Physiology, Neurobiology, and Cell Signalling Flashcards

Flashcards based on lecture notes covering cardiovascular system, blood vessels, innervation, respiration, neurobiology, and muscle contraction.

What is the purpose of the Chordae tendineae?

They anchor the leaflets of the AV valves to the ventricular space, preventing backflow of blood and overstretching.

What is the role of the Sinoatrial node?

It is the pacemaker of the heart, initiating contraction from within the right atrium.

Why do myocytes have long refractory periods?

To prevent tetanus, which would stop blood flow.

What happens during diastole compared to systole?

Diastole is twice as long as systole.

What is the role of the AV node?

The AV node delays the signal until the atria are empty of blood

Explain the concept of Starlings Law

Greater stretch of muscle fibres leads to a greater muscle contraction because the contractile proteins become more sensitive to calcium.

What are the three tunics of blood vessels?

Tunica intima, tunica media, and tunica adventitia.

What is the role of elastic arteries?

They smooth the pulsatile flow of high-pressure blood by storing energy in systole and releasing it in diastole.

What is the WIndkessel effect?

Arteries stretch as blood pumps in and recoil in diastole to maintain blood flow

What is Poiseuille's Law?

A small change in radius has a big change in resistance

What do Precapillary sphincters do?

Control flow of blood into capillaries, directed by nerve and hormone signals

What is oncotic pressure?

Constant pressure in the capillary due to large molecules being retained in circulation, maintains equilibrium between plasma and interstitial fluid.

What is the Starling hypothesis?

Filtration pressure = hydrostatic pressure - oncotic pressure. Filtration and reabsorption depend on the difference between hydrostatic and oncotic pressure.

How is venous return maintained?

Low atrial pressure during diastole, muscle pumps, and respiratory pumps.

What are the sympathetic effects on the heart

Sympathetic effect on the heart: increases heart rate and conduction through noradrenaline

What are the Parasympathetic effects on the heart

Parasympathetic effect on the heart: decreases heart rate and conduction through acetylcholine

What is Chronotropic?

affects heart rate. Alters pacemaker potentials, changing conduction of Na+ and K+ channels and their influx to alter heart rate.

What is Dromotropic?

affects the conduction of electrical impulses through the heart

What is Inotrophic?

affects the contraction force of cardiac muscle

What is the formula for Cardiac output?

Cardiac output = stroke volume x heart rate

How is MAP calculated?

Mean arterial blood pressure (MAP) = 2/3 diastole x 1/3 systole = cardiac output x total peripheral resistance.

What is the role of baroreceptors?

Detect pressure changes, feed back to vasomotor centres, which stimulate the branches of the ANS to make necessary changes (alters cardiac output and total peripheral resistance, increasing heart rate and constriction of vessels)

What is the function of ANP?

Cause Na+ to be released in urine so less water is retained and extracellular fluid decreases (opposes angiotensin 2)

What happens during Atrial stretch receptor activation?

Send a signal to the hypothalamus to decrease ADH secretion, reduces extracellular fluid, and protects other chambers from overfilling

What are the roles of Anti-diuretic hormone (ADH)?

Secretion decreased upon atrial stretch receptor activation. Causes sodium retention hence water retention, increasing extracellular fluid

How does Angiotensin 2 work in the body?

Powerful vasoconstrictor, stimulates thirst, and water retention in blood vessels

How is blood volume controlled?

Chemicals involved in blood volume control are Atrial natriuretic peptide (ANP), Anti-diuretic hormone (ADH), and Angiotensin 2.

What happens to vessels in pulmonary circulation?

Pulmonary vessels have thin walls, high compliance, and lower pressure than systemic circulation, preventing fluid buildup in the lungs.

How do low oxygen levels affect vessel dilation?

Low O = vasoconstriction, perfusion is matched to ventilation to move blood away from poorly ventilated, damaged areas

What is the haemorrhage reflex?

Maintains blood pressure and cardiac output and restores circulating fluid volume

How does the body correct the increase in blood pressure?

The hydrostatic pressure falls, meaning interstitial fluid is reabsorbed at the capillary bed to restore blood volume, compromising its viscosity

List the steps in treating a haemorrhage

Prevent bleeding, provide fluids (blood or saline with colloid), and monitor filling pressure with a catheter.

How is blood supply redistributed to skeletal muscle during exercise?

Vasoconstrict peripheral tissue while vasodilating muscle blood vessels.

How deos Adrenaline work on skeletal muscles?

Normally a vasoconstrictor, but acts as a vasodilator at skeletal muscle beta receptors (floods muscle with blood)

Why does Starlings law not apply in exercise?

At high filling pressure, stroke volume no longer increases in proportion, and very high filling pressure can cause oedema in the lung.

How does the heart protect itself from overfilling during exercise?

Reducing diastole, achieved by increasing heart rate which reduces filling time.

What is the function of Cutaneous vasodilation?

Part of thermoregulation to reduce total peripheral resistance, though it will divert blood from muscles and is abandoned if central venous pressure falls too low.

How is blood delivered to the myocardium in exercise?

In diastole, blood flows to the myocardium (more needed in exercise). Myoglobin makes heart very good at extracting oxygen

What is Angina?

1st sign of coronary artery disease in exercise, blood supply becomes insuffient

What is the function of respiration?

Exchange of oxygen and carbon dioxide between an organism and external environment

Where is reflexive breathing controlled?

In the medulla (in brainstem)

What is the pFRG's main function?

The parafacial respiratory group (expiratory oscillator) control expiration

How does the BotC ensure inspiration and expiration are separate?

full of inhibitory neurons to ensure inspiration and expiration are separate

Where does Voluntary control of breathing originate?

In the motor cortex

What is the function of the Red nucleus?

Coordinates breathing with other things, eg, talking.

Where do Corticospinal pathway projections take place when controlling breathing?

Emotional control of breathing is achieved through the corticospinal pathway projections, not from the pons

Are main controller of breathing is __

CO2 levels

How does Hypoxia impact the body?

Hypoxia modulates breathing less potently than hypercapnia, as the oxygen levels must fall by half before breathing is stimulated

What do Slowly adapting pulmonary stretch receptors monitor?

The inflation of the lung, signal lung volume to brain in response to stretch, They can inhibit inspiration and length expiration (Hering Breuer reflex), Regulate respiratory rhythm

Where are the receptors for cough reflex found?

Epithelial cells of upper airway

How does Post-Inspiration work?

Recruitment of post-inspiratory muscles, slow diaphragm recoil and coordinate orofacial movement. Prevents the diaphragm slamming up and hitting the lungs

What kind of compartment is the thorax?

The thorax is a closed compartment that is separated from the abdomen by the diaphragm.

What is the function of the Pleural cavity?

maintains a partial vacuum which helps keep the lungs expanded

Describe Boyle's law

Predicts that if the volume inside the lungs is changed, the pressure inside the lungs will also change

What is Dead space?

Traps CO2 rich air, and Prevents pH differences between alveoli and body cells (keeps pH stable)

What does The Bohr effect trigger

more O2 is unloaded where CO2 levels are high

What happens in Carbon monoxide poisoning?

oxygen unable to bind to haemoglobin, CO2 dissolved in plasma doesn’t change, no reflex increase in breathing due to no effect on dissolved O2 and CO2, Haemoglobin has a high affinity for CO

Where does Neuron doctrine start?

neuron doctrine thatEarly ideas about neurons, neurons are the structural and functional units of the nervous system

Name two CNS glial substaces.

Supports the CNS, forming its myelin sheath and Microglia that find damage, phagocytose debris and launch an immune response

Why are Ganglia needed in the central nervous system?

a collection of neurons that allows for easier conduction

How is Cerebrospinal fluid made

Made by the ventricular system, protects the brain and enables its buoyancy, and has less proteins and glucose than plasma

List twi Resting membrane potential requirements

Ion concentration gradients and membrane permeability to ions

How is resting potential calculated?

The Nernst equation calculates the ideal resting potential

Are VG Na+ activated by depolarisation?

VG Na+ channels are activated upon depolarisation (synaptic transmission, generator potential etc.) and Na+ moves into the neuron down an electrochemical gradient

True or false: Electrical synapses: plastic and bidirectional

True: Electrical synapses: plastic and bidirectional, 2 hemi channels align to form an ion-permeable channel between 2 cells (gap junction)

What 5 characterictics are considered in neurotransmitters?

Synthesised in the neuron, Activity-dependent release from the terminals, Has the same effect of stimulation when applied in a lab setting, Inhibited by antagonists in a concentration-dependent manner, Removed from the cleft by specific mechanisms (uptake into glia, reuptake into neurons, diffusion, extracellular metabolism)

How do SNAP and SNARE proteins react in neurotransmitters releases?

SNAP and SNARE proteins dock the vesicle onto active zones of the presynaptic membrane

How does endocytosis affect chemical synapses?

the vesicle is recycled

What system recieves and interprets internal and external information?

Sensory system

What function is controlled by the integrating system?

integrates sensory information into the motor system and makes decisions. Stores previous inputs as memories

What does the Motor system motor neuron do?

motor neurons (found in ventral horn) and central motor areas

Is the Somatotopic map a corresponding of an area of the body to a specific point on the CNS?

True: Somatotopic map correspondence of an area of the body to a specific point on the CNS

Why is the corticospinal pathway important?

Essential for coordinating voluntary movement

How do Ach activate Nicotinic receptors?

Activates nicotinic receptors on muscle (ion channels which depolarise muscle fibres)

How does Acetylcholine cause muscle to recruit?

More motor units engaged enable a larger contraction. Recruited in size order due to threshold values

Where does calcium store in the body?

Stored in the SR, and Binds to troponin C (on tropomyosin) to move tropomyosin from the AM binding site

Where doe most tissue recieve a basal level of input?

From autonomic tone: most tissues receive a basal level of input

Describe Adrenal glands.

sympathetic preganglionic neuron from spinal cord enters the adrenal medulla

Is Multi-unit smooth muscle under fine control?

Multi-unit smooth muscle: one varicosity targets each muscle cell, fine control

What causes T tubules to create a triad?

T tubules create a triad with 2 SR membranes to allow ion exchange in muscle contraction