Test 1: Animal Physiology

Gardner-Webb University

What is Homeostasis?

Maintaining subtle and chemical conditions inside despite disturbances. Avoid foreign or destructive particles.

What are things that an organism needs to have to stay alive and reproduce?

• Organization

• Regulation

• Support and Movement

• Replication

What is diffusion?

Diffusion is when chemicals diffuse from areas of high concentration to areas of low concentration.

During diffusion, why would small molecules diffuse more effectively than macroscopic ones?

Higher surface area of a molecule promotes better exchange with the environment. Lower (macroscopic) molecules are not able to interact as well with the environment around.

Think: The size correlates with weight. The larger the molecule, the heavier it weighs, which means that it could “force” its way into diffusion while the smaller one is weak and doesn’t have as much weight to push its way through.

What is allometry?

Allometry is the idea that size correlates with weight.

What is the Krogh Principle?

The Krogh Principle is the idea of determining which animals of what species will be the most convenient options to study.

Some questions asked during this time are:

• Can you easily access the species?

• Is the species easy to take care of? Easy to train?

• What is the size of the animal? Bigger nerves=faster signals, larger axons (fast thinking to get out of dangerous situations)

Aspects of Negative Feedback

The results cause control and decrease.

During negative feedback what is the set point?

The set point is a desired value or range of a physiological aspect. Can be thought of as a reference point.

What is the antagonistic control in negative feedback?

The Antagonistic control is the stimulus that responds to the signal and pushes back to the middle level.

What is positive feedback?

The result causes more of teh stimulus to happen

What are some possible adjustments when working with homeostasis?

• Acclimation: Adjust to experimental control of the change

• Acclimatization: Adjust to natural varieties

• Phenotype Plasticity

  • 1. Polyphenism: Discrete change

  • Reaction Norm: Range of ways to change

Organisms that are closely related to each other have ______ physiology.

similar

What are some of the various forms of energy that organisms need?

• Food

• Radiant energy, sunlight, photosynthesis

• Symbiosis - cells take basic chemicals an turn them into a useable form of energy.

What are the 4 major organic molecules in living organisms?

1. Proteins → enzymes, chemical reactionss

2. Carbohydrates → Major source of energy

3. Lipids → fats, calories, energy storage

4. Nucleic Acids → DNA

What are the different forms of energy?

1. Potential (stored)

2. Kinetic (moving)

3. Thermodynamic (heat)

   1. 1st law: conservation of energy

   2. 2nd law: Increasing entropy

What does the mitochondria do?

• it is the main producer of ATP in the cell

• Requires oxygen to function

• Has its own DNA

Issues with fermentation and how to fix them?

• Sometimes fermentation yields small amounts of ATP due to the products that were fermented can sometimes be toxic (lactic acid, ethanol)

• More mitochondria (more productive mitochondria) have better fermentation efficiency. They can process glucose, amino acids, and fats.

How can you get more out of glycolysis?

• Store lots of glycogen

• Efficient waste disposal/les toxic → ammonia waste

• Add steps that get more ATP

What are obligate Aerobes?

Obligate Aerobes are organisms that require oxygen continuously in order to survive.

Most animals use less oxygen that mammals and birds and can tolerate low oxygen for longer.

What are Facultative Anaerobes?

These are organisms that can adapt to anaerobic conditions for days or months (ex. brine shrimp embryos).

Various animals live in low oxygen settings (or no oxygen settings)

• Examples are water animals, shelled animal, underground animals

What are obligate anaerobes?

organisms that can be inhabited or killed in the presence of oxygen.

This has not been confirmed for any animals.

What can an agonist do?

Substitute for a signal molecule

What can an antagonist do?

Block receptor function

What are some possible styles of communication regarding signaling?

• Temporary cell-to-cell contact

• Direct cell signaling through gap junctions

• autocrine or paracrine signaling

• endocrine signaling

• neural signaling

What are the advantages and disadvantages of small molecules regarding endocrine and exocrine functions?

Advantages: Move around easily, easily manipulates

Disadvantages: so small, incorrect signaling can occur

What are the types of signaling molecules?

• Peptide hormones: Synthesized as large precursor proteins, cleaved, packaged into secretory vesicles; chains of amino acids , hydrophilic (ex. Insulin)

• Amines: Derived from amino acids or similar molecules, mostly hydrophilic (ex. Catecholamines → epinephrine)

  • Thyroid hormones are the hydrophobic aspect

• Steroids: Made from cholesterol; hydrophobic, slow to break down (ex. mineralocorticoids, glucocorticoids)

• Fatty Acid derivatives: Hydrophobic, quickly break down (ex. Neurotransmitters)

• Purines: Hydrophilic, nucleic acid bases (A or G); paracrine, neurotransmitter, modular

• Gases: Nitric oxide; H2S, CO: relatively hydrophobic, quickly broken down.

What does the endocrine system do?

Regulates and coordinates distant organs through secretion of hormones.

4 main receptors for endocrine system

1. Ligand gated ion channels

2. Receptor-enzyme

3. G protein-coupled receptor

4. Intracellular receptor → in the cell.

Why is the signal termination so important?

If a signal were to continuously go off, how would one know when to stop responding? Would you just do the same thing forever, in response to that same stimulus? NO

What are some of the possible cues for growth regulation?

• Nutrition

• Stressors

• Environment

What is Hyposecretion?

Hyposecretion is the inadequate secretion of a hormone. There are two types.

1. Primary Hyposecretion: Abnormality within the gland

2. Deficiency of tropic hormones (hormones that trigger other hormone production)

What is Hypersecretion?

Excessive secretion of hormone.

• Receptors may be over or under sensitive which can cause type 2 diabetes.

Endocrine disruption chemicals (EDC’s)

• May be human made substances released into the environment.

• mimic or oppose the actions of the hormones

• Ex. DDE and DDT act as anti-androgens in animals, eggshell production in birds

What does the pineal gland do?

• Secretes melatonin

• Differentiates from night and day with hormonal aspects

What does the pituitary gland do?

• Combines nervous and glandular epithelial tissue

• Directly regulated by the brain (hypothalamus)

• The secretions regulate many other endocrine many endocrine organs

• two parts

  • Posterior Pituitary: secretes neurohormones

  • Anterior Pituitary: immediate destination of neurohormones from hypothalamus

Hormones of the anterior pituitary gland

• Growth Hormone → stimulates growth

• Thyroid stimulating hormone (TSH) → stimulates thyroid hormones

• Adrenocorticotropic Hormone → stimulates cortisol secretion

• Follicle-stimulating hormone → Regulates gamete production

• Lutenizing hormone → regulates sex hormone secretion

• Prolactin: Stimulates milk production by mammary glands. Associated with incubation in birds.

What does the thyroid gland do?

In the neck, uses iodine

• Increases basal metabolic rate (BMR) through increased mitochondria and Na+ - K+ pump activity

• Molting in birds and mammals, metamorphosis in amphibians

• Sympathomimetic effect: an effect like the sympathetic system, increase- target cell responsiveness to epinephrine / norepinephrine

• Increase HR and force of contraction

• Essential for growth

Hyperthyroidism

High thyroid levels

Hypothyroidism

Low Thyroid activity

Adrenal Glands

• Kidney → renal

• steroid hormones

  • mineralocorticoids - ex. aldosterone

  • Glucocorticoids - ex cortisol

  • sex steroids - ex. dehydroepiandrosterone

• Tyrosine derivatives: Norepinephrine (NE) and epinephrine

Examples of abnormal adrenocortical functions

• Cushing’s Syndrome

  • High blood glucose & protein loss

  • Redistribution of fat in humans and dogs

• Addison’s disease (deficiency of adrenal steroids)

  • Most common cause is autoimmune destruction of the adrenal cortex

  • Aldosterone deficiency can be fatal

  • Cortisol deficiency causes poor response to stress, hypoglycemia, and lack of permissive actions

Absorptive state

Full of freshly obtained nutrients

• glucose is plentiful and used as the major energy source

  • excess stored as glycogen (less) or triglycerides (most)

Postabsorptive state

In between meals (fasting)

• Endogenous energy stores are mobilized to provide energy

• Fatty acids are the major energy source for most tissues

What is the role of the pancreas in digestion?

Exocrine

• major regulator of digestion and metabolism

Calcium

• often stored in skeletons and skulls, high level in fluids associated with the skeletons

• Only the free Ca2+ in plasma is biologically active

• Ca2+ homeostasis and ca2+ balance must be regulated

What is hyperparathyroidism?

excess calcium release

Which type of animals are most susceptible to vitamin D deficiency?

• animals deep underwater

What could be an important cue regarding the idea that something needs to be changed?

• Cells may need to be replaced (dying cells don’t work well)

• Externally, migration times lead to reproduction time. sun → flowers → bugs → food for baby birds

What is the overall physiological importance of the endocrine system?

• hormone signaling and processing on what to do in the body, quick signals.

What are the 4 main steps to send a signal using a neuron?

1. Receive

2. Integrate → decide and send

3. Conduct

4. Transmit

What is the resting membrane potential of a neuron?

-70 mv

Which effect does letting Na+ vs K+ through have?

Depolarization

What is an action potential?

Transmits signal along longer distances (up to many meters)

What has to happen within a neuron for a signal to be sent?

• If the axon hillock passes the threshold (-55 mv) a signal is triggered

Neurotransmitter example: Acetylcholine (ACh)

• Main neurotransmitter for vertebrate neuron-muscle communication.

• Acetylcholinase breaks down ACh down into acetate and choline (AChE)

  • AChE - Breaky heart

What is myasthenia gravis?

• Autoimmune attacks nicotinic ACh receptors, decreasing muscle responsiveness

What are the different functions of neurons?

• sensing

• interneuron

• efferent

RNA editing regarding Na+ K+ channels and neurons

• Genes for voltage gated k+ channels show little difference, the editing leads to different proteins that function fast at the temperature by different species.

• Opening and closing gates are the rate limiting step in this process. Farther between or faster gates speeds signals.

Velocity of action potential propagation

Ranges from 0.7 m/s for small, unmyelinated fibers up to 120 m/s for large, myelinated fibers.

Tetrodotoxin

blocks voltage gated Na+ channels.

• This can cause paralysis.

Tetraethylammonium (TEA)

blocks gated K+ channels

Ouabain

stops the Na+ K+ pump.

ex: African arrow poison. certain rats chew on this and it spreads to their fur.

Strychnine

Completes with inhibitory neurotransmitter, glycine, and postsynaptic receptors

Tetanus toxin

Prevents release of GABA from inhibitory presynaptic axons

Both strychnine and tetanus toxin can cause _____

unchecked excitation, muscle spasms, and death.

Treatment for myasthenia gravis

Inhibits acetylcholinease, prolonging the activity of ACh in the synapse.

How does the cell move?

• Only the cytoskeleton moves

• Cytoskeleton moves, motor proteins attached to cell membrane

  • Extension and retraction of cell projections (microvilli)

• Cytoskeleton stable, motor proteins move along it

• Cytoskeleton and motor proteins both move relative to each other in a complex arrangement

  • muscles, cilia, flagella

Microtubules

largest, tubulin units

Microfilaments

Smallest, actin (interacts with myosin)

Intermediate filaments

Intermediatest varied structure

Breakdown of actin-myosin interaction

• Myosin uses energy from ATP to power movement

• Head region breaks phosphate from ATP, uses the energy to power its attaching, bending, and detaching along an actin chain

• Neck regulates the motion, attaches to other regulatory proteins

• Tail attaches to other proteins (often another myosin, in some forms)

What is the sliding filament powered by?

ATP

Two types of muscle

Striated and smooth

Characteristics of thick and thin fibers

Thick fibers: Many myosin units (about 300 individual myosin molecules) attached together

Thin fibers: a-actin vs B-actin in usual microfilaments) stabilized - not growing or shrinking all the time

• All muscles are made of these; the arrangement differs in different types.

Twitch vs Tonic muscles

Twitch: One or few synapses

• May be faster or slower

• Contracts or not

• Number of fibers triggered controls response size

Tonic: Many synapses

• Essentially simultaneous triggering of entire fiber

• Slower, longer contraction

• Holds longer