Heart's Electrical System and Blood Flow

Here are the study notes:

The heart is a muscular organ that pumps blood throughout the body
Composed of 4 chambers: left and right atrium, left and right ventricle
Blood flow: Right atrium -> Right ventricle -> Lungs -> Left atrium -> Left ventricle -> Rest of the body
Depolarization spreads across the system of electrical receptors from the SA node to both atrium and then to both ventricles
Stroke volume is the volume of blood ejected after each contraction
Cardiac output = Stroke volume x Heart rate (altered by the autonomic nervous system)
Arteries are elastic and retain the pumping force from the heart

Blood flows from high pressure to low pressure
Arterial system is under high pressure, while venous system is under low pressure
Systolic (contract) and Diastolic (relax) pressures

Carries various substances around the body through:
- Movement between the endothelium (layer of the capillary)
- Transcytosis
- Bulk flow (driven by pressure) out of the capillary

Returns filtered fluid (interstitial fluid) to the circulatory system to maintain proper blood pressure

Gas exchange: uptake of oxygen and removal of CO2
Mechanism of breathing:
- Negative pressure breathing (inspiration): chest wall expansion and diaphragm contraction
- Expiration: relaxation of diaphragm and chest wall
Gas exchange at the alveoli:
- Millions of alveoli with a high surface area for rapid diffusion of O2 into surrounding capillaries
O2 and CO2 transport:
- O2 is carried via red blood cells using hemoglobin
- CO2 is dissolved in plasma or via red blood cells (bound to it or converted into bicarbonate)

Classification of interactions between organisms:
- Amensal (incompatible)
- Parasite/pathogen (one partner benefits, one is harmed)
- Commensal (one partner benefits)
- Mutualist (both partners benefit)
Exposure to microbes: necessary for development of entire body systems (immune, endocrine, neural)
Gut microbiome:
- Stable resident microbial community in the small and large intestine
- Composed of bacteria, archaea, and eukaryotic microbes
Microbiome influences on nutrition:
- Presence of microbes decreases food requirement and increases quality of food
- Microbes produce enzymes that break down carbohydrates and fiber
Control of microbes:
- Nutrient control determines population and activity of microbes in the gut
- Immune function controls the location of microbial activity within the gut

Functions:
- Ingestion
- Secretion
- Motility
- Digestion
- Absorption
- Protection
- Elimination
Organic compounds absorbed:
- Carbohydrates
- Proteins
- Lipids
- Nucleic acids
Digestion:
- Physical (mechanical breakdown of food)
- Chemical (enzymes break down food into smaller particles)
Oral Cavity:
- Includes accessory organs (teeth, tongue, salivary glands)
- Ingestion: forms bolus
- Digestion: teeth and saliva (salivary amylase for starch and lingual lipase for triglycerides)
- Secretion: saliva lubricates food
- Protection: saliva has antimicrobial properties

...and so on. Let me know if you'd like me to continue with the rest of the text!### Concepts in Biology

Evolution is defined as the survival of the fittest, where organisms adapt to their environment to reproduce successfully.
Cell Theory states that all organisms are made of cells, and cells originate from preexisting cells that have multiplied.

Eukaryotic organisms can be unicellular or multicellular, have a present nucleus, linear DNA, and a cell membrane.
Prokaryotic organisms are unicellular, lack a nucleus, have circular DNA, and no cell membrane.

Epithelial tissues cover and line body surfaces and hollow organs, performing functions like protection, absorption, and excretion.
Connective tissues support, connect, and bind other tissues, and include blood, bone, cartilage, and adipose tissues.
Muscle tissues perform mechanical functions through contraction and extension.
Nervous tissues receive external signals, direct them to the central nervous system (CNS), and deliver signals throughout the body.
Adipose tissues are composed of body fat.

The body balances pH through respiratory, metabolic, and renal mechanisms.
Respiratory mechanisms involve CO2.
Metabolic buffers, such as bicarbonates, help regulate pH.
Renal mechanisms regulate electrolyte concentrations, including sodium, potassium, and chloride.

The cytoskeleton is a network of protein filaments and tubules that maintains cell shape and structure, and facilitates intracellular transport.
The nucleus controls and regulates cell activities and stores DNA.
The nucleolus produces and assembles ribosomes by making ribosomal RNA, which translates into protein synthesis.