Biology Module 3 concepts

Main characteristics of an animal

multicellularity and multiple tissues

gastrulation

a series of cell and tissue movements in which the blastula-stage embryo folds inward, producing a three-layered embryo, the gastrula.

protosomes

-blastophores develop into a mouth

-exhibits determinate cleavage

-gut forms the anus by tunneling itself into the embryo

comprised of a solid ventral cord

deuterostomes

-blastophores develop into an anal opening

-exhibits indeterminate cleavage

-gut forms the mouth by tunneling itself into the embryo

comprised of a hollow nerve cord

endocrine glands

ductless glands that secrete hormones directly into blood

exocrine glands

Secrete substances through ducts to surfaces.

endocrine and exocrine glands connection to epithelial tissue

both originate from epithelial tissue/cells

actin

globular protein; helps maintain cell shape,enable cell movement, essential for processes and intracellular transports

myosin

motor protein; converts chemical energy from atp into mechanical work

neuroglia assists nervous tissue

supporting neurons, nutrient and oxygen supply, protection and immune responses, insulation, environmental regulation, repair and regeneration, communication

nervous system of cnidarians

nerve net, no complex centralization

nervous system of bilaterians

centralized nervous system, distinct ganglia (brain)

regenerative capacity of central nervous system

-limited

-neurons do not regenerate effectively

-dont regrow axon

-scar tissue forms, impedes regeneration

regenerative capacity of peripheral nervous system

-high activity

-axons can regenerate and reconnect with target tissue

-schwann cells provide a growth-promoting environment

connection between action potential and ion-gated channels

action potentials are electrical impulses that travel along neurons and muscle cells, driven by the movement of ions through ion-gated channels

action potential propagation

the movement of an action potential along an axon; in myelinated axons, it occurs via saltatory conduction

steps for synaptic transmission to occur

1. Action Potential Reaches the Axon Terminal

2. Opening of Voltage-Gated Calcium Channels

3. Neurotransmitter Release

4. Neurotransmitter Diffusion Across the Synaptic Cleft

5. Binding of Neurotransmitter to Receptors

6. Postsynaptic Potential (PSP)

7. Generation of Action Potential in the Postsynaptic Neuron (if Threshold is Reached)

8. Termination of the Signal

9. Recycling of Synaptic Vesicles

Vision matches to

photoreceptors

Hearing matches to

mechanoreceptors

Balance matches to

mechanoreceptors

taste matches to

chemoreceptors

smell matches to

chemoreceptors

Proprioceptors

monitor the position and movement of skeletal muscles and joints

Interoceptors

monitor visceral organs and functions

Exteroceptors

Respond to stimuli arising outside the body

Receptors in the skin for touch, pressure, pain, and temperature

Most special sense organs

How does skin work with mechanoreceptors

to detect mechanical stimuli such as touch, pressure, vibration, and stretch. Various types of mechanoreceptors are specialized for detecting different types of mechanical forces and relay this information to the central nervous system for processing. This allows us to experience and respond to sensations like feeling textures, detecting changes in pressure, and maintaining body balance and coordination.

gastrovascular cavity

Digestive chamber with a single opening, in which cnidarians, flatworms, and echinoderms digest food

digestive tract

The organs through which food passes during the process of being digested. These include the mouth, esophagus, stomach, small intestine, large intestine, rectum, and anus.

physical digestion

the process of breaking food into smaller pieces (example: chewing)

chemical digestion

Process by which enzymes break down food into small molecules that the body can use

GI Tract

the long, continuous tube that directly handles food intake, digestion, nutrient absorption, and waste elimination.

digestive accessory organs

(liver, pancreas, gallbladder, and salivary glands) assist the GI tract by producing or storing substances like bile, enzymes, and saliva, which are necessary for the efficient breakdown of food. These organs are not part of the continuous tube but are crucial to the digestive process.

How does the appearance, composition, and pH of ingested material change as it movesthrough the digestive tract?

Appearance: The food starts as solid food, becomes liquid (chyme) in the stomach, and progressively becomes more solid as water is absorbed in the large intestine, finally forming feces.

Composition: The food is initially complex (carbohydrates, proteins, fats) and is gradually broken down into smaller molecules (amino acids, simple sugars, fatty acids) as digestion progresses. By the large intestine, the remaining material consists mostly of undigested fiber and waste.

pH: The pH starts neutral or slightly acidic in the mouth, becomes highly acidic in the stomach, and then becomes neutral to slightly alkaline in the small intestine, before returning to slightly acidic in the large intestine.

What end products of digestion are absorbed, and where

The small intestine is the primary site for the absorption of nutrients, including carbohydrates, proteins, fats, vitamins, minerals, and water. Different nutrients are absorbed through specialized mechanisms (e.g., active transport, facilitated diffusion, osmosis), and the absorbed products enter the bloodstream or lymphatic system for transport to the liver or other tissues for use. The large intestine also plays a role in absorbing water and some electrolytes, further concentrating the remaining waste for excretion.

What does it mean when it says that respiratory gases are nonpolar?

highlighting the fact that molecules like O₂ and CO₂ do not have significant charge separation across their structure, meaning they are electrically neutral. This property plays a role in their diffusion across cell membranes and their interaction with other molecules in the body.

What is hemocyanin?

A blue pigment containing copper that binds to oxygen in arthropods and molluscs

How is blood flow regulated in a closed circulatory system?

The heart adjusts the heart rate and stroke volume to meet the body's needs.

Blood vessels (particularly arterioles) constrict or dilate to regulate blood pressure and the distribution of blood.

Baroreceptor reflex helps maintain blood pressure homeostasis.

Capillary beds regulate local blood flow based on metabolic demand.

Hormones and kidney function play a role in long-term regulation by adjusting blood volume and vascular resistance.

Venous valves role in venous return

Prevent backflow of blood, ensuring it flows toward the heart.

Skeletal Muscle Pump role in venous return

Muscle contractions compress veins and help propel blood upward.

Respiratory Pump role in venous return

Pressure changes during breathing assist in moving blood toward the heart.

Venous Tone role in venous return

the constriction of veins enhances blood flow toward the heart.

Gravity role in venous return

Works against venous return, especially from the lower body.

Blood Volume role in venous return

More blood in the veins increases venous return.

Pressure Gradient role in venous return

A lower pressure in the veins compared to the heart encourages blood flow to the heart.

Posture role in venous return

Lying down or elevating the legs aids venous return.

Venous Distensibility role in venous return

More distensible veins can accommodate more blood, aiding venous return.

Sympathetic Nervous System and Hormones role in venous return

Increase venous tone and venoconstriction to help blood flow toward the heart.

Muscle Contractions and Exercise role in venous return

Exercise and muscle contractions enhance venous return by activating the skeletal muscle and respiratory pump

What is the pattern of blood flow through the heart

1. Deoxygenated blood enters the right atrium from the body via the superior and inferior vena cavae.

2. Blood flows through the tricuspid valve into the right ventricle.

3. The right ventricle pumps blood through the pulmonary valve to the pulmonary trunk and then to the pulmonary arteries that lead to the lungs.

4. Oxygenated blood returns from the lungs via the pulmonary veins into the left atrium.

5. Blood flows through the bicuspid valve (mitral valve) into the left ventricle.

6. The left ventricle pumps oxygenated blood through the aortic valve into the aorta, which distributes it to the body.

What do the pulmonary and systemic circuits deliver oxygen to

pulmonary: lungs

systemic: rest of body

Why is homeostasis dynamic?

because it is constantly adjusting to the changes that the systems encounter

What does it mean when we say homeostasis is not equilibrium?

Homeostasis is about maintaining internal stability through constant adjustments, and it is dynamic, not static.

positive feedback loop cycle

Increasing/enhancing a stimulus until a particular event occurs; Examples: Blood clotting and child birth

extrinsic regulation

Responses controlled by nervous and endocrine systems

difference between hydrophilic and lipophilic hormones

Responses controlled by nervous and endocrine systems

difference between extracellular vs intracellular receptors

extracellular receptors deal with fast signaling via cell surface receptors, while intracellular receptors handle slower, long-term regulation by influencing gene expression.

alpha cells

secrete/produce glucagon

beta cells

secrete/produce insulin