b3 topic blurt

tissue - a group of cells that work together to carry out specific function

3 main types of epithelial tissue

squamous

columnar

endothelial

squamous epithelial tissue

structure - made up of flattened cells

forms a thin , smooth layer

function - allows for efficient transport across membranes (lungs and intestines)

ideal for areas where rapid diffusion or exchange is needed

advantages - thin and smooth layer enables fast diffusion of gases and substances

allows for diffusion of gaases

filtiration (in kidneys) - provides a smooth lining for blood to flow easily

disadvanatge - easily damaged by harmful substances (smoke)

smoking damages epethilium

related condition - COPD , caused by damage and inflammation of the epithilium

symptoms:

breathlessness

phlegm production and coughing

caused by smoking

copd reduces lung efficiency and makes breathing difficulty

structure linked to function:

thinnes - short diff pathways - faster exchange of substances

flat shape - ideal for forming smooth surfaces

single cell layer - efficient for diffusion and filtiration

columnar epithelial tissue

structure:

  • made up of tall , column shaped cells

may have cillia (tiny hair like structures ) called ciliated columnar epithelium

nuclei usually located at base of cells

function : involved in absorption , secretion and movement of substances

cillia helps move mucus and trapped particles

location: respiratory tract - trachea and bronchi - cilliated type

non cilliated type - contain microvilli which increase the surface area and helps with absorpotion of nutrients and secretion of digestive enzymes

goblet cells - part of the clumnar epithelial - acts along side cilliated cells - shown by coughing - produces mucus and mucus traps pathogens so they dont eneter lungs

advantage:

  • cillia help move mucus an prevent infection - cillited

  • efficient for nutrient absorption and secretion of enzymes and mucus - non cilliated

disadvantage:

smoking can damage the cillia reducing the ability to clear mucus leading to infections and COPD

structure linked to function:

tall shape - more room for organneles involved in secretion and absorption

cillia - moves substances along surfaces (mucus in the airways)

microvilli - increases the surface area or efficient absorption

endothelial tissue

structure : made up of flat thin cellls simular to squamous

forms the inner lining of blood vessels , heat and lymphatic vessels

function: provides smooth surface for blood flow and controls the exchange of materials (oxygen and nutrients between the blood and surrounding tissue)

location:

capillaries

blood vessels (arteries and veins)

heart chambers

advantage :

thinness allows for efficient diffusion of substances in and out of the bloodstream

smooth surfaces help prevent blood clots

disadvantage:

damaged by high blood pressure, cholesterol, smoking , bad diet and exposure to carbon monoxide

damage may lead to cardiovascular disease including atherosclerosis

stages of atherosclerosis:

1) damage to the lining of the artery ( endothelium) is damaged and it caused bu factors like high bp , bad diet , smoking

2) cholesterol inhillitation - bad cholestrol eneters the damaged area of the artery wall and the cholesterol becomes oxidised triggering an immune response

3) white blood cells response

macrophages - a type of wbc move to the area to remove the oxidised cholesterol and in the process they engulf the cholestrol turning it into foam cells

4) fatty streak formation - foam cells build up forming a fatty strek in the artery wall - more cholesterol and cells accumulate

5) plaque formation - a fibrous coating forms over the fatty streak creating a plaque - the plaque narrows the artery making it less flexible

6) reduced blood flow - narrowed artery reduces blood flow to the organs and tissue which can cause chest pains ( angina ) - if it affects the heart

7) plaque ruptures - if the plaque burts it can cause blood clots ( thrombus) to form which ca block the artery completely leading to a heart attack or stroke

Muscle tissue - responsible for enabling the body to move - movement can either be voluntary or involuntary - different types of muscles control the different movements

3 types of muscle of tissue:

structure of the mylien sheath

  • (made from/consists of) Schwann

    cells (1)

    (Schwann cells are) flattened

    mainly cell surface membrane/

    little cytoplasm/loss of organelles

    (

    (with) high lipid/fat content

    has a nucleus

    wrapped

    around/surrounds/spirals/insulates

    (axon) (1

    has many layers/ thick layer (1

  • skeletal muscle - attached to the skeleton and brings about movement ( whole-body movements like legs and arms) - under the voluntary control of the body

  • smooth muscle - found in the walls of organs and blood vessels - not voluntary - involuntary - controls movement of substances through organs (stomach and intestines)

  • cardiac muscles - only found in the heart - involuntary - contraction comes from the inside of the muscle tissue itself

skeletal muscle - looks striped under a microscope

  • this striated appearance is due to the regular arrangement of muscle fibers and proteins, which enables efficient contraction.

  • banding - myosin and actin are dark bands formed a bands - dark due to overlapping of filaments

  • composed of thin filaments - lightbands that consist primarily of actin, and are referred to as I bands, which also contribute to the overall striated appearance - move accross the thick filaments resulting in decrease in the size of the i band.

    h zone - the region within the A band that appears lighter, representing the area where only thick filaments (myosin) are present without overlap from thin filaments (actin).

action potential - a term that is used to describe the movements of an impulse across a neuron - the potential is not being transmitted then the neuron is said to be maintaining a resting potential

resting potential - sodium and potassium pumps move 3 na + and 2 k+ ions in through an active process

k+ diffuses back out as a membrane is permeable

more ion moves out than are moved back in

inside is negatively charged relative to the outside

this is the resting potential if measures approximately - -70 mv in the neuron with some variation from cell to cell may be 60 sometimes.

action potential

a change in the polarity occurs

na + channels open allowing na + to flood into the cell and causing the inside of the neuron to become positively charged ( + 30 mv action potential)

a positively charged neuron is considered depolarised

repolarisation

at peak depolarisaton (+ 30 mv) the na channels close and repolarisation causes the k+ channels to open allowing positevly charged ions to exit the cell restoring the neurons charge

more k+ diffuses out than required - period of hyperpolarisation where polarity drops below resting potential

factors affecting the speed of an action potential

axon diameter - larger axons can conduct faster

number of synapses - if a signal has to cross many synpases than it will be slower

myelination - if a nueron is mylinated it will conduct faster

synapse - a gap which uses chemicals (neurotransmitters) to pass an action potential across the space between neurons

1) an action potential reaches the end of a neuron - causes opening of ca2+ channels

2) as ca2+ can increase - synapse vesicles move towards the presynaptic membrane

3 ) synaptic vesicles fuse with the membrane and realeases contents into the cleft

4 ) neurotransmitters diffuse accross the gap and bind to receptors

5) binding to receptors causes the Na+ channels to open and Na+ enters post synaptic neuron continuing the action potential

6) enzymes in the post synaptic neuron breaks down the neurotransmitters nce they have bound so over excittion does not occur

neurotransmitters

many exist with different roles on the post synaptic neuron including exciting the post synaptic neuron ( excitatory nt) or inhibitory - when nt signal stops at the post synaptic neuron from triggering this is inhibatory

acetylcholine - most common neurotransmitter - synapses that use it are called cholinergic and they are excitatory

dopamine - a neurotransmitter that plays a key role in reward, motivation, and motor control, and can exhibit both excitatory and inhibitory effects depending on the receptor type it binds to.

serotonin - a neurotransmitter that regulates mood, appetite, and sleep, primarily exerting inhibitory effects on the post synaptic neuron, thereby contributing to feelings of well-being and stability.

parkinson’s - insufficient formation and activity of dopamine - neurotransmitter

few symptoms appear until 80 percent of dopamine producing cells are gone

  • diagnosis - typical cases are diagnosed mainly based on symptoms

  • neuroimaging and tests may be used to confirm the diagnosis

symptoms of parkinsons:

tremors - usually begin in one hand and gradually spread and become more noticebale

slowness of movement - diffuculty in starting movements and slowed actions during mocements

stiffness in muscles - muscles feel tight or rigid , can be problematic after inactivity (sleeping)

treating parkinsons:

difficulty is that most of the damage has already been done by the time it is dagnosed

crossing the blood brain barrier is not easy - dopamine cannot cross the bbb or treatment would be much more straightforward

  • MOAHB inhibitors - these compounds help to enhance the availability of dopamine in the brain by inhibiting its breakdown, thus improving motor function in patients. - breaks down dopamine in the brain synapse

  • gene therapy - a promising approach that involves delivering healthy copies of genes to replace or repair defective ones, potentially restoring normal dopamine production and function. This could offer a more effective solution for conditions that affect dopamine levels. difficult as it requires delivering genes to target areas of the barin

  • dopamine agonists - medications that mimic the effect of dopamine by stimulating dopamine receptors directly, providing relief for symptoms associated with conditions like Parkinson's disease.

  • L - dopa - a precursor to dopamine that can cross the blood-brain barrier, making it an effective treatment option for increasing dopamine levels in patients with parkisons - once inside brain iis converted into dopamine

  • L dopa often taken with carbidopa, which helps prevent L-dopa from converting to dopamine outside the brain and enhances its availability to the central nervous system.

  • reduces the side effects - nausea , and incrases the ammount of L-dopa hat acctually reaches the brain

  • advantages for l dopa - imporves muslce stiffness , tremors and slow movement

  • disgadvnatge -nausea , low blood pressure but overtime drug becomes less effective , increases side effeects as you may need higher doses if it doesnt wok

seretonin and depression - seretonin made from NT amino acid tryptophan

seretonin secreted by neurons in the brain stem - there axons extend to many areas of the braon including te cerebal cortex , cerbellum and spinal chord.

symptoms of clinical depression:

  • persistent sad, anxious, or "empty" mood

  • feelings of hopelessness or pessimism

  • irritability

  • feelings of guilt, worthlessness, or helplessness

  • decreased energy or fatigue

  • difficulty concentrating, remembering, or making decisions

  • insomnia or sleeping too much

  • appetite or weight changes

  • thoughts of death or suicide, or suicide attempts

  • aches or pains, headaches, cramps, or digestive problems without a clear physical cause.

treatments for depression:

  • antidepressant drugs - maintain seretonin levels so maintaining level of nervous system activity by use of drugs to ingibit sereretonin breakdown

  • inhibit seretonin reuptake at sunapse (prozac) by inhibiting the reuptake transporter

  • ssris - prevents the reuptake of sertenonin vack inot the pre synatpic mebrane means more seretonin remains in synapse increasing action on post synaptic receptors which helps improve mood and reduce depressive symptoms

  • advatcnges of ssris - first ine of treatment for depression , non addictive adn gernally safe for long term use and ocd and anxeity

  • disadvanatges- nausea , headcahes , trouble sleeping and sexual side effects

slow and fast twitch fibres:

  • Slow-twitch fibres contract slowly and generate less force.

  • They are best suited for steady, controlled movements rather than fast or explosive actions.

2. Fatigue and Endurance

  • These fibres are very resistant to fatigue, allowing them to work for long periods without tiring.

  • They are perfect for endurance sports where long-duration activity is needed.

3. Energy System and Oxygen Use

  • Slow-twitch fibres rely on aerobic respiration, which is more efficient and sustainable.

  • They use oxygen to generate ATP over a long period.

4. Mitochondria and Myoglobin Content

  • Contain many mitochondria, allowing them to produce more ATP via aerobic respiration.

  • Have high levels of myoglobin, which helps store and transport oxygen within the muscle cell.

  • This gives them a dark red appearance.

5. Capillary Network

  • They have a rich supply of capillaries, ensuring a constant and efficient delivery of oxygen and removal of carbon dioxide.

  • This supports their high aerobic capacity.

6. Fat Stores

  • Slow-twitch fibres also use fat as a fuel source, especially during prolonged exercise.

  • This further increases their endurance capacity.

⚽ Relevance to Sport

  • Fast-twitch fibres are crucial for explosive strength and speed – e.g., sprinters, jumpers, weightlifters benefit from more Type II fibres.

  • Slow-twitch fibres are essential for stamina and endurance – e.g., long-distance runners, cyclists, rowers rely heavily on Type I fibres.

  • Athletes often have a genetic predisposition to higher amounts of one fibre type, which can influence their sporting success.

fast twitch fibres:

1. Contraction Speed and Force

  • Fast-twitch fibres contract rapidly and produce high force.

  • This is due to a higher activity of myosin ATPase, an enzyme that breaks down ATP quickly to power contractions.

  • This makes them ideal for explosive movements like sprinting or jumping.

2. Fatigue and Endurance

  • They fatigue quickly because they rely on anaerobic respiration, which is less efficient at producing ATP and leads to lactic acid buildup.

  • This limits how long they can be used continuously.

3. Energy System and Oxygen Use

  • Fast-twitch fibres rely mainly on anaerobic pathways (e.g. glycolysis).

  • They don’t use oxygen efficiently, so they do not require a large supply of oxygen or a high number of mitochondria.

4. Mitochondria and Myoglobin Content

  • These fibres contain fewer mitochondria (the site of aerobic respiration) and less myoglobin (the oxygen-binding protein).

  • This gives them a pale/white appearance under a microscope.

5. Capillary Network

  • There are fewer blood capillaries around these fibres because they don't rely heavily on oxygen delivery.

  • As a result, oxygen supply is limited.

6. Glycogen Stores

  • Fast-twitch fibres have large glycogen stores for anaerobic energy production.

  • This helps fuel short, intense activity.

ECG graphs:

  • P Wave:

    • Atrial depolarisation.

    • Atria contract.

    • Small upwards bump.

  • QRS Complex:

    • Ventricular depolarisation (ventricles contract).

    • Atrial repolarisation (atria relax).

    • Sharp spike, deep dip, and quick rise.

  • T Wave:

    • Ventricular repolarisation.

    • Ventricles relax.

    • Rounded, medium-sized wave.