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Human Biology C9
Human Structure and Function C9
Question | Answer |
---|---|
Cauda equina | The roots of spinal nerves that extend inferiorly from the lumbosacral enlargements and the conus medullaris |
Cerebellum | A part of the brain which is attached to the brain stem posterior to the pons |
Cerebral cortex | The grey matter on the outer surface of the cerebrum |
Cervical | Relating to spinal nerves 1-8 |
Coccygeal | Relating to spinal nerve 31 |
Conus Medullaris | The region on the spinal cord where the spinal cord tapers to a cone-like shape |
Diencephalon | A part of the brain, between the brainstem and cerebrum, which is composed of the thalamus, subthalamus, epithalamus and hypothalamus |
Endocrine | Relating to endocrine glands which secrete hormones into the blood stream |
Endoneurium | A delicate connective tissue layer that surrounds an axon and its myelin sheath |
Epineurium | A dense connective tissue layer that surrounds nerve fascicles |
Fissure | A groove in the brain |
Gyrus | Folds on the cerebrum of the brain |
Hormone | A chemical substance that is secreted by endocrine glands |
Hypothalamus | The most inferior part of the diencephalon |
Lumbar | Relating to spinal nerves 21-25 |
Medulla Oblongata | The most inferior part of the brain stem that is continuous with the spinal cord |
Negative feedback | The response to the original stimulus resulting in a smaller deviation from the set point |
Perineurium | A connective tissue layer that surrounds a group of axons |
Pituitary | The endocrine gland attached to the hypothalamus |
Sacral | Relating to spinal nerves 26-30 |
Sulcus | Grooves on the cerebrum of the brain |
Thalamus | The largest part of the diencephalon |
Thoracic | Relating to spinal nerves 9-20 |
Vertebrae | Bones of the vertebral column which encase the spinal cord |
What kind of tissue would these layers be in a peripheral nerve? | Connective Tissue |
What important property do these plastic (connective tissue) layers give to a real nerve? | Strength and protection |
What is the name of the three layers that surround and protect: 1. axons 2. groups of axons 3. the whole nerve | 1. Endoneurium (inner) 2. Perineurium (middle) 3. Epineurium (outer) |
These layers are found in peripheral nerves but not within the brain and spinal cord? Why do you think these protective layers are not present in neurons in the brain? | The skull, vertebrae and CSF protect the nerves in the brain and spinal cord. The lack of CT layers in the nerves in the brain is functionally important as it allows for increased communication between neurons without CT “getting in the way” |
Identify endoneurium, perineurium and epineurium | Layer: epineurium Surrounds: the whole nerve (binds fascicles together to form a nerve) Layer: perineurium Surrounds: groups of axons (nerve fascicle) Layer: endoneurium Surrounds: each axon and its Schwann cell sheath |
Why are there so many blood vessels around neurons? | There are so many because neurons are very active and require a constant source of glucose and oxygen as well as efficient waste removal |
Region Nerves Vertebrae Cervical Thoracic Lumbar Sacral Coccygeal Total 31 30 | Region Nerves Vertebrae Cervical 8 pairs 7 Thoracic 12 12 Lumbar 5 5 Sacral 5 5 Coccygeal 1 1 (5 fused) Total 31 30 |
Are the spinal nerves motor, sensory or mixed? | Mixed |
State whether motor or sensory information is travelling through each of the following Dorsal (posterior) root = Ventral (anterior) root = | Dorsal (posterior) root = sensory Ventral (anterior) root = motor |
What is the conus medullaris? | The tapered inferior end of the spinal cord. |
Are the spinal cord and the vertebral column the same length? Why or why not? | No. They start off the same but as an individual grows the vertebral bones get bigger but the spinal cord does not. By the time the bones stop growing, the end of the spinal cord is approximately the level of the 2nd lumbar vertebrae. |
Why do you think why it is called the cauda equina‟? | It looks like a horses tail. The cauda equina occurs because the spinal cord is shorter than the vertebral column. |
Function of... Midbrain | Generates reflex movements of the head, eyes and body. Hearing, and maintains muscle tone. Relays motor impulses from cortex to pons and sensory information from the spinal cord to the thalamus |
Function of... Pons | Respiration and sleep control. Relays impulses from left to right cerebellar hemispheres and different parts of the brain to each other. |
Function of... Medulla | Autonomic reflex centre that maintains homeostasis – e.g. cardiovascular and respiratory regulation. Relays motor and sensory info between SC and other parts of brain. |
Why may someone with quite severe damage to their cerebrum still have normal breathing and heart function? | Because these vital function are controlled by the brainstem. The cerebrum may be damaged but the brainstem fully intact and functional. |
Is the diencephalon white or grey matter? | Grey |
List the four structures that make up the diencephalon. | Thalamus, hypothalamus, epithalamus and subthalamus |
What are the functions of the hypothalamus? | 1. Coordination of autonomic reflexes 2. Controls sleep patterns, hunger 3. Regulation of emotions 4. Regulation of food and water intake 5. Influences hormone release from pituitary gland 6. Stimulates sexual development, arousal and behaviour |
What gland is the hypothalamus connected to? | Pituitary gland |
If your hypothalamus was damaged, would homeostasis be disrupted and why? | YES All hypothalamus functions processes would be disturbed in various ways. |
Look at the surface of the cerebellum, is it convoluted like the cerebrum? | Yes, it is highly convoluted, although the convolutions are smaller and tighter than the cerebrum |
What are the functions of the cerebellum? | Control of balance, eye movements, posture, smooth locomotion, proprioceptive information from muscles and joints (informs brain about stretch and tension of muscles and positions of joints) and planning movements |
The cerebellum has an outer layer of grey matter and inner white matter. How is the grey and white matter in the cerebrum and spinal cord organised (are they the same as the cerebellum?) | The cerebrum and cerebellum are the same The spinal cord is opposite with the grey matter internal and white matter external. |
What is grey matter and white matter composed of (think of parts of a neuron)? | White matter = axons, myelin Grey matter = synaptic terminals, glial cells, dendrites, cell bodies. |
What is/are the function/s of each cerebral lobe? Parietal Frontal Occipital Temporal | Parietal Receive and evaluate somatic sensory information Frontal Voluntary motor commands, motivation, aggression, smell, decision making, mood, personality Occipital Vision Temporal Hearing and memory |
Longitudinal fissure What does this fissure divide the brain into? | Left and right hemispheres |
Lateral fissure/sulcus What lobes does this fissure separate? | Temporal from parietal and frontal lobes |
Central sulcus What lobes does this fissure separate? | Frontal and parietal lobe |
Pre-central gyrus In which lobe is this gyrus found? | Frontal |
Post-central gyrus In which lobe is this gyrus found? | Parietal |
On the Anatomage table select Preset 2, slice the brain in a mid-sagittal plane and identify the corpus callosum. What two parts of the brain does this white matter connect? | left and right hemispheres |
In cases of severe epilepsy, the corpus callosum is sometimes severed (corpus callosotomy) to reduce the incidence of grand mal seizures. What will severing the corpus callosum do to the transfer of information between the hemispheres? | It is much harder for the brain to send messages between the hemispheres. Surprisingly this doesn’t seem to have too many negative effects, although speech can be affected. |
Select Preset 3 then slice the brain in a coronal plane and look at a cross section of the brain. Identify the grey and white matter. Is the grey matter mainly on the outside or inside? | Grey matter is on the outer surface of the brain, with some patches also deep in the brain. |
Identify the convolutions on the surface of the brain. What is the significance of these? | The convolutions allow creates more space to fit in more neurons. More brain power! |
Name of lobe: Insula Function: | Name of lobe: Insula Function: Receives and evaluates taste information. Integrates autonomic functions |
Dura mater – Arachnoid mater - Pia mater - | Dura mater – thickest membrane, tough, holds the brain in place in the skull Arachnoid mater - thin, wispy Pia mater - bound tightly to the surface of the brain. |
Use the textbooks provided and list three functions of CSF. | Allows brain to “float” within cranial cavity Protects CNS from blows and other trauma Provides some nutrients to CNS tissue |
What do you think would happen if CSF was not able to drain properly and accumulated in the sub-arachnoid space? | The excess fluid applies pressure to the brain externally, compressing neural tissue and potentially causing brain damage. |
The video refers to hormones as the “wifi” of the body. What does this mean? | Hormones are chemical messengers produced in one part of the body that affect cells in another part of the body. They are an “indirect” mode of communication as compared to the direct communication as seen in the nervous system |
Type of hormone Activity? (e.g. within a cell, cell-cell, regionally, distant) 1 Endocrine 2 Paracrine 3 Autocrine | Type of hormone Activity? (e.g. within a cell, cell-cell, regionally, distant) 1 Endocrine Can affect distant organs with the correct receptors 2 Paracrine Regionally active 3 Autocrine Within a cell, from cell to neighbouring cell |
Why is the pituitary gland often called the “master gland”? | The pituitary gland produces hormones that act on other endocrine glands and controls their hormone production |
Thyroid stimulating hormone (TSH) Hormone produced by anterior pituitary? Organ or cells it acts on it ? Hormones produced by organ? Effects on the body? | Thyroid stimulating hormone (TSH) Thyroid gland T3 and T4 (thryoxine) Control of metabolism, appetite, thermoregulation |
Adrenocorticotropic hormone (ACTH) Hormone produced by anterior pituitary? Organ or cells it acts on it ? Hormones produced by organ? Effects on the body? | Adrenocorticotropic hormone (ACTH) Adrenal cortex cortisol, aldosterone, androgens Cortisol – activates anti-stress and anti-inflammatory pathways Aldosterone – salt balance |
Follicle stimulating and hormone (FSH) and luteinizing hormone (LH) Hormone produced by anterior pituitary? Organ or cells it acts on it ? Hormones produced by organ? Effects on the body? | Follicle stimulating and hormone (FSH) and luteinizing hormone (LH) Testes / ovaries testosterone (men) oestrogen (women) Production of sperm / eggs, secondary sex characteristics |
Growth Hormone Hormone produced by anterior pituitary? Organ or cells it acts on it ? Hormones produced by organ? Effects on the body? | Growth hormone Liver and other target cells in body IGF-1 (liver) Muscle and bone growth |
Prolactin Hormone produced by anterior pituitary? Organ or cells it acts on it ? Hormones produced by organ? Effects on the body? | Prolactin Breast cells - Production of milk |
Tropic: | Tropic: it acts on the liver to produce IGF-1 which then acts on target cells |
Non-tropic: | Non-tropic: GH directly binds to many cell types to stimulate protein synthesis Hormones can also act directly on a target cell to produce an effect. These are called non-tropic hormones. |
A tropic hormone is | A tropic hormone is one that acts on another endocrine gland, which then produces another hormone. |
The anterior pituitary is | The anterior pituitary is the main gland that produces tropic hormones. Because the anterior pituitary produces hormones that influence other endocrine glands, we often call it the master gland |
Most endocrine glands (e.g. gonads, pancreas, adrenal glands) produce | Non-tropic hormones |
Negative Feedback - | Hormone secretion is inhibited by the hormone itself, once blood levels have reached a certain point and there is enough hormone to activate the target cell i.e. it is a self-limiting system. Most hormone levels are regulated by a negative feedback loop. |
Positive Feedback - | Positive feedback Some hormones are regulated by positive feedback, but this is less common. A good example is Oxytocin released by the posterior pituitary. This example is in the Endocrine lecture. (Labour) |
Thyroid Releasing Hormone (TRH), Thyroid Stimulating Hormone (TSH) and T3/T4. Process steps 1 and 2. | 1. Release of TRH is increased in response to stress/hypothermia 2. Increased TRH causes anterior pituitary to secrete TSH, which passes into circulatory system |
Thyroid Releasing Hormone (TRH), Thyroid Stimulating Hormone (TSH) and T3/T4. Process steps 3 and 4. | 3. TSH causes the thyroid to increase release of T3 and T4. 4. T3 and T4 act on target tissues (that have the correct receptors for these hormones) to produce a response |
Thyroid Releasing Hormone (TRH), Thyroid Stimulating Hormone (TSH) and T3/T4. Process step 5. | 5. Increased levels of T3/T4 inhibit the secretion of TRH from the hypothalamus, and TSH from anterior pituitary. So T3/T4 levels will then decrease again. Should more T3 and T4 be required again later, the cycle will start again. |