Intro to cells

Feedback loops

These are control pathways that go with or against homeostasis

Homeostasis

Keeping the internal body the same with different external influences (heat, ph changes, etc)

Which of the organs is the control centre for homeostasis?

Hypothalamus

Which of these are not controlled by the hypothalamus to maintain homeostasis?

A) B and D

Circadian Rhythms

Controls when and where you are sleepy, based on the amount of light you get and the temperature of your body

• Temperature increases as you reach bedtime

Set points

The way your body maintains homeostasis is not a set number but rather keeping it in a certain area (Ie 36.5 to 37.5)

Why does oscillation occur around the set points

Negative feedback

Positive feedback

This reinforces stimulus

• oxytocin does this

Parts of the cells

• Plasma membrane

• Cytoplasm; Cytosol (gooey interior) and the organelles

• Nucleus; Chromosomes and genes

Why do cells differentiate from each other?

Functions are different

Nucleus

• Cell replication and repair

• Usually only one

Which are the two exceptions that a cell only has one nucleus?

C) A and D

Why do red blood cells not have a nucleus

They must fit through the capillaries, a nucleus is too large

Why do long muscles have multiple nucleuses

they are long and under lots of stress, so repair must be quick

Ribosomes

Free or attached, they make proteins

• muscles will have a lot of these

Attached proteins

Found on the rough ER, they make proteins for export

What are the 3 functions for the smooth ER?

• Calcium storage; skeletal muscles

• Detoxification; liver

• Steroid production; reproductive organ

What are the functions of the rough ER?

• Protein export

• Creation of organelles

The pancreas will have a lot of these because elf insulin production

Golgi Complex

Re-packages the rough ER’s protein into vesicles to be transported out

• pancreases will have a lot of these

Free ribosomes

Will make proteins for the cells

Peroxisomes

These are oxidative enzymes that remove free radicals

• Metabolism for lipid synthesis

• Detoxify waste into safer chemicals

Found in the liver!

Lysosomes

• Sac of digestive enzymes

• Repair and removal of forgiven matter

Found in white blood cells

What happens when homeostasis is not reached?

The body will then fall into diseases and illnesses

Negative Feedback

Stimulus is sent, causes a reaction that decreases the cause, the stimulus is turned off.

• maintains homeostasis

What type of errors can occur in negative feedback loops?

• overcompensation

• disease

• competing regulators

Proteosomes

Large protein complexes that removes old organelles (tagged organelles)

Cytoskeleton

Large, complex protein network to protect and maintain the cell

Microtubules

• transports secretory vesicles

• forms the spindle fibres in mitosis

Tubulin!

Microfilaments

• Contract system

• Muscles

• Stiffeners

Myosin and Actin

Intermediate filaments

• resist stress

• Hair and skin

Keratins!

Centrosomes/Centrioles

Type of organelle found mainly in the skin for cell replication. 

• Creates spindle fibres 

Cilia 

One-way movement 

• found in the trachea and uterine tubes 

• power stroke and recovery stroke

Flagella

On moving the cell 

• only located on the sperm 

Mitochondria

• Recycles energy for ATP production

• TCA and ETC

How many types of cells are there in the body?

200

What are the two factors that play into the cell’s function?

• Shape of the cell 

• Type of organelles present 

What happens to our cells as we age?

• Deterote

• Loss of extracellular components

• Free radicals

Free radical theory

• Damaged byproduct from cellular metabolism

• Damage to essential molecules (o2 to o3)

• caused by aging

Mitochondrial theory 

Decrease production of energy that weakens the cell with age 

Genetic Theory

• Aging is caused by our genes

• With the replication of DNA, telomeres disappear, causing the chromosome to degrade

• Signals the start of aging

What does the Plasma Membrane mainly contain?

• Physical barrier

• Gateway for exchange

• Communication

• Cell structure

What does the cell membrane contain?

Mainly phospholipids and cholesterol for fluidity

Phospholipids

Protect the cell externally

• Choline head (polar)

• Fatty acid tails (non-polar)

Glycocalyx

These are glycoproteins(on a protein) and glycolipids(within the cell membrane)

• cell identity and cell orientation (pushes away other cells so there is room to growth)

What are the two types of membrane proteins?

• Integral/transmembrane proteins

• Peripheral proteins

What are the 7 functions of membrane protein?

• Ion channels (small, charged chemicals)

• Carrier (larger uncharged molecules)

• Receptor sites (identify)

• Enzymes (triggers)

• Pores (movement of H2O)

• Structural (maintain shape)

• Cell adhesion (Groups proteins)

The membrane is selectively permeable

True

How do molecules move into the membrane

• Small uncharged and non-polar molecules move through the membrane

• Transmembrane proteins more polar particles

• Macromolecules use vesicles

What is the difference between passive and active transport

Passive goes with the gradient and active goes against, using AT in the process

What are the 3 types of gradients

• Concentration

• Electrical

• Electrochemical

Simple diffusion

• Movement of molecules from a high to low concentration because of collisions

• No usage of proteins

Ie, steroids and small, non polar molecules

Net movement

The total amount of molecules moving in or out of the cell membrane

What controls simple diffusion

• Temperature

• Concentration

• Distance

• Mass

Diffusion across the membrane is controlled by what 4 factors

• Permeability

• Surface area

• Gradient

• Temp

Osmosis

The movement of water down its own concentration radiant

Tonicity

The total number of non-diffusible particles

Hypertonic

• Tonicity is high, pulling water out (crenation)

Isotonic

Tonicity is the same

Hypotonic

Tonicity is low, water is pulled in (hemolysis)

What is facilitated diffusion

• Usage of proteins to move molecules without ATP

What are the two types o facilitated diffusion

Open and closure of these proteins allows to move along the concentration gradient

• Channel: molecules can move down or up (Na and K)

• Carrier: will attach and move (Glucose)

What is an example of primary active transport

Na/K ATP pump

Co-Transport Mechanism

• Secondary active transport

• One against one with in the same direction

• Symporter

Counter-Transport Mechanism

• One with and one against moving in opposite directions

• Anti-porter

Receptor/ligand-mediated endocytosis

• Binds and takes in molecules via a vesicles

Ie, Lipids, vitamins, iron, antibodies

Phagocytosis

Removal of molecules from the cell

Ie, white blood cells

Pinocytosis

Movement of water into the cell (can come with molecules)

Epithelial Transport

Combination of diffusion and active transport for movement

Ie, Gut and Kidney

Ligands

Special molcules that bind with receptors

Channel-linked receptors

Allows ions to move in and out of the cell through ligands binding, initiating electoral changes and opening channels.

Ie, neurotransmitters

Enzymatic Receptors

Ligand binds to the receptors releasing protein kinase enzymes that turns on enzymatic activity

G-Protein coupled receptors

• Indirectly activates the protein kinase enzymes

Secondary Messenger response

Creates a response by activating a 2nd part of the line

cAMP

Activates protein kinase which in turn, create a rapid response

Calcium

• Activated IP3 releases Ca2+ from the ER

• DAG and IP3 activate enzymes and kinase

Calmodulin

Activates kinase protein (same as cAMP)