BIO209 - Midterm #1

What are 2 types of signals?

Chemical messages + electrical messages

What are 3 examples of chemical messages?

Ions, neurotransmitters, hormones

What is an example of an electrical message?

Ions involved in membrane potential changes (Na, K) causing action potential traveling through neuron (fast)

What is the signaling mechanism of the endocrine system?

Chemical, where the primary chemical signal is hormones

What are 2 signaling mechanisms of the nervous system?

Chemical/electrical, where the primary chemical signal is neurotransmitters

What are the distance & speed for signals in the endocrine system?

Long or short distance traveled, fast or slow response time (slowest compared to nervous, blood, lymph)

What are the distance & speed for signals in the nervous system?

Always short distance traveled, always fast response time

What are organ system connections for the nervous system?

Nervous to any other system

What are organ system connections for the endocrine system?

Endocrine to any other system

What is the environment targeted by the endocrine system?

Internal

What are 2 environments targeted by the nervous system?

Internal & external

What are 5 types of hormones?

Proteins, peptides, steroids, amines, glycoproteins

What is a hormone?

Chemical messager that travels through the body via the bloodstream to affect the activity of only its target cells, which have receptors for that particular hormone

How do hormones regulate physiological processes?

Binding to receptor initiates response of target cell

What are 3 hormones that regulate calcium homeostasis?

PTH (parathyroid hormone), vitamin D/calcitriol, calcitonin

What is the negative feedback loop for increased calcium level? (3)

Thyroid gland releases calcitonin, osteoclast activity is inhibited & calcium reabsorption in the kidneys decreases, blood calcium level decreases

What is the negative feedback loop for decreased calcium level? (3)

Parathyroid glands release PTH, osteoclasts release calcium from bone (demineralization) & calcium is reabsorbed from urine by kidneys & calcium absorption in the small intestine increases via vitamin D/calcitrol synthesis, blood calcium level increases

What are 5 signals in calcium homeostasis?

Calcium, calcitonin, PTH, osteoclast, osteoblast (any player involved in interactions leading to a physiological change)

What is transport in calcium homeostasis?

Thyroid/parathyroid glands to osseous tissue, renal tissue (kidneys), & digestive tissue (intestine)

Why does the endocrine system involve a slow response?

Signals are transported via circulating blood, which takes more time than direct communication between neurons & other cells

What are 2 components of blood?

Plasma (majority) + formed elements (minority)

What is plasma?

Fluid in which formed elements are suspended

What are 4 components of plasma?

Water (vast majority), plasma proteins (smallish %), other hormones/regulatory proteins (very small %), other solutes like ions (small %)

What are 2 ways hormones circulate in plasma?

Transport proteins or freely

What are 3 components of formed elements?

Red blood cells/erythrocytes (vast majority), white blood cells/leukocytes (very small %), platelets (very small %)

What is the buffy coat of formed elements?

White blood cells + platelets

What is the hematocrit of formed elements?

Red blood cells

What is the composition of blood when spun down in a centrifuge?

From top to bottom / lightest to heaviest: plasma, buffy coat, hematocrit

What is the normal composition of blood (top to bottom)?

Abundant plasma, very small % of buffy coat, abundant hematocrit

What is anemia?

Low hematocrit % (elevated plasma %)

What is polycythemia?

Elevated hematocrit (low plasma %)

What is the difference in blood composition between males & females?

Females have higher % of hematocrit on average

What are 3 components of the lymphatic system?

Lymph vessels, lymph nodes, organs such as thymus & spleen

What are 2 components of lymph?

Interstitial fluid + white blood cells

What is the speed of circulating blood & lymph?

Slow signal & slow response

Where do lymph vessels and blood vessels connect for exchange of solutes?

Capillary beds

What 2 ducts does the lymphatic system drain into the cardiovascular system through?

Thoracic duct on left + lymphatic duct on right drain into venous section of cardiovascular system

Why does the lymphatic system drain into veins?

Return “recycled blood plasma” in lymph (interstitial fluid + white blood cells) to blood, as lymph is rich in white blood cells for immune system response & protection of the body

What is the function of white blood cells?

Defence against foreign bodies

What are 2 developmental origins of white blood cells?

(1) Development of RBCs, WBCs, & platelets + (2) development of different lymphocytes

How do cells of immune response & blood arise?

Differentiation from multipotent hematopoietic stem cells (hemocytoblast) in the hematopoietic system of the bone marrow

What are platelets?

Cell fragments involved in blood clotting

What is transport by blood? (3)

Speed = slower (cycles of circulation), distance = long, organ system connections = involved in transport of signals/nutrients & messages for all systems

What is transport by lymph? (3)

Speed = slower (cycles of circulation), distance = long, organ system connections = drainage into cardiovascular system (venous system)

What are the 3 anatomical planes?

Sagittal, frontal, transverse

What is the sagittal plane?

The vertical plane that divides the body/organ vertically into right and left sides

What is the frontal/coronal plane?

The vertical plane that divides the body/organ into an anterior (front) portion and posterior (rear) portion

What is the transverse plane?

The horizontal plane that divides the body/organ into upper and lower portions, producing images referred to as “cross sections”

Where is the heart located? (3)

Above the diaphragm, posterior to the sternum, between the lungs in the thoracic cavity (medially but slightly to the left of the body)

What protects the heart?

Pericardium in the pericardial cavity

What are the 6 layers around/in the heart in order from superficial to deep?

Fibrous pericardium, parietal layer of serous pericardium, pericardial cavity, visceral layer of serous pericardium (epicardium), myocardium, endocardium

What are the 2 layers of the pericardium?

(Outer) fibrous pericardium + (inner) serous pericardium

What are the 2 layers of the serous pericardium?

Outer parietal serous layer + inner visceral serous layer (epicardium)

What is viscera?

Closer to the organ

What is the myocardium?

Muscle layer of the heart (cardiac muscle)

What is the endocardium?

Inner lining of the heart (lining outlining all the chambers)

What are 5 structures of the heart visible in the anterior view?

Apex, right atria, auricle of the left atria, right ventricle, large part of left ventricle

What are auricles?

Muscular pouches of atria

What are 4 blood vessels of the heart visible in the anterior view?

Superior & inferior vena cava, aorta, pulmonary arteries & veins, coronary arteries & veins

What are the superior & inferior vena cava?

Major vein bringing blood to the heart from the body

What is the aorta?

Major artery sending blood from the heart to the body

What are the 3 sections of the aorta?

Ascending aorta, aortic arch, descending aorta

What are the pulmonary arteries and veins?

Heart’s connections to the lungs

What are coronary arteries & veins?

Smaller vessels that provide blood supply to the hard-working cardiac muscle

What are 5 structures of the heart visible in the posterior view?

Apex, left atria, right atria, complete left ventricle, most of the right ventricle

What are 4 blood vessels of the heart visible in the posterior view?

Superior & inferior vena cava, aorta, pulmonary veins & arteries, coronary sinus

What is the coronary sinus?

Larger blood vessel that divides into coronary arteries & veins

What view allows internal heart structures to be visible?

Anterior view with some of the heart chambers in frontal sections

What are the 2 atrioventricular valves?

Tricuspid + bicuspid

What is the tricuspid valve?

Between right atrium & right ventricle

What structure attaches the tricuspid valve?

Chordae tendineae attaches tricuspid valve to inferior part of the right ventricle

What is the bicuspid/mitral valve?

Between left atrium & left ventricle

What are the 2 semilunar valves?

Aortic + pulmonary

What is the aortic valve?

In aorta connected with left ventricle to send blood towards the body

What is the pulmonary valve?

In pulmonary artery connected with right ventricle to send blood towards the lungs

How are the heart’s valves one-way?

Only allow blood from atria to ventricles or from ventricles to major blood vessels

What view allows for blood flow to be visible?

Transverse sections of the heart at the level between atria & ventricles

How does blood flow through both sides of the heart?

Blood flow through both sides of the heart happen simultaneously

What is blood flow through the heart on the right side? (3)

Body to right atrium via superior/inferior vena cava (blood low in oxygen), right atrium to right ventricle through tricuspid valve, right ventricle to lungs through pulmonary valve into pulmonary arteries (to be oxygenated)

What is blood flow through the heart on the left side? (3)

Lungs to left atrium via pulmonary veins (rich in oxygen), left atrium to left ventricle through bicuspid valve, left ventricle to body through aortic valve into aorta

How is cardiac muscle (myocardium) similar & different to skeletal muscle?

Both have striated appearance, but cardiac muscle is shorter & thinner

What is the result of structural differences between cardiac muscle & skeletal muscle?

Differences in electrical conductivity through the muscle

What are 3 differences of cardiac muscle from skeletal muscle?

Less T-tubules, rich in mitochondria, intercalated disks rich in desmosomes & gap junctions

Why does cardiac muscle have less T-tubules?

Less calcium stores, so supply is needed

Why is cardiac muscle rich in mitochondria?

Constant & hard work of muscle tissue

Why does cardiac muscle have intercalated disks rich in desmosomes & gap junctions?

Ensure that all sections of the muscle are well-connected with each other so that signals (ions) can move fast through different muscle sections, allowing cardiac contraction to be synchronous

What are desmosomes?

Cell junctions that anchor adjacent cells together structurally

What are gap junctions?

Specialized intercellular channels connecting cytoplasms that enable direct communication between neighbouring cells by allowing passage of ions & small molecules

Where does the electrical potential of the heart take place?

Conductive heart cells

What does electrical conduction in the heart stimulate?

Contraction in contractile heart cells

What are the 2 axes of a graph of an action potential through conductive heart cells?

Membrane potential (mV) vs. time (s)

What are 3 stages of an action potential through conductive heart cells?

Slow influx of sodium (prepotential, depolarization), rapid influx of calcium (depolarization), outflux of potassium (repolarization)

What are the membrane potential values for an action potential through conductive heart cells?

Resting membrane potential = -60 mV, threshold = -40 mV, +20 mV = peak of depolarization

What is the slow influx of sodium (Na) in an action potential through conductive heart cells?

Depolarizes membrane to a threshold of about -40 mV by increasing positive polarity of the membrane with influx of Na+

What is the rapid influx of calcium (Ca2+) in an action potential through conductive heart cells?

Rapidly depolarizes the membrane after the threshold is reached to about +20 mV

What is the outflux of potassium (K+) in an action potential through conductive heart cells?

Repolarizes membrane like in neuronal action potential

What causes the prepotential / spontaneous depolarization?

Slow influx of sodium ions until threshold is reached

What is the significance of the prepotential in an action potential through conductive heart cells?

Membrane reaching threshold to initiate the spontaneous depolarization & contraction of the cell

What is the resting potential in an action potential through conductive heart cells?

Lack of a longer resting potential, as prepotential immediately begins again after reaching polarized -60 mV

What does an action potential through contractile heart cells cause?

Cardiac muscle contraction