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Year 1 > Life sciences > Flashcards

Life sciences Flashcards

Including microbiology and body systems

1
Q

Regional anatomy

A

All structures in one area studied together. Eg muscles/bones/nerves in the leg.

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2
Q

Systemic anatomy

A

The study of the gross anatomy of bodily systems. Eg studying the heart and blood vessels of the cardiovascular system

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3
Q

Surface anatomy

A

Study of internal body structures in relation to the overlaying skin surface. Eg location of blood vessels/bones/muscles

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4
Q

Embryology

A

Study of developmental changes pre birth

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5
Q

Surface anatomy

A

Study of internal body structures in relation to the overlaying skin surface. Eg locating blood vessels, bones, muscles

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6
Q

Palpation

A

Examiner feels body surfaces with hands (pulse and heart rate determination)

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7
Q

Auscultation

A

Examiner listens to body sounds to evaluate the function of certain organs (listening to lungs/heart)

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8
Q

Percussion

A

Examiner taps on the body surface with their fingertips and listens to resulting echo

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9
Q

Prone body position

A

Face down

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10
Q

Supine body position

A

Face up

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11
Q

Superior direction

A

Direction towards the head/upper body

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12
Q

Inferior direction (caudal)

A

Direction away from the head/ towards the lower body parts. Eg the stomach is inferior to the heart.

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13
Q

Anterior direction (ventral)

A

Direction towards the front of the body (in front of). Eg the nose is anterior to the ears

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14
Q

Posterior (dorsal)

A

Direction towards the back of the body (behind). Eg the heart is posterior to the sternum

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15
Q

Medial (mesial)

A

Direction towards midline (centre) of body. Eg the ulna is on the medial side of the forearm.

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16
Q

Lateral

A

Direction away from the midline of the body. Eg the eyes are lateral to the bridge of the nose.

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17
Q

Intermediate

A

Between a more medial and more lateral structures. Eg the clavicle (shoulder bone) is intermediate between the sternum and the shoulder

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18
Q

Proximal

A

Closer to the origin body part/point of attachment of a limb to the body trunk. Eg the elbow is proximal (closer to point of attachment) to the wrist.

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19
Q

Distal

A

Farther from the origin of the body part or the point of attachment of a limb to the body trunk. Eg the knee is distal (further from point of attachment) to the thigh

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20
Q

Superficial direction

A

Direction towards the body/skins surface. Eg the skin is superficial to the skeleton.

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21
Q

Deep direction

A

Direction away from the body surface (more internal). Eg the skeleton is deep to the skin.

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22
Q

Ipsilateral

A

On the same side of the body. Eg the gallbladder and ascending colon are ipsilateral (both on the left)

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23
Q

Contralateral

A

On opposite sides of the body. Eg the ascending and descending colons are contralateral ( one on left one on right)

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24
Q

Parietal

A

Outer wall of a body cavity (organ/tissue)

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25
Q

Visceral

A

The covering of an organ within the ventral body cavity

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26
Q

Sagital

A

Vertical plane that divides the body into left and right. (midline of the body)

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27
Q

Frontal

A

Vertical plane that divides bodies into front (anterior) and back (posterior) parts.

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28
Q

Transverse

A

Horizontal plane that divides the body into top (superior) and bottom (inferior) parts, similar to a cross section.

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29
Q

Axial and Appendicular

A

Axial makes up main axis of the body eg. head, neck, trunk. Appendicular is the appendages (limbs) that are attached to the body eg. arms, legs.

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30
Q

Nucleotide

A

deoxyribose(pentose sugar), nitrogenous base and a phosphate group

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31
Q

Telomeres

A

regions of short repetitive DNA that protects chromosomal ends from shortening (linked with ageing and cancer protection)

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32
Q

Centromeres

A

regions of repetitive DNA that give chromosomes their constricted appearance, also holds sister chromatids together in mitosis and meiosis and is where the spindle fibres attach

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33
Q

Semi-conservative Replication

A

Weak hydrogen bonds break. As DNA unzips the 5’ to 3’ strand is continuous and the 3’ to 5’ is discontinuous. Both strands are free to act as a template. Complementary nucleotides align via complementary base pare ruling. DNA polymerase joins adjacent nucleotides via phosphodiester bonds (Strong covalent bonds)

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34
Q

Exonuclease

A

Required for DNA replication. Group of enzymes that remove nucleotide bases from the end of a DNA chain

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35
Q

Topoisomerase

A

Required for DNA replication. Unwinds and rewinds DNA strands to prevent the DNA becoming supercoiled

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36
Q

DNA primase

A

Required in DNA replication. Synthesises RNA primers that act as templates for the starting point of DNA replication

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37
Q

DNA Ligase

A

Facilitates joining of DNA strands by formation of phosphodiester bonds

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38
Q

Central Dogma of Molecular biology

A

Concept that genetic information flows from DNA to mRNA and then to protein.

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39
Q

Somatic and Germ-line mutations

A

Somatic- only occurs in somatic cells and only affects the individual with the mutations arises. Germ-line- alters gametes and is passed to the next generation

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40
Q

Shine-Dalgarno sequence

A

Prokaryotic mRNA has this for ribosome binding. The sequence helps recruit the ribosome to the mRNA to initiate protein synthesis by aligning the ribosomes with the start codon,

The shine-Dalgarno sequence is typically found around position -7 to -4 of the start codon.

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41
Q

First amino acid sequence

A

formylmethionine in prokaryotes.

methionine in eukaryotes.

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42
Q

Parts of the GI tract (muscular alimentary canal)

A

Mouth
Pharynx
Oesophagus
Stomach
Small intestine
Large intestine
Anus

Accessory organs - supply secretions (enzymes) for breakdown of food; salivary glands, gallbladder, liver, pancreas.

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43
Q

Digestive Process

A
  1. Ingestion
  2. Propulsion (movement of food) - peristalsis which is the propulsion by alternate contraction and relaxation.
  3. Mechanical digestion
  4. Chemical digestion - by enzymes
  5. Absorption - transport of digested end products into blood and lymph in wall of canal
  6. Elimination - elimination of indigestible substances from body as faeces
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44
Q

4 layers from oesophagus to anal canal

A

Mucosa
Submucosa
Muscularis externa
Serosa

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45
Q

Mucosa (inner layer)

A

Mucous membrane with 3 sublayers:

Lining epithelium- absorbs nutrients, secretes mucus. Continuous with ducts and secretory cells of intrinsic digestive glands. Extrinsic (accessory) glands: liver and pancreas.

Lamina propria - loose connective tissue with nourishing and absorbing capillaries. Contains most of mucosa-associated lymphoid tissue (MALT)

Muscularis mucosae - thin layer of muscle producing local movements.

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46
Q

Submucosa

A

This is connective tissue containing major blood and lymphatic vessels and nerves with many elastic fibres.

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47
Q

Muscularis externa

A

Two layers of smooth muscle responsible for peristalsis and segmentation.

The inner circular layer squeezes and acts as valves and the second layer is the outer longitudinal one.

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48
Q

Serosa (visceral peritoneum)

A

Simple squamous epithelium, thin layer areolar connective tissue underneath.

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49
Q

Smooth muscle

A
  • spindle-shaped cells with one central nucleus
  • grouped into sheets that run perpendicular to each other
  • no striations
  • Contractions are slow, sustained and resistant to fatigue
  • does not always require a nervous signal, can be stimulated by stretching or hormones

Major locations: inside the eye, wall of vessels, respiratory tubes, digestive tubes, urinary organs, reproductive organs.

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50
Q

Nerves in the NS

A

Enteric NS:
Visceral plexuses within gut wall controlling muscles, glands with sensory info.

Autonomic NS (speeds or slows down):
Parasympathetic - stimulates digestive functions.
Sympathetic - inhibits digestion

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51
Q

Mesentery (folding of the peritoneum)

A

Two ventral mesenteries: falciform (ligament) and lesser omentum (fatty skin)

Double layer of peritoneum that extends to digestive organs from body wall. It holds organs in place and is the site of fat storage. Most are dorsal (extends from gut to posterior abdominal wall) and is the route by which circulatory vessels and nerves reach organs. Ventral mesentery is from stomach and liver to anterior abdominal wall.

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52
Q

Mouth/lips/cheeks

A

Mouth = oral cavity, thick stratified squamous epithelium.

Lips = orbicularis oris muscle

Cheek = buccinator muscle

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53
Q

Tongue

A

Mostly muscles, grip and reposition food, forms ‘bolus’ of food (lump), helps in swallowing and speech.
Taste buds - circumvallate and fungiform papillae
Lingual tonsil - back of tongue

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54
Q

Pharynx

A

Membrane lined cavity behind the nose and mouth, connecting them to the oesophagus which contains the oropharynx and the laryngopharynx.

3 constrictor muscles that sequentially squeeze bolus of food into oesophagus

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55
Q

Oesophagus

A

Continuation of pharynx, muscular tube that descends through thorax.

Joins the stomach at the cardiac orifice

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56
Q

Gallbladder

A
  • Bile is produced in the liver and stored in the gallbladder
  • Bile is excreted into the duodenum when needed (fatty meal)
  • Bile helps dissolve fat and cholesterol.

If bile salts crystallize, gall stones are formed which case intermittent pain, infection, fever and vomiting.

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57
Q

3 types of muscles

A

Skeletal

Cardiac

Smooth

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58
Q

Skeletal muscle structure

A

Attaches to bones, skin or fascia.
Striated: light & dark bands are visible with a microscope
Voluntary control (except reflex movements)

Function: movement, posture/muscle tone, heat production. Most skeletal muscles contain all 3 fibres (I/IIa/IIb)

For movement, muscles pull on bones. As muscle fibres shorten, the bones to which they are attached move closer. Generally it is insertion bone that moves.

Skeletal muscles are under somatic control. Motor neurons are long and myelinated, so they can quickly carry action potentials long distances. Nerve terminals release acetylcholine into the NMJ

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59
Q

Skeletal muscle movement

A

Voluntary muscular movement is smooth as muscles work in teams.

Muscles work as agonists and antagonists, the muscle that is contracting is the agonist, whereas the muscle that is relaxing and lengthening is the antagonist.

In a team of muscles that is contracting, the one muscle that is mostly causing the movement is the ‘prime mover’ and the other helping muscle is the ‘synergist’.

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60
Q

Types of skeletal muscle contraction

A

Concentric- occurs when the length of a muscle shortens as tension is being generated.

Eccentric- occurs when a muscle lengthens as tension is being generated (muscle are acting as breaks, eg running downhill)

Isotonic- occurs when a muscle changes length whilst generating tension

Isometric- occurs when a muscle’s length doesn’t change when generating tension

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61
Q

Tonic contractions

A

Muscles involved in maintaining body position.

Here only a few fibres in a muscle shorten together and then maintain position.

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62
Q

Type I muscle fibres (slow twitch)

A

Type I- slow twitch fibres resist fatigue. These fibres are largely found in postural muscles as they can hold position for long periods. They are oxidative/aerobic and they contain lots of myoglobin (red) and mitochondria

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63
Q

Type II muscle fibres (fast twitch)

A

Type IIa are intermediate
- many mitochondria, but not as much myoglobin (red)
- they do not fatigue as quickly as type IIb, but they cannot generate as much explosive energy. - these are fast oxidative muscles.

Type IIb fibres have larger diameters
- more glycolytic/anaerobic
- they can produce rapid, forceful contractions, but they fatigue quickly
- they do not contain as much myoglobin (white) or many mitochondria
- such fast-twitch muscles are utilized in sprinting, jumping etc

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64
Q

Cardiac Muscle

A

This forms the contractile tissue of the heart.

  • It is straited muscle, of uninucleate, branching cells joining together at intercalated discs
  • It autorhythmic and under involuntary control.
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65
Q

Smooth muscle

A

Found in the GI tract, walls of arteries, arterioles, venules and veins, attached to hair follicles in the skin, in the walls of hollow organs, can form sphincters etc. Non-striated and involuntary.

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66
Q

Excitability

A

Respond to neurotransmitters.

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67
Q

Conductivity

A

Propagate electrical signals over membrane

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68
Q

Contractility

A

shorten & generate force

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69
Q

Extensibility

A

Can be stretched without damage

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70
Q

Elasticity

A

Return to original shape after being stretched.

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71
Q

Skeletal Muscle Fibre Anatomy

A

Skeletal muscle fibres are long cylindrical cells with several nuclei (multinucleated) appearing just under the plasma membrane (sarcolemma).

The sarcoplasm (muscle cell cytoplasm) is filled with myofibrils and myoglobin (red-coloured, oxygen-binding protein similar to haemoglobin).

Sarco-/sarc- denotes muscle or fleshy tissues

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72
Q

Sarcoplasmic Reticulum (SR)

A

Sarcoplasm contains large amounts of glycogen, muscle cells contain all other usual organelles along with the SR, T-tubules and myofibrils.

SR is a form of endoplasmic reticulum, which forms a meshwork of interconnecting tubules that surrounds each myofibril and also forms end sacs (terminal cisternae). The SR regulates [Ca 2+], by storing it at rest and then releasing it when a muscle is stimulated to contract.

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73
Q

T Tubules

A

T tubules (transverse tubules) are from the sarcolemma forming hollow tubes that penetrate into the cell near the location of the terminal (can have 1000s). Since they are hollow they contain extracellular fluid, so can aid the delivery of O2, glucose etc to deeper parts pf the muscle cells.

Action potentials (coming from NMJ) travel along the sarcolemma and continue down T tubules. Therefore, T tubules conduct action potentials deep into the muscle cells close to the terminal cisternae of the SR.

Triads are successive groupings of three membranous structures: terminal cisternae/T tubules/ terminal cisternae.

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74
Q

Myofibrils

A

These are the contractile parts of muscle cells. Muscle cells contain hundreds to thousands of rod like myofibrils, which run in parallel and extend the length of the cell.

Myofibrils are densely packed together. Organelles like mitochondria appear squeezed in between. They are made of small contractile units that are arranged in chains, these are called sarcomeres or muscle segments

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75
Q

Bands, Zones and Lines

A

Dark bands are anisotropic (polarize visible light) and are called A bands.

Light bands are isotropic (non-polarizing) and are called I bands

Each A band has a slightly lighter zone in the middle called the H zone, which is most visible in relaxed muscle.

The middle of an H zone has a dark line called the M line. The of an I band also has a dark line the Z line or disc.

A sarcomere, the smallest contractile unit, is the region between two Z lines.

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76
Q

Actin and Myosin

A

Thick filaments are mostly made of the protein myosin. A strand of myosin has a rod like tail and two globular heads.

The heads are often called cross bridges, as they link thick and thin filaments during contractions. One thick filament within a sarcomere contains ~ 200 myosin molecules. Heads posses ATPase activity and split ATP for energy during contraction.

Thin filaments are mostly made of actin. Subunits of actin filaments are the sites to which myosin heads attach during contraction.

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77
Q

Regulatory Proteins

A

Tropomyosin is a protein that spirals around filaments cores and when relaxed they block actin’s attachment sites for myosin.

Troponin binds to actin, tropomyosin and Ca 2+ ions. Both these proteins help control actin myosin interactions and thus muscle contraction and relaxation

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78
Q

Other proteins associated with muscle

A

Titin: stretchy protein that attaches thick filaments to Z disc. It can stretch to 4x resting length % spring back. It helps stabilise sarcomeres.

Myomesin: connects to titin and adjacent thick filaments.

Nebulin: inelastic protein that aligns thin filaments.

Dystrophin: links thin filaments to sarcolemma & transmits tension generated tendons.

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79
Q

Sliding filament mechanism (actin & myosin)

A
  • myosin cross bridges pull on thin filaments
  • thin filaments slide inwards
  • z discs come towards each other
  • sarcomeres shorten
  • muscle fibres shorten
  • thick and thin filaments do not change length.
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80
Q

Synaptic clefts

A

Tiny and filled with basal lamina (gel like glycoprotein rich substance) and the sarcolemma that forms the motor end plate is highly folded, so increasing its surface area to pack in a large number of Nicotinic ACh receptors.

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81
Q

Muscle relaxation

A

ACh is hydrolysed into acetylcholinesterase (AChE) enzymes found on the surface of the motor end plate and in the basal lamina to form acetic acid and choline.

Motor end plate potentials stop.

Ca 2+ relase from the SR stops.

Active transport pumps Ca 2+ ions back into sarcoplasmic reticulum.

Tropomyosin-troponin complexes shield myosin binding sites on actin.

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82
Q

Circular muscle fibre bundle

A

Muscle bundle are arranged in concentric rings. This muscle arrangement surrounds external body openings, which they close by contracting. A general term for such muscles is ‘sphincters’

Eg. muscles surrounding mouth and eyes

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83
Q

Convergent muscle fibre bundle

A

Muscle bundles that have a wide origin, and converges towards a single tendon.

Eg the pectoralis major

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84
Q

Parallel muscle fibre bundle

A

The long axis of the muscle bundles run parallel to the long axis of the muscle.

Eg. biceps brachii and sartorius muscles

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85
Q

Pennate muscle fibre bundle

A

Muscle bundles are short and attach obliquely to a central tendon (like a feather). Bundles attaching to one side of the tendon are ‘unipennate’ (extensor digitorum longus); bundles attaching to opposite are ‘bipennate’ ‘rectus femoris’

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86
Q

Axial & Appendicular skeleton

A

Skeleton: rigid framework of connected bones that gives form to the body, protects and supports soft tissue, and provides attachment for muscles and a system of levers essential for locomotion. The human skeleton consists of 206 named bones.

The axial skeleton consists of 80 bones and is divided into the skull, vertebral column and bony thorax regions.

The appendicular skeleton consists of the bones of the limbs and their girdles. Yoke-like pectoral girdles attach the upper limbs to the body trunk. The pelvic girdle secures the lower limbs

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87
Q

Articulations (joints)

A

Sites where two or more bones meet
Hold the skeleton together
Give the skeleton flexibility

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88
Q

Functional joints

A

Amount of joint movement

  • Synarthroses: immovable (skull)
  • Amphiarthroses: slightly movable (vertebrae)
  • Diarthroses: freely movable (shoulder/ankle)
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89
Q

Structural joints

A

Material binding joints together

  • Fibrous: generally immovable
  • Cartilaginous: rigid or slightly movable.
  • Synovial: freely movable
90
Q

Fibrous joints

A

Structure: seams that occur between bones of the skull, interlocking edges, bones fuse into a single unit by adulthood

Syndesmoses: bones connected by a cord or sheet of fibrous connective tissue. The joint has ‘give’ but no true movement, eg. distal tibiofibular joint

Gomphoses: tooth peg-in-socket joints

91
Q

Cartilaginous joints

A

Synchondroses: cartilage bars or plates that connect together bones, allow bone growth in epiphyseal plates.

Symphyses: compressible and resilient cartilage pads. Permits limited movement eg. invertebral joints.

92
Q

synovial joint structure

A

Articular cartilage: glassy smooth, spongy cartilage cushions cover opposing bone surfaces.

Joint cavity: filled with synovial fluid

Articular capsule: double layered capsule enclosing the joint cavity. Outer layer is a tough flexible fibrous capsule.

Synovial membrane: composed of loose connective tissue, lining the fibrous capsule and all non- cartilage covered surfaces.

Synovial fluid: small amount of slippery fluid occupies all free spaces in the joint capsule. Reduces friction within the joint.

93
Q

Gliding (synovial joints)

A

Flat/nearly flat bone surfaces glide or slip over one another, resulting in a displacement. Gliding occurs at intercarpal and intertarsal joints, and between flat articular processes of the vertebrae.

94
Q

Angular (synovial joints)

A

Increase or decrease the angle between two bones. Such movement includes flexion (decrease angle), extension (increase angle), abduction (moving away from medial plane) and circumduction (cone shaped movements).

95
Q

Rotation (synovial joints)

A

Turning a bone around its own long axis. Such movements occurs around the hip and shoulder joints, as well as between the two cervical vertebrae.

96
Q

Levers

A

A levers is a rigid bar that moves on a fixed point (fulcrum) when a force is applied to it. The applied force (effort) is used to move a resistance (load).

3 types of lever

97
Q

Muscular Dystrophy

A

Any one of a group of genetic conditions that causes a progressive weakness and degeneration of skeletal muscles. Sarcolemma can tear during muscle contraction, leading to degeneration of individual muscle fibres and atrophy of muscles.

98
Q

Rheumatoid Arthritis

A

An autoimmune and inflammatory condition that may affect the joint of the fingers, wrists, feet, ankles, etc in a symmetrical pattern.

99
Q

Osteoporosis

A

Loss of bony tissue, resulting in bones at higher risk of fracture.

100
Q

Cardiovascular system (CVS)

A

AKA circulatory system and comprises of the heart and two networks of blood vessels (systemic and pulmonary).

The CVS has other roles other than oxygen and nutrients, eg the endocrine system uses it for the distribution of hormones. The immune system uses it for leukocyte and antibody distribution, it also has a role in homeostasis.

101
Q

Multicellular v Unicellular (CVS)

A

The CVS circulates blood around the body which is essential for larger, multicellular organisms.

Unicellular organisms rely on diffusion to carry useful molecules from their surrounding environment to them and carry waste materials away.
Multicellular pros
Pros:
- transport of nutrients absorbed by GI tract.
- transport of O2 absorbed by the lungs
- transport of CO2 removed by the lungs
- transport of other waste products removed by kidneys and GI tract
- transport of cell-cell signals (hormones)

102
Q

3 Components of the CVS

A

Blood, which get distributed around the body and provides a vehicle for the transport of a wide variety of substances.

Vessels, which provide a network of tubes around the body throughout which blood flows.

Heart, which acts as a pump to generate pressure. Blood therefore flows through the blood vessels from and area of high pressure.

Fish have tubular hearts of 2 chambers, Birds/amphibians/mammals have a more complex two sided heart with 4 chambers.

103
Q

Blood

A

Blood contains both solid and liquid components. It circulates around the body bringing O2 and nutrients to tissue and removing CO2 and waste products, etc

~8% of the body weight is blood, average volume for an adult 4-5L
- 55% plasma
- 1% is a buffy coats (leukocytes and platelets)
- 45% is erythrocytes

104
Q

Plasma

A

Straw coloured fluid containing dissolved salts:
- water 90% of plasma volume
- Proteins 8% by weight (albumin, globulins, clotting factors, enzymes, hormones etc
- non-proteins nitrogenous substances (urea, uric acid, creatinine etc
- nutrients ( simple carbohydrates, amino acids, triglycerides, fatty acids, glycerol, cholesterol, vitamins
-electrolytes (Na+, K+, Ca2+, Mg2+, Cl-, SO42-, HCO3- etc

Plasma proteins- Apart from hormones and antibodies, most plasma proteins are made by the liver. Albumin (60% of the proteins), is a major contributor to oncotic pressure), which helps to keep water in the blood.

Electrolytes also helps to maintain plasma osmotic pressure and normal blood pH

105
Q

Leukocytes

A

These helps defend against disease. When required, they can leave the circulation and enter into tissue to encounter invading bacteria, viruses, parasites, toxins and some tumour cells.

The types of leukocytes:
- Granulocytes
- Neutrophils
- Eosinophils
- Basophils

106
Q

Granulocytes

A

Their cytoplasmic granules can easily be stained. They also have lobed nuclei. Neutrophils, eosinophils and basophils are types and granulocyte.

107
Q

Neutrophils

A

Are the most numerous and contains granules of peroxidases and hydrolytic enzymes (lysosomes) as well as defensins (spear like peptides that poke holes in membranes of rivals). They are attracted to sites of inflammation and can engulf invading cells. Reactive oxygen species get generated during a respiratory burst.

108
Q

Eosinophils

A

Do not contain enzymes that specifically target bacteria, instead they are more focused on attacking parasitic worms (tapeworms, flukes, pinworms, hookworms.

These are too big to engulf, so eosinophils gather around a warm and release their attacking enzymes onto the parasite’s surface.

109
Q

Basophils

A

Contains large amounts of histamine, which when released dilates arterioles, increases postcapillary venule permeability and attracts other leukocytes to area (mast cells have a similar function.

110
Q

Agranulocytes

A

Include lymphocytes and monocytes and lack visible cytoplasmic granules.

  • Lymphocytes
  • Monocytes
  • Platelets
111
Q

Lymphocytes

A

Exist in large numbers, but only a small portion of them are in the blood. Most are found in lymph nodes.

In general T-lymphocytes are active against situations like virus infected cells and some tumours.
B-lymphocytes form plasma cells to produce antibodies.

112
Q

Monocytes

A

Leave the blood and enter into tissue to form macrophages and will then tackle viruses and bacteria. Important in atherosclerosis (lipid-loaded macrophages = foam cells)

113
Q

Platelets

A

These are really important in clotting. They are quiescent when circulating around the blood, but active to form a plug to reduce/arrest bleeding.

Platelets are tiny, they have no nucleus and are made from fragments of larger cells called megakaryocytes. They contain granules composed of 5-HT (serotonin) causes vasoconstriction (which reduces blood flow to the damaged vessel), ADP, platelet-derived growth factor, Ca2+ ions and enzymes, all of which aid clotting.

When activated, platelets adhere to damaged or breached areas of blood vessels. They will also release molecules that activate other platelets, so they will begin adhering to each other, to try and plug up the breach.

Platelets contain smooth muscle, so after a while they will contract, to drag the damaged edges of the blood vessels together

114
Q

Erythrocytes

A

These are biconcave disks with no nuclei. The cells are packed with haemoglobin (Hb), their shape gives them a larger SA:V which helps with gas exchange.

Hb readily and reversibly binds up to 4 molecules of O2. One erythrocyte contains around 250 million molecules of Hb so can bind around 1 billion O2 molecules.

On reaching the lungs, dark red deoxygenated erythrocytes get exposed to O2 diffusing from alveoli. O2 binds to Hb, forming bright red oxy-Hb. In tissues this process is reversed and O2 leaves the blood and diffuses through extracellular fluid and them into cells.

115
Q

Systemic Circulation

A

Blood vessels that supplies all parts of the body, except for lungs (starting with the aorta and its branches carrying oxygenated blood and all veins carrying deoxygenated blood and finishing with the vena cava.

116
Q

Pulmonary circulation

A

Blood vessels carrying blood from the heart to the lungs and back to the heart

117
Q

Vessels

A

Blood vessels are basically tubes that carry blood away or towards the heart. They are the means by which blood circulates throughout the body.

Tunica adventitia (externa): the outer most layer, made of strong connective tissue and resists pressure.
Tunica media: the middle elastic layer of smooth muscle, which enables dilations and constrictions.
Tunica interna: the internal layer of basement membrane and endothelial cells and enables blood to flow smoothly.

118
Q

Arteries

A

These carry blood under high pressure and most carry oxygenated blood, but the pulmonary artery carries deoxygenated blood from the heart to the lungs. Walls or arteries are thick, due to thick layers of tunica media and adventitia. Only contain 25% of the total volume of blood in the body.

The elastic nature and smooth muscle content of the tunica media allows for distension to accommodate pulsatile blood flow and control the lumen diameter.

119
Q

Artery types

A

2 main types: muscular and elastic.

Elastic: largest diameter, nearest to the heart, thick elastic layer, allow distension to accommodate blood pumped from the heart, recoil keeps blood flowing between beats.

Muscular: between elastic arteries and capillaries, smooth muscle to be able to relax or contract, adjusts diameter of lumen, controls flow of blood through capillary bed.

Vasodilation and vasoconstriction direct blood to different parts of the body. Small arteries and arterioles are resistance vessels, participate in blood pressure regulation via control of the peripheral resistance.

120
Q

Arterioles

A

Branches/divisions along the length of arteries which lead to smaller arteries then arterioles,

Arterioles are very small arteries that go on to form many smaller vessels that then finally divide to form capillaries. Just as with arteries, arterioles have walls that can withstand blood pressure and contain smooth muscle.

The sympathetic NS regulates the contraction and dilatation of arterioles and so these are important controllers of blood flow through organs and tissues.

121
Q

Capillaries

A

These are very thin walled vessels, their walls are one cell thick and made of endothelial cells and basement membrane.

Capillaries have a narrow lumen, less than the diameter of an erythrocyte, so it maximises the are of contact between the two. This is where exchange occurs between blood and tissues.

smallest type of vessels, smaller than arterioles and venules.

122
Q

Endothelial/epithelial

A

The endothelium is a single layer of cells that lines the heart, blood vessels.

Epithelial cells cover the external surface of the body and line hollow structures (except blood and the lymphatic vessels.

123
Q

Blood out of the heart to into the heart

A

Aorta
Artery
Arteriole
Precapillary sphincter
Capillary
Postcapillary sphincter
Muscular venule
Vein
Vena cava

124
Q

Venules

A

Tiny vessels that drain blood from capillaries.
Post capillary venules form when two or more capillaries join together. The walls of the postcapillary venules are mostly endothelial cells with just a few fibroblasts. These are still quite porous and are more similar to capillaries than veins. Fluid and leukocytes can easily pass through their walls. Many venules join together to form a vein

125
Q

Veins

A

These carry blood under low pressure and most carry deoxygenated blood but the pulmonary vein carries oxygenated blood from the lungs to the heart.

Veins have larger lumens and thinner walls compared to arteries. Contain around 75% of blood volume and veins are capacitance vessels. They have little effect on peripheral resistance but exert a crucial influence in cardiac output through control of the volume of blood returned to the heart.

Due to their lower operating pressure, their tunica adventitia is thin and doesn’t contain much connective tissue. The tunica media is thin too but there is still some smooth muscle that can dilate and contract and vasoconstriction can help aid venous return.

The tunica interna of most veins have semilunar values to stop the backflow of blood.

126
Q

Venous return

A

Venous pressure is rather low, so additional factors aid venous return:

Respiratory pump

Muscle pump

127
Q

Respiratory pump

A

During breathing pressure changes within the chest draws blood towards the heart. Inhalation causes intra-thoracic pressure to decrease, which expands thoracic veins to speed blood delivery to the right atrium. Inhalation also increases abdominal pressure, squeezing veins to force blood towards the heart (valves prevent backflow)

128
Q

Muscle pump

A

Contracting skeletal muscle around a vein presses on the vessel wall to propel blood towards the heart.

129
Q

Lymphatic system

A

Two parts: lymphatic vessels, lymphoid tissue (defense response)

Hydrostatic and osmotic pressures force fluid out of capillaries around the arteriole end and most of this is reabsorbed around the venous end. The fluid that remains mingles with extracellular fluid.

130
Q

Lymphatic vessels

A

These collect any excess fluid and return it back to the blood. Once inside a lymphatic vessel, the fluid gets called lymph. This is a one way drainage system, where lymph flows back to the heart.

Lymph capillaries are very porous, blind ended and found in most tissues. The edges of their endothelial cells loosely overlap each other, forming flap-like one way valves. The lymph capillaries unite to form collecting vessels, which unite to form trunks that then finally form ducts.

Collecting vessels have the same 3 tunics as the veins, but have thinner walls. Lymphatic vessels have more valves than veins.

131
Q

Lymphoid ducts

A

The right lymphatic duct drains the right side of the head, neck, right arm and right side of the thorax.

On the left, the bigger thoracic duct drains the right side of the head, neck, right arm and right side of the thorax.

On the left, the bigger thoracic duct drains the rest of the body.

Lymph is returned to the venous circulation at the junction of the internal jugular vein and subclavian vein on the left and right sides.

132
Q

Blood pressure (BP)

A

This drives blood flow around the CVS. Blood flows from an area of high pressure to an area of low pressure.

Arteries have the highest pressure.
- 80 to 120 mmHg
Capillaries have the medial pressure.
- 16 to 35 mmHg
Veins have the lowest pressure.
- 4 to 7 mmHg

Such pressure gradient will maintain blood flow.

The term BP nearly always refers to the systemic arterial blood pressure, which when measured is expressed as two numbers eg. 120/80. The first number refers to the systolic pressure. The second refers to the diastolic pressure

Blood pressure = Blood flow x vessel resistance

133
Q

BP/CO equations

A

BP = blood flow (cardiac output) x vessel resistance

Cardiac output = heart rate(BPM) x stroke volume (blood ejected from left ventricle with each beat, in L)

134
Q

Peripheral resistance

A

AKA vascular resistance.

This is the opposition to blood flow. There are 3 variable factors that contribute to this:
Blood vessel length
- longer vessels = more resistance
Blood viscosity
- thicker blood = more resistance to flow
Blood vessel diameter
- vasoconstricted vessels have more resistance, vasodilated vessels have less resistance.

135
Q

Control of BP

A

Hypertension and hyperextension are not good, but regulation is needed.

The cardiovascular centre in the medulla oblongata controls BP by altering cardiac output and blood vessel diameter. The cardiac centres and vasomotor centre form the cardiovascular centre. The cardiovascular centre receive information about BP from baroreceptors.

Baroreceptors are sensory nerves that are sensitive to stretch and monitor changes in BP, they are found in the carotid sinuses and aortic arch as well as in walls of other large arteries, veins and the heart.

Inputs from else where occur, such as parts of the CNS, which is why emotions can effect HR.

136
Q

Baroreceptors

A

Baroreceptors in the carotid sinus send signals via carotid sinus nerve that merges to glossopharyngeal to the medulla oblongata. Baroreceptors in the aortic arch send signals via the aortic nerve which combines with the vagus to the medulla oblongata.

The medulla oblongata adjusts autonomic activity to modify CO and peripheral resistance.

So increased BP ought to reduce vasoconstriction and CO.

BP = HR x SV x TPR (peripheral resistance)

137
Q

Molecular Mediators

A

Some of the numerous molecules that can influence BP include:

  • Atrial natriuretic peptide
  • Antidiuretic hormone (ADH)
  • Angiotensin II
  • Endothelin
  • Nitric oxide (NO)
  • Mediator of inflammation
  • Increased sympathetic tone
  • alcohol (inhibits ADH release so causes vasodilation so a decreases in BP)
  • exercise changes levels of O2 and O2 will regulate BP by chemoreceptors reflexes, so baroreceptor control is reduced so reduces BP.
138
Q

Atrial natriuretic peptide

A

Reduces BP

Released due to high BP causing atria to stretch, this peptide antagonizes aldosterone, so causing the kidneys to reabsorb less sodium and water. Vasodilation occurs too.

139
Q

Antidiuretic hormone (ADH)

A

Increases BP

Mostly released if BP is dangerously low (cases of haemorrhage) from the hypothalamus and causes the kidneys to reabsorb more water. Vasoconstriction happens too.

140
Q

Angiotensin II

A

Increases BP

When renal perfusion is inadequate, the kidneys release the enzyme renin. This acts on angiotensinogen in the blood and in two steps forms angiotensin II, a potent vasoconstrictor that also stimulates aldosterone release.

141
Q

Endothelin

A

Increases BP

A potent vasoconstrictor released from the endothelium in response to blood flow.

142
Q

Nitric oxide (NO)

A

Decreases BP

A vasodilator released from the endothelium in response to high blood flow.

143
Q

Mediator of inflammation

A

Decreases BP

Histamine and other such molecules cause vasodilatations.

144
Q

Increased sympathetic tone

A

Influences BP (Increases HR)

Adrenaline and noradrenaline will increase HR and effect the tone of arteries: vasodilation will occur in arteries supplying tissues important for exercise. Vasoconstriction is likely to occur to divert blood away from tissues not actively participating.

145
Q

Hypertension

A

High BP

BP = HR x SV x TPR

HR - to reduce HR they block sympathetic stimulation by the use of beta-blockers. These are beta adrenergic receptor antagonists. (Atenolol/Metoprolol are both beta 1 selective)

SV - to reduce SV they decrease water retention in blood (Indapamide).

TPR - to reduce TPR they inhibit vasoconstriction (ACE inhibitors eg. Ramipril) (calcium channel blockers eg. Amlodipine)

146
Q

Sides of the Heart

A

Right: Supplies pulmonary circulation, receives blood from the vena cava, pumps blood into the pulmonary artery.

Left: supplies systemic circulation, receives blood from pulmonary vein, pumps blood into aorta.

147
Q

Chambers of the heart

A

Each side of the heart has two chambers: Atrium/atria and ventricle(s)

Atrium/atria is the first chamber:
- receives blood from great vein
- during diastole, blood flows through the atria to fill the ventricles, once these are full then atria will fill
- Pumps blood into ventricles at the start of systole.

Ventricle(s) is the second chamber:
- receives blood from atrium
- pumps blood into artery
- provides pumping pressure for blood flow
- thick walls.

148
Q

Heart valves

A

Starts at the vena cava:
The tricuspid valve (3 caps)(AV valve) joins the right atrium to the right ventricle.

This follows on to the semilunar valve (pulmonary valve) which joins the right ventricle to the pulmonary artery (deoxygenated blood to the lungs).

Starts at the pulmonary vein:
The bicuspid valve joins the left atrium to the left ventricle

This follows on to the other semilunar valve (aortic valve) which joins the left ventricle to the aorta (oxygenated blood to the whole body.

149
Q

Electrical Conductivity of the Heart

A

An inherent and rhythmic ability to generate action potentials is the reason why the heart can depolarize and contract without nervous stimulations (NOT sympathetic NS).
The sino-atrial node (SAN) is an area in the right atrium that beats a little more often than the rest of the muscle, which then causes the whole heart to beat. This rhythm is influenced by the autonomic NS.

The SAN is composed of self-excitatory cells, which depolarize rhythmically, so causing depolarization rhythmically, so causing depolarization to spread throughout surrounding atrial tissues and to the atrioventricular node (AVN).

An action potential then flows down the bundle of his and purkinje fibres to cause ventricular contraction. Ventricles begin contracting from the bottom apex, so forcing blood up through the SL valves

150
Q

Heart sounds

A

‘LUB’ :
First sound, halfway through systole, closing of AV valves.

‘DUB’ :
Second sound, end of systole, closing of SL valves.

151
Q

Diastole

A
  • Heart is relaxed
  • Blood enters atria and ventricles
  • Arterial blood pressure lowest: systemic
    pressure = 80 mmHg, pulmonary pressure =
    20 mmHg
152
Q

Systole

A
  • Heart contracts
  • Atria pumps blood into ventricles
  • Ventricles pump blood into arteries
  • Arterial blood pressure highest: systemic
    pressure = 120mmHg, pulmonary pressure =
    40mmHg
153
Q

Cardiac Action potential Cycle

A

More free Na+/Ca2+ ions outside the cell compared to inside where more k+ is. The inside is more negative charged at rest.

Phase 0: rapid depolarisation
Phase 1: partial repolarisation
Phase 2: plateau
Phase 3: repolarization
Phase 4: depolarisation

154
Q

Human NS

A

CNS
- brain/spinal cord
- process sensory input that generates motor output

Peripheral NS (PNS)
- peripheral nerves
- cranial nerves (12 pairs)
- spinal nerves (31 pairs)
- afferent sensory communication with CNS/efferent motor output from CNS

155
Q

Afferent nerves

A

Afferent nerves take signals from peripheral tissues and external environment to the CNS.

afferent arrives

156
Q

Efferent nerves

A

Efferent nerves take signals from the CNS to peripheral tissues.

efferent exists

157
Q

Neurons

A

Cells that form part of the central and peripheral NS carry out signals along their membranes in the form of nerve impulses or action potentials.
- have a high rate of metabolism and require a continuous delivery of O2 and glucose
- can have extreme longevity (in optimum conditions may last a lifetime)
- once formed and functioning they can loose their ability to divide (amitotic)

158
Q

Information flow (nerves)

A

Information input (dendrites)
information processing (soma)
information output (axon)

159
Q

Dendrites of neurons

A

Dendrites receive signal inputs, which then gets converted into changes of membrane voltage (Vm) but these electrical signals are not action potentials, but are short distance graded potentials, which then spread.

Integration of Vm changes by different dendrites result in an average Vm change reaching the soma.

160
Q

Cell body (soma) of neurons

A

This consists of a large nucleus with a noticeable nucleolus surrounded by granular cytoplasm. Mitochondria and Golgi are found throughout the cell body.

Microtubules and neuro-filaments are also seen throughout and are important in intracellular transport and in maintaining cell shape.

Function:
- aggregates all inputs from the dendritic tree
- then changes in Vm get transferred to the axon hillock

161
Q

Axon of Hillock of neurons

A

This is the first part of the output pathway of the neuron.

Function:
- it generates action potentials if receiving enough stimulation from the cell body.
- it expresses the ion channels that are needed for action potentials.

162
Q

Axon of neurons

A

Each neuron has a single axon arising from the axon hillock. Different axons can vary their diameter which will reflect in their conduction speed. Large diameter = low resistance = faster conduction.

Individual axons retain a uniform diameter along the length. Axons may occasionally have branches coming off, called axon collaterals

Function:
- allows for action potential propagation towards targets
- allows for (axoplasmic) transport of molecules to the nerve terminals

163
Q

Myelin sheath

A

This is formed by myelinating cells (schwaan cells or oligodendrocytes), they wrap themselves around an axon in a swiss roll fashion. Initially this is quite loose, but over time cytoplasm is squeezed out to form many layers of tightly coiled membrane. The nucleus and cytoplasm is found underneath the outermost part of the plasma membrane.

The resulting cytoplasmic-free membrane has very few proteins and very few ion channels or transporter molecules which makes it a very good electrical insulator.

Myelinated nerve fibres conduct action potentials rapidly but dendrites are ALWAYS unmyelinated,

164
Q

Nodes of Ranvier

A

The gaps between myelin sheath is called Nodes of Ranvier cause action potentials to jump from node to node, which greatly increases conduction speeds for a given axon diameter.

This is known as saltatory conduction

165
Q

Switching off a synapse

A

Action potential propagation and neurotransmitter release stops.

Neurotransmitter is removed from the synaptic clefts by either:
- neurotransmitter breakdown
- neurotransmitter reuptake.

166
Q

Types of neurons

A

Functional classification
- sensory (afferent) neurons
- motor (efferent) neurons
- interneurons (connects sensory to motor)

Morphological classification
- pseudo unipolar neurons (only axons, NO dendrites)(sensory neurons)
- bipolar neurons (1 axon, 1 dendrite) (olfactory epithelium, retina)
- multipolar neurons (many dendrites, 1 axon) (motor neurons)
- unipolar neurons (only invertebrates, NOT humans)

167
Q

Transport through the plasma membrane

A

The plasma membrane of a cell provides a barrier between the intracellular and extracellular environments.
- hydrophilic substances such as Na+, k+,Ca2+ ions, glucose etc are unable to simply diffuse in and out so transporter proteins are required. Eg ion channel, protein pumps, proteins exchangers etc

Cells are able to control the movement of certain substances as well as increase (accumulate) or decrease the intracellular concentrations compared to the extracellular environment.

168
Q

Types of transport through plasma membrane

A

According to number of molecules being transported:
- uniport
- cotransport
~ symport
~antiport

According to energy requirements
- passive transport
- active transport
~ primary (Na+/K+ pump)
~ secondary (symport glucose/Na+)

169
Q

Voltage gated Na+ channels

A

Have a major role in normal nerve conduction. Local anaesthetics, eg Lidocaine, diffuse into axons and block Na+ channels.

Eventually so many Na+ channels become inactivated that an action potential can neither be sustained nor generated, and so analgesia occurs.

Channel blockers:
- local anaesthetics
- antiepileptics (phenytoin)
- antidysrhythmic (disopyramide)
- tetrodotoxin/saxitoxin/conotoxins

170
Q

Glia (CNS)

A

Glia cells are cells that form part of the central and peripheral NS.
- they have a supporting role (help maintain the environment around the neurons)
- have an important role in myelinating neurons

  • Oligodendrocytes (myelinate neurons in the CNS)
  • Astrocytes (supporting neurons environment and involved in BBB
  • Microglia (phagocytose foreign organism
  • Ependymal cells (produce cerebral spinal fluid in cerebral ventricles)
171
Q

Glia (PNS)

A
  • Schwaan cells (myelinate axon of PNS neurons)
  • satellite glial cells (myelinate the cell body of PNS neurons
172
Q

Layers surrounding the brain and spinal cord

A
  • dura mater (thick and tough)
  • arachnoid (web-like membrane)
    ~ subarachnoid space (CSF, trabecular)
  • pia mater (thin membrane held tightly to the cortex
173
Q

Forebrain

A

Cerebral cortex (cerebrum)
- thought and action, memory, motor skills, sensory information
- 2 hemispheres connected by the corpus callosum

174
Q

Brainstem

A

Midbrain is a complex structure of neuron clusters
- hearing
- movement

Pons is the connection between midbrain and medulla and the origin of the 4 cranial nerves
- tear production
- chewing
- focus vision, blinking

Medulla Oblongata
- heart rhythm
- breathing
- blood flow

175
Q

Limbic system

A

Thalamus- relays sensory information to the cortex

Hypothalamus- regulates pituitary gland (endocrine activity, sleep, hunger)

Amygdala- regulates emotions and contains many opiate receptors implicated in rage, fear and sexual feelings.

Hippocampus- memory forming, storing information, connects memories with senses.

176
Q

Pituitary gland

A
  • small gland (pea sized) located posterior to the bridge of the nose
    -link between the NS and the endocrine system
    ~ releases many hormones that affect
    growth, metabolism, sexual development
    and development of reproductive systems
    ~ connected to the hypothalamus
177
Q

Cerebellum

A

“little brain”
Has two hemispheres and a highly folded structure
- coordinates voluntary motor movements
- maintains balance, equilibrium

178
Q

Grey and White matter

A

Grey matter: formed by the neurons cell body (soma)
White matter: axons wrapped in myelin

179
Q

Cranial nerves

A

12 pairs of cranial nerves

  • 1 and 2 from the cerebrum
  • 3 to 12 originate from the brain stem

They are either sensory motor or mixed.

180
Q

Spinal nerves

A

31 pairs of spinal nerves that emerge between the spinal vertebrae

C1 to C8 are cranial nerves
T1 to T12 are thoracic nerves
L1 to L5 are lumber nerves
S1 to S5 sacral nerves
coccygeal

181
Q

Oxygen

A

Clear colourless gas with a low boiling point (-183 degrees C) and is a diatomic molecule.

O2 is very chemically active, with both combustion and respiration involving its combination with other molecules.

Ozone contains three oxygen atoms and forms a bluish gas. It is very active chemically and is only present in tiny quantities in normal breathing air.

Glucose+Oxygen=CO2+water (+ATP)

182
Q

Functions of the respiratory system

A

Exchanges of gases between the atmosphere and the blood

Homeostasis regulation of body pH

Protection from inhaled pathogens and irritating substances

Vocalization

183
Q

Respiratory Tract

A

Upper respiratory tract includes: the nose, nasal cavity, the mouth, the throat (pharynx) and the voice box (larynx)

Lower respiratory tract includes: the trachea, the bronchi, the bronchioles and the alveoli.

The right lung has 3 lobes the left lung has 2 lobes (heart next to it).

184
Q

The conducting zone

A

Consists of fairly ridged structures that conducts air to the sites of gaseous exchange. In addition to this, the conducting zone cleanses, humidifies and warms the incoming air.

185
Q

The respiratory zone

A

This is the actual site where gas exchange occurs. The respiratory bronchioles, alveolar ducts and alveoli from the respiratory zone.

186
Q

The nose

A

Only externally visible part of the respiratory tract.

The nasal cavity lies in and behind the nose. Air passes through the nostrils (external nares) and the nasal cavity is divided by the nasal septum.

Just inside the nostrils numerous hair follicles filter out large particulate matter.

The rest of the nasal cavity contains the olfactory mucosa (sense of smell) and the respiratory mucosa (secretes ~1L of mucus daily to trap dust and microbes etc. Ciliated cells of this mucosa moves most of this contaminated mucus to the pharynx where it gets swallowed (unconsciously) and then digested by the GI tract.

Colder days = slower cilia movements = more mucus in the nasal cavity = runny nose on colder days.

187
Q

Air turbulence

A

Occurs in the nasal cavity, which swirls the air and deflects particulate matter onto mucus coated surfaces, trapping them. It facilitates humification, filtration and warming of the air.

Sensory nerves in the area respond to irritating particles by triggering sneezing, which helps to expel irritants. In the cold, veins under the nasal epithelium vasodilate to help warm inhaled air. This also increases the risk of nosebleeds for susceptible individuals

188
Q

Paranasal Sinuses

A

The sinuses lighten the skull and the nasal cavity both help to warm and moisten inhaled air.

Cold viruses, streptococcal bacteria etc. can cause inflammation of the nasal mucosa, which also results in an increase of mucus production. This can spread to the sinuses.

Sinusitis is the inflammation of the sinuses which results in a sinus headache and can be uncomfortable.

189
Q

The Pharynx

A

Is a muscular tube extending from the top of the oesophagus to the base of the skull. It is a common pathway for food and air and acts as a resonance chamber for the voice. The opening to the Eustachian tubes occurs here too.

190
Q

The Larynx

A

Sits on top of the trachea. It houses the vocal chords, it keeps the airway open and it diverts food into the oesophagus and air into the trachea.

When only air is flowing the inlet to the larynx is open. When swallowing a reflex causes the larynx to pull up and the epiglottis to tip over to cover laryngeal inlet. Thus food is kept out of the lower respiratory tract and explains why breathing is interrupted when swallowing.

If swallowed matter enters the larynx, coughing occurs to expel the substance due to a reflex.

This system does not work when the person is unconscious.

191
Q

The trachea

A

Is a flexible tube that descends from the larynx, passes through the neck and ends by dividing into two primary bronchi. It is anterior to the oesophagus to prevent it collapsing, C-shaped rings of hyaline cartilage occurs within its walls.

The epithelium contains goblet cells and expresses cilia, that wafts debris towards the pharynx, so stopping it accumulating in the lungs.

Smoking destroys the cilia so smokers can only clear airways by coughing.

The open ends of the c-shaped cartilage rings are connected by smooth muscle tissue, which can contract and relax to constrict or dilate the trachea respectively.

192
Q

Bronchi

A

Forms when the trachea divides into two, the right primary bronchus is wider, shorter and more vertical than the left, so the inhaled objects are more likely to be lodged here.

Air reaching here is warm, moist and mostly clean. Bronchioles have a diameter below 1mm and terminal bronchioles below 0.5mm

Cartilage rings are replaced by cartilage plates for support but are absent in the bronchioles.

The wall of smaller airways contain smooth muscle which alter airway resistance by causing constrictions and dilations.

193
Q

Sympathetic vs parasympathetic (lungs)

A

The tone of bronchiole smooth muscle is controlled by the autonomic NS. The lungs are sparsely innervated by sympathetic nerves. The bronchiole smooth muscle have B2 adrenoceptors, so there cells respond more to adrenaline than noradrenaline.

Parasympathetic innervation is by cranial nerve X ( the vagus nerve)

194
Q

Alveoli

A

Terminal bronchioles divide into respiratory bronchioles, and protruding from these are the alveoli. Most of the lungs are compromised of alveoli (~300 million) which provide a large SA for gas exchange.

The walls of the alveoli are a very thin layer of cells called type I squamous alveolar cells supported by a thin basal lamina.

The second type is type II alveolar cells. These secrete a fluid containing a surfactant across the air side surface. This reduces surface tension of the alveolar fluid, so prevents alveolar collapse.

195
Q

Pleura

A

Thin, double layered serosal membrane that forms a closed sac. A serous membrane (serosa), is a smooth transparent membrane, that lines some large body cavities: the parietal portion of this membrane lines the walls of the cavity, the visceral portion covers the organs enclosed by the cavity (external lung surface).

These pleurae produce pleural fluid, which acts as a lubricant to allow the lungs to easily move during breathing. Surface tension between the pleurae resists separation, so the lungs cling to the thorax wall.

Pleurisy occurs when inflammation causes decreased secretion, so pleural surfaces become dry/rough/sticky, causing painful breathing.

196
Q

Mechanisms for breathing

A

Inhalation and exhalation are the two phases of pulmonary ventilation. The difference in respiratory and atmospheric pressure causes the movement of air in and out of the lungs.

197
Q

Inhalation (inspiration)

A

The diaphragm contracts and flattens, external intercostal muscles contract to lift the ribs and move the sternum forwards.

Both of these increase the volume of the thoracic cavity, so lowering pressure and drawing air in.

198
Q

Forced inhalation (inspirations)

A

The volume of the thoracic cavity is increased more by the activity of accessory muscles:

The scalene and sternomastoid muscle (found in the neck) and the pectoralis minor muscles in the chest contract to further raise the ribs. The back extends to straighten the thoracic curvature (erector muscles relax).

199
Q

Exhalation (expiration)

A

A passive process whereby inspiratory muscles relax and the volume of the thoracic cavity decreases to force air out of the lungs.

In forced expiration, the wall of the abdomen contracts to increase intra-abdominal pressure and move some abdominal organs up against the diaphragm, as well as depress the ribcage. Internal intercostal and latissimus dorsi muscles, also contract to depress the rib cage.

200
Q

Avg Lung capacities

A

Total lung capacity = 6000ml

Tidal volume = 500ml

vital capacity = 4800ml

*all are averages

200
Q

Transport of gases in the blood

A

Arterial blood:

O2 is dissolved in plasma then O2+Hb=HbO2 which is then transported to cells here HbO2 is separated and the O2 is used in cellular respiration.

Venous blood:

CO2+Hb=HbCO2 which is then transported to the lungs where dissociation occurs and the removal of CO2 from the blood.

201
Q

Control of breathing

A

The dorsal respiratory group (DRG) and the ventral respiratory group (VRG) in the medulla oblongata are important for respiration.

DRG is sometimes called the inspiratory centre as it cyclically sends action potentials along the phrenic and intercostal nerves to cause contraction of the diaphragm and intercostal muscles. In severe hypoxia the DRG generates gasping breathing. DRG can be completely suppressed in an opioid/alcohol overdose and respiration will cease leading to a coma then death.

The VRG controls muscles involved in forced inspiration and forced expiration. Fibres from the VRG also innervate muscles of the larynx, pharynx and tounge to keep the upper airways open during breathing.

202
Q

Partial pressure of CO2

A

The Partial pressure of CO2 has a big influence on breathing. If the rate of CO2 production by the cells exceeds the rate of CO2 removal from the blood, arterial PCO2 increases. In the brain, CO2 form the blood diffuses into CSF and combines with water to form carbonic acid which dissociates to form H+ ions. The lower pH excites chemoreceptors in the medulla so ventilation increases so more removal of CO2.

203
Q

Lower pH in arteries

A

Change in arterial pH can affect respiration but the effect on central chemoreceptors is only slight, as H+ ions in the blood poorly diffuse through the blood brain barrier.

Low blood pH is more likely to affect peripheral chemoreceptors

204
Q

Partial pressure of O2

A

Some cells in the aorta and the carotid arteries are sensitive to O2. Normally the direct effect of declining arterial PO2 is not very dramatic. This mostly enhances the effect of increasing PCO2. PO2 is normally between 75 to 100 mmHg, a drop below 60mmHg will stimulate increased ventilation.

205
Q

Cell cycle

A

G1 - new organelles produced and other proteins via translation, transcription also occurs here.
S - synthesis, DNA replication.
G2 - prepare for mitosis, make spindle fibres that are used in anaphase.
Mitosis (PMAT)
Cytokinesis

G1, S , G2 are part of interphase (longest part of the cell cycle).

*G0 is a part where cells are when they have no need to replicate eg. neurons in the brain. There is no growth in this phase.

206
Q

PMAT

A

P - nuclear envelope breaks down and chromosomes super condense and form 2 sister chromatids joined by a centromere. Spindle fibres form.
M - spindle fibres attach to the centromeres and the chromosomes align on the equator.
A - centromeres break down and spindle fibres pull chromatids to opposite poles.
T - spindle fibres break down and the nuclear envelope reforms and the cytoplasm begins to split.

207
Q

Cytokinesis

A

Splitting of the cytoplasm.

Last part of mitosis and 2 daughter cells are produced.

208
Q

Microbiology

A

The study of the biology of microscopic organisms.

eg viruses, bacteria, algae, fungi, smile moulds and protozoa.

209
Q

Cellular

A
  • Maintains structure by taking up chemicals and energy from the environment
  • Responds to stimuli in the external environment
  • Reproduce and pass on their organization to their offspring
  • Evolve and adapt to the environment
210
Q

Acellular

A
  • Not consisting of, divided into, or containing cells
  • eg. viruses
  • Non-living cells that lack a cellular structure.
211
Q

Prokaryote

A

No nucleus

  • unicellular
  • DNA is circular and without proteins
  • no membrane bound organelles
  • smaller ribosomes
  • cell division is by binary fission
  • reproduction is always asexual
  • smaller
212
Q

Eukaryote

A

Nucleus containing

  • animal, fungi, plant and protist kingdoms
  • larger
  • membrane bound organelles
  • DNA is linear and associated with histones
  • cell division by mitosis or meiosis
  • reproduction can be sexual or asexual
  • larger ribosomes
213
Q

Gram + cell wall

A

Type of bacterial cell wall

Thicker cell wall, provides greater protection from environmental stresses. They are composed of 20 layers of peptidoglycan and teichoic acid.

214
Q

Gram - cell wall

A

Type of bacterial cell wall

Cell wall is multi-layered and quite complex. It only contains a thin single layer of peptidoglycan and also has a periplasm and outer membrane.

The outer layer protects them from their environment. These bacteria can use this membrane to selectively keep antibiotic drugs from entering. Germs get rid of the antibiotics using pumps in their cell walls to remove antibiotic drugs that enter the cell.

215
Q

Use of Penicillin

A

Disrupts cell wall synthesis

216
Q

Use of Chloramphenicol

A

Disrupts protein synthesis

217
Q

Use of Polymyxins

A

Disrupts membranes/ gram negative bacteria

218
Q

Use of Fluoroquinolones

A

Disrupts DNA sysnthesis

219
Q
A

Year 1 (3 decks)

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