BIOL-122 Organisms and Their Environment

Unit 4

How do animals acquire oxygen and expel carbon dioxide?

Respiration=Gas Exchange

Cellular Respiration: needs O2 to produce energy (ATP) for biosynthesis.

What are some major differences between humans, insects, and birds with respect to their respiratory systems?

Insects: NO LUNGS, tracheal system, closed respiratory system separate from the open circulatory system

Mammals/Humans: Diaphragm expands cavity during inhalation, oxygen-rich air enters alveoli, O2 is transferred to deoxygenated blood, CO2 is transferred from deoxygenated blood to alveoli, exhaled out of the body as the diaphragm restricts cavity.

Birds: weird, but highly efficient!, able to uptake O2 during both inhalation and exhalation, Air sacks!

How is respiration regulated in the human body?

Sensors in the brain,
aorta, and carotid
arteries detect pH
and partial pressure
of carbon dioxide
and oxygen

How are oxygen and carbon dioxide transported throughout the human body?

O2 is transported via the HEMOGLOBIN (4 oxygen molecules per hemoglobin). CO2 may diffuse freely in the blood or be bound to hemoglobin.

Aquatic Respiration

Relies on dissolved O2

Water passes over gills, dense capillary beds populate each gill filament, O2 is absorbed, and CO2 is released.

CONCENTRATION GRADIENT- O2 is higher in water than in Blood, opposite for CO2. passive transportation reaching equilibrium.

What are the structures and functions of the circulatory system?

What are the similarities and differences between open and closed circulatory systems?

Open: The Respiratory system is separate, so the heart does not move O2 or CO2- USES LESS ENERGY

Closed: circulatory fluid, vascular to carry fluid, pump to move fluid, giant circle or giant 8 based on single or double.

How do closed circulatory systems differ across vertebrates, and why are these differences important? Specifically, how do they affect the efficiency of gas exchange, and are there any examples of convergent evolution?

Amphibians: 3-chambered heart, single ventricle, oxygenated and deoxygenated blood are fully mixed.

Reptiles: 3-chambered (separated) heart, single ventricle, but partially divided (septum). Partially mixed blood.

Mammals/Birds/Crocodile: 4-chambered heart, two ventricles, never mixed blood.

Birds and mammals’ heart-convergent evolution.

How does gas exchange occur in closed circulatory systems?

• Oxygen uptake: Deoxygenated, carbon dioxide-rich blood from the body is pumped to the lungs (pulmonary circulation in mammals). In the lungs, tiny air sacs called alveoli are in direct contact with a dense network of capillaries.

• Diffusion: Due to a higher partial pressure of oxygen in the inhaled air within the alveoli compared to the blood in the capillaries, oxygen diffuses rapidly from the alveoli into the blood.

• Carbon dioxide release: Simultaneously, the partial pressure of carbon dioxide is higher in the blood than in the alveolar air, causing carbon dioxide to diffuse from the blood into the alveoli to be exhaled.

• Transport: The now oxygen-rich (oxygenated) blood returns to the heart to be pumped to the rest of the body. 

How does blood flow through the heart?

body-veins-Vena Cava- Right Atrium- Right Ventricle-Pulmonary Artery-Lungs-Left Atrium-Left Ventricle-Aorta-Body

Why is it difficult to extract DNA from human blood?

DNA is in the white blood cells, which the human blood has very few of compared to red blood cells, which do not carry DNA.

What are the major organs and glands that contribute to the endocrine system?

The endocrine system includes the hypothalamus, pituitary gland, pineal gland, thyroid gland, parathyroid glands, adrenal glands, pancreas, ovaries (in females), and testes (in males). These components produce and secrete hormones directly into the bloodstream, regulating various bodily functions. 

What are hormones?

Chemical messengers that enable communication between cells in different parts of the body.

How are hormones produced and regulated?

The Endocrine system.

How do hormones travel to and affect their targets?

produced by endocrine glands and travel via the bloodstream to target cells, controlling mood, growth, metabolism, and reproduction, with production and release primarily regulated by negative feedback loops where rising hormone levels signal the body to stop production, alongside direct nervous system (neural) or fluid (humoral) signals

How do hormones assist the organism in responding to changes in external environmental conditions?

Hormones act as crucial chemical messengers, linking external environmental changes (like temperature, light, food, or stress) to internal physiological responses, coordinating long-term adjustments for survival, growth, and reproduction by traveling through the bloodstream to target cells, altering gene expression, and regulating body functions to maintain balance (homeostasis) or adapt to new conditions.

How do hormones affect development and behavior?

controlling everything from metabolism and reproduction to mood, learning, and social behavior, influencing brain structure, stimulating growth spurts, triggering sexual maturation (like secondary sex characteristics), and driving complex behaviors like aggression, bonding, and appetite regulation, often interacting with genetics and environment.

Primary Functions of the Endocrine System.

1) Homeostasis

2) thermoregulation

3) growth and metabolism

4) Biological Rhythms and Sleep

5) Reproduction

What are the major structures and functions of the vertebrate nervous system and the human brain?

The central nervous system (CNS) and the peripheral nervous system (PNS), work in concert to process information and direct behavior. The human brain, as the command center of this system, has specialized structures responsible for complex functions. 

What are the structure and functions of neurons?

Cell body: houses
organelles & nucleus

Dendrites: receive
messages from others
neurons and relay signals

Axon: transmits signals to
recipient cells

Nerve: A Bundle of multiple
neurons

What are action potentials? How are sodium-potassium pumps, ion channels, and concentration gradients involved?

• Membrane
Potential =
difference in
charge between
cell interior &
The exterior acts as a
“battery” (stored
energy)
INSIDE
OUTSIDE

Sodium-potassium pump = 3 Na+ ions out, 2 K+ ions in
• “Salty Banana” Analogy
• Requires energy (ATP) to break equilibrium & create
a concentration gradient! – ACTIVE TRANSPORT!
• Exterior of cell is slightly more positive - difference in charge
results in an electrochemical gradient across the cell membrane

How do human senses of sight, hearing, taste, and smell work?

Sight (Vision)

• Process: Light enters the eye, focusing on the retina, where rods and cones (photoreceptors) convert light into electrical signals.

• Pathway: Signals travel via the optic nerve to the thalamus, then to the visual cortex (occipital lobe) for processing. 

Hearing (Audition)

• Process: Sound waves are funneled into the ear canal, vibrating the eardrum and tiny bones (ossicles). These vibrations move fluid in the cochlea, stimulating hair cells.

• Pathway: Hair cells generate nerve impulses sent via the auditory nerve (part of the vestibulocochlear nerve) to the thalamus and then the auditory cortex (temporal lobe). 

Smell (Olfaction)

• Process: Airborne chemical molecules bind to olfactory receptors in the nasal cavity.

• Pathway: This is unique; signals go directly from the olfactory bulb to parts of the brain (like the olfactory cortex), bypassing the thalamus, connecting strongly to emotion and memory. 

Taste (Gustation)

• Process: Chemicals from food (dissolved in saliva) activate taste receptors (TRCs) in taste buds on the tongue.

• Pathway: Signals travel through cranial nerves (facial, glossopharyngeal) to the brainstem and then to the gustatory cortex (parietal lobe). Flavor perception also heavily relies on the sense of smell.

What is an ethogram, and why is it important for
studying animal behavior?

Detailed description of all the behaviors that an
animal exhibits
– Simple: walking, eating, etc
– Complex: communicating, hunting, etc.
– The list is long

traits that can be measured

What are Tinbergen’s 4 questions?

1. How does it develop?
2. What mechanisms activate it?

Proximate Level

1. Why is it adaptive/beneficial?
2. How did it evolve?
Ultimate Level

What are the different modes of animal
communication?

1. Auditory
2. Visual
3. Chemical
4. Tactile
5. Seismic
6. Electric
7. Infrared
• Multimodal

What is sensory exploitation?

using animal sensory use in the animals’ environment.

Ex: prangmantice that looks exactly like a flower to bring in food.

Ex: squall defending territory in the presence of snakes by moving heat to their tails.

Why are females often the “choosy sex?”

Sex differences in energy allocation to offspring!
• Anisogamy – differences in size of sperm and egg

• The “choosier” sex is one that
provides more parental effort –
usually females.
• The less “choosy” sex often has
traits they use to display quality –
usually males.
• Origin of sexually selected traits
– characteristics that don’t always
enhance survival, but do enhance
access to mates and reproductive
success (fitness)

What selective pressure caused ducks to develop
corkscrew-shaped penises and vaginas?

sexual conflict

• Females have a corkscrew-shaped vagina!!
• How could something like this evolve?
• Forced copulations (rape)
are common in ducks
• Vaginal morphology (corkscrew in opposite
direction) makes it more difficult for males to
be successful, which maintains a female’s ability
to choose their mates…