Final Major Revision

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)

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)

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

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

Synovial joint structure

• Articular cartilage → reduces friction

• Joint cavity → allows movement

• Synovial fluid → lubrication

• Joint capsule → encloses the joint

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

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

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

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.

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 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 legs

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

Anterior Muscles

Posterior Muscles