BIOM - In semester (weak areas)

Golgi Apparatus

Modifies, sorts, and packages proteins and lipids for transport to different parts of the cell or for secretion outside the cell.

Lysosomes and peroxisomes

Membrane bound organelles

Lysosomes:

• Break down of organic material inside the cells

Peroxisomes:

• Degrade toxic molecules inside the cell

What molecules can penetrate and not through the plasma membrane

Penetrating molecules:

• Gases (O2 & CO2)

• Water

• Ethanol

Non-penetrating molecules

• Ions

• Glucose & proteins

Difference between simple and facilitated diffusion

Simple diffusion:

• Where small molecules move directly through the cell membrane (O2, CO2)

Facilitated diffusion:

• Molecules move from high to low, however uses the help of proteins such as channel and carrier proteins.

Osmosis

Diffusion of water across a partially permeable membrane.

Isotonic solution - No net movement of water (does not change shape)

Hypotonic solution - water moves into the cell, lower solute concentration outside of the cell (cell will swell)

Hypertonic solution - Water moves out of the cell, higher solute concentration outside of the cell (cell will shrink)

Compare and contrast primary and secondary active transport.

Similarities

• Both move substances against their concentration gradient

• Both require membrane transport proteins

• Both are essential for maintaining cellular homeostasis

Differences

• Energy source:

  • Primary → Direct ATP use

  • Secondary → Indirect (ion gradient energy)

• Protein type:

  • Primary → ATPase pumps

  • Secondary → Carrier proteins

• Dependency:

  • Primary → Independent

  • Secondary → Relies on primary transport

• Examples:

  • Primary → Na⁺/K⁺ pump

  • Secondary → Na⁺–glucose symporter

Myelination

Myelin protects and electrically insulates the axon, making it increase the speed of electrical signals

Created by:

• Schwann cells (PNS)

• Oligodendrocytes (CNS)

Stages of action potentials

Important:

• The threshold must be reached in order for an action potential to even occur

Compare and contrast graded potentials and action potentials.

Similarities

• Both are changes in membrane potential

• Both involve movement of Na⁺ and K⁺ ions

• Both are used for neuronal communication

Differences

1. Location

• Graded: dendrites & cell body

• Action: axon

2. Type of channels

• Graded: chemically-gated (stimulus-controlled)

• Action: voltage-gated

3. Direction

• Graded: spreads in multiple directions

• Action: one direction along axon

4. Type of signal

• Graded: can be depolarising OR hyperpolarising

• Action: always follows the same pattern (depolarisation → repolarisation)

5. Distance

• Graded: short, decreases with distance

• Action: long, does not decrease

Compare and contrast the functions of the sympathetic and parasympathetic divisions of the autonomic nervous system (ANS).

Similarities

• Both are divisions of the autonomic nervous system (ANS)

• Control involuntary functions

• Act on the same organs

• Work together to maintain homeostasis

Differences

• Role

  • Sympathetic: fight or flight

  • Parasympathetic: rest and digest

• Overall effect

  • Sympathetic: prepares body for activity

  • Parasympathetic: calms and restores body

• Heart rate

  • Sympathetic: increases

  • Parasympathetic: decreases

• Digestion

  • Sympathetic: inhibits (redirects energy away from it)

  • Parasympathetic: stimulates

• Pupils

  • Sympathetic: dilate

  • Parasympathetic: constrict

• Energy use

  • Sympathetic: uses energy

  • Parasympathetic: conserves energy

Three Sympathetic preganglionic neurons

• Sympathetic chain ganglia

• Collateral ganglia

• Adrenal medullae

Receptor that responds to ACh

Nicotinic receptors

• Receptor at the ganglionic neuron

Muscarinic receptors

• Receptor at all of the parasympathetic target organs

Receptor that responds to NE

Adrenergic receptors

• Receptor that is found at all the sympathetic target organs

Name the various divisions/regions of the brain and their functions.

• Diencephalon

  • Thalamus → relays sensory information to the cortex

  • Hypothalamus → maintains homeostasis, and regulates emotions

  • Epithalamus (pineal gland) → day and night cycles (melatonin produced in response to darkness)

• Brainstem

  • Midbrain → visual and auditory reflexes

  • Pons → Relays signals between brain regions and regulates sleep and breathing

  • Medulla oblongata → Controls autonomic functions

• Cerebellum

  • Coordinates movement, balance, and posture (works subconsciously)

Describe the structure and function of the spinal cord.

Function

• Provides two-way communication (sensory info and motor commands) between brain and body

• Acts as a major reflex centre (reflexes are processed in the spinal cord)

Key features

• Filum terminale: anchors spinal cord to coccyx

• Cauda equina: spinal nerve roots

Spinal nerves

• Connect to spinal cord via two roots:

  • Dorsal root: sensory input

  • Ventral root: motor output

Functions of Cerebrospinal fluid (CSF)

• Supports the brain and spinal cord (provides buoyancy)

• Cushions/protects the CNS against shock and injury

• Maintains a stable chemical environment for neurons

Peripheral nerve structure

It is a bundle of axons (these are composed of dendrites, axon hill, cell body, axon and myelin sheath)

Peripheral nerve structure

• Endoneurium: around each axon

• Perineurium: around bundles of axons

• Epineurium: outer covering of whole nerve

To describe the 5 components of a reflex arc.

1. Receptor – site of stimulus action.

2. Sensory neuron (afferent) – Carries the afferent impulses to the CNS.

3. Integration centre – Processes the information in the spinal cord via synapses, with or without interneurons

4. Motor neuron (efferent) – Carries the efferent impulses from the integration centre to the effector organ.

5. Effector – Produces a response to the efferent impulses (e.g., muscle contracts or gland secretes).

Stimulus → Receptor → Sensory → CNS (integration centre)→ Motor → Effector → Response

Usually occurs in the spinal cord of the CNS

To understand the function of muscle spindles

Muscle spindles are sensory receptors located within skeletal muscle that monitor muscle length and the speed of stretch.

Core functions:

• Detect muscle stretch

  • Sense changes in muscle length

• Maintain muscle tone

  • Provide continuous feedback to the spinal cord to keep muscles slightly contracted even at rest

• Enable the stretch reflex

  • Muscle contraction to prevent overstretching.

Pathway of stretch reflex

The stretch reflex is a fast, automatic, monosynaptic spinal reflex that resists sudden muscle stretch.

1. Muscle is stretched

2. Muscle spindle is activated

3. Sensory neuron (Ia afferent) sends signal to spinal cord via dorsal root

4. Direct synapse with alpha motor neuron at integration centre

5. Motor neuron activates muscle through ventral root

6. Muscle contracts (opposes stretch)

Key term often required:

• Monosynaptic reflex (one synapse)

la afferent - a fast sensory nerve fibre that carries information from muscle spindles to the spinal cord about muscle stretch.

To differentiate between the stretch reflex and tendon reflex.

Stretch reflex

• Receptor: Muscle spindle

• Stimulus: Muscle is stretched (length increases)

• Response: Muscle contracts

• Pathway: Monosynaptic (direct sensory → motor neuron)

• Function: Maintains posture and muscle tone

• Example: Knee-jerk reflex

Tendon reflex (Golgi tendon reflex)

• Receptor: Golgi tendon organ

• Stimulus: High muscle tension (force)

• Response: Muscle relaxes

• Pathway: Polysynaptic (via interneuron)

• Function: Prevents muscle/tendon damage

• Example: Dropping a heavy weight causing muscle relaxation

Key difference

• Stretch reflex = contract when stretched

• Tendon reflex = relax when too much force is applied

Classifications of bones

Long bones

• Longer than wide

• Help with movement

• Examples: femur, humerus

Short bones

• Small and cube-shaped (equal length, width, and thickness)

• Give stability

• Examples: wrist (carpals), ankle (tarsals)

Flat bones

• Thin, flat, and usually curved

• Protect organs

• Examples: skull, ribs, sternum

Irregular bones

• Odd-shaped

• Have special jobs (support/protection)

• Examples: vertebrae, pelvis

Sesamoid bones

• Small bones in tendons

• Help reduce friction

• Example: kneecap (patella)

Gross structure and key anatomical features of long bones

Compact bone: Dense outer layer

Spongy bone: Honeycomb like bone found within

Connective tissue:

• Periosteum covers outside of the impact bone

• Endosteum covers the inside portion

Long Bone structure:

• Diaphysis: Forms long axis, tubular shaft

• Epiphyses: The end of long bones, made up of compact bone and spongy bone

• Metaphysis: Region between diaphysis and epiphysis and contains the growth plate

The axial skeleton

1. Cervical: 7 vertebrae
2. Thoracic: 12 vertebrae
3. Lumbar: 5 vertebrae
4. Sacrum: one bone formed from fusion of
several (5) bones, articulates with hip
5. Coccyx: fused (4) bones

Common structure of all vertebrae

Cervical: Small oval body, large triangular vertebral foramen, small transverse process

Thoracic: Heart shaped body, smaller circular vertebral foramen, large transverse process

Lumbar: Very large, thick oval body, smaller triangular vertebral foramen but bigger than thoracic, short and flat transverse process

Joints of the vertebral column

Intervertebral discs – cushion-like pad between vertebrae that act as shock absorbers

Upper limbs

Arms: Hummeruss

Forearm: radius and ulna

Hand: carpals (8 - wrist), metacarpals (5 - palm), phalanges (14 - fingers)

Lower limbs

Thigh: Femur and patella
Leg: Tibia and Fibula
Foot: tarsals (7 - hind foot), metatarsals (5 - midfoot), phalanges (14 - toes)

Understand changes to the skeleton during development, ageing, and disease.

Bone Development

• Starts as cartilage → ossifies in embryo

• Long bones: ossification ~8–25 weeks

• Growth continues until ~25 years

Age-Related Changes

• Children: formation > resorption → growth

• Young adults: formation = resorption → stable

• Adults: resorption > formation → bone loss

Osteoporosis

• Resorption > formation → low bone mass

• Common in elderly (especially women)

• Prevention: weight-bearing exercise

Functional classifications of joints (degree of movement)

• Synarthrosis (none to very little movement)

• Amphiarthrosis (slight movement)

• Diarthrosis (freely movable)

Fibrous

• bones joined by collagen fibres

• No joint cavity

• Synarthrosis, Amphiarthrosis

Cartilaginous

• Bones joined by cartilage

• No joint cavity

• Synarthrosis or Amphiarthrosis

Synovial

• Bones are separated by fluid filled cavity

• Contains synovial fluid and a joint capsule

• Diarthrosis

Synovial joint structure

• Articular cartilage → reduces friction

• Joint cavity → allows movement

• Synovial fluid → lubrication

• Joint capsule → encloses the joint

Types of range of motion

Nonaxial: intercarpal joints

Uniaxial: elbow

Biaxial: knuckle

Multiaxial: shoulder

Types of synovial joints

• Plane/gliding

• Hiinge

• Pivot

• Condylar/Saddle

• Ball-and-socket

Plane/gliding

• Slight movement along relatively flat surfaces

• Nonaxial

• Intercarpal joints

Hinge

• Cylinder nests in trough

• Uniaxial

• Elbow

Pivot

• Axle fits into a sleeve

• Uniaxial

• Neck

Condylar/saddle

• Biaxial

• Wrist (C) and base of thumb (S)

Ball and socket

• Multiaxial

• Shoulder

Hierarchical organisation of skeletal muscle

1. Muscle (organ)

   • Whole muscle (e.g. biceps)

   • Surrounded by epimysium

2. Fascicles (bundles)

   • Bundles of muscle fibres

   • Surrounded by perimysium

3. Muscle fibres (cells)

   • Long muscle cells

   • Surrounded by endomysium

4. Myofibrils

   • Tiny rods inside muscle fibres

   • Made of repeating units (sarcomeres)

5. Sarcomeres (functional unit)

   • The smallest working units of muscle that make it contract

3 levels of connective tissue

• Epimysium: dense irregular connective tissue surrounding entire muscle

• Perimysium: fibrous dense connective tissue surrounding bundles of fascicles

• Endomysium: fine areolar connective tissue surrounding each muscle fiber

Different muscle architecture types

• Pennate

• Parallel

• Circular

Parallel

Fascicles lie parallel to muscles line of action
• Strap
• Fusiform

Pennate

Fascicles at angle relative to the line of action
• Unipennate
• Bipennate
• Multipennate

Fascicle architecture linked to function

• Pennate muscles have fascicles arranged at an angle which produces a reduced range of motion, due to shorter fibre lengths. Whereas, parallel muscles have fibres running parallel to the line of pull with longer fascicles, allowing for a larger range of motion through its longer muscle fascicles.

• This results in the Pennate muscles to pack a higher volume of muscle fibres, allowing for higher power (higher PCSA), but less range of motion. With the parallel muscles, its longer muscles makes it where there is less volume of it, reducing its power (lower PCSA), giving it a higher range of motion.

Physiological Cross-Sectional Area - PCSA

Major muscle compartments

• Thorax and abdomen

• Shoulder and upper arm

• Thigh (anterior)

• Thigh (posterior)

• Lower leg

Thorax and abdomen

Shoulder and upper arm

Thigh anterior

Thigh posterior

Lower leg

Main body Cavities

• Thoracic cavity

  • luns, heart, trachea and esophagus

• Abdominopelvic cavity

  • intestines, live,stomach, spleen ect

• Pelvic cavity

  • bladder, rectum and reproductive organs

Where exactly does the heart sit

• Thoracic cavity → mediastinum (central region)

• Mediastinum → pericardial cavity

• Pericardial cavity → heart

Structure that makes up the wall of blood vessels

1. Tunica intima (inner layer)

• Endothelium (smooth epithelial lining)

• Thin connective tissue layer
  Function: smooth blood flow, reduces friction

2. Tunica media (middle layer)

• Smooth muscle + elastic fibres
  Function: controls vessel diameter (vasoconstriction/vasodilation) and blood pressure

• Thickest in arteries

3. Tunica externa (outer layer)

• Connective tissue (collagen + elastin)

• May contain small blood vessels (vasa vasorum)
  Function: support and anchoring

Compare arteries, veins and capillaries

It should be noted:

• The pressure is high in arteries as it needs to be pumped throughout the whole body.

• Wall thickness is important in arteries as it needs to withstand all that pressure, whereas in veins its doesn’t face such pressure and in capillaries it needs to be thin to allow diffusion.

• Lumen affects flow speed, so in arteries it’s narrow to maintain high pressure whereas in veins its wide in order to carry large volumes of blood, and very narrow in capillaries, however due to being arranged in a large cross-sectional area it slows blood down to giving it time for exchange.

• The reason valves are present in veins is to prevent backflow.

• And as for function, in capillaries especially its is used to exchange gases, nutrients and wastes

How does veins transport blood

Through the use of one way valves

Skeletal muscle contractions

Respiratory pump

Structure of cardiac muscle its relationship to its function

Structure

• Striated cells → contain proteins that cause contractions

• Short, branched cells → form a connected network

• Intercalated discs (join cells):

  • Desmosomes → hold the myocytes together

  • Gap junctions → allow ions & electrical signals to pass through the membrane

    • Cardiac cells can contract simultaneously due to rapid flow of action potentials between the cardiac myocytes

Relationship to Function

• Striations → strong contractions to pump blood

• Branching network → rapid spread of contraction

• Desmosomes → prevent cells pulling apart during forceful beats

• Gap junctions → fast electrical communication, so cells contract together

Important: Cardiac myocyte = cardiac muscle cells

Action potentials in Cardiac Pacemaker cell

No stable resting potential

1) Leaky sodium channels (funny current), slow rise with the potassium channels closed. Pacemaker potential

2) Once threshold is achieved calcium (influx) comes in, more positive than sodium, so depolarises faster reaching the action potential

3) The repolarization of this is the calcium channels inactivating and the potassium channels opening (efflux)

This is the firing that is repeated over and over at the SA node

SA node to the AV node there is a pause of 0.1 second to allow the ventricles to fill

Function link

• Generate rhythmic impulses automatically

• Set heart rate and timing (natural pacemaker activity)

Action potentials in cardiac muscle cells

Stable resting membrane potential

1) Rapid depolarisation of Na influx through fast voltage gated Na channels

2) Plateau phase of where there is a slow influx of calcium keeping the cell depolarised. THIS IS WHERE THE CONTRACTION TAKES PLACE

3) Repolarisation is when the calcium channels becomes inactivated, opening the potassium channels, and resting to the resting voltage

Long Absolute refractory period

Function link

• Produces strong, coordinated contractions

• Plateau allows sustained force for blood ejection

• Prevents continuous contraction → ensures relaxation between beats

Similarities and Differences of Autorhythmic cells and Contractile cells

Similarities

• Both involve Na⁺, Ca²⁺, and K⁺ ions

• Both propagate electrical signals in the heart

• Both are essential for coordinated heartbeat

Differences

• Autorhythmic cells → initiate impulses (no resting potential, automatic firing)

• Contractile cells → produce force (plateau phase, strong contraction)

• Autorhythmic = set the rhythm of the heart

• Contractile = execute the pumping of blood

Flow of electrical activity

• SA node fires

  • Impulse spreads across both atria

  • Causes atrial contraction

• AV node (atrioventricular node)

  • Receives impulse

  • Delays it briefly (allows ventricles to fill)

• Bundle of His and bundle branches

  • The bundle of His separates into right and left bundle branches, carries the electrical to the apex.

• Purkinje fibres

  • Spread impulse through ventricular walls

• Ventricles contract

  • Blood is pumped to lungs and body

The five volume stages of the cardiac cycle

Ventricular and atrial diastole

• Passive filling of ventricles and atria with blood

Atrial contraction (atrial systole)

• Blood is moved from the atria to the ventricles

Isovolumetric ventricular contraction (ventricular systole)

• Ventricles contract but don’t yet eject blood (done to close the AV vales)

Ventricular ejection (ventricular systole)

• Blood is ejected into arteries

Isovolumetric ventricular relaxation (ventricular diastole)

• Ventricles relax and remaining blood stays in ventricles

Mean Arterial pressure

Mean arterial pressure = cardiac output x total peripheral resistance

Cardiac output → Blood coming out of the heart into the arteries

Total peripheral resistance → Diameter of the blood vessels

Cardiac Output

Heart rate

Parasympathetic nervous system

• Slows down action potential firing in the SA node - pacemaker activity

  • Causes hyperpolarisation, slowing time to reach threshold, thus starting an action potential

Sympathetic nervous system

• Increases rate of action potential firing in the SA node - pacemaker activity

  • Causes depolarisation, reducing time to reach threshold, thus starting an action potential

This is how heart rate is regulated

Stroke Volume

Stroke volume (SV) = EDV - ESV

• End diastolic volume → Volume of blood in the ventricles before contraction or end of diastole

• End systolic volume → Volume of blood that is left in the ventricles after contraction

This is how Stroke Volume is regulated

Factors affecting stroke volume

Venous Return

• Amount of blood returning to the heart

  • Higher venous return INCREASES EDV, thus increase cardiac output

• causes a greater stretch for the heart muscle

Sympathetic NS increases venous return

Contractility of the heart

• How hard the heart is contracting

  • Harder contraction means more blood ejected thus DECREASES end systolic volume, ESV

Sympathetic NS increases contractility of the heart

Total peripheral resistance

• Resistance to blood flow is determined by:

  • Blood viscosity (usually constant)

  • Blood vessel length (Usually constant)

  • Blood vessel diameter

What determines the total peripheral resistance (TPR)

Radius of arterioles can be increased or decreased
• Increase radius → vasodilation → reduced TPR
• Decrease radius → vasoconstriction → increased TPR

Describe two pathologies that result from abnormal blood pressure

1. Hypertension (high blood pressure)

• Chronically high pressure damages vessel walls

• Leads to heart strain, stroke risk

2. Hypotension (low blood pressure)

• Low pressure reduces blood flow to organs

• Causes dizziness and fainting

Baroreceptor reflex and the autonomic nervous systems role

• Detects changes in blood pressure via stretching of blood vessel walls

• Sends signals to the medulla

↑ Blood pressure

• ↑ firing (too much pressure) → ↑ parasympathetic, ↓ sympathetic

• Leads to, ↓ heart rate, vasodilation → BP decreases

↓ Blood pressure

• ↓ firing (not enough pressure) → ↑ sympathetic, ↓ parasympathetic

• Leads to, ↑ heart rate, vasoconstriction → BP increases

The autonomic nervous system adjusts heart rate and vessel diameter to keep blood pressure stable.

Understand what ECG measures and what creates the different ECG waveforms

ECG measures electrical activity (voltage changes: depolarisation and repolarisation) of the heart

Waveforms you must know:

• P wave → atrial depolarisation

• QRS complex → ventricular depolarisation

• T wave → ventricular Repolarisation

Describe how the ECG correlates with the cardiac cycle

• P wave → atria depolarise → atria contract (atrial systole)

• PR interval → delay at AV node → ventricles fill with blood

• QRS complex → ventricles depolarise → ventricles contract (ventricular systole) - AV valves close

• ST segment → ventricular contraction → blood is ejected

• T wave → ventricles repolarise → ventricles relax (diastole)

Explain how the ECG is measured using leads

A lead is not a wire, but a view of the heart’s electrical signal (looking from positive to negative) created by comparing voltage between two electrodes.

• Limb leads (I, II, III): Measure heart activity in the frontal plane using arms and legs. BIPOLAR LEADS

  • Lead I: Right arm → Left arm

  • Lead II: Right arm → Left leg

  • Lead III: Left arm → Left leg

• Augmented leads (aVR, aVL, aVF): Provide additional frontal-plane views. UNIPOLAR LEADS

  • aVR: Right arm perspective

  • aVL: Left arm perspective

  • aVF: Foot (inferior) perspective

• Chest leads (V1–V6): Measure activity across the chest in the horizontal plane.

  • V1–V2: Right heart / septum

  • V3–V4: Anterior wall

  • V5–V6: Lateral wall

Explain common causes of heart rate changes that can be measured with ECG

Tachycardia: Faster heart rate

• Exercise

• Stress / adrenaline

• Fever

Bradycardia: Slower heart rate

• Sleep

• High fitness (athletes)

Explain the concept of the mean electrical axis (cardiac axis), what it measures, and how it changes with physiological and pathological factors

The cardiac axis (mean electrical axis) is the average direction of the heart’s ventricular electrical activity during contraction, shown as an angle on an electrocardiogram (ECG).

What it measures:

• The net direction of the heart’s electrical activity during ventricular contraction

• Represented as an angle in degrees

Key idea:

• It summarises all ventricular electrical forces into one main vector

Why it matters:

• Helps detect cardiac enlargement or hypertrophy

• Identifies conduction defects and some cardiac pathologies

Describe some pathologies that can be detected by ECG

• Extrasystoles and sinus arrhythmia → irregular heart rhythms

• Supraventricular tachycardia (starts at the atria) and ventricular tachycardia (starts in the ventricles) → abnormally fast heart rates

• Heart block → delayed or blocked electrical conduction

Name the arteries which branch off the Aorta to give rise to the arteries in different regions of the body

• Aorta

  • Ascending Aorta

  • Descending Aorta

  • Aortic arch

Name the arteries of the arms

Name the arteries of the head

Internal Carotid = for the brain

External Carotid = for the face and neck

Vertebral = Goes through the cervical holes and up to the head

Name the arteries of the torso (paired and unpaired branches from Aorta)

Name the arteries of the legs

What vein drains the head