Physiology

Question 1

Define homeostasis

Answer 1

“the maintenance of a relatively stable internal environment NOTWITHSTANDING swings and changes in external environment. Self-regulatory/self adjusting/reflexive”

Question 2

Why do we need homeostasis?

Answer 2

Create ideal environment for cells to function

Question 3

What are the 5 elements of a negative feeback regulation system?

Answer 3

1. What is being controlled
   
   2. How the stimulus is measured (sensor)
   3. Set point
   4. Comparator
      
      5. Motor output

Question 4

Explain some of the reasons homeostasis is dynamic

Answer 4

• Variations in populations
  
  • Can change with age
  • Circadian rhythm

Question 5

What are the 3 types of sensory receptors and what is the primary role of a sensory receptor

Answer 5

Primary role: turn physical stimulus into biological signal

1. stretch receptors
2. temperature receptors
3. chemoreceptors

Question 6

Explain the function of each sensory receptor

Answer 6

1. Stretch receptors
   ○ Baroreceptors
   § Detect stretch of vessel wall = change in pressure
   § Blood pressure regulation
   ○ Osmoreceptors
   § Detect stretch of cell membrane = change in cell volume
   § Involved in body fluid homeostasis
   
   2. Temperature receptors
      ○ Measure core body temperature
   3. Chemoreceptors
      Detect chemical changes in the body (blood gas, pH, potassium)

Question 7

What is the difference between baroreceptors and osmoreceptors?

Answer 7

○ Baroreceptors
§ Detect stretch of vessel wall = change in pressure
§ Blood pressure regulation
○ Osmoreceptors
§ Detect stretch of cell membrane = change in cell volume
Involved in body fluid homeostasis

Question 8

What are the types of efferent signals?

Answer 8

Neuronal (ANS)
Chemical
- endocrine
- chemokine

Question 9

What are the types of chemical signals used in homeostasis

Answer 9

endocrine and chemokine

Question 10

name the homeostatic effectors

Answer 10

○ Smooth muscle
§ Blood vessels
§ GI tract
○ Cardiac muscle
○ Glands
§ Endocrine
§ Paracrine
§ Adipose tissue, liver
○ Skeletal muscle (respiration, shivering)
Renal collecting ducts

Question 11

Explain the different thermoregulatory responses

Answer 11

○ Metabolism
§ Non-shivering thermogenesis
□ Sympathetic regulation
□ Endocrine
§ Shivering thermogenesis
□ Somatic regulation
□ Endocrine
○ Skin blood flow
§ Sympathetic
□ Vasoconstriction
□ Active vasodilation
○ Sweating
sympathetic

Question 12

Which types of muscle cells are striated?

Answer 12

Cardiac and Skeletal

Question 13

Which type of muscle is unstriated?

Answer 13

Smooth muscle

Question 14

What type of muscles are involuntary?

Answer 14

Cardiac and smooth muscles

Question 15

What type of muscle is voluntary?

Answer 15

Skeletal muscle

Question 16

Cardiac muscles cells are…

Answer 16

mono-nucleated
striated
branching
intercalated discs

Question 17

What two features help electronic signals pass between cardiac cells

Answer 17

intercalated discs and gap junctions

Question 18

Which chemical is essential in the communication signals of cardiac cells?

Answer 18

Calcium

Question 19

Where is the SA Node located

Answer 19

right atrium

Question 20

Do cells spontaneously depolarize in the nodes?

Answer 20

Yes

Question 21

At depolarization what do the cells do?

Answer 21

initiate muscle contraction

Question 22

Explain how cardiac muscles contract and relax

Answer 22

action potential enters from adjacent cells -> voltage gated calcium channel opens -> calcium enters cell and induces calcium release through ryanodine receptor channels ->calcium sparks to create signal -> calcium ions bind to troponin to initiate contraction -> calcium is pumped back into the sarcoplasmic reticulum for storage -> calcium is exchanged with sodium -> sodium gradient is maintained by the sodium potassium ATPase

Question 23

Where are the purkinjie fibres located?

Answer 23

ventricles (right and left)

Question 24

Does the AV node have fast or slow conduction?

Answer 24

slow

Question 25

What effect does the sympathetic nervous system have on the heart?

Answer 25

increased heart rate and increased force of contraction

Question 26

What effect does the parasympathetic nervous system have on the heart?

Answer 26

slows heart rate

Question 27

What anatomical features allow for sympathetic and parasympathetic innervation of the heart?

Answer 27

Sympathetic: sympathetic chains (along spinal column) Parasympathetic: Vagus nerve

Question 28

Rank the action potential time from fastest to slowest for: nerves, skeletal muscle and cardiac muscle

Answer 28

1. nerves 2. skeletal muscle 3. cardiac muscle

Question 29

What are the 5 phases of cardiac action potential?

Answer 29

Phase 0: rapid rising phase (depolarisation) Phase 1: Early repolarisation Phase 2: plateau phase Phase 3: Repolarisation phase Phase 4: restoration phase

Question 30

Which is faster action potential response? Ventricular cardic myocyte or atrial cardiac myocyte?

Answer 30

Ventricular cardiac myocyte

Question 31

What are the three different types of capillaries and what differentiates them?

Answer 31

1. Continous capillary = most common, edges of endothelial cells joined by tight junction 2. Fenestrated Capillary = gaos in the endothelial cell membrane. permeable to fluids and small solutes. found wherever filtration and reabsorption occues (Kidney etc.) 3. Sinusoid Cappilary = leaky capillaries with large fenestrations. found in liver, bone marrow, spleen, adrenal medulla

Question 32

What is pinocytosis?

Answer 32

transport vesiciles (small) across the cell