digestion physio

Top 4 elements in the human body

Oxygen, carbon, hydrogen, nitrogen

Major elements

those that make up at least 0.01% of body mass and are essential for life: Oxygen, Carbon, Hydrogen, Nitrogen, Calcium, Phosphorus, etc

Trace elements

elements needed in very small amounts (usually 0,01%) but are still essential for body functions iron (Fe), zinc (Zn) copper, magnese, iodine, selenium

How can we achieve the diversity of life structures with limited building blocks?

Despite having a limited set of basic “building blocks” (carbon, hydrogen, oxygen, nitrogen, and a few other elements) the immense diversity of life arises. Atoms combine in many different ways to form molecules with diverse structures, carbon atoms form long chanes, there are different arrangmenets, and a complex three-dimensional structure

Explain how specific atoms in our bodies are not constant but the general composition and positioning is fairly consistent

Atoms in the body are constantly replaced as moelcules break down and are rebuilt, yet the overall composition and arrangement remainds relatively stable:

Human cells and molecules are in a dynamic state (metabolism)

atoms in water molecules or proteins are replaced continuously through intake and biochemical processes, but the body maintains homeostasis, keeping consistent rations of elements and molecules in cells + tissues

Carbohydrates

Made up of carbon, hydrogen, and oxygen

Sources: fruits, veggies, grains, sugars

Function: primary energy source (glucose) energy storage (glycogen) structural roles (cellulose in plants, not digestible in humans)

used in cellular respiration to produce ATP

Lipids

Made mostly of carbon and hydrogen, with fewer atoms

Sources: made mostly of carbon, hydrogen, with fewer oxygen atoms

Sources: oils, butter, fatty meats, nuts

Function: long-term energy storage (triglycerides), structural components of cell membranes (phospholipids), signaling molecules (steriods like hormones)

stored in adipose tissue

Proteins

made up of amino acids (C, H, O. N, sometimes S)

sources: meat, dairy, beans, nuts

Functions: structural (hormones), movement (muscle proteins)

synthesized by cells according to genetic instructions

Simple carbohydrates

Monosaccharides (like glucose, fructose) and disaccharides (like sucrose, lactose)

quickly absorbed, rapid source of energy

examples: table sugar, fruit sugar

Complex carbohydrates

Polysaccharides (long chains of monosaccharides)

take longer to digest, provide sustained energy

examples: starch (plants), glycogen (animals), dietary fiber (cellulose)

complex carbs often contain fiber which humans cannot digest but aids in digestion

Fiber

a type of complex carbohydrate (mostly cellulose) found in plant cell walls. It is non-digestible by human enzymes

• It adds bulk to stool, promoting regular bowel movements

• helps control blood sugar levels by slowing glucose absorption

• may reduce cholesterol levels by binding bile acids

• supports a healthy gut microbiome by serving as food for beneficial bacteria

What are 3 major types of lipids found in cells and their function

Triglycerides

• strcture: glycerol + 3 fatty acids

• function: energy storage, insulation, and protection

Phospholipids

• Structure: glycerol + 2 fatty acids + phosphate group

• function: major component of cell membranes forming bilayers that control passage of substances

Steriods:

• structure: 4 fused carbon rings

• function: signaling molecules (e.g. cholestrol, steriod hormones like estrogen, testorone), maintaining a membrane fluidity

3 functions of proteins

structural : forming tissues like muscles, skin, hair (e.g. collagen, keratin)

enzymatic : catalyzing biochemical reactions (enzymes lower activation energy)

transport : carying molecules across membranes or in blood (e.g. hemoglobin carries oxygen

Function of an enzyme and how is it reliant on its shape

Enzymes are “biological catalysts” that SPEED UP chemical reactions by LOWERING activation

The enzyme’s active site fits specific substrate molecules like a lock and a key

The shape of the enzyme is crucial - any change (denaturation) can prevent substrate binding and stop the enzyme activity

factors affecting shape: pH, temperature, inhibitors

Describe the major function of the digestive system

• To break down food into smaller molecules (mechanically and chemically)

• to absorb nutrients (carbohydrates, lipids, proteins, vitamins, minerals) into the bloodstream or lymph'

• To eliminate waste products as feces

Mouth

mechanical digestion (chewing), chemical digestion (saliva enzymes)

Salivary glands

produce saliva containing enzymes (amylase)

Pharynx

passageway for food from mouth to esophagus

Esophagus

transports food to stomac via persistalsis

Stomach

secretes acid and enzymes, churns food into chyme

Pancreas

Secretes enzymes into small intestine, regulates blood sugar via insulin, glucagon

Liver

produces bile (emulsifies fats), detoxifies substances

Gallbladder

stores and releases bile into intestine

Small intestine

site of most digestion and nutrient absorption

Lagre intestine (colon)

Absorbs water and electrolytes, forms feces

Rectum

stores feces prior to elimination

Sympathetic activation of the digestive system

(Fight or flight) → inhibits digestion, decreases blood flow to digestive organs, reduces motility and secretion

Parasympathetic activation of the digestive system

(Rest & digest) → simulates digestive activites, increases saliva production moltility, enzyme secretion

Why is blood sugar regulated

Blood sugar (glucose) must be kept within a narrow range for proper body function, especially brain cells that rely on glucose

Role of insulin and glucagon

Insulin: released by pancreas when blood glucose is high

• promotes uptake of glucose into cells and storage as glycogen in liver and muscle, lowering blood sugar

Glucagon

• released when blood glucose is low

• simulates breakdown of glycogen to glyocogen to glucose in liver, increasing blood sugar

Describe Type I and Type II Diabetes including pathology, risk factors and treatment

Type I diabetes: juvenile onset, insulin-dependent

• autoimmune destruction of pancreatic beta-cells → no insulin production

• risk: genetics, early life triggers

• treatment: insulin injections, blood sugar monitoring

Type II Diabetes (adult-onsent, insulin resistance)

• body cells become less responsive to insulin, pancreas may produce less insulin over time

• risk factors: obesity, sedentary lifestyle, poor diet, genetics

• treatment: lifestyle changes (diet, exercise), oral medications, sometimes insulin

At a high level, explain how the food we eat is incorporated into our bodies, supports our lives, and how waste is execrated

Food is digested into small molecules (amino acids, sugars, fatty acids)

nutrients are absored into the bloodstream and transported to cells

nutrients provide energy (ATP), build/repair tissues, regulate body processes

Waste products from digestion and cellular metabolism are excreted via the digestive system (feces), urinary system repsiratory (C02)

Explain the connection between sunlight, photosynthesis, and the food that we eat

Sunlight: provides energy for plants in photosynthesis, producing glucose and oyxgen

plants convert sunlight, C02, and water into chemical energy (carbohydrates_

animals and humans eat plants to obtain this energy

• the sun is the orignal energy source

Describe the role of our gut microbiome in digestion

The gut microbiome is a collection of microbes (bacteria, fungi) living in the digestive tract, they help break down certain foods (like fiber), produce vitamins (K, some B vitamins) and support immune function

• they contribute to gut health, protect against pathogens, and influence metabolism

Trace element

essential elements required in tiny amounts

Vitamin

organic compounds needed in small amounts, usually from diet

Organic compound

contains carbon-hydrogen bonds

Inorganic compound

Does not contain carbon-hydrogen bonds

Esophagus

Muscular tube transporting food to stomac