Cellular Physiology Flashcards
4 classes of cells in the body
- > muscle cells
- > nerve cells
- > connective tissue/cells
- > epithilial cells
*ALL ORGANS ARE MADE UP OF ALL 4 CLASSES BUT HAVE DIFFERENT RATIOS OF EACH*
classes of MUSCLE cells and what do they control
- Skeletal muscles (motion)
- Smooth muscles (controls fluid flow)
- Cardiac muscles (controls bloodflow)
Which two types of muscle cells are the most similar
skeletal and cardiac cells are the most similar of the muscle cells; smooth muscle cells are more unique than the other two
Characteristics of skeletal muscles
- > also know as striated muscle (because or parallel arragement of filaments)
- > cylindical, multi-nucleated
Name the layers of A muscle
Outer
Epimysium
Perimysium (wraps fasicle)
Endomysium (wraps muscle fibre/cell)
Inner
Sarcomeres
individual units within a muscle fibre/cell which are composed of various fibres and proteins that play a role in contraction and the regulation of contraction
Sub-classes of skeletal muscle fibres
- Slow Twitch
- > slow activation/contraction and are relatively resistant to fatigue - Fast Twitch
- > fast activation/contraction and not as resistant to fatigue
Metabolic sub-classes of skeletal muscle fibres
*muscles are made up of various sub-classes*
- Slow Oxidative (SO Fibres)
- > slow twitch; relies on O2 - Fast Glycolitic (FG Fibres)
- > fast twitch; can produce ATP anaerobically - Fast Oxidative-Glycolytic (FOG Fibres)
- > fast twitch; O2 requiring but can also function anaerobically
Which muscles produce more ATP… Oxidative pathways or Glycolitic
Oxidative Pathways (mitochondria needs O2)
Pathway of skeletal muscle activation
Activation/Contraction of smooth muscle is through what?
- Spontaneous electrical activity initiated by pacemaker cells
the SEA gives a baseline level of contraction/relaxation as it plays a role in paristalsis and segmentation
- Nerves and hormones
- Local factors
pacemaker cells
*SA NODES*
create these rhythmic impulses, setting the pace for blood pumping; they directly control heart rate
Explain the innervation of smooth muscle by the autonomous nervous system
sympathetic nervous system
- > solely innervates Vascular smooth muscle
- > there is always some baseline level of stimulation of vascular smooth muscle
parasympathetic nervous system
- > healily innervaes the GI smooth muscle
Explain how local factors work to make changes within the body
LF’s are released by a cell (usually epithilial) and affect the smooth muscle in the region of release
- > many LF’s are responsible for vascular smooth msucle relaxation (+ some contraction)
smooth muscle activation/contraction pathways
- Single-unit smooth muscle
- > all cells/fibres work together with a single activating event - Multi-unit smooth muscle
- > each cell/fibre must be activated seperately
Differences between cardiac and skeletal muscles
- > cardiac muscle cells are spearated by intercalcated discs (desmosomes)
- > cardiac muscles only have the capacity to contract with O2 (oxidative phosphorilation) so it needs more mitochondria as that is where OP occurs
- > cardiac fibres are not arraged in a tight, parallel orientation
How are SA Nodes innervated
SA node are innervated by the Autonomous nervous system
(sympathetic raises heartrate parasympathetic lowers it)
- > this occurs due to circulating hormones that bind to receptors on cardiac muscle cells
characteristics of general epithilial cells
- > located at the surface or line the walls of tubular and hollow structures
- > rest on non-cellular material (basement membrane)
- > regulate the movement of molecules in and out of organs, tissues, and body fluids
- > epithelial cell membranes have different functions depending on which side of the epi.cell the membrane lies
membranes of general epithilium
luminal membrane
- > part of the epi.membrane that faces the inside of the organ/tube
Basolateral (outter)
- > the part of the epi.mem. that faces the basement membrane, which is the outer surface of the organ/tube
these two membranes work together to determine the movement of substances in/out of fluid in lumen
Paracellular transport vs Transcellular transport
PT
- > “leaky” epi. allows small molecules to pass between cells
TT
- > tight junctions between epithelium forces movement to occur through the basolateral membrane, into the epi. cell and into the hollow tube/organ (this process helps regulate)
Classification of glands
Exocrine glands
- > secrete through ducts to the outside of the body (i.e. sebacous glands)
Endocrine glands
- > secretes directly into the blood (usually systemic circulation beu sometime locally)
componants of extracellular matrix
collagen fibres, elastin fibres, reticular fibres
mostly proper connective issue
componants of extracellular fluid
Extracellular fluid = interstitial fluid + plasma
Interstitial fluid is the fluid that surrounds all cells, tissues and organs
plasma is the fluid portion of blood
Intracellular vs Extracellular fluid vs interstitial fluid
fluid inside vs outside fluid of the cell that differs in terms of ions molecular content
interstitial fluid and plasma make up extracellular fluid
pH fluid ranges within the body
most body fluids
- > 6.8(acidic) - 7.8(alkaline)
intracellular fluids
- > 7.0(neutral) - 7.2(slightly alkaline)
blood/plasma
- > 7.38-7.45
gastric acid
- > around 1.4 (highly acidic for chemical breakdown)
urine
- > 6.0 (can fluctuate based on sex,diet,time of day)
What happens to pH when [H} increases vs decreases
[H] increases
- > fluid pH decreases (more acidic)
[H] decreases
- > fluid pH increases (more alkaline/basic)
A solution has a [H] of 10^-6 mol/L… what’s its pH
6
why must body fluid pH stay in between a certain range? what is this range?
6.8-7.8
must stay in this range beacuse the vast majority of enzymes and proteins involved in all physiology only function in a narrow range of pH
is water a polar or non polar molecule
POLAR
Can polar molecules dissolve in water? Why is this important
YES
blood plasma is 90% water and transports dissolved substances through the body
ampipathic molecules
molecules with polar and non polar groups
How can hydrophobic/non-polar molecules travel through blood
hydrophobic molecules usually have to be attached to a plasma protein to be able to travel trough blood as it cannot dissolve in water/blood
Carbohydrates
sugars(monosaccharides) used for energy/ATP production
Glucose
- > primary monosaccharide
- > used to synthesize metabolic pathways
- > 22 glucose molecules make up glycogen (stored mostly in liver and some in skeletal muscle)
What occurs to carbohydrates when ATP supplies are sufficient?
excess carbohydrates are converted into glycogen and stored mostly in the liver, some in skeletal muscles, or stored as fat (triglycerides) in adipose tissue
triglycerides
Type of fat
a glycerol molecule with 3 fatty acid side chains
- > stored as fat in adipose tissue
Polysaccharides
aka. starch
- > formed by plants
- > broken down during digestion to release glucose
Cellulose
aka fibre
a complex polysaccharide
- > formed by plants
- > unable to be digested by humans, helps with digestion
Lipids
made up of fatty acids and glycerol
- > glucose when taken up by adipose cells is transformed to glycerol phosphate and combined with fatty acids
Fatty Acids
- > formed by the liver, breakdown of triaglycerols from dietary sources , and breakdown of triglycerides in adipose tissue to form fatty acids
Saturated fatty acids
- > all carbons are linked with single bonds; solid at room temperature
Unsaturated fatty acids
- > one or more carbons are linked with a double bond; liquid at room temp
roles of fatty acids
- > help form triglycerols
- > play a role in formation of energy substrates
- > plays a role as chemical messenger
- > helps form phospholipides (membrane)
Phospholipids
- > major building block of the cell membrane
- > composed of a phosphate group, glycerol (polar head) and 2 fatty acids (sometimes more) (non polar tail)
Eicosanoids and the most important member of the family
- > molecules/chemical messengers derived from arachidonic-acid (20 carbon fatty acid with 4 double bonds)
- > prostaglandins are the most important member of the eicosanoid familt and are responsible for blood clotting, inflammation, labour contractions, pain, fever
Activation of arachidonic acid
arachidonic acid is broken/cleaved into smaller molecules which act as second messengers
Steroids
- > used as a chemical messenger
- > important componant of membrane structure (it allows some fluidity as it makes space in between the phospholipids of the membrane)
- > cholesterol is an important steroid as it plays a major role in mantenance of membrane structure and is also a precursor for other hormones in the body (progesterone, testosterone,cortisol,estradiol)
Lipoproteins and the different types
- > lipid + protein based structure that transports [fatty acids and cholesterol] in blood
HDL’s - > high density lipoproteins
LDL’s - > low density lipoproteins
[not dissolved in blood]
HDL’s vs LDL’s
HDL’s
- > transport excess cholesterol from the peripheral tissues to the liver where it is excreted in bile (excess cholesterol and F.A in the circulation may initiate the formation of plaque on the blood vessel wall)
LDL’s
- > transports cholesterol in the peripheral tissues for the membrane or hormone synthesis or storage (excess cholesterol + F.A will remain in the vasculature if HDL’s are not available for removale; may initiate atherosclerosis )
VLDL’s
very low density lipoproteins
- > transports triglycerides to the peripheral tissues
- > VLDL become LDL
relate saturated and unsaturated fatty acids to HDL/LDL pathways
(iffy???)
- > saturated fatty acids stimulate LDL pathways, increase liver synthesis of cholesterol and inhibits excretion of cholesterol
(still stands)
- > unsaturated fatty acids stimulate HDL pathways and enhance excretion cholesterol
Trans Fatty acids in relation to HDL and LDL
TRANSFORMED UNSATURATED FATS
- > stimulate the LDL pathways and increase liver synthesis and inhibits excretion of cholesterol even more that saturated fats
Omega-3
omega-3 fatty acids decrease the availibility of saturated fatty acids (from triglycerol breakdown) and lowers bloods cholesterol
Integral proteins vs peripheral proteins
integral proteins
- > embedded within the bilayer; polar groups on the plasma membrane, non-polar groups within the bilayer
peripheral proteins
- > polar proteins, loosely attached, usually on the intracellular side of plasma membrane
- > involved in cell signalling and activation of cell response
Glycocalyx
aka. glycoprotein
- > carbohydrate-protein complex that extends into extracellular fluid
i. e. antigens on RBC; immunoglobulins (antibodies)
Channel proteins
- > a type of integral proteins that span across the membrane and form water-filled passages to allow water-soluble (polar) molecules to pass through the membrane
- > channels are very selective
Carrier proteins
a type of integral protein that spans the membrane and transfers specific substances accross the membrane that are incapable of passing through on their own
Receptor proteins
usually on the outer surface of the cell membrane and play a role in recognition and binding of specific molecules
- > this binding initiates a variety of membrane and cellular responses
cell adhesion molecules
type of protein that protrudes from the membrane surface and form “hooks” or “loops” that the cell uses to grasp connective tissue fibres to help hold cells in place in a tissue/organ
- > also play a role in cell signalling, especially in immune system
Membrane junction
a meeting spot between two cells
desmosomes
helps hold 2 closely adjacent cells but non-touching cells together in a tissue
- > uses glycoprotein fillaments to hold the cells together
- > found in cell populations that undergo stretching (i.e.skin)
tight junctions
2 adjacent plasma membranes joined together, such that there are no passageways between the cells
- > forms a “selective barrier” and are commonly found between epithelial cells
gap junctions
protein channels that link 2 cells for transmission of signals (especially electrical) between cells.
- > the watter filled protein channels that form the gap junctions allow for rapid passage of small particles, especially ions, between adjacent cells
