quiz 8 Flashcards
significance of maintaining bodily pH
- tons of bodily reactions driven by enzymes with specific optimal pH ranges
- pH varies in different areas of the body (even in different cell organelles) but all enzymes have narrow optimal pH
- overall body pH is 7.4, drop to even 6.8 would be huge
how does pH play a role in perms?
strong pH denatures proteins in hair
what receptors signal a change in breathing rate in the body?
- peripheral chemoreceptors (carotid bodies)
- central chemoreceptors (medulla in brain)
- stretch receptors in lungs
- emotions
differences between peripheral and central chemoreceptors
- peripheral chemoreceptors are carotid bodies, they sense O2 levels
- central chemoreceptors are located in medulla, they sense CO2 and pH levels
how does the heart contribute to human metabolism?
- heart is a pump; provides propulsion of blood through capillaries for nutrient/waste exchange
- metabolism increase can be sustained by increase in pump function (higher HR or stroke volume)
*higher oxygen demand for organisms requires greater separation of oxygenated/deoxygenated blood and higher blood pressure
two parts of the heart
we consider the heart to have 2 functional pumps for 2 circuits:
- low pressure pulmonary/lung circuit
- high pressure arterial/body circuit
open vs closed circulatory design
open systems: hemolymph (in insects) or other blood not enclosed in vessels, heart is a mixing chamber
closed system: everything enclosed in vessels/tubing, heart is a pump
how do open circulatory systems work in insects?
- dorsal heart tube along back contracts to move/mix blood
- hemolymph let in via small holes called otria
- contracts in both directions, blood squirts out excurrent openings on both ends
neuorogenic vs myogenic hearts
neurogenic hearts
- crustaceans, insects, annelids
- contraction under nervous control; no nerve = no heartbeat
myogenic hearts
- vertebrates, mollusks
- contraction initiated by heart cells
- nervous system can modify rate but isn’t required for beating
what triggers heart contractions in neurogenic hearts?
- regulated by peptide release from nerves
- on imaging, white areas around heart tubes are where peptides are released
different types of heart design
1-chamber (non-vertebrate): insects
2-chamber: fish; low pressure because blood travels far
3-chamber: amphibians; 2 atriums and 1 ventricle
3-chamber septated: reptiles; allows for less mixing within ventricle
4-chamber: birds and mammals; full septum
flow of blood in and out of the heart
pulmonary circuit:
vena cava - right atria - tricuspid valve - right ventricle - semilunar values - pulmonary artery - lungs
arterial circuit:
pulmonary veins - left atria - bicuspid/mitral valve - left ventricle - aorta
*values are key to one-way flow!
how is blood supplied to keep the heart functioning?
- coronary vessels penetrate heart from the surface
- blood supply to heart occurs between contractions
how is coronary blood flow blocked, and how is it fixed?
buildup of plaque in coronary arteries can threaten blood flow to heart
- bypass: blood vessels harvested to transport blood flow around problem area
- cardiac stents: mesh expanded via balloon; mesh pushes out against narrowing vessel
how do gap junctions work?
- each cardiac muscle cell has one connexon (hemichannel) which come together to form a gap junction
- each connexon has 6 subunits
- gap junctions allow passage of ATP, ions, signaling molecules, and electrical signaling for heart beat