T1 L2 Introduction to Physiology

What is physiology

study of bodily function and systems by approaching the problem with measurements from physics and chemistry

branches of physiology

• systems physiology (cardiovascular, gastrointestinal, neuro etc)

• Animal physiology, human physiology, comparative physiology

• Applied physiology

• General physiology (e.g. cell physiology)

systems

= a set of things working together as parts of a mechanism or an interconnecting network; a complex whole

what does systems include

1. organised responses from challenge states towards a target- homeosasis

2. states e.g awake and asleep

3. complex

4. feedback mechanisms to maintain/achieve targets

physiological

normal function in the body of salts/electrocytes

non-physiological definitions

• pathological= abnormal function in the body

• events only possible in a laboratory -outside the body

• the body but not in relation to function- structure= anatomy

• normal function in the body of enzymes or antibodies

areas of medicine physiology is important in

• anaesthetics

• heart

• lungs

• kidney

what does physiology provide medicine with

• the basis of therapeutics (pharmacotherapy)

• the basis of anaesthetics and patient monitoring during surgery

pathophysiology

the mechanism by which a disease process causes the organ to fail

pathophysiology in type 1 diabetes mellitus

autoimmune destruction of beta cells —> insufficient insulin —> hyperglycaemia over time —> excess glucose in blood leads to inability of kidney to reabsorb glucose —> glucose in urine (sign) + excess fluid in urine —> less glucose = weight loss, hunger, thirst and fatigue (symptoms)

four types of functional tissue

• muscle: drives movement and shape changes e.g cardiac muscle etc

• nervous: communicates signals rapidly e.g brain

• epithelial: controls transport and fluids, forms barrier protection e.g GI lining

• connective: supports, protects and repairs structure and shape e.g RBC and bone

example of pressure

• expansion of lung: thoracic wall expanding causes negative pressure between pleural membranes

• pneumothorax: when lung doesn’t expand- air or gas in pleural cavity = no lung expansion

example of force

• heart and filling: starling’s law- as heart stretches, more it wants to contract harder- with greater force

• dilated cardiomyopathy: The ventricular cavity expands so much that blood doesn't stretch cells in diastole. Starling's law doesn't occur (stretch=more pump), so insufficient pumping force won't pump enough blood

ECG

Electrocardiogram

Example of electricity

ECG: measures the electrical field given off by all the heart muscle cells acting in synchrony- shows if having a heart attack (acute myocardial infarct- shown by ST elevation)

physiological signs

• heart/pulse rate

• blood pressure

• respiratory rate

• temperature

• oxygen saturation (97%)

• urine production

• confusion/ mental status

• pain (is a symptom not a sign)

excitable tissue vs non-excitable tissue

excitable: muscle and nervous tissue

non-excitable: epithelial and connective tissue

homeostasis

regulation of the cell’s or the body’s internal environment so that it tends to maintain a stable, constant condition

• negative and positive feedback

about 10¹⁴ cells

parts of a feedback loop

perturbation

a change that the body actually detects

negative feedback: general principles with examples

• stability or set point: thermoregulation

• opposing influences: insulin and glucagon

• sensors: baroreceptors (in aortic arch and carotid sinus)

positive feedback

positive feedback: general principles with examples

• amplification: lactation to suckling and vice versa

• all-or-none: parturition (giving birth)

• 2 stages consisting of extrinsic (initiate) and intrinsic (amplify): action potential and depolarisation