Anatomy and Physiology 2 Block 1 Exam

Lectures January 17 - February 7

Homeostasis

the maintenance of a relatively stable internal environment, physiological processes operate to maintain it

The hypothalamus receives information from:

frontal lobe, limbic system, circulating hormones and signals, neural signal from sensory pathways

The hypothalamus sends instructions to:

pituitary gland, brainstem centers, spinal cord centers

What controls homeostasis?

the nervous and endocrine systems work together to regulate the activity of the human body

Dual Innervation

most organs receive both sympathetic and parasympathetic control

What cell types are effector cells of the autonomic nervous system?

smooth muscle, cardiac muscle, gland cells

Smooth Muscle Effector Cells

autonomic nervous system can increase or decrease the amount of contraction in a bed of smooth muscle

Cardiac Muscle Effector Cells

autonomic nervous system can increase or decrease the amount of contraction in the wall of the heart and regulate the rate of contraction

Gland Cells Effector Cells

autonomic nervous system can increase or decrease the amount of secretion produced and released form a gland

General Neurochemistry of the Autonomic System

1. the CNS stimulates an action potential in the preganglionic neuron

2. the preganglionic neuron releases neurotransmitter at a synapse in the autonomic ganglion

3. the neurotransmitter binds to a receptor on the postganglionic neuron

4. binding of the transmitter stimulates an action potential in the postganglionic neuron

5. the postganglionic neuron releases neurotransmitter on the target cell

6. binding of the transmitter stimulates the target cell

Neurochemistry of the Parasympathetic System

both neurons release acetylcholine which binds to a cholinergic receptor

Types of Acetylcholine Receptors

nicotinic types cholinergic receptor - binds nicotine and acetylcholine, muscarinic type cholinergic receptor - binds muscarine and acetylcholine. They both bind acetylcholine but not each other

Neurochemistry of the Sympathetic System

the preganglionic neuron of releases acetylcholine that binds to a nicotinic type cholinergic receptor, the post ganglionic neuron releases norepinephrine onto its receptor

Adrenergic Receptor

binds both norepinephrine and epinephrine, but have slightly different afinities for the 2 chemical forms

2 Exceptions in the Sympathetic System

sweat glands and adrenal medulla release epinephrine into the blood and leaves bloodstream everywhere, binds to any cells with an adrenergic receptor

Subtypes of Adrenergic Receptors

Alpla 1: usually causes contraction of smooth muscle

Alpha 2: usually found on the varicosities of sympathetic postganlionic neurons; negative feedback to inhibit further norepinephrine release

Beta 1: found on cardiac muscle cells

Beta 2: usually cause relaxation of smooth muscle

Two Ways to Activate Targets of the Sympathetic System

1. activate individual preganglionic neurons through connections in the CNS. this allows for fine control of individual organs

2. activate release of epinephrine from adrenal Galen; this activates adrenergic receptors everywhere

The parasympathetic system operates only by:

the activation of individual preganlionic neurons by the CNS (isn’t activates all at once, unless with drugs or toxins)

Drug Agonist

if it binds to a receptor and stimulates the same response in the cell as binding the transmitter

Drug Antagonist

if it binds to a receptor but doesn’t create a response in the cell; it blocks the action of the transmitter by occupying the binding site

Pharmacology of the ANS Acetylcholine

any drugs that mimics acetylcholine activates both sympathetic and parasympathetic neurons, also activates skeletal muscle

Aceltyocholinerase Inhibitors: Parasympathetic Pathways Activation

any drug that block the breakdown of acetylcholine prolongs activation of ANS simulations

Nicotine: Parasympathetic Pathways Activation

a drug that turns on sympathetic and parasympathetic systems by activating the nicotinic acetylcholine rvcprot at all ganglionic synapses, also activates skeletal muscle

Mascarine: Parasympathetic Pathways Activation

a drug found in certain mushrooms, activates all muscarinic receptors at target organs

Pharmacology of ANS Norepinephrine and Epinephrine

norepinephrine activates all adrenergic receptors, epinephrine released from adrenal gland actives all adrenergic receptors, drugs that are agents of epinephrine activate adrenergic receptors all over the body

Blood

classified as connective tissue, but a fluid rather than a solid

Functions of Blood

transporting dissolved gases, nutrients, hormones, and metabolic wastes, defending the body against toxins and pathogens, regulating pH and ion composition of interstitial fluids, restricting fluid loss at injury sites, regulating body temperature by absorbing and redistributing heat

Blood Composition

can be fractioned into 2 main components, one of them being plasma

Plasma

approximately 46-63% of blood volume, about 91% of plasma is water, 8% proteins produced by the liver mainly, and 1% other

The Formed Elements Fraction

contains red and white blood cells and cell fragments called platelets, 99.9% of cell fraction are red blood cells

Hemopoiesis (hematopoiesis)

the process of blood cell formation, occurs in the hollow center of a bone (red marrow), in fetal life before bones it occurs mainly in the liver and spleen, with gaining, marrow cavity becomes filled with fat (yellow marrow), hemocytoblasts are are stem cells that divide to form all types of blood cells (pluripotent stem cells)

Red Blood Cells (Erythrocytes)

carry oxygen to cells in the body, account for slightly less than half the blood volume, 99.9% of formed elements

Erythrocyte Production (Erythropoiesis)

red blood cells pass through erythroblasts and reticulocyte stages during which the cell actively produces hemoglobin, process speeds up within the prescience of erythropoietin

Oxygen passes through the membrane of a red blood cell by:

simple diffusion

Erythrocyte Structure

biconcave disc, provides a large surface-to-volume ration to maximize the rate of gas diffusion through the membrane, red blood cels lack organelles meaning they have no nucleus, shapes allows them to stack, bend, and flex

Hemoglobin

account for 95% of protein in red blood cells, a globular protein formed form 2 pairs of protein subunits (2 alpha and 2 beta subunits)

Hemoglobin Structure

each subunit contains 1 molecule of heme, each heme has an iron ion at its center, the iron reversibly binds an oxygen molecule (binds and releases), 1 hemoglobin molecule can bind up to 4 oxygen molecules

Life Span of Erythrocytes

approximately 1% of red blood cells are replaced daily at a rate of about 3 million entering the circulation per second, old/damaged red blood cells are removed form circulation by the spleen before they rupture (hemolyze), components of hemoglobin are individually recycled, global protein fraction is broken down to amino acids which are used to build other proteins, iron is recycled by being stored in phagocytes of transported through the bloodstream on an iron-binding protein

Disorders of the Blood: Jaundice

of the bilirubin formed in red blood cell breakdown, approximately 85% is removed from the blood and processed by the liver, failure of liver to “keep up” with red blood cell breakdown or blockage of the bile duct leads to buildup of bilirubin in blood causing it to diffuse out of the blood and into tissues of in the body giving a yellow color (most seen in sclera of eye and skin)

Disorders of the Blood: Anemia

a decrease in oxygen carrying capacity of blood, signs and symptoms include lethargy, weakness, muscle fatigue, and low energy, three types: iron deficiency, hemorrhage, aplastic

Disorders of the Blood: Sickle Cell Anemia

caused by a mutation of amino sequence of beta chain in hemoglobin, without sufficient oxygen bound to it hemoglobin molecules cluster into rods and force the cell into a stiffened, curved shape causing cells to get stuck in capillaries obstructing blood flow to the tissues which can cause pain and organ damage

White Blood Cells (Leukocytes)

lifespan varies by cell types (hours-years), removes toxins, waste and abnormal/damaged cells, defined the body against pathogens, some are capable of phagocytosis, are capable of amoeboid movement and positive chemotaxis

Diapedesis

white blood cells can leave the bloodstream in response to chemical signals by squeezing through gaps in the vessel wall

Classes of White Blood Cells: Granulocytes

named according to staining properties of cytoplasmic granules

Classes of White Blood Cells: Agranulocytes

lack of cytoplasmic granules

The Complete Blood Count (CBC)

common clinical test, blood test measuring most parameters of blood such as: hematocrit and hemoglobin concentrations, platelet count, white blood cell count, includes counts of relative number of each of the types of white blood cells, providing information relative to type of infection

Origin and Differentiation of Blood Cells

known common stem cells (myeloid vs lymphoid), known as end products not intermediate cells, chemicals that stimulate each type of white cell similar to EPO stimulates production of more red blood cells

Leukemia

cancer of white blood cell lines, immature and abnormal cells enter circulation and invade tissues, highly active stem cells, high energy requirements, may take over bone marrow replacing normal cells

Platelets

fragments of megakarocyte, not cells but flattened discs that are membrane bound sacs of chemicals, circulate for 9-12 days before being removed by phagocytes

Steps in Blood Clotting

1. vascular spasm reduces diameter of vessels

2. positive-feedback loop causing platelet aggregation to block hole in vessel wall

3. enlargement of clot

Coagulation Phase of Blood Clotting

many proteins involved, liver problems give coagulation problems, many clotting disorders due to many possible abnormal proteins, drugs can interfere with this process, final step: thrombin catalyzes conversion of fibrinogen to fibrin threads

Thrombus

blood clot formed by platelets adhering to the blood vessel wall, often at sites of arterial disease

Embolus

a piece of thrombus detaches and travels into the bloodstream, many block blood vessels in another part of the body

Breakdown of Clot: Fibrinolysis

eventual dissolution of clot, an inactive plasma enzyme (plasminogen) is converted to plasmin, plasmin digests fibrin threads of clot and it eventually breaks down

What makes blood move through vessels?

the pressure gradient: blood moves from areas of high to low pressure

Circulation Pattern: Lungs Function

exchange gas between blood and outside air

Circulation Pattern: Heart Function

create the pressure gradient to move blood

Circulation Pattern: Blood Vessels Function

the tubes that cary blood between the heart, lungs, and tissue beds

Systemic Circuit

blood passes to and from most organs through it, arteries carry blood that has high levels of oxygen and low levels of carbon dioxide, blood passes to and from the lungs through the pulmonary circuit

Arteries

carry blood away from the heart

Veins

carry blood toward the heart

Heart: Right Side Pump

deoxygenated blood, receives oxygen depleted carbon dioxide rich blood from the body through superior and inferior vena cava, and pumps it to the lungs through the pulmonary arteries

Heart: Left Side Pump

oxygenated blood, receives newly oxygenated blood rom the lungs via the pulmonary veins and pumps it out to the body through the aorta

Blood Vessels Anatomy

simple squamous epithelium (endothelium) is the innermost layer of every blood vessel, 3-layered wall (tunics)

Blood Vessel Diameter

when smooth muscle layer contracts, the vessel diameters narrows (vasoconstriction), when it relaxes the vessel diamonds increased (vasodilation), effected by sympathetic nerves that innervate blood vessels and the release of norepinephrine

Tunica Intima

innermost layer of blood vessels, lined by endothelium and supported by connective tissues (collagen)

Tunica Anedia

middle layer of blood vessels, smooth muscle with various amounts of elastic fibers

Tunica Externa

outer layer of blood vessels, connective tissue

Arteries have ___________ walls than the vein of the same size, artery generally contain more smooth muscle and often more elastic fibers

stronger, thicker

Capacitance Vessels

have little muscle and few elastic fibers in their wall, they have little ability to resist stretch and often hold much of the circulating blood

Elastic Arteries

the largest arteries closet to the heart contain a lot of elastic fibers and swell with blood each time the heart pumps

Muscular Arteries

small diameter arteries distributing to organs

Resistance Vessels

arterioles are small diameter with a few layers of smooth muscle; contraction or relaxation of that muscle creates great changes in resistance to blood flow

Exchange Vessels

capillaries are the only vessels where materials move through the vessel wall

Distribution of Blood

~60-65% of blood in venous system

~30-35% of blood volume contained in heart, arteries, and capillaries

Lower Body Veins

veins have valves to prevent blood from flowing back up, venous valves are formed form foldings of tunica intimacy, valve flaps move aside when blood flows towards heart and “catches” blood if it tries to flow backward

Back Pressure in Veins

creates dissension in vein walls, may be due to genetic factors or locally high venous pressure

Muscular Pump

skeletal muscle activity around deep veins comprises veins and pushes blood toward the heart

Anatomy of Capillaries

a little more than a tube of endothelial cells supported by basal lamina, the thin wall allows exchange of matters between the bloodstream and the cells in the organ, called exchange vessels

Continuous Capillaries

have complete continuous endothelial lining, are founding all tissues except epithelial and cartilage, permit diffusion of water, small solutes, and lipid-soluble materials, block red blood ells and plasma proteins, specialized capillaries are founding CNS and create the “blood brain barrier”

Fenestrated Capillaries

have small pores (fenestrations) in endothelial lining, permit rapid exchange of water and larger solutes between plasma and interstitial fluid, found in areas requiring more exchange

Sinusodial Capillaries

have large gaps between adjacent endothelial cells, permit free exchange of water and large plasma proteins between blood and interstitial fluid, phagocytic cells monitor blood at sinusoids

Precapillary Sphincters

regulate blood flow through a capillary bed, these sphincters contract acting as a valve to decrease blood low into exchange vessels

Systemic Arteries

single vessel leaving the left side of the heart (aorta), branches of the aorta carry oxygenated blood out to the body, parts include: aortic arch, thoracic aorta, abdominal aorta

Systemic Veins

blood returns to the right side of the heart through 2 large unpaired veins, above diaphragm: blood returns through the superior vena cava, below diaphragm: blood returns through the inferior vena cava

Mediastinum

where the heart lies in the thoracic cavity, between the two lungs

Heart Location

positioned just to the left of the midline, posterior to the sternum and ribs 2-4, the wide base is located superiorly and is attached by large blood vessels, the pointed apex lies inferiorly and rests on the diaphragm

Pericardial Sac

fibrous sac the heart is enclosed in, the outer part is dense connective tissue and doesn’t stretch easily, the inner lining is a moist membrane

Pericardial Cavity

surrounds the heart, formed form a single sheet of moist membrane enclosing a collapse space, no open space in the cavity only a thin layer of fluid that allows the visceral and parietal pericardial layers to slide against one another without friction as the heart fills and empties

Visceral Pericardium

the membrane that adheres to the heart surface

Parietal Pericardium

the outer layer of the pericardial cavity

Pericardial Effusion

caused by infection, inflammation, or a bleed leading to accumulation of fluid within the pericardial cavity that causes compression of the heart, preventing it from adequately filling with blood (cardiac tamponade)

Atrioventricular (AV) Valves

a valve on each side that separates the atrium from the ventricle

Surface Anatomy of the Heart

atria: thin-walled with outer expandable flap (auricle)

apex: most inferior part of left ventricle; the base is the superior end of the heart where great vessels attach

grooves (sulci): separate atria from ventricles, coronal arteries and veins travel in these surface grooves before entering the heart wall

Three Main Arteries to the Heart Wall

right coronary, circumflex, LAD

Circumflex Artery

supplies left atrium, septum, and posterior wall

Right Coronary Artery

supplies right atrium, both ventricles, SA and AV nodes, and posterior wall

Left Anterior Descending (LAD)/Anterior Interventricular Artery

supplies both ventricles anteriorly

Coronary Veins

collect deoxygenated blood from the heart wall and return it to the right atrium, veins travel alongside arteries

Layers of Heart Wall

endocardium: innermost, endothelium supported by connective tissue

myocardium: middle, cardiac muscle

epicardium, outer, connective tissue with fat, coronary vessels and visceral/pericardium