A&P 2 Unit 1

Central Nervous System

Brain and spinal cord

What are the two divisions of the ANS?

Sympathetic and parasympathetic

Which nerve comprises ~90% of parasympathetic nerve fibers?

Vagus nerve

Where do sympathetic neurons originate?

Thoracic and lumbar (thoracolumbar)

Where do parasympathetic neurons originate?

base of brain and sacral region of spine (craniosacral) (synapse at target organ)

Ganglia

bundle of neurosoma

Where are sympathetic ganglia?

close to spinal cord

Where are parasympathetic ganglia?

Near organs they affect

What is the difference between neurotransmitters and hormones

Neurotransmitters are transmitted via nerve fibers, hormones are transmitted via bloodstream

Sympathetic neurotransmitters

ACh sent from preganglionic fiber (cholinergic)

Norepinephrine sent from postganglionic fiber (adrenergic)

Parasympathetic Neurotransmitter

Ach release from both preganglionic and postganglionic fibers

Dual innervation

Nerve fibers from both parasympathetic and sympathetic

What kind of relationship do the parasympathetic and sympathetic nervous systems have?

Antagonistic

Exocrine glands

-Get something out of your body

-Ducts

-ex. sweat, saliva, digestive enzymes

Endocrine glands

-No ducts

-Secrete into bloodstream

What are the three chemical classes of hormones?

Steroids, monoamines, peptides

The knee jerk reflex (when the quadriceps muscles contract after the patellar tendon is tapped) is directed by the

somatic nervous system

Which sympathetic pathway involves only a preganglionic axon going to the effector?

Adrenal medulla pathway

Motor neurons of the _________blank nervous system contain more rapidly conducting axons.

somatic

In the brain, the _________blank is the integration and command center for autonomic functions.

hypothalamus

Which sympathetic pathway is responsible for activating the esophagus, heart, lungs, and thoracic blood vessels?

postganglionic sympathetic nerve pathway

Steroids

Derived from cholesterol, ex. testosterone, estrogen, cortisol

Monoamines

Made from amino acids, ex. dopamine, epinephrine, norepinephrine, melatonin

Peptides/proteins

made from chains of amino acids, ex. insulin, glucagon, oxytocin

Hormone secretion: Neural stimuli

Nerve signals to endocrine glands—> hormone release, ex.oxytocin

Hormone secretion: Hormonal stimuli

Hormones from one source stimulate release of hormones from another

Hormone secretion: Humoral stimuli

Levels of substances in blood stream stimulate hormone secretion, ex. blood sugar

What are the three things to consider about overall effect of hormones?

Amount, receptors, interactions

Synergistic effect

Multiple hormones act together for greater effect

Permissive effect

One hormone must be present for another to have an effect

Antagonistic effect

Hormones have opposite effects on cell

How many hormones are produced in the hypothalamus?

8 (6 to anterior pituitary, 2 to posterior pituitary)

Gonadotropin hormones

Causes release of another hormone, target gonads (FSH and LH)

What are the two hormones stored in the posterior pituitary?

ADH and OT

What are the two major divisions of the circulatory system and what do they do?

Pulmonary Circuit: carries blood to lungs for gas exchange and back to heart

Systemic circuit: Carries oxygenated blood to all tissues of the body and returns deoxygenated blood to heart

How many chambers are in the heart?

4, right and left atrium, right and left ventricle

Semilunar valves

Control blood flow into major arteries

Order of blood flow through the heart

1. Vane cavae

2. Right atrium

3. Right AV valve

4. Right ventricle

5. pulmonary semilunar valve

6. Pulmonary trunk/artery

7. Pulmonary veins

8. Left atrium

9. Left AV valve

10. Left ventricle

11. aortic semilunar valva

12. aorta

13. body

What are the two types of cells in cardiac muscle?

Cardiomyocytes and pacemaker calls

Cardiomyocytes

99% of cardiac muscle, contractile cells

Pacemaker cells

1%, Generate their own action potentials w/o external stimulus

Sinus rhythm

Normal heartbeat triggered by SA node

pacemaker potential

gradual depolarization

What is an SA node?

Sinoatrial node, the natural pacemaker of the heart that generates electrical impulses to start each heartbeat

Tachycardia

Resting adult heart rate above 100bpm

Bradycardia

Resting adult heart rate less than 60bpm

Intrinsic regulation

Not dependent of neural of hormonal regulation ex. when exercising, blood flowing through the heart more quickly

Extrinsic regulation

Autonomic innervation, cardiac centers in medulla receive info from sensors in different areas of body→ directs response in HR (sympathetic and parasympathetic)

Cardiac output

amount of blood ejected by a ventricle in 1 minute

What is the end diastolic volume of a full ventricle?

130mL

How much does a ventricle expel (stroke volume)

70mL

What is the end systolic volume of a ventricle?

60mL

How much is passively added to a ventricle during atrial diastole?

30mL

How much blood is added to the ventricle by atrial systole?

40mL

Wiggers Diagram

Shows major events of the cardiac cycle and how they occur simultaneously

Cardiac cycle

events that occur from beginning of one heartbeat to the next

Electrical impulses in the heart are initiated by ______ and spread via ______

Sinoatrial nodes, gap junctions

Systole

Contraction

Diastole

Relaxation

Depolariztion

Opening of voltage gated Na+ channels

Repolarization

Closure of Na+ and opening of K+ voltage gated channels

Plateau phase of cardiomyocyte action potential

Sustains contraction for expulsion of blood from heart

Slow Ca² + channels open and Ca²+ enters the cell

pacemaker potential

gradual depolarization

SA Node fires ______

Spontaneously (not due to signals from nervous system)

EKG

Measures action potentials of heart cells

The effect of autonomic fibers on target cells is _________. The effect of somatic fibers on target cells is __________.

Excitatory or inhibitory, always excitatory

Adenohypophysis

Anterior pituitary

Neurohypophysis

Posterior pituitary

What hormones are produced by the hypothalamus?

TRH, CRH, GnRH, GHRH, Somatostatin, Dopamine, Oxytocin, ADH

What hormones are produced in the anterior pituitary?

FSH, LH, AcTH, PRL, GH, TSH