HUBS191 Health Science A+ Notes Otago University PDF

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Contents Basic Cellular Biology & Homeostasis (Lectures 1-4)

2

Anatomical Terminology (Lecture 5)

6

Skeletal System (Lectures 6-8)

8

Joints & Supporting Tissues (Lectures 9-11)

12

Muscles (Lectures 12-16)

15

Cells & Divisions of the Nervous System (Lectures 17-18)

19

Neuroanatomy (Lectures 19-21)

21

Core Neurophysiology (Lectures 22-25)

25

Neuromuscular Physiology (Lectures 26-28)

28

Systems Neurophysiology (Lectures 29-32)

32

Endocrinology (Lectures 33-39)

38

Immunology Basics & The Innate Immune System (Lectures 40-42)

45

The Adaptive Immune System (Lectures 43-46)

49

Immunology in Practice (Lectures 47-50)

53

Basic Cellular Biology & Homeostasis (Lectures 1-4)

Fundamentals Organisation of Human Body By level (from smallest to largest): Chemical → Organelle → Cell → Tissue → Organ → Organ System → Organism

Tissue Comprises cells embedded within Extracellular Matrix (ECM) – thus different tissues differ by cell type and composition of the ECM.  ECM varies by levels of certain substances (chiefly water, proteins & proteoglycans)  Cells vary by type (e.g. myocytes in muscle vs neurons in nerves)

Tissue Epithelial

Structure  

Layers/sheets of cells Little matrix

Function  

Connective

 

Sparse cells Lots of matrix, mainly containing fibres

 

Example

Lines & protects body surfaces Lines cavities

  

Skin Lining of tracts Glands

Supports structures Transports substances

  

Bones Fat Cartilage/tendons

Muscle

 

Long fibre-like cells Strong fibres capable of pulling loads



Produces movement & heat



Skeletal, smooth & cardiac muscle

Nervous



Highly cellular, varied types Conducting & supporting

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Communication & co-ordination between body parts

  

Nerves Brain & spinal cord Sensory organs

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th

(Adapted from Patton & Thibodeau 8 edn)

Fluid Physiology The Internal Environment In contrast to unicellular organisms which require specific external environments in order to survive, humans and other multicellular organisms have an internal environment which can be kept constant in a variety of external environments, thus allowing them to survive. → This internal environment is essentially the Extra-Cellular Fluid or ECF. Reference Ranges for Important ECF Variables: Variable Na K Ca Glucose pH

RR (mmolL-1 excluding pH)

135-145 3.5-5 2.1-2.6 3.5-6 7.35-7.45

Basic Cellular Biology & Homeostasis (Lectures 1-4)

Important ECF Constituents 

 

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Sodium Main extra-cellular cation – essentially determines total body fluid (thereby also affecting blood pressure). Also important in the generation of action potentials (see Core Neurophysiology summary) Potassium Main intra-cellular cation – main determinant of resting membrane potential (see below) Calcium Important in neurotransmission, muscle contraction and coagulation; also structural component of bone and teeth Glucose Used by cells to produce ATP (energy); high or low levels cause other problems

Osmolarity and Tonicity 



Osmolarity is a measure of the total number of solute particles per litre in a solution. Units = osmol/L or mosmol/L – normal is 275 to 300 mosmol/L (Sometimes people talk about osmolaLity - the number of solute particles per kg, but this is not important for HUBS191) Tonicity refers to the effect that a solution has on cell volume: whereas osmolarity is purely a measure of the number of particles, tonicity takes into account whether the different particle types can cross the semi-permeable membrane of the cell

Membrane Transport Mode Simple diffusion

Facilitated diffusion (AKA Carrier-mediated passive transport)

Primary Active Transport Endocytosis & Exocytosis

Explanation

Example

Random movement of molecules down their concentration gradient – either directly through lipid bilayer of membrane, or via membrane channels Substance binds to carrier on ECF side of membrane, which induces carrier to change shape & release substance to other side (ie into cell)

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

Glucose entering cells when insulin is present

Energy from the hydrolysis of ATP is used to move substances against their concentration gradient

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Na/K ATPase pump

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Neutrophils engulfing microbes (Endocytosis β cells in pancreas secreting insulin (Exocytosis)

Substances transported into or out of cell in vesicles (ie with a lipid layer surrounding them)

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Steroid hormones directly through membrane Water through aquaporins

Basic Cellular Biology & Homeostasis (Lectures 1-4)

Resting Membrane Potential (This is explored further in the Core Neurophysiology summary)  Inside of cell is more negatively charged than outside owing to separation of a small number of oppositely charged ions across the lipid bilayer membrane +  The main ion contributing to RMP is Potassium (K )  Normal magnitude is about -70mV

Homeostasis Basics Definition The maintenance of relatively constant conditions in the internal environment in the face of change.

Key concepts    

Controlled variable – variable to be kept stable Set point – target point for the controlled variable Variation – in controlled variable values within and between ‘normal’ people Reference range – range of values within which the controlled variable is normal (In the lab, RR = range within which 95% of ‘normal people’ lie – that is, 5% of people will have their ‘normal’ outside the RR but they are healthy)

Homeostatic mechanisms Feedback & Feed-forward 



Feedback is a response to change: - Negative feedback responds to a change and seeks to return it to normal (more common) E.g. shivering in response to cold - Positive feedback responds to a change and seeks to continue/advance the change (rarer) E.g. stronger and more frequent contractions in labour in response to stretch Feed-forward anticipates change – involves detection of conditions or situations which could alter a controlled variable if some sort of action was not taken, and responds accordingly E.g. producing more salivary amylase (to help digest food) in response to smelling or even thinking about food

Control System For negative feedback  Sensor – monitors the actual value of the variable  Integrator – compares the actual value to the set point, then determines and controls the response (note this can be the same cell/system as the sensor)  Effector(s) – produce the response(s) to restore the controlled variable to the set point  Communication pathways – carriers signals between components – can be: Neuronal: involves propagation of action potentials along nerves – fast & specific → good for brief responses Hormonal: involves release of hormones into blood/ECF and communicates with any cells which have receptors for the hormone – slow & widespread → good for sustained, generalised responses

Basic Cellular Biology & Homeostasis (Lectures 1-4)

Practical examples of homeostasis Core Body Temperature

Diabetes Type 1 Diabetes = NO insulin produced  Type 2 Diabetes = peripheral tissues have ↑resistance to insulin (+ some ↓production of insulin)  Normally insulin is released by the β cells in the pancreas in response to ↑glucose absorption from the GI tract: it causes muscles, liver and other tissues to take up th (From Patton & Thibodeau 7 edn) more glucose  Thus in Type 1 Diabetes individuals have abnormally high blood-glucose levels  Accordingly, principles of treatment are replacing body’s natural feed-forward and negative feedback control systems – regimen might typically include: - Daily injection of long-acting insulin based on anticipated food intake & energy expenditure (Feed-forward) - Additional doses of short-acting insulin based on actual blood glucose measurements (Negative feedback)

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Haemorrhage Not expected to know specifics until HUBS192 – don’t get hung up on details. Key aspects are 1. Clotting (Positive feedback mechanism) 2. Cardiovascular response - Negative feedback: sensors in large arteries detect ↓BP, send signals via communication pathways (nerves) to integrator (brainstem) causing changes in effectors (heart & vessels) to help restore cardiac output and blood pressure. 3. Kidney response – Negative feedback : sensors in renal arterioles detect ↓BP, integrators (specialised cells in kidney) cause communication (mainly hormones) to effectors (numerous)

Anatomical Terminology (Lecture 5)

The Anatomical Position, Terms of Direction & Planes The Anatomical Position 

Standing, facing forward with palms forward (illustrated below left)

Terms of Direction

th

Marieb & Hoehn 9 edn

Planes

Basic Movements Movement Flexion

Explanation

Extension

Increases angle of the joint

Decreases angle of the joint

Diagram

Anatomical Terminology (Lecture 5)

Movement Dorsiflexion

Explanation

Diagram

Plantarflexion

Toes towards the ground

Abduction

Movement away from midline

Adduction

Movement towards midline

Circumduction

Mixture of flexion/extension and abduction/adduction in a circular motion

Rotation

Rotation around the long axis of a joint

Internal/Medial rotation External/lateral rotation

Towards axis of body Away from axis of body

Pronation

Palm of hand posterior (imagine bouncing a basketball like a ‘pro’ baller)

Supination

Palm of hand anterior (imagine if you held a bowl of ‘soup’ in one hand)

Eversion

Sole of foot away from midline

Inversion

Sole of foot towards midline

Toes brought towards face

Images adapted from teachmeanatomy.info

Skeletal System (Lectures 6-8)

Overview Functions of Skeleton     

Support – of other body structures Movement – bones can change position with respect to each other Protection – of internal organs Storage – of nutrients and other substances RBC formation – occurs in the marrow

Gross Anatomy Bone Classes Class Long

Features  

Function

Image

Example(s)

Longer than they are wide Compact bone in diaphysis; cancellous bone in epiphysis (see below) Near equal in length & width Mostly cancellous bone

Levers for movement

Femur, humerus

Weight-bearing & shock absorption

Carpals

Short



Flat

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Flat! Composed of thin plates of mainly compact (but some cancellous) bone

Protection &/or muscle attachment

Scapula

Irregular



Irregular in shape! Variable composition of compact vs cancellous bone

Variable

Bones of pelvis, vertebrae



Images adapted from humananatomy.co

Axial Skeleton Skull Consists of cranium, facial bones & mandible

Netter’s Atlas of Human Anatomy 5th edn

Vertebral column  Cervical (7)  Thoracic (12)  Lumbar (5)  Sacrum & coccyx (mainly fused) Ribs & Sternum 12 ribs in total; sternum has 3 parts – manubrium, body & xiphoid process

TeachPE.com Adapted from GetBodySmart.com

th

Patton & Thibodeau 7 edn

Skeletal System (Lectures 6-8)

Appendicular Skeleton Limbs in general  Consist of a single proximal long bone with 2 distal long bones, then hands/feet  Attach at either pectoral girdle (clavicle & scapula) or pelvic girdle (hip bones – ilium, ischium & pubis) Upper Limbs Humerus Radius (lateral) Ulna (medial) Carpals (8) Metacarpals (5) Phalanges (3 per finger; 2 for thumb)

Lower Limbs Femur Tibia (medial) Fibula (lateral) Tarsals (7) Metatarsals (5) Phalanges (3 per toe; 2 for great toe)

TeachPE.com

Histology Basic Structure Comprises cells + 2 extracellular components Cells:  Osteoblasts - bone-forming cells, build the ECM  Osteocytes - in the lacunae of mature cells. Larger & important for communication  Osteoclasts - break down ECM Extracellular components 1  Organic ( /3) – collagen & ground substance (proteoglycans) – function is to resist tension 2  Inorganic ( /3) – mineral salts (hydroxyapatite made of Ca & PO4) – function is to resist compression & provide rigidity

Types of Bone Cancellous Bone (aka trabecular or spongy bone)  Composed of trabeculae or struts of lamellar bone, with the interspersed cavities filled by marrow (which contains blood vessels)  Osteocytes are housed in lacunae on surfaces of trabeculae  Osteoblasts & osteoclasts are around the margins for constant remodelling  Nutrients diffuse through ECM from marrow to cells  Function: resist stress/forces from many directions

th

Patton & Thibodeau 7 edn

Skeletal System (Lectures 6-8) Compact Bone (aka cortical bone) 





Main unit is osteon – comprises a central canal (Haversian canal) which contains blood vessels, surrounded by concentric lamellae – sheets of ECM. Osteocytes sit in lacunae & have processes called canaliculi to communicate with blood vessels Function: Resist stress through longitudinal axis – able to receive nutrition without compromising density

Growth 

Primary centre of ossification = diaphysis (shaft)

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Secondary centre = epiphysis (growth plate), formed of cartilage

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Bones grow in length via the epiphysis: Chondrocytes proliferate & secrete ECM → Old chondrocytes die → Blood vessels fill spaces left behind → Ossification as fibroblasts differentiate to osteoblasts and Ca & PO4 are added to the ECM

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Bones grow in width via proliferation of osteoblasts in periosteum: this is regulated by osteoclasts which also mould the shape & form the medullary cavity

th

Patton & Thibodeau 7 edn

Pathology Osteoporosis    

Caused by abnormal homeostasis/turnover ( ↑osteoclast vs ↓osteoblast activity) Results in thinner compact bone & more porous cancellous bone Causes include ageing, lack of exercise, nutritional factors & low peak bone mass Consequences include ↑fracture risk & compression fractures of vertebrae causing pain

Skeletal System (Lectures 6-8)

Fractures Type of # Closed/simple

Definition

Open/compound

A wound through the adjacent or overlying soft tissues communicates with the site of the break

Greenstick

An incomplete fracture in which the bone is bent but broken only on the outer arc of the bend, common in children

Visual representation

Skin in-tact

Images from medical-dictionary.com

Healing  Stage 1: Formation of haematoma, clearance of foreign material by immune system (phagocytes)  Stage 2: Formation of soft callus by chondroblasts – hence ‘fibrocartilaginous callous’  Stage 3: Formation of bony callus by osteoblasts  Stage 4: Remodelling – re-orientation of bony framework (failure to ‘set’ bone properly results in ‘pseudoarthrosis’ where bone heals in an odd shape

Joints and Supporting Tissues (Lectures 9-11)

Cartilage Basic Structure  

Consists of cells (chondrocytes, which live in lacunae) & ECM (organic component only – collagen fibres in a ground substance) Avascular – nutrients diffuse through matrix by joint loading

Types of Cartilage Hyaline cartilage     

Collagen fibres barely visible High water content in matrix Moulds to bone surfaces where they articulate Function is to resist compression Provides smooth, frictionless surface

Fibrocartilage    

Collagen fibres form bundles throughout matrix Lower water content in matrix Orientation of fibres aligns with stress Function is also to resist compression, plus resisting excessive tension

Menisci These are crescent-shaped structures made of fibrocartilage which provide structural integrity of a joint as it undergoes tension & torsion – they are present in several joints but most notably in the knee.

Ligaments & Tendons

Insertion onto bone Not important to know in detail – key points are:  Tissue between tendon/ligament and bone is called the enthesis  It is mainly composed of fibrocartilage, which becomes calcified nearer the bone

Joints and Supporting Tissues (Lectures 9-11)

Types of Joint Mobility vs Stability Main connective tissue Examples

Fibrous

Fibrocartilaginous

Synovial

Little or no mobility, very stable DFCT

Some mobility, moderately stable Fibrocartilage

High mobility, less stable

Cranial sutures, distal tibiofibular joint

Rib cartilages, intervertebral discs, pubic symphysis

Most limb joints

Varies

Synovial joint structure Relevance of bony congruence/shapes of bone ends Synovial joints have space/potential space between bone ends – the shapes of these bone ends (along with their articular tissues and ligaments) thus determine the movements possible at the joint.

Cartilage Articular cartilage covers bone ends where they articulate and anywhere they might move each other. Underlying the cartilage is subchondral bone – this is smooth.

Adapted from Netter’s Atlas of Human Anatomy 5th edn

Ligaments 



Capsular ligaments: hold bones together but with potential space in between (joint cavity). Tight and thick at ends where more support is required; looser on sides for movement Intracapsular ligaments: hold bones together to restrict their movement

Synovial membrane Aka synovium, this lines the inner surface of the joint capsule and secretes synovial fluid into the joint cavity for lubrication.

Menisci These deepen articulation making joint more stable

Bursae These are fibrous sacs filled with synovial fluid, providing cushioning where tendons pass over muscles- sometimes form sheathes around tendons. The knee has 13 bursa – called ‘bursitis’ when these become inflamed

The Knee as an example Adapted from newhealthadvisor.com

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Capsular ligaments – collateral ligaments: medial restricts abduction; lateral restricts adduction Intracapsular ligaments – cruciate ligaments, arise from tibia and insert onto femur (named for where they arise on tibia, ie anterior cruciate ligament arises from anterior tibia) - ACL restricts posterior displacement of femur (hyperextension) - PCL restricts anterior displacement of femur

Joints and Supporting Tiss...