enzymes from the pancreas and of bile from the gallbladder
secretin stimulates the pancreas to release bicarbonate which neutralizes chyme