DO NOW How does your body communicate with itself? How does your body communicate with itself? What controls your body’s functions? What controls your body’s functions?

The Nervous System

Function Receive sensory input from inside and outside of the body. Receive sensory input from inside and outside of the body. Make sense of this input Make sense of this input Respond to the stimuli Respond to the stimuli

Neurons The neuron (nerve cell) is the smallest unit of the nervous system. The neuron (nerve cell) is the smallest unit of the nervous system. Neurons have three parts: Neurons have three parts: –Dendrite –Cell Body –Axon

Neuron Parts Dendrites receive information from another cell. Dendrites receive information from another cell. The cell body contains the organelles typical of all eukaryotic cells. The cell body contains the organelles typical of all eukaryotic cells. The axon conducts messages away from the cell body. The axon conducts messages away from the cell body.

Types of Neurons Three types of neurons occur. Three types of neurons occur. Sensory neurons carry messages from receptors in skin and muscles to the central nervous system. Sensory neurons carry messages from receptors in skin and muscles to the central nervous system. Motor neurons transmit messages from the central nervous system back to the muscles. Motor neurons transmit messages from the central nervous system back to the muscles. Interneurons are where the sensory neuron connects to the motor neuron. Interneurons are where the sensory neuron connects to the motor neuron.

Synapses The space between nerve cellsis called a synapse. Messages travel here by electricity and special conductor called neurotransmitters. The space between nerve cellsis called a synapse. Messages travel here by electricity and special conductor called neurotransmitters.

There are 2 Parts of the Nervous System The Central Nervous System (CNS) is the brain and spinal cord. The Central Nervous System (CNS) is the brain and spinal cord. The Peripheral Nervous System (PNS) is all nerves outside the CNS. The Peripheral Nervous System (PNS) is all nerves outside the CNS.

The Reflex Arc The reflex arc is an automatic, involuntary reaction to a stimulus. The reflex arc is an automatic, involuntary reaction to a stimulus. When the doctor taps your knee with the rubber hammer, she/he is testing your reflex (or knee-jerk). The reaction to the stimulus is involuntary, with the CNS being informed but not consciously controlling the response. When the doctor taps your knee with the rubber hammer, she/he is testing your reflex (or knee-jerk). The reaction to the stimulus is involuntary, with the CNS being informed but not consciously controlling the response. Examples of reflex arcs include balance, the blinking reflex, and the stretch reflex. Examples of reflex arcs include balance, the blinking reflex, and the stretch reflex.

The Autonomic Nervous System - Part of the PNS The Autonomic Nervous System is that part of PNS consisting of motor neurons that control internal organs. AUTOMATIC The Autonomic Nervous System is that part of PNS consisting of motor neurons that control internal organs. AUTOMATIC The autonomic system controls muscles in the heart, the smooth muscle in internal organs such as the intestine, bladder, and uterus. The autonomic system controls muscles in the heart, the smooth muscle in internal organs such as the intestine, bladder, and uterus.

That was the PNS – now for The Central Nervous System The Central Nervous System (CNS) is composed of the brain and spinal cord. The CNS is surrounded by bone-skull and vertebrae. The Central Nervous System (CNS) is composed of the brain and spinal cord. The CNS is surrounded by bone-skull and vertebrae. Fluid and tissue also insulate the brain and spinal cord. Fluid and tissue also insulate the brain and spinal cord.

The Brain The brain is composed of three parts: the cerebrum (conscious activity), the cerebellum, and the medulla oblongata (these latter two are "part of the unconscious brain"). The brain is composed of three parts: the cerebrum (conscious activity), the cerebellum, and the medulla oblongata (these latter two are "part of the unconscious brain").

The Medulla The medulla oblongata is closest to the spinal cord, and is involved with the regulation of heartbeat, breathing, vasoconstriction (blood pressure), and reflex centers for vomiting, coughing, sneezing, swallowing, and hiccuping. The medulla oblongata is closest to the spinal cord, and is involved with the regulation of heartbeat, breathing, vasoconstriction (blood pressure), and reflex centers for vomiting, coughing, sneezing, swallowing, and hiccuping. Involuntary reactions!!!!!!! Involuntary reactions!!!!!!!

Cerebellum The cerebellum is the second largest part of the brain, after the cerebrum. The cerebellum is the second largest part of the brain, after the cerebrum. It functions for muscle coordination and maintains normal muscle tone and posture. The cerebellum coordinates balance. It functions for muscle coordination and maintains normal muscle tone and posture. The cerebellum coordinates balance.

Cerebrum The cerebrum, the largest part of the human brain, is divided into left and right hemispheres. The cerebrum, the largest part of the human brain, is divided into left and right hemispheres. The hemispheres are covered by a thin layer of gray matter known as the cerebral cortex. The hemispheres are covered by a thin layer of gray matter known as the cerebral cortex.

Cerebrum (con’t) The cerebrum is the center for thought, memory and learning. The cerebrum is the center for thought, memory and learning. It interprets messages from the sense organs and initiates all conscious or voluntary movements. It interprets messages from the sense organs and initiates all conscious or voluntary movements.

What is the Endocrine System For? To secrete hormones and get them to the organs and tissues to which they act upon. To secrete hormones and get them to the organs and tissues to which they act upon.

Endocrine Organs Hypothalamus Hypothalamus Pituitary Pituitary Thyroid Thyroid Parathyroid Parathyroid Adrenals Adrenals Islets of Langerhans Islets of Langerhans Gonads Gonads

The Endocrine Glands

Hypothalamus Influences the activities in the Pituitary Gland. Influences the activities in the Pituitary Gland.

Pituitary Gland Located at base of brain Located at base of brain GSH – Growth Stimulating Hormone GSH – Growth Stimulating Hormone TSH – Thyroid Stimulating Hormone – Secrete Thyroxin from thyroid TSH – Thyroid Stimulating Hormone – Secrete Thyroxin from thyroid FSH – Follicle Stimulating Hormone – development of follicle in ovary and sperm in testes FSH – Follicle Stimulating Hormone – development of follicle in ovary and sperm in testes

Thyroid gland Secretes thyroxin Secretes thyroxin This regulates metabolism in body’s cells This regulates metabolism in body’s cells Essential for normal physical and mental development Essential for normal physical and mental development

Parathyroid gland Secretes parathormone Secretes parathormone Controls calcium metabolism Controls calcium metabolism Required for many different functions Required for many different functions Blood clotting Blood clotting Growth of teeth and bones Growth of teeth and bones

Adrenal glands On top of each kidney On top of each kidney Secretes adrenaline Secretes adrenaline –Increases the blood glucose level –Accelerates heartbeat –Accelerates breathing rate –Released in times of stress and heavy exercise

Islets of Langerhans Found in the pancreas Found in the pancreas Secrete insulin and glucagon which are both hormones Secrete insulin and glucagon which are both hormones Insulin lowers blood sugar level Insulin lowers blood sugar level Glycogen raises blood sugar level Glycogen raises blood sugar level Helps to maintain homeostasis Helps to maintain homeostasis

Gonads Male gonads are the testicles Male gonads are the testicles Female gonads or the ovaries Female gonads or the ovaries Testes secrete testosterone hormone Testes secrete testosterone hormone –Sperm development –Secondary sex characteristics Ovaries secrete estrogen and progesterone hormones Ovaries secrete estrogen and progesterone hormones –Egg production –Secondary sex characteristics

Negative feedback Works like a thermostat Works like a thermostat Secretes or stops production of a certain hormone in order to keep a stable level of hormone in the body Secretes or stops production of a certain hormone in order to keep a stable level of hormone in the body Maintain homeostasis Maintain homeostasis

Disorders of the Endocrine System Goiter Goiter –Enlargement of the thyroid –Caused by a lack of iodine in the diet Diabetes Diabetes –Not enough insulin is it secreted –Blood sugar level is elevated