HHP-M2

What is a cell?

the smallest functional unit of life

Cell theory

cells are the basic unit of life, all living things are made of 1+ cells, cells come from other cells

Eukaryotic cells

nucleus & membraned bound organelles

What reads mRNA from the nucleus?

ribosomes

Where is the ER located?

near the nucleus

Smooth ER functions

• produces lipids, steroids

• detoxifies substances entering cell

• stores calcium

Rough ER function

• studded with ribosomes

• mRNA exiting nuclear pores is processed into proteins here

Golgi Apparatus

vesicles with proteins from rough ER come here to be processed

Golgi apparatus function

• sort proteins

• modify proteins to function at their final location

• places vesicles in position to be released from the cell

Lysosome

degrades items taken in by cell from the environment

Mitochondria

• produces energy/ ATP via oxidative phosphorylation

Mitochondrial matirix

fluid inside mitochondria where enzymes of krebs cycle are located

Cytoskeleton

gives cell shape and allows for movement

3 types of filaments

• microfilaments

• intermediate filaments

• microtubules (cilia and flagella)

Plasma membrane

selectively permeable, not everything can enter the cell

In what ways does membrane transport occur?

• diffusion

• carrier proteins

• active transport

Simple diffusion

non-polar molecules can move through the cell membrane easily

Carrier proteins/ facilitated diffusion

help polar/ charged molecules move through nonpolar cell membrane

Active transport

movement of molecules across membranes with aid of carrier molecules using ATP

Where is the cytoskeleton located?

in the cytoplasm

Function of cytoskeleton

• provides support

• maintains 3D shape of cell

• transportation network

• force transmission

How are polymers classified?

by width —> microfilaments —> intermediate filaments —> microtubules

Microtubule function

• important for cell division

• minus ends are anchored in centrosome

Centrosome

non-membrane bound organelle

Cell junctions

multi-protein complexes which connect cells to each other or to the extracellular matrix

Ex. adheren

Adheren junctions

anchors/ link neighboring cells cytoskeleton

• actin skeleton of one cell can be mechanically coupled to neighboring cells cytoskeleton

What alters protein structure/ behavior?

• proteins can bind ions which alters their structure/ behavior

• proteins can sense force which alters their structure behavior

What are muscles?

a type of tissue in the body

3 types of muscles

skeletal, cardiac, and smooth

Skeletal Muscle

• multinucleated

• striated

• long cylindrical cell (fibers)

• cells cannot divide

• voluntary force

Cardiac muscle

• single nucleus

• striated

• branched/ connected cells

• involuntary force

Smooth muscle

• not striated

• forms bands or sheets

• involuntary force

Myocardium

muscle thats part of the heart wall made of muscle cells and collagen

Myofibrils

smaller fibers that produce force

What are myofibrils made of?

repeating units called sarcomeres

What activates the sarcomere?

Ca2+ (calcium)

What produces force from the sarcomere?

myosin uses ATP to generate force

How does the sarcomere shorten?

filaments slide past each other (actin slides past myosin)

What is the leading cause of death worldwide?

heart failure

Heart Failure w/ reduced Ejection Fraction (HFrEF)

systolic heart failure

Heart Failure w/ preserved Ejection Fraction (HFpEF)

diastolic heart failure

• almost half of patients w/ diabetes

Ejection fraction

percent of blood pumped out of left ventricle

Diastole vs. Systole

• diastole: heart relaxing to fill

• systole: heart pumps blood

Muscular dystrophy

progressive muscle weakness

4 types of general tissues

epithelial, connective, muscle, and nervous

Epithelial

cells that cover structures

Connective

cells that hold structures together or connect 2 points

Muscle

specialized cells for movement

Nervous

cells that send information

Architectural rule

form follows function

Epithelial tissue

Cells form a layer that is covering organs or lining cavities in the body

Epithelial tissue functions

• diffusion, osmosis, & filtration

• secretion of materials

• absorption of ions

• protection

Simple membranous epithelium

single layer of epithelial cells

• diffusion, osmosis, filtration, absorption (small intestine)

Stratified membranous epithelium

more than one layer of epithelial cells

• protection (epidermis)

Connective tissue

tissue that binds the cells and organs of the body together

• bodys glue

Connective tissue features

• specialized cells

• ground substance varies by type of CT Ex. blood = plasma / bone = mineralized content

• Protein fibers: collagen, reticular, elastic

Tendons

connect muscle to bones

Ligaments

connect bone to bone

Fibroblast

specialized cell that synthesize/ secrete the extracellular matrix and collagen

Adipose tissue

modified type of loose connective tissue; when fat cells accumulate in large numbers in loose connective tissues

Why do fat cells look irregular?

because the hydrophobic effect causes the cytoplasm & nucleus to be squashed against the cell periphery

Stem cells

cells that

1. self renew

2. can become other cell types

Adult stem cells

stem cells in mature humans after development

• internal repair to replace damaged cells in certain tissues

Embryonic stem cells

• important for human development

• one cell can become any cell type

• necessary to make a whole human

Cell re-programming

• cells can be re-programmed into another cell type in vitro into cells called induced pluripotent stem cells (iPSC)

Regenerative medicine

engineering and replacing or restoring patient’s damaged cells with functional ones

Precision medicine

using patient specific traits like genetics to personalize treatments

Neurons

conducting cells

Neuroglia

non-conducting cells

Nerve

many neurons

Neuroglial cells

• do not conduct/ produce electricity

• support maintenance of neurons

Structure of a neuron

cell body, dendrites, axons, axon terminals

Cell body

the nucleus & cytoplasm

Dendrites

external appendages that transmit bioelectric impulses toward the cell body

Axon

large process that transmits impulse away from cell body

Axon terminals

end of axon; communication link to another cell

Myelin sheath

• coats axon

• lipid

• increases speed of nerve impulses

Neuron function

generate and receive electrical impulses

Dendrites & Axons

dendrites receive info and axons send out info

Afferent neurons

• receive input

• integrate information (CNS)

Efferent neurons

• motor output

• provides basis of automatic reflexes

Rest

neuron is not sending any information

• more sodium outside more potassium inside

Resting membrane potential

stable negative charge in a cell when it is not actively sending signals

Sodium potassium pump when resting

• 3 sodium out

• 2 potassium in

• more sodium outside more potassium inside

Action potential

how neurons send information

• all the same size

All or none principle

an individual neuron or muscle fiber fires completely or not at all in response to a stimulus

What can cellular events cause

depolarization events

• ions crossing the membranes

Action potentials are generated when

when a cellular stimulus causes a depolarization event, pushing the resting membrane potential toward a threshold of approximately -55 mV

Depolarization event/ action potential

open sodium channels, sodium flows into cell, increasing voltage, then potassium channels open (slow), potassium goes out of cell, decreasing voltage

Energy balance

Ein=Eout

• intake

• output

Energy intake

food, drink

Energy output

useful energy + heat

Metabolism

sum of total life processes

1st law of thermodynamics

energy can neither be created nor destroyed but can be converted from one form to another

calorie vs. Calorie

• calorie = gram

• Calorie = kilogram

Caloric content in food 449

• carbohydrates: 4 kcal/ g

• proteins: 4 kcal/ g

• fats 9 kcal/ g

Energy output equation

RMR + DIT + PA

RMR

resting metabolic rate

• largest component of Eout

DIT

diet induced thermogenesis

• 10% of energy intake

PA

physical activity

• highly variable person-to-person