If I Only Had a Brain A Heart. (The Nerve!)
Regions of the Brain Cerebral hemisphere Diencephalon Cerebellum (b) Adult brain Brain stem
Regions of the Brain: Cerebrum Precentral gyrus Frontal lobe Central sulcus Postcentral gyrus Parietal lobe Parieto-occipital sulcus (deep) Lateral sulcus Occipital lobe Cerebral cortex (gray matter) Fissure (a deep sulcus) Gyrus Sulcus Cerebral white matter Temporal lobe Cerebellum Pons Medulla oblongata Spinal cord
Regions of the Brain: Cerebrum Parietal lobe Left cerebral hemisphere Frontal lobe Temporal lobe Occipital lobe Cephalad Caudal Brain stem Cerebellum
Regions of the Cerebrum Primary motor area Premotor area Anterior association area Working memory and judgment Problem solving Language comprehension Central sulcus Primary somatic sensory area Gustatory area (taste) Speech/language (outlined by dashes) Posterior association area Broca s area (motor speech) Olfactory area Visual area Auditory area
Figure 7.14
Longitudinal fissure Lateral ventricle Basal nuclei (basal ganglia) Thalamus Superior Association fibers Commissural fibers (corpus callosum) Corona radiata Fornix Internal capsule Third ventricle Pons Medulla oblongata Projection fibers Figure 7.15
Third ventricle Anterior commissure Hypothalamus Optic chiasma Pituitary gland (a) Mammillary body Pons Medulla oblongata Spinal cord Cerebral hemisphere Corpus callosum Choroid plexus of third ventricle Occipital lobe of cerebral hemisphere Thalamus (encloses third ventricle) Pineal gland (part of epithalamus) Corpora quadrigemina Midbrain Cerebral aqueduct Cerebral peduncle of midbrain Fourth ventricle Choroid plexus Cerebellum Figure 7.16a
Cerebral hemisphere Diencephalon Cerebellum (b) Adult brain Brain stem Figure 7.12b
Cerebral hemisphere Corpus callosum Choroid plexus of third ventricle Occipital lobe of cerebral hemisphere Thalamus (encloses third ventricle) Hypothalamus Pineal gland (part of epithalamus) Corpora quadrigemina Cerebral aqueduct Midbrain Cerebral peduncle of midbrain Fourth ventricle
Radiations to cerebral cortex Visual impulses Reticular formation Ascending general sensory tracts (touch, pain, temperature) Auditory impulses Descending motor projections to spinal cord (b) Figure 7.16b
Thalamus Regions of the Brain: Diencephalon Surrounds the third ventricle The relay station for sensory impulses Transfers impulses to the correct part of the cortex for localization and interpretation
Regions of the Brain: Diencephalon Hypothalamus Under the thalamus Important autonomic nervous system center Helps regulate body temperature Controls water balance Regulates metabolism Houses the limbic center for emotions Regulates the nearby pituitary gland Produces two hormones of its own
Regions of the Brain: Diencephalon Epithalamus Forms the roof of the third ventricle Houses the pineal body (an endocrine gland) Includes the choroid plexus forms cerebrospinal fluid
Regions of the Brain: Brain Stem Attaches to the spinal cord Parts of the brain stem Midbrain Pons Medulla oblongata
Third ventricle Anterior commissure Hypothalamus Optic chiasma Pituitary gland (a) Mammillary body Pons Medulla oblongata Spinal cord Cerebral hemisphere Corpus callosum Choroid plexus of third ventricle Occipital lobe of cerebral hemisphere Thalamus (encloses third ventricle) Pineal gland (part of epithalamus) Corpora quadrigemina Midbrain Cerebral aqueduct Cerebral peduncle of midbrain Fourth ventricle Choroid plexus Cerebellum Figure 7.16a
Regions of the Brain: Brain Stem Midbrain Mostly composed of tracts of nerve fibers Has two bulging fiber tracts cerebral peduncles Has four rounded protrusions corpora quadrigemina Reflex centers for vision and hearing
Regions of the Brain: Brain Stem Pons The bulging center part of the brain stem Mostly composed of fiber tracts Includes nuclei involved in the control of breathing
Regions of the Brain: Brain Stem Medulla oblongata The lowest part of the brain stem Merges into the spinal cord Includes important fiber tracts Contains important control centers Heart rate control Blood pressure regulation Breathing Swallowing Vomiting
Regions of the Brain: Brain Stem Reticular Formation Diffuse mass of gray matter along the brain stem Involved in motor control of visceral organs Reticular activating system (RAS) plays a role in awake/sleep cycles and consciousness
Radiations to cerebral cortex Visual impulses Reticular formation Ascending general sensory tracts (touch, pain, temperature) Auditory impulses Descending motor projections to spinal cord (b) Figure 7.16b
Regions of the Brain: Cerebellum Two hemispheres with convoluted surfaces Provides involuntary coordination of body movements
Third ventricle Anterior commissure Hypothalamus Optic chiasma Pituitary gland (a) Mammillary body Pons Medulla oblongata Spinal cord Cerebral hemisphere Corpus callosum Choroid plexus of third ventricle Occipital lobe of cerebral hemisphere Thalamus (encloses third ventricle) Pineal gland (part of epithalamus) Corpora quadrigemina Midbrain Cerebral aqueduct Cerebral peduncle of midbrain Fourth ventricle Choroid plexus Cerebellum Figure 7.16a
Superior vena cava Right pulmonary artery Right atrium Right pulmonary veins Fossa ovalis Right atrioventricular valve (tricuspid valve) Right ventricle Chordae tendineae Inferior vena cava Aorta Left pulmonary artery Left atrium Left pulmonary veins Pulmonary semilunar valve Left atrioventricular valve (bicuspid valve) Aortic semilunar valve Left ventricle Interventricular septum Myocardium Visceral pericardium (b) Frontal section showing interior chambers and valves. Figure 11.3b
The Heart: Chambers Right and left side act as separate pumps Four chambers Atria Receiving chambers Right atrium Left atrium Ventricles Discharging chambers Right ventricle Left ventricle
Superior vena cava Right pulmonary artery Right atrium Right pulmonary veins Fossa ovalis Right atrioventricular valve (tricuspid valve) Right ventricle Chordae tendineae Inferior vena cava Aorta Left pulmonary artery Left atrium Left pulmonary veins Pulmonary semilunar valve Left atrioventricular valve (bicuspid valve) Aortic semilunar valve Left ventricle Interventricular septum Myocardium Visceral pericardium (b) Frontal section showing interior chambers and valves. Figure 11.3b
Left ventricle Right ventricle Muscular interventricular septum Figure 11.5
The Heart: Valves AV valves Anchored in place by chordae tendineae ( heart strings ) Open during heart relaxation and closed during ventricular contraction Semilunar valves Closed during heart relaxation but open during ventricular contraction Notice these valves operate opposite of one another to force a one-way path of blood through the heart
(a) Operation of the AV valves 1 Blood returning to the atria puts pressure against AV valves; the AV valves are forced open. 2 As the ventricles fill, AV valve flaps hang limply into ventricles. 3 Atria contract, forcing additional blood into ventricles. Ventricles 4 Ventricles contract, forcing blood against AV valve flaps. 5 AV valves close. 6 Chordae tendineae tighten, preventing valve flaps from everting into atria. AV valves open; atrial pressure greater than ventricular pressure AV valves closed; atrial pressure less than ventricular pressure Figure 11.6a, step 6
(b) Operation of the semilunar valves Pulmonary trunk Aorta 1 As ventricles 2 As ventricles contract and relax and intraventricular intraventricular pressure rises, pressure falls, blood is pushed up blood flows against semilunar back from arteries, valves, forcing filling the leaflets them open. of semilunar valves and forcing them to close. Semilunar valves open Semilunar valves closed Figure 11.6b, step 2
Capillary beds of lungs where gas exchange occurs Venae cavae Pulmonary arteries Pulmonary Circuit Pulmonary veins Aorta and branches Left atrium Left Right ventricle atrium Heart Right ventricle Systemic Circuit KEY: Oxygen-rich, CO 2 -poor blood Oxygen-poor, CO 2 -rich blood Capillary beds of all body tissues where gas exchange occurs Figure 11.4
Blood Flow to the Brain
The Circle of Willis
Superior vena cava Sinoatrial (SA) node (pacemaker) Left atrium Atrioventricular (AV) node Right atrium Bundle branches Purkinje fibers Atrioventricular (AV) bundle (bundle of His) Purkinje fibers Interventricular septum Figure 11.7
ECG Electrocariogram Sinoatrial node Atrioventricular node QRS complex R Ventricular depolarization Atrial depolarization P Ventricular repolarization T P-R Interval Q S-T Segment S Q-T Interval 0 0.2 0.4 0.6 0.8 Time (s)
Cardiac Output Stroke Volume x Heart Rate Avg: 70 ml/beat x 72 beats/min = 5020 ml/ min MUST be equal from both chambers Congestive Heart Failure
Homeostatic Imbalances Tachycardia: abnormally fast heart rate (>100 bpm) If persistent, may lead to fibrillation Bradycardia: heart rate slower than 60 bpm May result in grossly inadequate blood circulation May be desirable result of endurance training
The Heart: Regulation of Heart Rate Increased heart rate Sympathetic nervous system Crisis Low blood pressure Hormones Epinephrine Thyroxine Exercise Decreased blood volume
The Heart: Regulation of Heart Rate Decreased heart rate Parasympathetic nervous system High blood pressure or blood volume Decreased venous return
Heart Affects the Brain Oxygen delivery CHF can lead to hypoxia
Brain Affects Heart Cardiovascular centers in medulla oblongata Cardioacceleratory center Cardioinhibitory center
Nerves Carotid sinuses monitor pressure & oxygen Via Glossopharyngeal nerve (CN IX) Medulla integration of pressure & oxygen
Nerves Vagus nerve sends inhibitory impulses Sympathetic nerves send acceleratory impulses
To Make It All Work The heart provides the oxygenated blood to the brain The brain keeps the oxygen flowing by regulating the heart rate & strength of contraction The nerveprovide constant communication between the two organs to survive