Animal Systems
AP Review
Energy exchange
Organisms exchange energy with their environment
Autotrophs convert light energy into chemical energy
Heterotrophs acquire energy from organic molecules made by other organisms
Cellular respiration harvests the chemical energy from food which is stored as ATP; this energy is then used for
work or lost as heat
Types of organisms
Endotherms: animals that generate their own body heat
Require more calories than ectotherms
Many are homeothermic (body temperature must be maintained within narrow limits)
Ectotherms: animals that acquire heat from the environment
Inverse relationship between metabolic rate and size
The smaller the animal, the more calories needed and the higher the respiration and heart rates
Body plans
Body size and shape affect interactions with the environment
Animals need enough surface area in contact with the environment to allow exchange of materials
Adaptations: highly folded, branched internal surfaces for material exchange, circulatory system for movement of
materials
Advantages: avoids dessication, cells are bathed with body fluids to help maintain homeostasis
Changing heat exchange rate
Heat loss is reduced by hair, feathers, fat
Change in amount of blood flowing to the skin
Vasodialation: increases blood flow to the skin so more heat can leave the animal
Vasoconstriction: decreases blood flow to conserve heat
Change rate of metabolism
Increase in skeletal muscle activity increases metabolic heat
Moving or shivering produces heat
Hormonal action can increase metabolic rate and production of heat instead of ATP
Torpor or hibernation (decrease in metabolism) conserves energy during extreme conditions (lack of food, extreme
temps, etc)
Digestive system
Ingestion is the act of eating
Digestion is the process of breaking food down into molecules small enough to absorb
Absorption is uptake of nutrients by body cells
Elimination is the passage of undigested material out of the digestive compartment
Digestive Compartments
Most animals process food in specialized compartments
These compartments reduce risk of self-digestion and allow for specialization
In intracellular digestion, food particles are engulfed by endocytosis and digested within food vacuoles
Extracellular digestion is the breakdown of food particles outside of cells
It occurs in compartments that are continuous with the outside of the animal’s body
Animals with simple body plans have a gastrovascular cavity that functions in both digestion and distribution of
nutrients
More complex animals have a digestive tube with two openings, a mouth and an anus
This digestive tube is called a complete digestive tract or an alimentary canal
It can have specialized regions that carry out digestion and absorption in a stepwise fashion
Each organ of the mammalian digestive system has specialized food-processing functions
The mammalian digestive system consists of an alimentary canal and accessory glands that secrete digestive juices
through ducts
Mammalian accessory glands are the salivary glands, the pancreas, the liver, and the gallbladder
Food is pushed along by peristalsis, rhythmic contractions of muscles in the wall of the canal
LO 1.14
The student is able to pose scientific questions that correctly identify essential properties of shared, core life
processes that provide insights into the history of life on Earth
LO 1.15 The student is able to describe specific examples of conserved core biological processes and features
shared by all domains or within one domain of life, and how these shared, conserved core processes and features
support the concept of common ancestry for all organisms. [See SP 7.2
LO 1.16 The student is able to justify the scientific claim that organisms share many conserved core processes and
features that evolved and are widely distributed among organisms today. [See SP 6.1]
LO 4.18 The student is able to use representations and models to analyze how cooperative interactions within
organisms promote efficiency in the use of energy and matter. [See SP 1.4]
Coordination systems
Nervous system: carries high speed messages
Endocrine system: produces and releases chemical messages; slower speed
Both systems are integrated and help maintain homeostasis
Both systems are regulated by positive and negative feedback mechanisms
Negative feedback
A change in an internal condition is sensed by the brain
The brain causes a production of the needed chemical (response)
Once enough of the chemical has been produced, the response stops
Example: temperature regulation in mammals
Positive feedback
A change in conditions causes the brain to react by increasing the change
Example: childbirth
LO 2.15 The student can justify a claim made about the effect(s) on a biological system at the molecular,
physiological or organismal level when given a scenario in which one or more components within a negative
regulatory system is altered. [See SP 6.1]
LO 2.16 The student is able to connect how organisms use negative feedback to maintain their internal
environments. [See SP 7.2]
LO 2.17 The student is able to evaluate data that show the effect(s) of changes in concentrations of key molecules
on negative feedback mechanisms. [See SP 5.3]
LO 2.18 The student can make predictions about how organisms use negative feedback mechanisms to maintain
their internal environments. [See SP 6.4]
LO 2.19 The student is able to make predictions about how positive feedback mechanisms amplify activities and
processes in organisms based on scientific theories and models. [See SP 6.4]
LO 2.20 The student is able to justify that positive feedback mechanisms amplify responses in organisms. [See SP
6.1
LO 2.21 The student is able to justify the selection of the kind of data needed to answer scientific questions about
the relevant mechanism that organisms use to respond to changes in their external environment. [See SP 4.1]
LO 2.25 The student can construct explanations based on scientific evidence that homeostatic mechanisms reflect
continuity due to common ancestry and/or divergence due to adaptation in different environments. [See SP 6.2]
LO 2.26 The student is able to analyze data to identify phylogenetic patterns or relationships, showing that
homeostatic mechanisms reflect both continuity due to common ancestry and change due to evolution in different
environments. [See SP 5.1]
LO 2.27 The student is able to connect differences in the environment with the evolution of homeostatic
mechanisms
LO 2.28 The student is able to use representations or models to analyze quantitatively and qualitatively the effects
of disruptions to dynamic homeostasis in biological systems. [See SP 1.4]
LO 3.31 The student is able to describe basic chemical processes for cell communication shared across evolutionary
lines of descent. [See SP 7.2]
The Nervous System
Sensory receptors receives signals (stimulus) from the outside world and send them to the brain along a sensory
neuron
The brain interprets the signals (interneuron)
A response is sent from the brain to the target organ along a motor neuron
Membrane potential
Membrane potential (unequal charge) arises from different ion concentrations inside and outside the cells
-Na+ ions are found mostly outside cells
-K+ ions are mostly inside with large anions (proteins, sulfates, phosphates)
-large anions can only cross the membrane through ion channels or using carrier proteins
K+ ions are pumped into the cell and Na+ ions are pumped out
K+ ions can diffuse out of the cell more easily than Na+ because they are smaller
Gives cells a resting potential (charge) of -70 mV
Transmission of impulses
Impulses travel through a nerve cell by creating an action potential
Stimulation causes the membrane of a neuron to open the Na+ ion channels allowing Na+ ions to rush into the cell
This causes the local area of the neuron to become positively charged (depolarized)
Depolarization causes the Na+ ion channels to close and the K+ channels to open
Diffusion of K+ ions out repolarizes the cell (necessary before another impulse can be carried down the neuron)
Depolarization of one area causes depolarization of the next area so the nerve impulse continues down the neuron
Wave of depolarization only moves in 1 directions from the dendrites to the cell body to the axon
Original stimulation must be above threshold level in order for an impulse to be started (all or nothing)
Transmission of impulses between neurons
Communication between cells occurs at synapses (gap between axon and neighboring dendrite)
Pre-synaptic cells contain synaptic vesicles which contain neurotransmitters
-action potential reaching the end of an axon triggers release of neurotransmitter into synapse
the neurotransmitter diffuses to the post-synaptic membrane where they bind to receptor molecules which starts
the action potential on this neuron
the neurotransmitter is degraded and the components are recycled
this system allows the transmission of signals in 1 direction only from axon to dendrite
LO 3.43 The student is able to construct an explanation, based on scientific theories and models, about how
nervous systems detect external and internal signals, transmit and integrate information, and produce responses.
[See SP 6.2, 7.1]
LO 3.44 The student is able to describe how nervous systems detect external and internal signals. [See SP 1.2]
LO 3.45 The student is able to describe how nervous systems transmit information. [See SP 1.2]
LO 3.46 The student is able to describe how the vertebrate brain integrates information to produce a response.
[See SP 1.2]
LO 3.47 The student is able to create a visual representation of complex nervous systems to describe/explain how
these systems detect external and internal signals, transmit and integrate information, and produce responses.
[See SP 1.1]
LO 3.48 The student is able to create a visual representation to describe how nervous systems detect external and
internal signals. [See SP 1.1]
LO 3.49 The student is able to create a visual representation to describe how nervous systems transmit
information. [See SP 1.1]
LO 3.50 The student is able to create a visual representation to describe how the vertebrate brain integrates
information to produce a response. [See SP 1.1]
Gas exchange
All organisms need to exchange gasses with their environment
Plants need carbon dioxide for photosynthesis and produce oxygen
Plants and animals need oxygen for cellular respiration and produce carbon dioxide
Gas exchange in heterotrophs
Gas has to dissolve in the fluid that covers the respiratory surface so it can diffuse across the membrane
Surface area has to be large enough to exchange gasses for the entire organism
Lower organisms
In unicellular organisms (bacteria, protozoans) gasses diffuse across the surface of the entire organism
In sponges, cnidarians, and flatworms, each cell is in contact with the outside environment and diffusion takes
place across the membrane of all body cells
Mammalian respiratory systems
Nostrils, Pharynx, Glottis, Larynx, Trachea, Bronchi, Bronchioles, Alveoli,Capillaries
Circulatory system
Functions:
Transports gasses and wastes
Helps maintain homeostasis
Contains immune system cells
Transports chemical signals
LO 4.8 The student is able to evaluate scientific questions concerning organisms that exhibit complex properties
due to the interaction of their constituent parts. [See SP 3.3]
LO 4.9 The student is able to predict the effects of a change in a component(s) of a biological system on the
functionality of an organism(s). [See SP 6.4]
LO 4.10 The student is able to refine representations and models to illustrate biocomplexity due to interactions of
the constituent parts. [See SP 1.3]
Excretory (Urinary) system
Functions:
Excrete nitrogen compounds (produced by protein metabolism)
Regulate ion concentration
Maintain water balance
Structures
2 kidneys, 2 ureters, 1 bladder, 1 urethra
Nephrons
Nephrons are the functional units of the kidney
Each kidney contains more than 1 million nephrons
They filter 1.5 L of blood per minute and return all but 1% to the blood stream
Parts: glomerulus, Bowman’s capsule, proximal tubule, loop of Henle, distal tubule, renal pelvis
Urine production
3 processes produce urine
Filtration of body fluids from the glomerulus into the nephron produces filtrate
The filtrate is then modified
Secretion of solutes into the filtrate in the proximal and distal tubule
Reabsorption of solutes back into the blood in all tubular parts of the nephron
Types of nitrogen wastes
Ammonia: most toxic; needs the most water to excrete; produced by organisms that live in water (fish,
protozoans)
Urea: less toxic; requires less water to excrete; produced by organisms that live in temperate land environments
(us)
Uric acid: least toxic; requires little water to excrete; produced by organisms that live in arid environments (insects,
birds, reptiles)
Control of urine formation
Controlled by ADH (anti-diuretic hormone)
Cells in the tubules and collecting ducts have receptors for ADH
If the hypothalamus detects a drop in blood volume, ADH is secreted, making the tubules more permeable to
water and making the urine more concentrated
If there is too much water, ADH decreases making the tubules less permeable so urine becomes more dilute
LO 4.18 The student is able to use representations and models to analyze how cooperative interactions within
organisms promote efficiency in the use of energy and matter. [See SP 1.4]
LO 2.25 The student can construct explanations based on scientific evidence that homeostatic mechanisms reflect
continuity due to common ancestry and/or divergence due to adaptation in different environments. [See SP 6.2]
LO 2.26 The student is able to analyze data to identify phylogenetic patterns or relationships, showing that
homeostatic mechanisms reflect both continuity due to common ancestry and change due to evolution in different
environments. [See SP 5.1]
LO 2.27 The student is able to connect differences in the environment with the evolution of homeostatic
mechanisms.
Structures in the Immune system
Lymph vessels and nodes, Spleen, Tonsils, Bone marrow, Thymus gland, Lymphocytes/leukocytes (white blood
cells)
Non-specific immunity
1st line of defense: skin and mucous membranes
Forms a protective barrier against all types of pathogens (disease causing agents)
Cilia, mucous, tears, saliva, enzymes are extra layers of protection
2nd line of defense: inflammatory response
Injured cells release histamine which causes capillaries to swell and leak fluids
Phagocytes (macrophages) also move out of capillaries to the site of injury and attack invaders
Local temperature rises to slow down pathogen reproduction
Specific immunity
Triggered by agents that disrupt dynamic homeostasis
Recognizes and destroys a particular pathogen
Pathogens are recognized by their antigens—”flags” that stick out of their cell membrane
Causes an immune response which uses the white blood cells and lymphatic system to fight the invader
Types of lymphocytes
B cells: mature in bone marrow and produce antibodies (proteins that attach to antigens)
T cells: mature in the thymus gland
Cytotoxic T cells: kill infected host cells
Helper T cells: work with B cells to make antibodies; target of the AIDS virus
Suppresser T cells: turn off B cells as the infection is brought under control
Macrophages: engulf and disassemble pathogens
Antibodies
B cells make antibodies in response to antigens
Antibodies are protein chains, most of which are the same—constant regions
At the ends are variable regions—areas that change to fit the antigen of a specific invader like a lock and key
Some antibodies stick out of B cell membranes while others are released directly into the blood stream
Each antibody can hold onto more than one pathogen, causing them to clump together, which makes them easier
to engulf
You need 1000’s of different antibodies because there are 1000’s of different antigens
This is a response to intracellular pathogens
Cytotoxic T cells attack the infected host cell when antigens are displayed on the outside of the cells
Antibody mediated (Humoral) response
Once the antibody and antigen have combined on a B cell it becomes activated and produces 2 kinds of cells
Plasma cells produce 1000’s of antibody cells per second and move to the sight of infection
Memory cells: remain in your body long after exposure which gives you immunity to the disease on subsequent
exposures
Auto-immune diseases
Self vs non-self system helps your immune system recognize your own cells so they are not attacked and destroyed
In auto-immune diseases T cells are produced that kill your cells
Lupus, rheumatoid arthritis, multiple sclerosis, scleroderma
Allergies
Are caused by overreactions to antigens
Antibodies combine with skin and mucous membranes and mast cells that release large quantities of histamines
and other compounds that cause the allergic reaction
Vaccines
Solutions made from weakened or dead pathogens or their antigens
Causes antibodies to form without making you sick
Production of antibodies gives you active immunity; can last for the rest of your life
Being given antibodies produced by someone else gives you passive immunity; only lasts a short time
LO 2.29 The student can create representations and models to describe immune responses. [See SP 1.1, 1.2]
LO 2.30 The student can create representations or models to describe nonspecific immune defenses in plants and
animals. [See SP 1.1, 1.2]
LO 4.8 The student is able to evaluate scientific questions concerning organisms that exhibit complex properties
due to the interaction of their constituent parts. [See SP 3.3]
LO 4.9 The student is able to predict the effects of a change in a component(s) of a biological system on the
functionality of an organism(s). [See SP 6.4]
LO 4.10 The student is able to refine representations and models to illustrate biocomplexity due to interactions of
the constituent parts. [See SP 1.3]