Nutrition: A Biology Perspective

Will BrownLecture 2

Objectives and Content

• Objective: Define the nutritional needs of a human being from a physiological and biological point of view

• Contents– Cells and cell structure– Cellular metabolism and respiration– Tissues and organ systems

Anatomy and Physiology

• What is the difference between anatomy and physiology?

• Anatomy – The structural elements that comprise an organism– Includes placement of various organs and organ

systems in relation to each other• Physiology – The function of the various organs

and organ systems• Remember that Structure dictates Function

Cells

• The most basic anatomical (structural) and physiological (functional) component of an organism

• Organelles – “Little organs” – Specialized structures and compartments within a

cell• There are 8 organelles that we are interested

in for this class

Plasma (Cell) Membrane• Outer most layer of animal cells – technically not an

organelle• Functions– Regulate transport into and out of the cell– Cell-to-cell communication– Defines what is outside and what is inside

• Composition– Phospholipid bilayer– Cholesterol– Proteins– Carbohydrates

Dhatfield; 2008

Cytoplasm

• Also, technically not an organelle• The inner fluid of the cell• Anaerobic metabolism can occur via chemical

processes– Sole source of energy production for red blood

cells

Mitochondria

• The “power plant” of the cell• Responsible for most of the energy production • Aerobic metabolism• Other things of note (but not test material)– Have their own genome; which is closer to

bacteria than to human– All of your mitochondria are maternally derived• There are specific metabolic diseases that are

maternally inherited

Nucleus

• All cells, expect RBC, have a nucleus. Some cells have multiple nuclei.

• Wrapped in it’s own double membrane• Houses genetic material– Consists of genes on chromosomes made from DNA– Contains all of the information and directions for

producing anything the cell needs– Sends out messages via messenger RNA (mRNA)

• DNA duplicated during cell replication

Gene Expression

More on this when we get into Proteins later in the quarter.

Endoplasmic Reticulum

• True organelle• Long network of tubes that continues off of the nucleus• Place where proteins are produced by “translating”

mRNA• Two types– Rough – associated with Ribosomes– Smooth – no ribosomes

• Other functions– Lipid synthesis– Detoxify toxic substances– Calcium storage and release

1. Nuclear membrane2. Nuclear pore3. Rough endoplasmic

reticulum (rER)4. Smooth

endoplasmic reticulum (sER)

5. Ribosome attached to rER

6. Macromolecules7. Transport vesicles8. Golgi apparatus9. Cis face of Golgi

apparatus10.Trans face of Golgi

apparatus11.Cisternae of Golgi

apparatusCourtesy of Pbroks13

Golgi Complex

• True organelle• Responsible for packaging of proteins for

export out of the cell• Packages are called secretory vesicles• Made up of multiple layers of sacs stacked on

top of one another

Lysosomes

• True organelle• Known as the “digestive system of the cell• Sacs that contain enzymes and molecules that

degrade (or digest) extracellular substances• Also degrade damaged cellular components• Very low pH (4.2) especially compared to

cytoplasm (7.2)

Peroxisomes

• True organelle• Contain enzymes responsible for detoxifying

harmful chemicals• Get their name from the formation of

hydrogen peroxide (H2O2) from enzyme activity• Contain an enzyme know as catalase– Prevents excess hydrogen peroxide accumulations

• Plays minor role in alcohol metabolism

Cell Metabolism

• Sum of all the chemical reactions in the cell• Takes place in the cytoplasm and organelles• Biochemical breakdown of food-by-products

and nutrients into usable components• Anabolic processes build and synthesize new

molecules and therefore require energy input• Catabolic processes break down nutrients and

therefore has a net energy gain

Cell Metabolism: Glycolysis and Cellular Respiration

• Primary energy yielding pathway in cells• Gycolysis: First step is the breakdown of

monosaccharides (mainly glucose); anaerobic• Products from glycolysis are moved into the

mitochondria to generate ATP; aerobic• ATP is the main energy currency in cells

DO NOT spend time trying to memorize this! It will not be on the test! I highlight this so you can understand the complexity of metabolism.

BREAK: 10 MIN

Tissues and Organ Systems

Tissues: 4 Primary Types• Epithelial

– Cells that cover both the inside and outside of the body– Secrete substances, import substances, excrete waste– Examples: lung tissue and gut tissue

• Connective– Supports and protects the body– Stores fat– Produces blood cels

• Muscle– Applies force on the connective tissue to allow for movement

• Nervous– Responsible for communication and sensory input– Examples: Brain and spinal column

Main Organ Systems

• Cardiovascular • Lymphatic• Nervous• Endocrine• Immune• Urinary • Digestive

• Integumentary• Skeletal• Muscular• Respitory• Reproductive

Cardiovascular and Lymphatic Systems

• Two different organ systems that circulate fluids– Cardiovascular System– Lymphatic System

Cardiovascular System• Primary pump in the CV is the heart

– Pumps ~50-90 beats/minute at rest• Blood is primary fluid

– Plasma– Red blood cells– White blood cells– Platelets– Other substances – ie: digested food

• Blood travels via blood vessels– Arteries – carry blood away from the heart– Veins – carry blood toward the heart– Capillaries – Smallest vessels that allow for oxygen/CO2, nutrient and waste

exchange

http://webschoolsolutions.com/patts/systems/diagcirc.gif

Lymphatic System

• Primary pump is muscle movement – the more you move the lymph flows

• Primary fluid is Lymph– Plasma– White blood cells

• Highly important for immune system• Eventually leads back to CV system• Responsible for transporting fat into the body

just after digestion – fat particles are to large to fit into capillaries

Nervous System• Regulatory system that controls most body functions• Monitors internal organs and external environment• Primary sensory organs

– Eyes– Ears– Skin– Nose– Stomach

• Responsible for muscle movement – both voluntary and involuntary

• Primary cell type is the neuron

Endocrine System• Primary system for regulating metabolism, reproduction,

water balance, and other functions• Signals by chemicals known as hormones that are

produced and secreted by endocrine glands• Hormone Function

– Permissive or excitatory – activate or turn on a signal– Antagonistic – turn off signals– Synergistic – amplify or work in cooperation with other signals

• In order for hormones to elicit function, responding cells must have corresponding receptor

Endocrine system: Examples

• Insulin – Produced by b-cells in the pancreas– Released after meal to help control blood glucose

levels– Lack of insulin or insulin function results in

diabetes• Thyroid hormones– Produced and released from the thyroid gland– Control rate of metabolism

Immune System

• Primary responsibility is to fight off infection• Works in cooperation with many other organ systems– Skin– Intestine– Bone marrow

• Primary organs– Spleen– White Blood Cells– Lymph nodes– GALT

Immune System• Two main branches

– Innate– Adaptive

• Innate immunity– Evolutionarily old– Early phase responses <7 days– Include swelling, histamine release, antigen recognition – Nonspecific

• Adaptive immunity– Found in higher order organisms– Late phase responses >7 days– Highly specific and directed response– Includes antibody production and cell killing– Provides long term immunity

Urinary system

• Comprised of kidneys, bladder, ureter, and urethra

• Responsible for filtering the blood and removing waste; primarily urine but also unused or un-needed vitamins and minerals

• Help to maintain pH balance in the blood• Responsible for conversion of Vitamin D to

erythropoietin

1. Urinary system2. Kidney3. Renal pelvis4. Ureter5. Urinary bladder6. Urethra (Left side with

frontal section)7. Adrenal gland8. Renal artery and vein9. Inferior vena cava10.Abdominal aorta11.Common iliac artery and

vein12.Liver13.Large intestine14.Pelvis

Jordi March i Nogué , 2010