Flashcards for Summaries
1
Q
What is Homeostasis?
A
A dynamic process where we adapt and adjust to maintain equilibrium in the bodies internal environment
2
Q
What are the components of a feedback system? (5)
A
Set point, Sensor, Control centre, effector and the regulated variable
3
Q
What does a large gain imply?
A
There is a more sensitive regulation to better maintain normal conditions
4
Q
What is ‘gain’ of regulated variable and what is it’s equation?
A
The gain of a variable is the precision by which a control system can prevent deviation from homeostasis.
Gain =
Amount of correction needed/Amount of abnormality after correction
5
Q
What is a reflex response?
A
Knowledge from an integrating centre and a circuitry that connects the
receptor and the effector.
6
Q
What is a local response?
A
Local homeostatic controls are highly significant because they allow individual parts of the body to self regulate their responses to certain conditions.
7
Q
What are the 5 intracellular communications?
A
1) Hormone secreting gland > hormone > blood vessel >target cell
2) Nerve cell > Nerve impulse > Neurotransmitter > neuron/effector cell
3) Nerve cell > Nerve impulse > Hormone > Blood vessel > Target cell
4) Local cell > paracrine agent > target cell
5) Local cell > Autocrine agent > back to local cell
8
Q
What are the bodies two main systems?
A
Endocrine and Nervous systems
9
Q
What are Hormones?
A
Hormones are chemical messengers carried by the blood to target cells to cause a response
10
Q
What are the 4 main functions of Hormones?
A
1) Hormones help regulate chemicals, metabolism, immune system, cardiac muscle fibres and glandular secretion
2) Control growth and development
3) Regulate operation of reproductive system
4) Help establish circadian rhythm
11
Q
What are the 3 main structures of Hormones?
A
Amines, Peptides/Proteins and Steroids
12
Q
How do Peptide hormones travel, compared to Amine and Steroids?
A
Peptides are water soluble therefore circulate dissolved in plasma whereas the others circulate bound to proteins
13
Q
What is mainly responsible for removing hormones ?
A
The Liver and Kidney
14
Q
What affects responsiveness of target cells to Hormones?
A
1) Hormones blood conc
2) Amount of target cells and/or receptors
3) Effects of other hormones
15
Q
What 6 things does the anterior pituitary gland secrete?
A
Growth Hormone (GH)
Thyroid stimulation hormone (TSH)
Adrenocorticotropic (ACTH)
Prolactin
Follicle Stimulating hormone (FSH)
Luteinizing hormone (LH)
16
Q
What does the posterior pituitary gland secretes ?
A
Oxytocin
Vasopressin
17
Q
Thyroid hormones function?
A
protein synthesis in follicular epithelial cells
increases DNA replication and cell division
produces thyroxine (called T4) and triiodothyronine (T3-major thyroid hormone)
18
Q
What are the physiological functions of cortisol? (Non stressful) (3)
A
Maintains a normal BP by affecting the responsiveness of smooth muscle cells to epinephrine and norepinephrine
Maintain enzymes conc required for metabolic homeostasis, preventing decreasing plasma glucose levels
Has anti-inflammatory and anti-immune functions
19
Q
What are the physiological functions of cortisol? (Stressful)
A
- Effects on metabolism
- Enhanced vascular reactivity, improving cardiovascular performance
- Unidentified protective effects against the damaging influences of stress
- Inhibition of inflammation and specific immune responses Inhibition of nonessential functions (e.g reproduction & growth)
20
Q
What is anterior pituitary gland secretion controlled by and what is the typical sequence of it?
A
It is controlled by Hypophysiotropic hormones from the hypothalamus via portal vessels
Hypophysiotropic hormones controls the secretion of APG hormone which then controls secretion of a 3rd hormone from an endocrine gland
21
Q
What is the hormone process?
A
Hormones are synthesized in the hypothalamus
axons pass down the infundibulum
terminate in the posterior pituitary and release hormones
22
Q
Sequence of hormone release?
A
Hypophysiotropic
hormone (hormone 1 from the hypothalamus)
controls the secretion of an anterior pituitary
gland hormone (hormone 2), which controls the secretion of a hormone by a third endocrine gland (hormone 3)
23
Q
Function of Growth hormone?
A
Major stimulus of postnatal growth.
It stimulates the release of IGF-1 to stimulate cell
division.
Stimulates protein synthesis.
24
Q
Where is testosterone found in males and females?
A
Males - Testes
Females - Ovaries, adrenal cortex and androgens
25
Function of testosterone?
muscle growth & development of male sex characteristics
26
Where is Estrogen and Progesterone found in males and females?
Females - Ovaries
Males - small tissue in the liver, kidney, bone, skin, brain, breasts and adrenal glands
27
Functions of Oestrogen and Progesterone?
Development of female sex characteristics
Regulates menstrual cycle and adipose tissue growth
Promotes endothelia function
28
What 4 things are muscles composed of?
- Muscle fibres (cells)
- Vascular cells
- Fibroblasts
- Satellite cells
29
What is the process of a cross bridge mechanism?
1. Calcium ions released into muscle sarcoplasm
2. Binding to troponin causing tropomyosin to change and move away from the binding site
3. Myosin head extend and binds forming a cross bridge
4. ATP binds to the head detaching
5. ATP is then hydrolysed and the energy is used to re-attach the head in another binding site
30
What are the 3 energy systems? And how do they arise?
Creative Phosphate - Provides energy fast forming ATP from ADP + P, only lasts 1-2 secs
Glycolysis - Energy from glucose in the absence of o2
Oxidative Phosphorylation - Energy from glucose or fat with o2 preset
31
What is Excitation-Contraction Coupling for relaxed muscle?
There are low calcium ions, therefore cross bridges cannot form as tropomyosin is covering the binding site
32
Sliding filament process?
1. Calcium ions released into muscle sarcoplasm
2. Binding to troponin causing tropomyosin to change and move away from the binding site
3. Myosin head extend and binds forming a cross bridge
4. ATP binds to the head detaching
5. ATP is then hydrolysed and the energy is used to re-attach the head in another binding site
33
Neuromuscular junction process?
1. Action potential arrives opening Ca2+ channels
2. Fuses vesicles with membrane releasing acetylcholine into synaptic cleft
3. Ach diffuses across binding to specific receptors on MEP
4. This opens ion channels allowing sodium ions in, resulting in depolarisation
5. Once threshold is reached another action potential occurs
6. Continues doing power strokes until muscle stimulation stops
34
Excitation-Contraction Coupling for an active muscle?
High Calcium, Calcium binds to troponin causing tropomyosin to move away from the binding site allowing actin to bind
35
What are the 3 muscle fibre types?
Type IIx
Type IIa
Type I
36
What is a motor unit?
A motor neuron and all the fibres it stimulates
37
What are the 5 mechanisms involved in muscle fatigue?
1. Conduction failure
2. Lactic acid build up
3. Inhibition of Cross-bridge cycling
4. Fuel substrates
5. Central command fatigue
38
What is Hypertrophy?
Increase in muscle fibre size due to addition of contractile proteins, protein synthesis > breakdown
39
What is hyperplasia?
Increase number of muscle fibres
40
How do neural/structural adaptations lead to increased strength?
Increase motor unit recruitment, firing rate and increase muscle mass
41
What does hypertrophy depend on?(3)
Initial strength
Duration of training
Training technique
42
Resistance training components?(9)
1- Time-under-tension
2- Intensity
3- Sets
4- Repetitions
(3-4 = volume)
5- Velocity
6- Exercise order
7- Recovery between sets
8- Frequency
9- Exercise type
43
What are the 4 main functions of the CV system?
1. Transport o2, nutrients, and metabolites to tissue
2. Remove waste
3. Distribute and secrete hormones
4. Involvement in Homeostatic mechanisms
44
Equation for resistance?
1/r^4 = Poiseuille's law
45
Equation for flow?
Pressure difference / Resistance = Darcy's law
46
How is flow created and what is this called?
Pressure difference between two points = Driving pressure
47
What changes resistance and how is flow affected?
The radius of the vessel, the narrower = higher flow as there is more pressure
48
What are the chambers in the Heart?
Right/Left Atrium
Right/Left ventricle
49
What are the valves of the heart?
Tricuspid valve
Mitral valve
Pulmonary valve
Aortic valve
Coronary arteries
50
What are the main blood vessels around the heart?
Superior/Inferior Vena Cava
Pulmonary artery
Pulmonary vein
Aorta
51
Blood passage through the heart?
Vena cava
Right atrium
Tricuspid valve
Right ventricle
Pulmonary valve
Pulmonary arteries
Pulmonary veins
Left atrium
Mitral valve
Left ventricle
Aortic valve
Aorta
52
Signal propagation at the heart?
Impulse generated at SA node, Atrium contract
Then to the AV node, pauses
Continues down to the bundle of HIS and divided down the bundle branches, stimulating the ventricles
Muscle fibres depolarise via the purkinje fibres
53
What is the excitation-contraction process in cardiac muscles?
1. Sodium enters the intracellular fluid
2. Calcium also enters via the L type Ca2+ channel
3. This triggers more Ca2+ to enter from the Sarcoplasmic reticulum through Ryanodine receptor channels
4. Thin filament are activatied
5. Cross bridge cycling, force generation, and sliding filament theory
7. Ca2+ ATPase pump - ADP generates ATP
8. Potassium leaves and enters T-tubule lumen
54
What is contractile force dependent on?
Contraction of cardiac muscle cells
is dependent on extracellular Ca2+
55
How is tetanic contractions prevented in cardiac muscles?
The refractory period of cardiac muscle is dramatically longer than that of skeletal muscle, therefore the sodium channels are closed so another action potential cannot occur.
56
What type of cell is the SA node and why?
Pacemaker cells as they can generate their own action potential due to an unstable membrane which is continuously drifting towards threshold
57
How is HR decreased?
Parasympathetic ((PS)) nervous system,
Vagus nerves secrete acetylcholine whichbinds to receptros on the SA node
Membrane is hyperpolarised causing slower depolirisation
Causing a slower rhythm/less impulses
= HR decreases
58
How is HR increased?
Sympathetic (S) Nervous system,
S fibres - Cardiac nerves release norepinephrine, alongside circulating epinephrine
= SA node stimulated
= membrane to become more polarised
= depolarising drift is faster
= faster rhythm
= Increase HR
59
Parts of ECG and what is occurring at each part?
P wave - Atrial activity
QRS - Ventricle activity
ST - Ventricle contraction but no electricity
T - Resetting for next contraction
60
Pressure difference in valves?
Tri (between ra-rv) -
Open when ra pressure > rv pressure
Pulmonary (between rv and pa) - Open when rv pressure > pa pressure
Mitral (between La-Lv) -
Open when la pressure > lv pressure
Aortic (between lv and aorta) - open when lv pressure > aorta
61
Anatomy of Arteries?Functions? (5)
Adventitia: Provides structural strength
Elastin: Gives vessels mechanical strength and their elastic properties
Smooth muscle: Supplies the vessels with contractile power and regulates the diameter of the lumen.
Endothelium: filtering interface between the blood, It also secretes various vasoactive products.
Pre-capillary sphinchter: Controls blood flow to specific capillary beds selectively.
62
Why is it important to monitor arterial pressure/diameter?
They are responsible for altering levels of blood flow to distribute blood around the body to where it is needed.
63
What is Active Hyperami?
Increase in blood flow according to needs of a certain tissue
64
What is flow autoregulation?
Maintenance of blood flow rather than changing it.
Eg when the driving pressure drops the vessels dilate, and when it increases the vessels constrict.
65
Capillary adaptation?
Large SA
Thin = quick diffusion
Spread across the whole body
Slow blood flow to allow time for diffusion
66
Fluid balance at the capillaries?
Filtration (movement from the capillaries to the interstitial fluid) takes place when hydrostatic pressure exceeds colloid
osmotic pressure.
Absorption (movement from the interstitial fluid to the capillaries) takes place when colloid osmotic pressure exceeds
hydrostatic pressure.
67
How do veins differ from arteries?(8)
Larger
Have valves
Less elastic
Thinner
Less smooth muscle
Larger volume
Closer to surface
More distensible
68
Why are veins blood reservoirs?
Contain more than 60% of blood volume with minimal pressure (10 mmHg)
They're affected by hydrostatic pressure which opposes blood flow
Cardiac output and displacement of blood from the veins to the heart are related via the Frank-Starling mechanism
69
What are two vein pumps?
Skeletal - Compression of muscles emptying the blood to the heart
Respiratory - Thoracic cavity pressure increases compressing the veins
70
Function of the lymphatic system?
Lymph vessels collect filtered fluid from the interstitial space and return it to the circulating blood volume.
Lymph composition is similar to plasma but with
lower protein content
71
What is Oedema?
Accumulation of excess fluid in the interstitial spaces as a result of a failed lymphatic system.
72
What is cardiac output?
Volume of blood pumped out of the heart every minute
73
Equation for Cardiac Output?
Heart rate x Stroke volume
74
What regulates SV?
1) Force at which cells contract which is regulated by
- length tension properties of cardiac muscle cells
- hormonal influence on contractility
2) Arterial pressure against which they have to eject blood
75
Starling’s Law of the Heart?
End-diastolic volume can be increased by greater venous return which causes greater stroke volume due to greater stretch on cardiac muscle fibres = increase force of contraction
76
What increases contractility of the cardiac muscles ?
Sympathetic nerve activity (norepinephrine) and circulating epinephrine increase the force of contraction, or contractility of cardiac muscles
77
Where is BP highest/lowest?
Highest closer to the heart, declines as it moves away
78
Why are elastic properties of artery walls important?
They ensure bloods keeps moving even if the heart is in diastole, it also does not exert pressure on the blood.
79
Methods of measuring BP?(6)
- Direct cannulation, 18th century
- Direct cannulation 21st century
- Cuff and stethoscope
- Automated arm cuff monitor
- Automated wrist cuff monitor
- Beat to beat blood pressure monitor
80
What is BP measurement dependant on?
Sounds produced by arteries as they open and close when occluded by a cuff
81
Factors affecting Blood pressure?
Age - loss of elasticity
Higher in foot than head - due to hydrostatic pressure
Gender - Women have lower on average
82
Renal system functions? (5)
1. Regulation of water, inorganic ion balance, acid balance
2. Removes metabolic waste from blood eg urea, creatinine
3. Removes foreign chemicals
4. Gluconeogenesis
5. Production of hormones/enzymes eg EPO, Renin
83
Structure of the Kidney?
Renal Pelvis
Ureter
Renal cortex and medulla
Nephron
84
Structure of Nephron?
Renal corpuscle which contains glomerulus and a Renal tubule which forms a cup around the glomerulus called the Bowman's Capsule
85
What is the tubule of the nephron divided into?
Extends from the Bowman's capsule and sub divides into proximal and distal convoluted tubule, loop of henle and collecting duct.
86
What happens at the collecting duct?
Multiple tubules join and and empty into the renal pelvis from which urine flows through the ureters to the bladder.
87
3 Main renal processes?
Glomerular filtration
Tubular secretion
Tubular reabsorption
88
Basic process of glomerular filtration?
Blood enters the glomerulus through the afferent arteriole and leaves through the efferent arteriole. High blood pressure in the glomerular capillaries forces fluid, electrolytes, small molecules, and waste products (except for larger molecules like blood cells and proteins) out of the blood and into the Bowman's capsule.
89
What is Tubular secretion?
Substances such as hydrogen ion, potassium, drugs, organic anions and more waste that was not filtered properly move
from the peritubular capillaries into the tubular lumen, via diffusion/active transport
90
What are the 4 main functions of Tubular secretion?
1. Disposing of drugs and drugs metabolites
2. Eliminating substances or end products that have been reabsorbed by passive processes eg urea
3. Removing excess K+
4. Controlling blood pH
91
What is Renal clearance ?
The amount of a substance filtered per minute, divided
by its plasma concentration
92
Equation for Renal Clearance?
Mass of substance excreted per unit / plasma concentration of substance
or
U x V / P (U= Conc of substance in urine , V = flow rate of urine, P + conc of substance in plasma)
93
What is GFR and the factors effecting it?
Amount of blood filtered by glomeruli each minute
1. Capillary permeability
2. Surface area - size of capillary bed
3. Hydrostatic pressure driving fluid out of capillaries
4. Osmotic forces within the capillaries which oppose exit
94
How is GFR measured experimentally? and estimated clinically?
Insulin clearance
Creatinine clearance
95
Where sodium and Water lost/gained?
Na+
Lost - Sweat
Gain - Ingestion
H2O
Lost - Urine, gastrointestinal tract, evaporation from skin
Gain - Ingestion and metabolism
96
Process of Sodium reabsoprtion?
1. Sodium/Potassium pump allows active transport of Sodium out of cells into Interstitial fluid
2. Intracellular sodium is low creating a conc gradient
3. Co-transport/ diffusion back across membrane
97
Process of Water Reabsorption?
1. Water filtered from blood into the glomerulus
2. Proximal convoluted tubule absorbs around 70%, and water moves back into the bloodstream down conc gradient.
3. Water is rebasorped in descending limb due to high solute conc, only the descending limb is permeable to water
4. Water is then regulated in the Distal convoluted tubule and collecing duct dependent on the bodies needs, water moves via aquaporins into the blood stream, and the rest is removed via urine.
98
Major function and controlling factor of Cortical and medullary collecting ducts?
Major Function - Fine tuning of water reabsorption, reabsorption of urea
Controlling factor - Vasopressin increases passive reabsorption of water
99
Major function and controlling factor of Distal tubule and cortical collecting ducts?
Major Function - Fine tuning of the reabsorption/secretion of remaining solute
Controlling factor - Aldosterone = stimulates Na= reabsorption and K+ secretion, Parathyroid hormones stimulates calcium ion reabsorption
100
Major function and controlling factor of Ascending limb ?
Major Function - Reabsorption of NaCl
Controlling factor - Passive water reabsorption, Active transport
101
Major function and controlling factor of Bowman's capsule/Glomerulus ?
Major Function - Forms ultrafiltrate of plasma
Controlling factor - Starling forces
102
Major function and controlling factor of Proximal tubule?
Major Function - Bulk reabsorption of solutes and water secretion of solutes
Controlling factor - Active transport of solutes with passive water reabsorption, and parathyroid hormone
103
Major function and controlling factor of Loop of Henle?
Major Function - Establishes osmotic gradient, secretes urea
Controlling factor - Passive water reabsorption, Active transport
104
Major function and controlling factor of Descending limb ?
Major Function - Bulk water reabsorption
Controlling factor - Passive water reabsorption, Active transport
105
What happens when MAP is increasing/decreasing ?
When increasing Baroreceptors fire more,
Parasympathetic nerve activity to the heart increases, outflow to the heart and vasculature increases
When decreasing it is the opposite - explain
106
Mean arterial pressure (MAP) equation?
Cardiac output x Total peripheral resistance.
107
What is the response difference with the CV system and Kidneys ?
CV responses are in seconds compared to hours.
108
What occurs at the onset of exercise?
Central command triggers an initial rapid rise in ventilation and Cardiac Output
Mechanoreceptors in the muscles providing further afferent feedback, both being fine tuned by chemoreceptors, and the CO further by the starling effect
109
What happens when exercise begins?
Metaboreflex increases (metabolism)
Sympathetic nerve activity increases = increase in HR and dilation of arterioles to the working muscles, and constriction of veins to redistribute more blood to the muscles.
110
What is the effects of increased endurance training?
Increase CO and SV
Decrease resting HR
111
Why are humans known as homeotherms?
They maintain their body temperature within a narrow limit, even though the temperature fluctuates throughout the day
112
Why are humans endotherms?
They generate their own body heat and do not rely on the energy of sunlight etc.
113
What are the 4 modes of heat exchange?
Conduction, Convection, radiation and evaporation
114
What is thermoregulation?
Maintaining a constant core body temp
115
What are the physiological heat loss mechanisms?
Vasodilation
Sweating
116
What are the mechanisms for heat conservation/production?
Shivering
Vasoconstriction
Muscular activity
non-shivering thermogenesis
117
Effects of acclimatization?(6)
Sweat more and sooner
Increased blood flow to skin
Have more dilute sweat (conserve electrolytes)
Increased blood volume and stroke volume
Have a lower body core temperature, heart rate, glycogen use and, thus, fatigue
overall improvement of thermoregulation of body temp
